The 100 most-cited articles in Industrial & Engineering Chemistry Research, 2019

Abstract The catalytic performance of Cu/ZnO/Al2O3 (CuZnAl) catalyst for CO2 hydrogenation to methanol was investigated over a period of 720 h time-on-stream, which showed that the space time yield of CH3OH was decreased by 34.5% during the long-term testing. Different characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and N2O adsorption experiments, were applied to study the deactivation reasons. XRD and N2O adsorption experiments indicated that there were no obvious changes in Cu particle size after the CuZnAl catalyst was exposed to reaction atmosphere for 720 h, while agglomeration took place on ZnO particles. XPS results revealed that part of the metallic Cu was oxidized to Cu2+. The CuZnAl catalyst deactivation was proved to be due to the comprehensive effect of Cu oxidation and ZnO species agglomeration during CO2 hydrogenation to methanol.

Defects, which are commonly in metal organic frameworks (MOFs), are closely related to the performance of materials in various applications. Unlike other MOFs where metal ion clusters are usually 4-, 5-, or 6-connected to the organic linkers, one secondary building unit (SBU) of UiO-66 is coordinated by 12 Zr 6 clusters via 12 benzen-1,4-dicarboxlate (BDC) linkers. Therefore, the integrity of the structure can be well maintained after linker or even cluster missing. So far, many methods have been reported on the defect engineering of UiO-66 including adjusting the synthesis conditions (temperature, Zr/linker ratio and choice of Zr precursor), addition of modulators, thermal activation/dehydration, linker modification and metal cation substitution. Various techniques have been used and developed to characterize the existence and concentration of defects, though each technique has its limitations. The formation of defects not only changes the pore structure, but also brings beneficial changes in thermal, electronic, catalytic and adsorbing abilities; thus improved performance can be…

Process monitoring is crucial for maintaining favorable operating conditions and has received considerable attention in previous decades. Currently, a plant-wide process generally consists of multiple operational units and a large number of measured variables. The correlation among the variables and units is complex and results in the imperative but challenging monitoring of such plant-wide processes. With the rapid advancement of industrial sensing techniques, process data with meaningful process information are collected. Data-driven multivariate statistical plant-wide process monitoring (DMSPPM) has become popular. The key idea of DMSPPM is first decomposing a plant-wide process into multiple subprocesses and then establishing a data-driven model for monitoring the process, in which process variable decomposition is important for guaranteeing the monitoring performance. In the current review, we first introduce the basics of multivariate statistical process monitoring and highlight the necessity of designing a distributed monitoring scheme. Then state-of-the-art DMSPPM methods…

ZnO nanoparticles are still a hot area for research even after ample work has been done by researchers across the world. It is a versatile material for doping of different transition metals among other metal oxides. Having a large family of morphological structures, high electron mobility, and n-type carrier defects, it is suitable for a number of applications such as memory devices, spintronics, optoelectronic devices, solar cells, and sensors. Here, we have emphasized a review of the effects of transition metal (TM) doping on the different physical properties of ZnO nanoparticles and their applications. We have gone through some theoretical models which were used by most of the researchers for explaining the variations in physical properties. Explanation of the sensing, photocatalytic, and optoelectronic processes in different classes of devices is briefly described. Lastly, the comparative studies of different devices are also made available for clear understanding.

Significant efforts have been made to fabricate drug-loaded nanoparticles for drug delivery. Nanoprecipitation is a simple and versatile method for making various types of polymer nanoparticles with well-controlled particle size, size distribution, and surface properties. This review presents a critical overview of three different widely used nanoprecipitation techniques, namely, traditional nanoprecipitation in bulk solutions, flash nanoprecipitation, and microfluidic-based nanoprecipitation. The review starts with the comparison of these three different nanoprecipitation methods summarizing their key characteristics, advantages, and disadvantages. Then, different types of nanoparticles synthesized using nanoprecipitation are presented including di-block copolymer nanoparticles and natural polymer nanoparticles. A special focus is placed on comparing different drug-loaded polymer nanoparticles prepared using different nanoprecipitation approaches including their synthesis methods, drug loading, encapsulation efficiency, nanoparticle properties (e.g., size, PDI, etc.), and…

Abstract The major challenges facing oil production during/after secondary recovery include oil entrapment by water and high water mobility. Hence, currently, Enhanced Oil Recovery (EOR) is considered a key solution for increasing oil production upon reaching the tertiary production phase. Unfortunately, EOR still has its drawbacks including the degradation of the chemicals (polymers and surfactants) used under reservoir conditions, large required volumes of chemicals, and their high cost. Nanotechnology is an emerging technology that has profoundly changed the course of different applications in various fields. In petroleum engineering, this modification can be attributed to the nanomaterials’ unique properties including high surface-to-volume ratio, wettability control, and interfacial tension reduction. To this end, the use of nanomaterials to enhance oil recovery is a very attractive, yet challenging task. This mini-review focuses on the recent efforts to explore the effects of various nanomaterial additives on the EOR process as well as the proposed mechanisms.

Surface tension is a key physiochemical property for the application of deep eutectic solvents (DESs) in the field of interface and colloid. However, the surface tension of DESs has not been systematically studied. Here, a comprehensive investigation on the surface tension of 50 typical DESs was carried out. The effect of hydrogen-bonding donors (HBDs) and hydrogen-bonding acceptors (HBAs) on the surface tension was investigated. Furthermore, the surface tension of mixed systems of DESs with other solvents, water, water+salt (e.g., KCl), ethanol, acetone, isopropyl alcohol, and ethyl acetate (EtAc), was studied. It was found that both HBDs and HBAs had a significant influence on the surface tension of DESs. The presence of crystal water in the salt component of DESs would decrease the surface tension of DESs. Besides, the surface tension of DESs increased significantly when the water mole fraction was higher than 0.9, which was well consistent with the tendency of IR spectra. However, the surface tension of DESs decreased continuously with the increase of the mole ratio of other…

Tissue engineering is a derivative of biomedical engineering, which deals with the repair and regeneration of organs or their tissues. Cell-embedded porous polymeric scaffolds unveil proficiency in rectifying the mechanical trauma of skin, bone erosion, and neurodegenerative diseases like spinal cord injury. Archetypically, pristine cell-based biomaterial scaffolds are utilized; however, investigations over time have validated that incorporation of additives such as silver nanoparticles or bioactive glass augments antimicrobial characteristics in conjunction with cell adherence. An ideal scaffold should exhibit ease of processability, biocompatibility, biodegradability, noncytotoxicity, and excellent mechanical property, and these properties can be achieved with biodegradable polymers. Researchers have extensively explored copious advanced as well as conventional fabrication technologies such as electrospinning, 3D and 4D bioprinting, among others, for contouring of porous polymeric scaffolds in tissue-engineering functions like skin, bone, liver, cardiac, and neural tissue…

Energy-efficient metal recovery and separation processes from a mixture of valuable metals are vital to the metallurgy and recycling industries. Oxalate has been identified as a sustainable reagent that can provide both the desired selectivity and efficient leaching capabilities for a variety of mixed metals under mild reaction conditions. The oxalate process has a great potential to replace many of the existing metal recovery processes that use inorganic acids such as sulfuric, hydrochloric, and nitric acids. In this Review, the use of oxalate chemistry in four major metal recovery applications is discussed, namely, spent lithium-ion batteries, spent catalysts, valuable ores, and contaminated and unwanted waste streams. Recycling of critical and precious metals from spent lithium-ion batteries and catalysts has significant economic opportunities. For efficient metals recovery, reaction conditions (e.g., temperature, pH, time, and concentration), metal–oxalate complex formation, oxidation and reduction, and metal precipitation must all be well-understood. This Review provides an…

Carbon capture and utilization (CCU) has attracted increased attention as a means to mitigate and adapt to climate change. CCU technology regards CO 2 as a raw material and reduces CO 2 emissions. However, purity and pressurization requirements in most CCU technologies are high. Flue gas that is emitted from industries and transportation requires advanced purification and pressurization, which limits the development and decreases the feasibility of CCU application. Hence, a new approach to CCU technology without CO 2 purification and pressurization is desirable. This study reviews differences between the CO 2 purity and pressure of waste CO 2 and feedstock CO 2, reviews difficulties of CO 2 purification and pressurization in recent developments of CCU, and provides several promising examples of CCU technologies without CO 2 pressurization and/or purification. Various promising CCU technologies and their future research prospects are discussed. Mineral carbonation and biological conversion appear to be possible solutions as CCU technologies without CO 2 purification and…

Fast pyrolysis of biomass produces bio-oil as a dominant product. However, the yield and composition of bio-oil are governed by numerous pyrolysis reactions which are difficult to understand because of the multiphase decomposition phenomena with convoluted chemistry and transport effects at millisecond time scales. In this work, thin-film pyrolysis experiments of biopolymers present in the biomass (i.e., cellulose (∼50 μm), hemicellulose (using xylan as a model biopolymer, ∼12 μm), and lignin (∼10 μm)) were performed over 200–550 °C, to investigate underlying thermal decomposition reactions, based on the product distribution obtained under reaction-controlled operating conditions. Experimental yields of non-condensable gases, bio-oil, and char at different operating temperatures and in the absence of transport limitations were obtained for each biopolymer. Cellulose- and xylan-derived bio-oil comprised of anhydrosugars, furans, and light oxygenates, in addition to pyrans in cellulosic bio-oil and phenols in xylan-derived bio-oil. Lignin pyrolysis bio-oil contained methoxyphenols,…

Abstract A high pressure semicontinuous batch electrolyzer is used to convert CO2 to formic acid/formate on a tin-based cathode using bipolar membranes (BPMs) and cation exchange membranes (CEMs). The effects of CO2 pressure up to 50 bar, electrolyte concentration, flow rate, cell potential, and the two types of membranes on the current density (CD) and Faraday efficiency (FE) for formic acid/formate are investigated. Increasing the CO2 pressure yields a high FE up to 90% at a cell potential of 3.5 V and a CD of ∼30 mA/cm2. The FE decreases significantly at higher cell potentials and current densities, and lower pressures. Up to 2 wt % formate was produced at a cell potential of 4 V, a CD of ∼100 mA/cm2, and a FE of 65%. The advantages and disadvantages of using BPMs and CEMs in electrochemical cells for CO2 conversion to formic acid/formate are discussed.

Removal of hydrogen sulfide (H 2 S) released from various source processes is crucial because this compound can cause corrosion and environmental damage even at low concentration levels. The porous materials offer a wide variety of chemical architectures with tunable pore size and high surface area that are very promising for the adsorption of H 2 S molecules. This review attempts to comprehensively compile the current studies in the literature on hydrogen sulfide removal in gas purification processes using highly porous materials such as zeolites, carbon materials, activated carbon, porous metal oxides, mesoporous silica, and metal–organic frameworks as highly effective adsorbents. Possible interactions between the H 2 S and active adsorption sites of these materials are also discussed. Surface functionality and porosity play a crucial role in the H 2 S removal performance by virgin or modified porous materials. However, tailoring these materials to obtain high adsorption capacity, good selectivity, and suitable stability and regenerability and to retain structural integrity under…

Abstract We use a high-pressure semicontinuous batch electrochemical reactor with a tin-based cathode to demonstrate that it is possible to efficiently convert CO2 to formic acid (FA) in low-pH (i.e., pH < pKa) electrolyte solutions. The effects of CO2 pressure (up to 50 bar), bipolar membranes, and electrolyte (K2SO4) concentration on the current density (CD) and the Faraday efficiency (FE) of formic acid were investigated. The highest FE (∼80%) of FA was achieved at a pressure of around 50 bar at a cell potential of 3.5 V and a CD of ∼30 mA/cm2. To suppress the hydrogen evolution reaction (HER), the electrochemical reduction of CO2 in aqueous media is typically performed at alkaline conditions. The consequence of this is that products like formic acid, which has a pKa of 3.75, will almost completely dissociate into the formate form. The pH of the electrolyte solution has a strong influence not only on the electrochemical reduction process of CO2 but also on the downstream separation of (dilute) acid products like formic acid. The selection of separation processes depends on the…

Abstract The role of choline chloride in biomass delignification by a deep eutectic solvent (DES) containing lactic acid was investigated. In this study, the influence of choline chloride on pulping of Eucalyptus globulus chips was determined. Pulping experiments were performed at 120 °C for 8 h with a DES to wood ratio of 20:1. Various experiments were performed to study the influence of choline chloride on lignin solubility, cleaving reactions, and mass transfer in order to gain an understanding of the observed pulping results. It was found that the chloride anion is the active component of choline chloride. In fact, the inexpensive salt NaCl performed as well as choline chloride in that respect. Furthermore, choline chloride is already effective in a 1:250 M ratio to lactic acid. Studies on milled wood lignin show that choline chloride increases the cleavage rate of β-O-4 and thereby increases the delignification rate of biomass. Furthermore, choline chloride slightly decreased the solubility of lignin in DESs and due to an increase in viscosity decreased the estimated mass…

Ni supported on calcined ceria nitrate catalyst is highly active and stable for low-temperature CO 2 methanation reaction (CO 2 conversion: 70% at 180 °C, 0.05 bar, and gas hourly space velocity (GHSV) of 14 400 L kg –1 h –1 ). We investigated CO 2 adsorption and CO 2 + H 2 reaction on the surface of Ni/CeO 2 and Ni/CeO 2– x catalysts to examine the structure and strength of adsorbed species using diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). At temperature of 180 °C, weakly adsorbed bridged carbonate was generated on the surface of CeO 2– x support by new active sites of oxygen vacancies created by addition of H 2 . High reducibility of Ni/CeO 2– x catalyst played an important role in increasing low-temperature CO 2 methanation catalytic activity.

In this work, graphene-derived N-enriched porous carbons were synthesized by urea modification and KOH activation of thermally shocked graphene oxide. The prepared sorbents were characterized by various techniques and investigated as potential CO 2 capture materials. The as-prepared sorbents possess high CO 2 adsorption capacity of 2.40 mmol/g (25 °C) and 3.24 mmol/g (0 °C) at 1 bar, which is higher than most graphene-based carbons reported previously. The nitrogen incorporation and narrow microporosity are the two major factors that determine CO 2 uptake for these graphene-derived carbonaceous adsorbents under ambient conditions. The adsorption kinetic data of the optimized sample were well-described by the classical Fick’s diffusion model with a high CO 2 diffusion rate. The fast CO 2 adsorption kinetics can be attributed to the short diffusion paths of this sample, which is composed of thin layers of graphene sheets. Moreover, these graphene-derived sorbents also demonstrate excellent stability and recyclability, high selectivity of CO 2 over N 2, suitable heat of adsorption, and…

Two dimensional nanomaterials have provided immense potential for separation applications to relieve the trade-off relationship between selectivity and permeability. Covalent organic frameworks (COFs) are highly compatible with polymers, which can be used to obtain defect free membranes with high flux and enhanced separation performance. The state-of-the-art COF-based membranes are concluded and discussed in this review based on their preparation method and application domains. The structure of nanochannels within the COF-based membranes, the separation performance, and COF design for accurate molecular sieving were discussed. Developing novel COFs with new linkages and binding blocks and COFs with functional groups greatly broadens its application in membrane separation. Although challenges are still in front that need to be conquered, the rapid development of COF forming technologies and its applications in membrane separation can serve as a valuable platform for future applications of such new types of porous materials. The variation of COFs’ structure and properties can provide…

Abstract Despite the fact that the methanol synthesis process includes industrially some of the most important catalytic chemical reactions, it is still not clear how different gaseous species impact catalyst component structure. With the goal to reduce CO2 emissions through hydrogenation to CH3OH, a higher H2O formation rate than in the production from compressed CO-rich feed should also be considered. It is known that steam accelerates the sintering of metals, several oxide compounds, and their interfaces. To determine the effect of moisture on the Cu/ZnO/Al2O3 catalysts, a commercial catalytic material was systematically aged at various gas compositions and analyzed using transient H2 surface adsorption, N2O pulse efficient chemisorption, X-ray photoelectron spectroscopy, scanning transmission electron microscopy mapping, X-ray powder diffraction, and N2 physisorption, and the mechanisms of deactivation were observed. A strong consistent relation between the compacting of Al2O3, the amount of water in the controlled streamflow, and the activity was found. This connected loss of…

Vitrimer is a new class of polymeric materials which can be reprocessed to any shape while being permanently cross-linked. We designed and synthesized a catalyst-free network with poly(dimethylsiloxane)etherimide (PDMS-NH 2 ), terephthalaldehyde (TA), and tri(2-aminoethyl)amine (TREA) through the condensation reaction between amino groups and aldehyde groups. As a result of the exchange reaction of the dynamic imine bond obtained, this PDMS network exhibits the nature of vitrimer-like material, which is examined by solubility and stress-relaxation experiments, and the relaxation time is as short as 64 s at 130 °C. In addition, the vitrimer-like PDMS is malleable and capable of self-healing, and the mechanical properties can be maintained even after three consecutive breaking/mold pressing cycles. Especially, besides heating, this vitrimer-like PDMS can also be recycled and reshaped at ambient temperature due to the exchange reaction of dynamic imine bond when immersed in water, which will potentially lead to green processing of the elastomers.

Capture and utilization or storage of CO 2 have been considered as the primary options to reduce the impact on the climate caused by CO 2 emissions. Several technological approaches have been proposed depending on the point of actuation (precombustion, postcombustion, or oxyfuel combustion), but absorption processes are still the most extended solution implemented in the industry. Alkanolamines are typical solvents used for CO 2 capture, even though they have a noticeable negative impact on the environment. Amino acids and their salts have been appointed as alternative solvents since their functional group is similar to that of alkanolamines but presenting better properties. In addition, they show very good performance in CO 2 capture. This manuscript reviews the state of the art of the use of amino acids in CO 2 capture and the main technologies involving the application of these solvents.

The separation of the ternary nonideal system ethyl acetate (EtAC)/ethanol (EtOH)/water with multiazeotropes is very important since they are always generated in the production process of n -butanol synthesis from ethanol, which is much more difficult due to the formation of the multiazeotrope and distillation boundary. Herein, a systematic conceptual design, optimization, and control approach for ternary extractive distillation of multiazeotrope mixtures EtAC/EtOH/water is proposed. The procedure involves entrainer screening, conceptual design, global optimization, process evaluation, and a robust control strategy. The optimization results demonstrate that the total annual cost, exergy loss, and carbon dioxide emissions of the proposed triple-column extractive distillation are significantly reduced compared with those of the existing process. Dynamic performances illustrate that the improved dual temperature and feedforward control strategy can well handle the three product purities, while two kinds of disturbances (i.e., feed flow rate and composition) are introduced.

Plasticized poly(vinyl chloride) (PVC) has been extensively utilized globally, with various applications in construction, piping, wiring and cable, installation, flooring, nonfood packing, windows, doors, and more. Phthalates have been the most commonly employed plasticizers for PVC, but some of these plasticizers demonstrate many toxic effects on the environment and human beings, which consequently limits the use of phthalate plasticizers. Growing awareness of the effects of plasticizers on the environment and the depletion of petroleum-based resources has made the development of an alternative biobased plasticizer for PVC formulation necessary. Recently, there has been an increased consciousness of the use of natural resource-based plasticizers instead of phthalates in PVC production, because they are eco-friendly in nature. This review paper covers the utilization of traditional and biobased plasticizers for PVC plasticization, and their effect on environmental, mechanical, and thermal properties has been reported.

Ablative composites are highly endothermic sacrificial thermal protection materials that are indispensable to the aerospace industry. Polymeric ablatives are the most versatile and the largest class of thermal protection materials due to their capability to be to varied hyperthermal environments. Carbon/carbon composites have outstanding mechanical properties at higher temperatures but they are susceptible to oxidation. The oxidation is addressed by matrix modification, application of a coat of ultrahigh temperature ceramics (UHTC), or also by the use of nanostructure-toughened UHTC coatings as discussed in this article. The article presents a comprehensive review of the science and technology of four distinct groups of ablative composites (carbon/carbon, carbon/phenolic, carbon/elastomeric and carbon/ceramic). The selection of the best material formulations for a given environment is ratified by the testing techniques, which have also been reviewed along with a brief discussion on the composites recycling technologies and their environmental and economic impacts.

Technology readiness levels (TRLs) have received increasing recognition throughout academia, industry, and policy-making as a tool for evaluating and communicating a technology’s maturity. Conventional scales are unspecific to technologies as they aim at evaluating and comparing technologies combining different fields. Hence, they present vague descriptions which leave considerable room for interpretation and subjective choices. For the chemical industry, adaptions and specific criteria are needed for more comprehensible TRL ratings. This paper specifies the nine conventional TRLs for the chemical industry as idea, concept, proof of concept, preliminary process development, detailed process development, pilot trials, demonstration and full-scale engineering, commissioning, and production. Adjusted descriptions and additional criteria with detailed indicators are presented, depicting the logical progression of a typical chemical innovation in the phases of applied research, development, and deployment. The specified TRLs facilitate evaluation and communication of a technology’s…

MXenes are two-dimensional metal carbides with promising applications in energy storage and sensors. Guidelines for safe, scalable MXene synthesis are important due to ongoing efforts to scale-up production of these novel nanomaterials. Hazard identification before scale-up will allow for inherently safer designs prior to actual implementation. Here, we investigate hazards associated with MXene production, including MAX phase synthesis from raw materials, etching of the MAX phase to MXene clay, exfoliation to MXene nanosheets, and postprocessing of MXenes with Ti 3 C 2 T x as a model species. The major hazards in MXene synthesis are the potential for dust ignition, runaway reactions, and toxic chemical exposure. Because the synthesis of MXenes is a multistep process, safety guidelines for each step are evaluated, including preventive and mitigating measures, best practices, and emergency procedures and responses. This includes handling of combustible powders, exothermic reactions, and harsh chemical etchants. This study is intended to facilitate safer MXene synthesis across various…

Abstract Multiphase systems and their behaviors/characteristics appear to be crucial in a variety of industries such as the oil and gas sector, pharmaceutical industry, and food industry. In this paper, the mesoscale simulation method is used to predict the interfacial behaviors of the water/oil systems at different temperatures and salt concentrations in the presence of a nonionic surfactant (hexaethylene glycol monododecyl ether). Dissipative particle dynamics (DPD) is employed to model the interfacial properties (e.g., interfacial density and interfacial tension) and structural properties such as the radius of gyration as a function of water/oil ratio, surfactant concentration, temperature, and salinity of oil/surfactant/water mixtures. Molecular dynamics (MD) simulations are carried out to estimate the Flory–Huggins chi parameter by means of temperature-dependent solubility parameter and cohesive energy calculations using Monte Carlo (MC) method, which is then utilized as an input for the DPD approach. The DPD repulsive interaction parameter (aij) is also obtained from the…

The electrocatalytic ammonia oxidation reaction (AOR) to molecular dinitrogen (N 2 ) is an essential component within a sustainable nitrogen cycle. The state-of-the-art Pt nanocatalyst, preferably terminated with (100) facets, suffers from a large overpotential (>0.5 V) and rapid deactivation, the origin of which remains largely unexplained due to the intrinsic complexity of solid-electrolyte interfaces. Within the framework of grand-canonical density functional theory (GC-DFT), we show that on Pt(100) the dehydrogenation of *NH 2 is the potential determining step and that the *OH species, thermodynamically stable at >0.5 V vs RHE while overlooked in previous studies, plays an important role in kinetics by preferential stabilization of *NH via hydrogen bonding. Attributed to such favorable adsorbate–adsorbate interactions, *NH 2 dehydrogenation is thermoneutral at 0.5 V vs RHE forming *NH species that can then dimerize easily at the 4-fold hollow sites, capturing the experimentally observed onset potential. At high operating potentials (>0.63 V vs RHE) where the *NH dehydrogenation…

With the merits of a naturally abundant sodium (Na) resource with similar electrochemical characteristics to that of lithium-ion batteries, Na-based batteries have been widely studied as the next-generation economical and practical energy storage choices. Particularly, the Na metal anode possesses a high theoretical specific capacity of 1166 mAh/g and low electrochemical potential of −2.71 V (vs standard hydrogen electrode), and it is therefore considered as the ultimate anode material for Na-based batteries. Nevertheless, the commercialization of the Na metal anode is still largely hindered by several long-lasting challenges, namely, metallic Na dendrite growth and unstable solid electrolyte interphase (SEI) formation. In this review, we first go over the fundamental mechanisms associated with these challenges. Then, we provide an in-depth discussion on the recent key advancements from the perspectives of liquid electrolyte optimization, artificial SEI fabrication, and solid-state electrolyte implementation. Lastly, we highlight the promising aspects from each strategy for the…

The transient, cyclic nature and flexibility in process design make the optimization of pressure swing adsorption (PSA) computationally intensive. Two hybrid approaches incorporating machine learning methods into optimization routines are described. The first optimization approach uses artificial neural networks as surrogate models for function evaluations. The surrogates are constructed in the course of the initial optimization and utilized for function evaluations in subsequent optimization. In the second optimization approach, important design variables are identified to reduce the high-dimensional search space to a lower dimension based on partial least squares regression. The accuracy, robustness, and reliability of these approaches are demonstrated by considering a complex eight-step PSA process for precombustion CO 2 capture as a case study. The machine learning-based optimization offers ∼10× reduction in computational efforts while achieving the same performance as that of the detailed models.

A series of commercially available (and low-cost) silica gels were amine-grafted under dry conditions using N 1 -(3-trimethoxysilylpropyl)diethylenetriamine (i.e., “triamine”). CO 2 capture performance, pore properties, and amine loading were investigated, and the results showed that the silica gel with the largest pores (150A) was the most suitable for further enhancement. Amine loading needed to be increased in order to further enhance the CO 2 adsorption capacity. The addition of water during the grafting process was implemented on the 150A silica gel. The wet-grafted 150A silica gel exhibited a 2.3 mmol/g adsorption capacity at 75 ° C and 1 bar, which is comparable to the best literature reported values that used similar synthesis methods. The wet-grafted 150A exhibited good cycle stability as well as fast CO 2 uptake rates. The fixed-bed breakthrough capacity for air capture (ambient air with 415 ppm of CO 2 at 25 ° C) under dry (0.773 mmol/g) and wet (1.098 mmol/g) conditions are among the highest CO 2 capacities for air capture. The capacity of the low-surface area silica gel…

This commentary discusses current capabilities of vat photopolymerization, an additive manufacturing (AM) technique also known as VP, with recent advances in the literature, current challenges/limitations, and future outlook in novel materials design. Current trends and recent research advances are broadly discussed covering a spectrum of material classes such as performance, medicine, energy, and active materials in parallel to their importance in diverse technologies. Current challenges and limitations of VP are also discussed in terms of material properties, photodegradation, and material toxicity with directions in future material design to overcome these challenges. This commentary paper is intended to be of broad interest to both chemists and engineers actively involved in the AM field, in terms of future material design and processing for further development of VP-based AM technology.

Correct and timely fault diagnosis is of great importance for enhancing the safety and reliability of modern chemical industrial processes. With the arrival of the big data era, data-driven fault detection and diagnosis (FDD) methods offer enormous potential for complex chemical processes. Deep learning-based data-driven FDD methods, which extract features from raw data using an artificial neural network (ANN), are attracting widespread attention. Among various types of neural networks, recurrent neural network (RNN) performs excellently when dealing with time-series data. However, a regular unidirectional RNN proceeds only in the positive time direction, resulting in insufficient feature extraction and inferior fault diagnosis performance. In this study, a bidirectional RNN (BiRNN) was employed to construct FDD models with sophisticated RNN cells. When applied to the benchmark Tennessee Eastman process, BiRNN-based FDD models exhibited a dramatically impressive performance, demonstrating the effectiveness of implementing BiRNN in chemical process fault diagnosis.

Abstract This review addresses the inconsistencies in interpreting measurements of intrinsic catalyst properties using lab-scale devices. Any experiment must be analyzed in the framework of a model for which the choice and assumptions regarding the necessary parameters must be based on critical reasoning. Physical intuition about the properties of the system is required for both rigorous 3D computational and simplified analytic descriptions. Any divergence between hypothesis and characteristics of the systems affects both the investigation of intrinsic catalytic properties and the later industrial design where parameters are extrapolated outside their obtained operating range. In this work, we make an overview of the underlying physics of photocatalytic reactions, while focusing on pertinent hypothesis, and discuss the consequences for the most basic reactor designs for which guidelines and criteria are provided to meet their premise.

In this paper, using carbonized hazelnut shells as the raw material and sodium amide as both activator and nitridation agent, N-enriched carbonaceous sorbents were successfully made by an one-step reaction at a relatively low temperature range of 500–600 °C. This strategy can effectively solve the corrosion problems caused by KOH activation, and avoid the tedious, time-consuming, and multistep nitriding-activation processes to prepare nitrogen-doped porous carbons. The resultant carbonaceous adsorbents were properly characterized, and their CO 2 adsorption properties were carefully investigated. Excellent CO 2 adsorption abilities, i.e., 4.32 and 6.23 mmol/g at 25 and 0 °C under 1 bar, respectively, were accomplished by these hazelnut-shell-based carbons. It is also found that their CO 2 uptake under the ambient conditions are determined by the comprehensive effects of narrow microporosity, N content, pore size, and pore size distribution of the adsorbents rather than by any single factor. Besides the high CO 2 uptake, these hazelnut-shell-derived carbons also display many other…

Abstract Although the organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) originate from the same urban area and contain similar organic matter, they are collected separately and handled with different technologies. In this work, a combined treatment of OFMSW–SS mixture was investigated at pilot scale, by using a three-step mixed microbial culture (MMC) process in order to produce polyhydroxyalkanoate (PHA) as final high value biobased product. Biomass selection efficiency was quantified by PHA-specific storage rate that was 258 mg CODPHA/g CODXa/h under the optimized process condition. In fed-batch tests, PHA-storing MMC was able to accumulate up to 46 wt % PHA. In the perspective of a full-scale application and taking into account the mass flows in each process step, an overall yield of 65 g PHA/kg TVS was estimated.

Immobilized lipase is a cost-effective biocatalyst for a wide variety of industrial applications, mainly in food, cosmetics, and pharmaceutics due to the huge number of so-called chemically catalyzed reactions of industrial interest that can be replaced by immobilized-enzyme catalysis. In this scenario, there is a growing demand to develop new products, supports, and immobilization protocols, as well as to elucidate the reaction mechanism aiming to cross the barrier imposed by the cost of immobilized lipases. As a large number of researchers have focused their efforts in order to find new applications taking into account new products emerging continuously, it is important to clarify the traditional and alternative process routes using immobilized lipases. In the past decade, almost 5000 research endeavors were reported, and this number continues to rise. This review reports the past 10 years of research work on the techniques used for lipase immobilization proposing a brief introduction about traditional immobilization techniques and an overview of the reactions catalyzed by…

Electromagnetic interference (EMI) shielding materials, entailing the efficient electromagnetic (EM) shielding and high EM wave (EMW) absorption, have become a further requirement for the upcoming 5G communication. Herein, the composite films with a multilayer sandwich structure from cellulose solution in ferric metal–organic frameworks (MOFs) (MIL-88B)-derived magnetic carbon-based materials (C-MIL-88B) and graphene nanoplates (GNPs) are successfully fabricated through a filtration-assisted self-assembly method. The resultant C-MIL-88B/GNP films possess satisfactory saturation magnetization and considerable conductivity with the introduction of Fe 3 O 4 –C. Interestingly, the composite film with five layers (0.12 mm) obtains a reliable EMI shielding effectiveness of 28 dB in the X-band frequency range, while the power coefficient of absorption ( A ) is up to 86%. The improved microwave absorption and attenuation properties of the C-MIL-88B/GNP film are resulted from the synergistic effect of dielectric loss, magnetic loss, and multilayer structure. This work highlights the…

In the development of metal–organic frameworks (MOFs), expansion of pore size and exploration of facile preparation conditions are considered as two major goals that are rarely realized together. This study develops a facile method for the room-temperature synthesis of hierarchically porous MIL-100(Fe) under HF-free conditions using a mixed-ligand strategy by simultaneously introducing p -benzoquinone and terephthalic acid (TPA). The resulting MIL-100(Fe) products exhibited abundant micropores, large mesopores (∼40 nm) and macropores, and high stability, as revealed by N 2 adsorption–desorption isotherms, pore size distributions, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The synthesis mechanism of hierarchically porous MIL-100(Fe) elucidated that the introduced p -benzoquinone accelerated crystallization, while TPA generated crystal defects. The as-synthesized hierarchically porous MIL-100(Fe) acted as adsorbents with significantly improved performance than conventional MOFs and zeolites used for toluene and p -xylene adsorption.…

In industrial processes, soft sensor models are commonly developed to estimate values of quality-relevant variables in real time. In order to take advantage of the correlations between process variables, two convolutional neural network (CNN)-based soft sensor models are developed in this work. By making use of the unique architecture of CNN, the first model is capable of utilizing abundant process data, and the complexity of this model remains low. The second model integrates finite impulse response and CNN, and process dynamics can be reasonably embraced in this model. The effectiveness of the two models is validated by a simulation case and a chemical industrial case. Since the finite impulse response–convolutional neural network (FIR-CNN) can give the best prediction accuracy and the most interpretable trend of a quality-relevant variable, it has promising application potential in the chemical industry.

Electrification of endothermic reactions has the potential to provide a compact and flexible reactor concept, and at the same time, substantially reduce CO 2 emissions relative to combustion-heated processes. Here, we show how integrated electrical heating using a wash-coated catalytic structure can resolve limiting thermal conductivity across the catalyst. The inherent uniform supply of heat enables engineering of catalytic efficiency to desired values by changing wash-coat thickness. Overall, the approach diminishes catalytic efficiency as a limiting design parameter. Instead, coat thickness will relate to catalyst lifetime, as very thin coats are more susceptible to deactivation. Characteristic time-scale analysis indicates heat transfer to be the least limiting mechanism, and reactor performance is instead governed by diffusion. Optimal performance based on fluid dynamic simulations favors internal diameters below 0.5 mm, and high linear gas velocities, toward alleviating mass transfer limitations. Integrated electrical heated steam methane reforming essentially inverts the…

Heavy metals released into the environment could accumulate in living organisms, thus causing various diseases and disorders. Diatomite, an eco-environmental functional material, has been proved to be a very promising and effective adsorbent in heavy metal-contaminated water treatment because of its high porosity, low density, high specific surface area, and surface silanol groups. This review (i) describes the characteristics, advantages, and limitations of diatomite; (ii) presents the capability of heavy metals adsorption onto diatomite-based functional materials; and (iii) discusses main adsorption mechanisms involved (ion-exchange, electrostatic interaction, chelation, and complexation) as well. Future studies about enhancing adsorption capacity and regeneration of diatomite-based functional materials are suggested.

Vitrimers are fascinating thermoset polymers to the industry since they can be recycled and reprocessed without compromising their mechanical strength and solvent resistance. Particularly, transesterification reaction in the epoxy resin (ER) vitrimers usually requires the incorporation of a catalyst, whereas most reports only focused on investigating the catalytic effect of small molecules, such as zinc acetate (Zn(OAc) 2 ) and triazabicyclodecene (TBD). In this work, a polymer catalyst, poly(acrylonitrile- co -zinc methacrylate) (Zn-PAM), was synthesized by the random copolymerization of zinc methacrylate and acrylonitrile, where the transesterification catalysis efficiency of Zn-PAM was systematically investigated and compared to that of Zn(OAc) 2 and TBD by temperature-dependent stress relaxation experiments. It was revealed that Zn-PAM has a higher catalysis efficiency than Zn(OAc) 2 and TBD under the same loading between Zn 2+ and TBD. Besides, only a tiny amount of polymer catalyst is needed to efficiently catalyze the transesterification reaction while in the meantime enhance…

Gas transportation is of significance, especially in carbon dioxide sequestration and successful performances of enhanced methane recovery from shale layers. Among the three primary transportation mechanisms for the gas phase in shale layers, diffusion is considered as the most important phenomenon. The main objective of this comprehensive study is to propose a mathematical model of unipore diffusion and modified unipore diffusion to consider the kinetic adsorption of methane and carbon dioxide for two different shale samples at different pressure ranges. To validate the accuracy of this model, experimental investigations such as methane kinetic adsorption at pressure ranges of 3.2–9.3 MPa and carbon dioxide kinetic adsorption at pressure ranges of 2.5–6.5 were performed to compare with the results of the proposed model. The kinetics adsorption analysis for methane indicated that the required time for the completion of fractional uptake process is about 4–13 min, whereas for the adsorption of carbon dioxide it takes approximately 5–17 min to reach 70% fractional uptake for both…

The present work deals with the preparation of reduced graphene oxide-Fe 3 O 4 (rGO-Fe 3 O 4 ) nanocomposite and its nanofluid by an ultrasound assisted method for convective heat transfer study. Formation of the rGO-Fe 3 O 4 nanocomposite with a uniform distribution of smaller sized (10–20 nm) Fe 3 O 4 nanoparticles on graphene nanosheets was confirmed from UV/vis, transmission electron microscopy, Raman, X-ray diffraction, and X-ray photoelectron spectroscopy analysis. Thermal conductivity of prepared rGO-Fe 3 O 4 nanocomposite based nanofluids with the aid of ultrasound showed an 83.44% enhancement for 0.2 vol % concentration of the rGO-Fe 3 O 4 nanocomposite at 40 °C. Rheological study revealed non-Newtonian behavior of the nanofluids. Various viscosity models were used to predict the behavior of rGO-Fe 3 O 4 nanocomposite based nanofluids. The estimated heat transfer coefficient with the use of 0.02 vol % rGO-Fe 3 O 4 nanofluid at the exit of the test section was 4289.5 W/m 2 ·K for the Reynolds number equal to 7510 ± 5. A new correlation for the estimation of Nusselt number…

Considering the great potential of deep eutectic solvents (DESs) for CO 2 capture, this work studies the CO 2 solubility in DESs by combining experimental measurement and molecular dynamics (MD) simulation. First, four phosphonium - based DESs are prepared in the laboratory, involving two types of hydrogen bond acceptors (HBAs), namely, tetrabutylphosphonium bromide and allyltriphenylphosphonium bromide, and two types of hydrogen bond donors (HBDs), namely, phenol and diethylene glycol. The CO 2 solubility in the obtained DESs is measured under 313.15–333.15 K and pressure below 2000 kPa and compared with those of previously reported DESs and ionic liquids. Second, MD simulations are performed to study the microscopic behaviors of the involved DESs and mixtures. Through the analyses of radial distribution functions, spatial distribution functions, and intermolecular interaction energy, the eutectic formation and CO 2 absorption mechanisms as well as the effect of HBA/HBD type and molar ratio are interpreted.

Polyethylene terephthalate (PET), a chemically stable polyester with multiple applications, has risen dramatically in manufacturing and consumption in the past decades. The increase in PET use has resulted in considerable volumes of waste PET pilling up and thus causing increased health and environmental concerns. Apart from the landfills and incineration solutions, the common waste PET recycling practices mainly focus on low-value downstream products. All the abovementioned factors have contributed to the lower waste PET recycling overall rate of less than 30% in South Africa and created a need for alternative treatment options. Our earlier work has proven the feasibility for converting clear PET bottles into high value-added metal–organic frameworks (MOFs) materials. The feedback from industries indicated that the colorful PET bottles and food trays are currently considered problematic to be recycled economically. In response, this work focuses on the use of various types of PET wastes as sources of benzene dicarboxylic acid (BDC) linker for the synthesis of the zirconium-based…

The hydrocracking of squalane and low density polyethylene (LDPE) into low molecular weight hydrocarbons has been demonstrated with the use of bifunctional zeolite catalysts, Pt-impregnated USY and Beta, with selectivity toward isomers of C 4 –C 6 alkanes. Quantification of liquid and gaseous products via GC-FID and GC-MS demonstrated that appropriate catalyst selection can yield >95% conversion of polymer to fluid products at mild reaction conditions of 330 °C and 20 bar of H 2 and short reaction times of <15 min in a batch system. Zeolite Beta exhibits marked selectivity toward C 4 hydrocarbons, and its efficacy in this reaction is related to its acidic and structural properties. The appropriate selection of reaction time, temperature, and Pt-loading are discussed.

Technical lignins, mostly generated as byproducts from the pulping industry, are highly abundant aromatic sources. However, they are underutilized due to their complexity, as well as structural alteration during chemical pulping processes. In-depth elucidation of technical lignins is becoming essential for their valorization in view of the lack of understanding of technical lignin structures. In this work, alkaline and kraft lignins were prepared and comparatively characterized by 2D HSQC NMR. By applying authenticated reference compounds, the phenylglycerol structures, characteristic of the cleavage of nonphenolic β-aryl ether by soda pulping, in the alkaline lignin were identified and quantified by 2D HSQC NMR. Phenylglycerol structures in alkaline lignin were estimated to be 8–14%, which was much higher than that in kraft lignin. This finding was supported by the results from model studies; i.e., the yield of the phenylglycerol product was 40% that obtained from the soda pulping treatment of a nonphenolic β-aryl ether compound while the yield of that from kraft treatment was…

Metal–organic frameworks (MOFs) have received special attention from scientists owing to their excellent adsorption performance. However, the difficulty in separating MOFs from adsorbed metals following use has limited their application. A zeolitic imidazole-based MOF with broad applicability for sorption of Pb(II) is examined. In this work, a novel adsorbent employing ZIF-8/calcium alginate microparticles was prepared using sodium alginate and ZIF-8. This adsorbent was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The performance of the ZIF-8@CA microparticles in adsorbing Pb(II) from a Pb(II) solution was investigated, and the impacts of the initial Pb(II) concentration, reaction time, pH, and reaction temperature on the reaction process were investigated. The results showed that ZIF-8@CA microparticles exhibited a maximum adsorption capacity of 1321.21 mg/g at pH 5 after 120 min, and the adsorption process was found to fit the Langmuir isotherm model ( R 2 = 0.9856) and…

A bench-scale direct air capture process is reported, based on CO2 absorption with aqueous amino acids and carbonate crystallization with a guanidine compound.

Abstract This work reviews research activities in the development of phase-change CO2 capture solvents and processes. The focus is on liquid–liquid phase-change solvents in which the CO2-lean phase can be recycled to the absorber prior to regeneration hence the energy demands may be substantially decreased compared to nonphase change processes. The review briefly provides the basic chemical and physical principles required to understand the phase-change behavior in postcombustion CO2 capture systems. The reviewed work is further organized per different solvent type into major sections including experimental property measurement studies, experimental pilot plant studies, thermodynamic and kinetic modeling studies, as well as process modeling and technoeconomic assessment studies. In all sections we provide details regarding experimental approaches, operating conditions of pilot plants, implementations in different industries, and performance data. Key findings include operating observations and performance indicators regarding the investigated solvents and processes as well as a…

Abstract Numerous research studies have recently demonstrated a huge physical potential of the cascade companies’ utilization of the renewable waste ligno-cellulosic biomass sources by the fractionation, de-polymerization and valorization of cellulose, hemicellulose, and lignin, separation, and subsequent catalytic conversion of the monomeric building blocks to biofuels, bio-based chemical substances and biomaterials. 5-Hydroxymethylfurfural (5-HMF), levulinic acid (LA) precursors, and furfural (FUR) are, in most characteristic platform compound compositions, produced by the water-mediated acidic hydrolysis of furans, pentose, and hexose carbohydrate sugars, which can be hydrogenated, oxidized, or dehydrated. These processes were subjected to surprisingly many systematic modeling applications on various operation scales. However, only a limited representative number of works managed to link any of atomistic- (ab initio density functional theory (DFT)), meso- (kinetic Monte Carlo (KMC), mean-field mechanistic rate micro-kinetics and diffusion) or macroscales (computational fluid…

CO 2 absorption is a key to alleviating the environmental consequences of fossil fuel combustion, which is a major source of global CO 2 emission. Membrane contactors have showcased several competitive advantages in CO 2 absorption over conventional gas–liquid contactors (e.g., packed towers), such as a large mass-transfer area and a safe operation owing to the membranes that physically separate the gas and liquid phases. This Review discusses the state-of-the-art studies related to CO 2 absorption using membrane contactors, with focuses on membrane materials, liquid absorbents, process design, and pilot-scale demonstration of membrane contactor processes. Critical challenges in membrane contactor-based CO 2 absorption processes, such as membrane fouling and pore wetting, are also discussed.

We present a machine learning-based predictive control scheme that integrates an online update of the recurrent neural network (RNN) models to capture process nonlinear dynamics in the presence of model uncertainty. Specifically, an ensemble of the RNN models are initially obtained for the nominal system, for which Lyapunov-based model predictive control (LMPC) is utilized to drive the state to the steady-state, and economic Lyapunov-based MPC (LEMPC) is applied to achieve closed-loop stability and economic optimality simultaneously. Subsequently, an event-trigger mechanism based on the decreasing rate of Lyapunov function and an error-trigger mechanism that relies on prediction errors are developed for an online model update, in which the most recent process data are utilized to derive a new ensemble of RNN models with enhanced prediction accuracy. By incorporating the event and error-triggered online RNN update within real-time machine learning-based LMPC and LEMPC, process dynamic performance is improved in terms of guaranteed closed-loop stability, optimality, and smoothness of…

Covalent organic frameworks (COFs) with atomically precise integration of scaffolds into 2D/3D topologies have shown great promise for separation applications. In this work, a porosity modulation approach was developed for the construction of 2D COFs for efficient volatile iodine adsorption. By rationally turning building blocks, significantly different iodine separation performance was obtained on COFs, where the best COF adsorbent exhibits a high-performance volatile iodine uptake of 4.0 g g –1 at 75 °C and under ambient pressure and full pore access of iodine was achieved. Most importantly, the separation experiments reveal that iodine uptake capacities on COFs are not only determined by their pore volumes but also significantly affected by their intrinsic pore sizes. Both should be regulated simultaneously to work in concert when designing new COFs for the capture of volatile iodine.

Deactivation of Ni/La 2 O 3 –αAl 2 O 3 catalyst in ethanol steam reforming (ESR) was studied in order to establish the optimal conditions for maximizing H 2 production and achieving steady behavior. The ESR reactions were conducted in a fluidized bed reactor under the following operating conditions: 500–650 °C; space-time up to 0.35 g catalyst h/g EtOH; and steam/ethanol (S/E) molar ratio in the feed, 3–9. The features of the deactivated catalysts and the nature and morphology of the coke deposited were analyzed by temperature-programmed oxidation, X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. Catalyst deactivation was solely caused by coke deposition, especially by encapsulating coke, with acetaldehyde, ethylene, and ethanol being the main precursors, whose concentration was high for lower values of space-time. Conversely, the filamentous coke formed from CH 4 and CO (with their highest concentration for intermediate values of space-time) had a much lower impact on deactivation. Owing to the effect of space-time on the extent of reactions leading to the…

Phase-change materials (PCMs) are utilized for thermal energy storage (TES) to bridge the gap between supply and demand of energy. Organic PCMs, similar to paraffins, fatty acids, and polyethylene glycol, are extensively explored, thanks to their high TES capacity (∼5–10 times more than the sensible heat storage of water/rock), wide temperature range (spanning from −5 °C to 190 °C), good thermal stability over heating–cooling cycles (∼100 cycles), etc. However, “leakage” of PCMs upon transformation from solid to liquid has limited their usage as TES materials; thus, PCMs are confined to a biopolymeric framework for circumventing seepages. However, extensive analysis has concluded that there is a deficiency in availability of consolidated data on biopolymeric-based framework for PCMs. Thus, this review covers various literatures on the application of assorted biopolymers as framework for PCM. Simultaneously, we have also discussed on importance of biopolymers for constructing a framework for PCMs. Finally, the review concludes with future prospects, along with possibilities and…

Aerogels with extraordinary properties have attracted much attention due to their suitability for different technologies. However, the drawbacks of aerogels, such as expensive raw materials and costly preparation methods, have motivated researchers to seek alternative materials. Meanwhile, rapid economic development has driven the generation of massive agricultural, biomass, and industrial wastes. Despite the huge potential of recycling wastes for preparation of various aerogels, related investigations are limited. This study reviews the variety of waste biomasses used for preparation of different types of aerogels and their applications, as well as the technologies used in their preparation. This study will draw the attention of researchers due to the potential of biomass as a sustainable resource for the production of aerogels. Future research challenges and directions for the commercial application of aerogels are presented.

Herein, a series of imidazole derived task-specific deep eutectic solvents (DESs) based on a protic ionic liquid were synthesized and used for CO 2 capture. These DESs exhibited excellent CO 2 absorption capacity up to 1.00 mol CO 2 /mol DES, and the absorption process could be adjusted by the mole ratio of hydrogen-bond acceptor and hydrogen-bond donor. The effect of temperature on the absorption process was also investigated. To deeply investigate the absorption mechanism of these DESs, the corresponding protic ionic liquid was studied and in situ IR analysis was applied for recording the absorption process. With the help of experimental results, NMR spectra analysis, and theoretical calculations, it was found that these DESs captured CO 2 via a synergism of cation and anion, and the protonated superbase played a key role in the absorption process. In addition, the DESs studied in this work showed high thermal stability and excellent recyclability.

Introducing reversible ionic interaction is one of the most effective methods to achieve self-healing behavior in rubbers. However, the strength of the rubbers only containing an ionic cross-linking network is quite limited, and their long-term stability is questionable. In this work, polar epoxidized natural rubbers (ENR) filled with zinc dimethacrylate (ZDMA) were vulcanized with a peroxide cure system to obtain a self-healing material. We controlled vulcanization parameters to inhibit the formation of covalent cross-linking network and constructed a network composed of covalent and ionic cross-linking. In the presence of a slightly covalent cross-linking network, the mobility of rubber chains is almost unlimited, and the composite exhibits high strength and stability. The rearrangement of rubber chains is still prone to occur, which promotes the self-repairing behavior of the rubber and allows the fully cut sample to undergo proper self-healing at ambient temperature.

We demonstrate a novel, innovative photothermal nanofibrous composite membrane for ultraviolet light-driven membrane distillation (UVMD) in which the photothermal nanoparticles, i.e., silver nanoparticles (Ag NPs), are embedded in a porous membrane to capture light (provided by an ultraviolet LED light) without any other heating methods, completing the photothermal transformation at the interface between the surface of the membrane and the water, providing a high-efficiency (53 ± 7%) heating method for the MD process. Here, Ag NPs were incorporated into the hydrophobic polyvinylidene fluoride (PVDF) nanofibrous membranes by an electrospinning technique. The photothermal heating effect on the desalination capability of the PVDF-Ag nanofibrous membrane was investigated by a UVMD module coupled with a 50 W, 400 nm LED light irradiation source. During the 60 h UVMD test period (3.5 wt % NaCl salt feed), membranes with 20 wt % Ag NPs (with respect to PVDF polymer) presented a flux of 2.5 kg/(m 2 ·h) and low permeate conductivity (2.65 μs/cm) with no pore wetting detected. These results…

Carbon capture technologies are expected to play a key role in the global energy system, as it is likely that fossil fuels will continue to be dominant in the world’s energy mix in the near future. Pressure swing adsorption (PSA) is a promising alternative among currently available technologies for carbon capture due to its low energy requirements. Still, the design of the appropriate PSA cycle for a given adsorbent material is a challenge that must be addressed to make PSA commercially competitive for carbon capture applications. In this work, we propose and test a model reduction-based approach that systematically generates low-order representations of rigorous PSA models. These reduced-order models are obtained by training artificial neural networks on data collected from full partial differential algebraic equation (PDAE) model simulations. The main contribution of this paper is the development of surrogate models for every possible step in PSA cycles: pressurization, adsorption, and depressurization steps in cocurrent and counter-current operation. Three different PSA cycles…

Separation in organic mixtures is challenging but inevitable in many chemical and pharmaceutical processes. A membrane-based technique known as organic solvent nanofiltration (OSN) offers a sustainable and reliable solution due to its characteristics of low energy consumption and high efficiency. However, fabrication of a robust membrane that can maintain its separation performance in direct contact with organic solvents for a long period of time is challenging. The most common way to make a polymeric membrane resistant to organic solvents is to cross-link it with a three-dimensional network of polymer chains. However, selection of the right cross-linker for a particular polymer may not be very straightforward. Therefore, in this review, we aim to briefly introduce the common materials used for the fabrication of OSN membranes and demonstrate the state-of-art cross-linking procedures to improve the chemical stability of the membranes. This review may be helpful to researchers when selecting and modifying materials for the development of OSN membranes.

Polyethylene glycol (PEG)-based solid–solid phase change materials (SSPCMs) were first synthesized using PEG and hexamethylene diisocyanate trimer (HDIT) via one-step and solvent-free approach. When HDIT content is 5 wt %, the obtained SSPCM has no leakage at 80 °C which is higher than the melting temperature of PEG, the phase change temperatures, maximum latent heat and relative enthalpy efficiency of the obtained SSPCM are 65 °C, 136.8 J/g and 87.1%, respectively. After 200 thermal cycles, the latent heat remains nearly constant. It proves that the fabricated SSPCMs has good thermal reliability and reusability. At the same time, the SSPCMs own excellent light-thermal conversion performance and good thermal stability in a broad temperature range of applications. All the above results show that the obtained SSPCMs own great potential as direct solar light absorber for solar thermal energy storage.

This work aims to evaluate the benefits of the continuous process in biopharmaceutical manufacturing of monoclonal antibodies (mAbs). An integrated continuous process is designed and built using a process simulator and compared with a fed-batch process production line. The comparisons are based on cost of goods (COG/g) calculation and sensitivity analysis. The fed-batch process results in operating COG/g of $99/g in mAbs production, whereas the continuous process accounts for $51/g. Because of the smaller footprint and fewer storage tanks required in the continuous process, the facility cost reduced by 66%, compared to the fed-batch process. In continuous production, there is a better utilization of the primary capture resin, which leads to a reduction in consumables cost by 68%. Sensitivity analysis is used to evaluate the process in different manufacturing scales (50–1200 kg/yr), upstream titers (1.5–5.5 g/L), and downstream yield (70%–80%). Cost savings can be observed through the entire range.

We report the fabrication of a robust, transparent, and superhydrophobic organic–inorganic composite coating with simple, low-cost, effective, and environmentally friendly characteristics. First, a waterborne polyurethane (WPU) emulsion and silica fluoride (F-SiO 2 ) nanoparticle dispersion were synthesized. Subsequently, the organic–inorganic superhydrophobic surfaces with low surface energy were constructed by spraying, in order, the WPU emulsion and F-SiO 2 nanoparticle dispersion on substrates. The robust composite coating had superhydrophobicity and good optical transparency, in which the WPU provided a strongly adhesive elastic substance for the anchoring of superhydrophobic F-SiO 2 nanoparticles to further construct a mechanically and chemically resilient nanocomposite coating. After 250 cycles of abrasion, a long period of ultraviolet irradiation, and oil-pollution and cross-cut tests, the nanocomposite coating still exhibited excellent properties including good self-cleaning, transparency, abrasion resistance, aging resistance, and strong adhesion. Even after being…

Previously, we 3D-printed polymer-zeolite monoliths by layer-wise phase separation. Importantly, this technique used liquid printing dopes, which exhibit a better rheology than traditional bentonite inks. In this work, we expanded polymer printing to metal–organic frameworks (MOFs) to address their rheological limitations. Initially, MOF-74 and HKUST-1 monoliths, with a composition of 40 wt % MOF and 60 wt % polyamide(imide) (Torlon), were printed. However, only HKUST-1 exhibited full crystalline retention. In contrast, the polymer solvents partially decomposed MOF-74, and the retained crystals were used as growth seeds. This approach produced dense MOF film monoliths with 40 wt % loading. The analysis of CO 2 adsorption capacities revealed CO 2 uptakes proportional to MOF loading for HKUST-1@Torlon monoliths. Moreover, secondary growth led to a 5-fold increase in CO 2 capacity for MOF-74@Torlon. Namely, the isothermal adsorption capacities for the directly printed and secondary growth MOF-74 monoliths were 0.5 and 2.5 mmol/g, respectively, at 25 °C and 1 bar CO 2 . The dynamic…

Indirect Z-scheme assembly of graphene-bridged 2D ZnV 2 O 6 /pCN nanosheets composite has been fabricated by one-step solvothermal process and tested for photoinduced CO 2 conversion under visible-light irradiations. The highest CH 3 OH production of 3488 μmol g-cat –1 was obtained over ZnV 2 O 6 /RGO/g-C 3 N 4 composite, 1.02 and 1.25 times higher comparing to ZnV 2 O 6 /RGO and ZnV 2 O 6 /g-C 3 N 4 samples, respectively. This enhanced efficiency can be ascribed to well-designed ternary heterojunction with hierarchical structure and efficient charges separation by RGO. More importantly, CH 3 OH yield was further improved by introducing RGO/pCN as an electron sink, which led to a 1.07 times higher yield than using only RGO. This reveals that ternary 2D ZnV 2 O 6 /RGO/pCN nanostructure has higher visible-light absorption, improved charge separation, and enhanced photocatalytic efficiency due to RGO/pCN as multiple mediators. The stability of composite catalyst also prevailed for 32 h for continuous CH 3 OH production. Therefore, structured Z-scheme composite with multiple electron…

In the present study, sorption of pharmaceuticals ((acetaminophen (ACP), carbamazepine (CBZ)) and personal care products (bisphenol A (BPA), caffeine (CAFF), triclosan (TCS)) using a graphene oxide (GO)-based composite adsorbent was extensively studied. Structural characterization indicated the incorporation of activated carbon and chitosan onto the GO. For both classes of pollutants, the adsorption kinetics followed a pseudo-second-order kinetic model. On the other hand, the Langmuir isotherm showed a better fit compared to the Freundlich isotherm. Maximum adsorption capacities of ACP, CBZ, BPA, CAFF, and TCS were found to be 13.7, 11.2, 13.2, 14.8, and 14.5 mg/g, respectively. Desorption of ACP, BPA, and CAFF was significantly higher in a polar solvent (70%–80%), whereas CBZ and TCS were able to desorb (60%) in a nonpolar solvent. DFT calculations indicated that the adsorption mechanism is majorly accompanied by size-related diffusion and also a minor contribution by synergetic combination of hydrophobic/hydrophilic, hydrogen bonding, electrostatic, and π–π interactions. Overall,…

The high polysaccharide content of sugar cane bagasse associated with its availability makes it a promising source of fermentable sugars for the production of second-generation ethanol. In this context, the separation the macro components in the cell walls of sugar cane bagasse can be performed by organosolv processes. This research was carried out to study the effect of the solvents on the organosolv delignification of sugar cane bagasse by using Hansen’s solubility parameters. Thus, a new and optimized sphere of solubility for sugar cane bagasse lignin was determined, with δ D = 21.42 MPa 1/2, δ P = 8.57 MPa 1/2, δ H = 21.80 MPa 1/2 and R o = 13.56. It was observed that this new lignin sphere of solubility allowed a linear correlation between the solvent/solute distance and the delignification extent data (linear regression coefficient of 0.93856). These results indicate that the Hansen solubility parameters can be used as a tool for choosing the solvent for an effective delignification of lignocellulosic raw materials.

ZSM-5 zeolites, Ga modified via different methods (in situ hydrothermal synthesis, mechanical mixing, incipient wetness impregnation, solid-state ion exchange, and liquid phase ion exchange), were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), 29 Si, 27 Al, and 71 Ga magic-angle spinning (MAS) NMR, and H 2 temperature-programmed reduction (H 2 -TPR). It is important to prove that both impregnation and liquid phase ion exchange could facilitate the incorporation of Ga species into the framework in addition to in situ hydrothermal synthesis. The liquid phase ion exchange method drove part of the Ga species into the framework, and it was further migrated into the framework by drying, while the incipient wetness impregnation method promoted part of the Ga species into the framework only during the calcination process. In the n -heptane catalytic aromatization procedure on the fixed bed, Ga modified ZSM-5 by in situ hydrothermal synthesis showed the highest benzene, toluene, ethylbenzene and xylene (BTEX) selectivity, owing to the…

According to the World Health Organization, every year 2 billion people worldwide get sick because of unsafe food. For this reason, food preservation from fungi, bacteria, and other contaminants is important to ensure the safety and quality of food to the consumers. Nowaday, there is an increasing demand in the food industry for natural preservatives which are safe. Among these natural compounds with antimicrobial activity, essential oils have aroused considerable interest in the food industry. Unfortunately, essential oils have numerous limitations in their use, mainly due to their hydrophobic property, and therefore they need to be encapsulated before use. The main goal of this specific review is to focus on the encapsulation of essential oils using edible polymers.

This article describes a simple preparation of chitosan/gelatin (CG) spherical hydrogel particles for the effective removal of multiple heavy metal ions. The CG hydrogel particles were prepared by inverse emulsion from the aqueous solutions of chitosan, gelatin, and glutaraldehyde. The oven-dried C2G1 hydrogel particles showed a maximum removal efficiency of 98% for Hg(II) ions in a single metal ion solution and which was higher than C1G1 (85%) and C1G2 (58%) particles. This result was affected by the composition of the hydrogels rather than the pore size or degree of swelling. Remarkably, the removal efficiencies for the Pb(II), Cd(II), Hg(II), and Cr(III) ions reached about 73%–94% in a multiple metal ion solution. The results indicate that the CG hydrogel particles can be used to remove coexisting heavy metal ions from wastewater, providing a versatile method to remove multiple metal ions from natural or industrial wastes.

This article is meant to frame the challenges and opportunities of the methane conversion to methanol via a chemical looping (or redox) process by comparison with the industrial performance criteria. Accordingly, the low methanol productivity and the expected long cycle time result in an overall production rate that falls a factor of ∼50 below the industrial threshold and leads to the prohibitive material cost. With this analysis, we aim to stimulate the diversification of the research directions toward making the process more economically interesting. We also extend this analysis to a variety of the chemical looping processes and conclude that they all fall short of the simple productivity criteria. We therefore recommend researchers pay more attention to improving productivity in these processes.

Traditional solvents are harmful to human health and the environment. Here, we use a green solvent, dimethyl sulfoxide (DMSO), to replace traditional solvents partly as well as improve membrane performance. The amphiphilic copolymer poly(vinyl chloride)- graft -poly(ethylene glycol) methyl ether methacrylate (PVC- g -PEGMA) is blended with PVC to improve the membrane performance. PVC cannot dissolve in DMSO, so based on the Hansen solubility parameter calculation, we investigated the mixture solvents of traditional solvents and DMSO. We found that membranes fabricated by solvent 1-methyl-2-pyrrolidinone (NMP)/ N, N -dimethylacetamide (DMAc)/DMSO = 4/3/3 had the highest pure water flux of 891.54 ± 64.41 L m –2 h –1 bar –1 and the highest sodium alginate (SA) rejection of 94.7 ± 1.3%. Other studies have rarely reported modified PVC membranes with such good performance. This membrane was a successful attempt to use a green solvent in membrane fabrication, meeting the challenges of sustainability in chemical enterprises.

Extractive distillation is a widely accepted and commercialized process for separating azeotropic mixtures compared to conventional distillation. The search for high-performing solvents, or entrainers, needed in extractive distillation is a challenging task. The heuristic guideline or experiment-based method for the screening of entrainers is usually not very efficient and limited to the existing, well-known solvents. In this contribution, we propose a multistage theoretical framework to design solvents for extractive distillation. A multiobjective optimization-based computer-aided molecular design (MOO-CAMD) method is developed and used to find a list of Pareto-optimal solvents. In the MOO-CAMD method, two important solvent properties (i.e., selectivity and capacity) that determine the extractive distillation efficiency are simultaneously optimized. The next step involves a further screening of the Pareto-optimal solvents by performing rigorous thermodynamic calculation and analysis. Finally, for each of the remaining solvents, the extractive distillation process is optimally…

Scientific advancements in the field of high-power transmission and distribution of electrical energy revolutionized the field of high-performance polymer-based electrical insulation systems. Cross-linked polyethylene (XLPE) and its nanocomposites have gained substantial attention in the area of insulation, and these materials play a prodigious role in the arena of cable insulation. This paper includes various strategies for cross-linking PE coupled with different nanofillers to enhance the electrical insulation properties to attain high power transmission. It summarizes the significance of SiO 2 -, alumina-, TiO 2 -, and MgO-based XLPE nanocomposites as potential candidates for insulation in high voltage cables, electrical chips, and transistors and boron nitride-based XLPE nanocomposites for thermal insulation applications. Major challenges in dielectric insulation for cables, like partial discharge, space charge accumulation, water trees, volume resistivity, and DC breakdown strength, are addressed.

Polyurethane (PU)/acrylic hybrid dispersions are an important class of polymeric dispersions that are produced on an industrial scale. In this review, we detail the design and synthesis of PU/acrylic dispersions, with a particular focus on how the structure of the hybrid can be tuned toward commercial applications. After a brief introduction, we describe the building blocks used in each polymer and their role in the synthesis/application of the final dispersion. Subsequently, we discuss the range of procedures that have been developed for the synthesis of such hybrids and how the structure of the hybrids influences the physical properties of films cast from the dispersion. Finally, we highlight commercial applications of PU/acrylic hybrids, with a focus on potential future developments.

Thin-film nanocomposite (TFN) membranes incorporating nanofillers in ultrathin and selective polyamide layers have improved desalination performance in conventional reverse osmosis (RO) membranes. However, further enhancement of RO performance in TFN membranes using only a single nanofiller remains challenging due to difficulties in optimizing permselectivity, dispersibility, and chemical stability. To circumvent this limitation, we prepared hybrids of zeolitic imidazole framework-8 (ZIF-8) and carbon nanotubes (CNTs) to exploit the advantages of both filler phases for the development of high-performance TFN RO membranes. The synthesized ZIF-8/CNT hybrids showed continuous and well-distributed ZIF-8 nanocrystals grown on one-dimensional CNT templates. TFN membranes containing ZIF-8/CNT hybrids outperformed those prepared with a single phase both in RO performance and chlorine stability, attributed to a high aspect ratio and microporosity and the radical scavenging effect of oxygen functional groups in CNT templates. The results demonstrate that MOF/carbon hybrid nanofillers can…

A novel trimethyl-substituted carboxyl-containing polyimide was synthesized via a one-pot high-temperature polycondensation reaction of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,5-diamino-2,4,6-trimethylbenzoic acid (TrMCA). The polyimide (6FDA-TrMCA) displayed a Brunauer–Emmett–Teller surface area of 260 m 2 g –1, demonstrating intrinsic microporosity, in contrast to the related low-free volume COOH-functionalized polyimide 6FDA-DABA. Compared to the nonfunctionalized 6FDA polyimide analogue made from 2,4,6-trimethyl- m -phenylenediamine (TrMPD)—also known as 6FDA-DAM—carboxyl functionalization in 6FDA-TrMCA resulted in reduced surface area, lower fractional free volume, and tighter average chain spacing. Gas permeabilities of 6FDA-TrMCA were typical of functionalized polyimides of intrinsic microporosity (PIM–PIs). For example, at 2 atm and 35 °C, 6FDA-TrMCA showed pure-gas H 2 and CO 2 permeability of 193 and 144 barrer, coupled with H 2 /CH 4 and CO 2 /CH 4 selectivity of 61 and 45, respectively. Notably, in mixed-gas permeation tests with an equimolar CO…

The encapsulation of volatile fragrances within porous materials is capable of increasing their stability for long-term controlled release; however, the introduction of low biocompatible carrier materials also increases safety concerns, thus limiting their applications. Here, we demonstrate the usage of a nontoxic biocompatible porous material, γ-cyclodextrin-based metal–organic framework (γ-CD-MOF), for the effective encapsulation and sustained release of fragrances. Two ester- and two terpene-type fragrances were used as model fragrances for encapsulation. Compared with γ-CD, the γ-CD-MOF nanocrystals showed higher encapsulation capability for the two ester-type fragrances and superior sustained release for all of the tested fragrances. The host–guest hydrophobic and hydrogen-bonding interactions between the fragrant molecules and the γ-CD units/γ-CD-MOFs were studied by Fourier-transform infrared spectroscopy and molecular docking. We find that the release profiles of the two ester-type fragrances are linear and can be fitted well by the zero order model, whereas those for…

Hollow latex (HL) particles of polymers or hybrid polymer/inorganic materials have advantages in efficient encapsulation of active ingredients, ability to improve opacity or hiding power, and low density. Due to the flexible design for achieving the desired functionality, polymeric HL particles serve as stimuli-responsive capsules for drug delivery and cosmetics, white pigment for coatings, as well as nanoreactors for the confined reactions. Among numerous studies on the synthesis of HL particles for specific applications, this review article summarizes the recent works on the HL particles prepared from both synthetic and natural polymers. The template-based methods using sacrificial hard or soft template, self-templating, and nonsacrificial techniques are described. Various factors affecting morphologies and properties of HL particles are discussed in detail. Their applications in coatings, cosmetics, biomedicines, electronics, and others are also presented.

The selectivity of hydrogenation of furfural can be tuned to furfuryl alcohol, cyclopentanone, and cyclopentanol by tuning the reaction conditions with a Cu catalyst. Catalyzed by Cu 0.4 Mg 5.6 Al 2, furfural can be hydrogenated and dehydrated smoothly to furfuryl alcohol, cyclopentanone, and cyclopentanol in high yields, respectively. At 110 °C and under 2.0 MPa H 2 pressure, furfuryl alcohol can be obtained in 99.5% yield. Moreover, the Cu 0.4 Mg 5.6 Al 2 catalyzed hydrogenation of furfural in water gave cyclopentanol in 98.6% yield. Additionally, cyclopentanone can also be obtained in 98.1% yield. The catalyst Cu 0.4 Mg 5.6 Al 2 can be reused several times with only slightly deactivation. Additionally, the hydrogenation of furfural gave well to excellent yield of cyclopentanol in high concentration (15–30 wt % solution of furfural in water), which improved the practicability and efficiency of the process. The hydrogenation of furfural is high efficient, practical and green process of biomass application.

In this article, we have developed a computational model to determine the droplet formation regime and its transition in a square microfluidic flow-focusing device that eventually dictate the droplet shape, size, and its formation frequency. We have methodically explored the influences of various physicochemical parameters on the droplet dynamics and flow regime transition, which are essential in the development of new methods for on-demand droplet generation. On the basis of the droplet formation mechanism, we have formulated flow maps for different liquid–liquid systems, and have also proposed a scaling law to predict the droplet length for a wide range of operating condition resulting from the variation of flow rates, and viscosities of the continuous phase as well as the interfacial tension. This work can effectively contribute in providing helpful guidelines on the design and operations of droplet-based flow-focusing microfluidic systems.

2-Methylfuran production through catalytic transfer hydrogenation (CTH) of furfural in liquid phase has been investigated over CuZnAl catalysts using alcohol as hydrogen donor. Results suggested that furfuryl alcohol was generated immediately and subsequently transformed into 2-methylfuran. The cleavage of C–O(H) was the rate-determining step and positively relied on the copper content. Prereduction of CuZnAl by H 2 provided surface reduced Cu 0 and Cu + species with the preservation of the CuAl 2 O 4 phase. By using the Cu 2.5 Zn–Al-600 catalyst with a Cu/Zn molar ratio of 2.5, we can achieve a 72% 2-methylfuran yield and a specific rate of 7.5 mmol MF /(g Cat. h) under ordinary pressure in N 2 at 180 °C, which is even superior to the reported noble metal catalysts. After six reaction cycles, the catalytic activity remained almost unchanged. The low cost and facile availability of the CuZnAl catalyst make it available for the potential use in industry.

N 2 O formation over Cu-SSZ-13 during selective catalytic reduction (SCR) of NOx with NH 3 under different conditions was experimentally investigated based on a flow reactor and in situ diffused reflectance infrared Fourier transform spectroscopy experiments. The results show that the NSCR and the nonselective NH 3 oxidation are the major pathways for N 2 O formation over Cu-SSZ-13. N 2 O formation at low and high temperatures usually occurs via different mechanisms. The N 2 O formation at low temperatures is mainly ascribed to the decomposition of NH 4 NO 3, which mainly forms on Cu(OH) +, while at high temperatures, N 2 O is formed because of the NH 3 oxidation by O 2 and NOx. Besides, the effect of ANR, NO 2 /NOx ratio, and O 2 and H 2 O concentrations on N 2 O formation were also studied. They all affect N 2 O formation, and the effects on the two mechanisms are totally different at low and high temperatures.

Sustainable textile wastewater treatment strongly demands an indispensable paradigm shift from removal of contaminants to effective recovery of resources. In this work, a hybrid tight ultrafiltration (TUF) and bipolar-membrane electrodialysis (BMED) process was explored to recover resources (i.e., dye extraction, acid/base conversion, and pure water regeneration) from highly saline textile wastewater. Using a TUF membrane with 5000 Da molecular weight cutoff (MWCO) can obtain a sufficient rejection (>99.6%) of both reactive and direct dyes, due to the dye aggregation. Additionally, the considerably large pore size of the TUF membrane endowed the process with free transport of NaCl and Na 2 SO 4 (i.e., >99.42%), exhibiting promise as an alternative means of separation of dyes and Na 2 SO 4 . Additionally, an integrated TUF-based diafiltration was designed to separate the model dye (i.e., reactive blue 194) and Na 2 SO 4 . Particularly, reactive blue 194 was remarkably concentrated from 997.9 to 7952.8 mg·L –1 by the TUF membrane with 99.5% dye recovery and 99.95% desalination…

Mixed matrix membranes (MMMs), which are fabricated by incorporating dispersed fillers into a continuous polymeric matrix, have been broadly utilized in gas separation due to their unique hierarchical structures and enhanced separation performance. Fillers of intrinsic nanopores (FINs) have drawn considerable attention because they not only can provide additional molecular transport channels but also have a potential size-sieving property. Although many excellent reviews about MMMs have been published, quite few of them are specifically designed for MMMs containing FINs. This Review focuses on three kinds of FINs, covalent organic frameworks (COFs), zeolites, and metal–organic frameworks (MOFs), as the representatives of organic, inorganic, and inorganic–organic FINs. The typical physical and chemical features of these three kinds of FINs are introduced. Afterward, methods to prepare FIN-based MMMs are briefly introduced. Particularly, solutions to prevent the aggregation and improve the dispersion of FINs within the polymeric matrix are proposed. Next, this Review will discuss the…

Properties of ionic liquids (ILs) are required for the design of products and processes involving ILs. Although innumerable ILs may be generated through the combination of a variety of cations, anions, and substituents, only a small part of them have been reported to exist (have been synthesized). The available experimental data are generally limited and sometimes even contradictory. A detailed knowledge about the properties of ILs is critically important, especially for ILs not yet available. Based on collected experimental data from numerous literature sources, a series of group contribution models have been developed for estimating various properties (density, heat capacity, viscosity, surface tension, melting point) of ILs. To evaluate the predictive capability of the proposed or employed group contribution models, nearly 70% of the data sets (i.e., training sets) are used for correlation, and then the remaining data sets (i.e., test sets) not included in the training sets are used for prediction. The calculation results show that the proposed group contribution models can…

Over the past several years, selective catalytic reduction of NO x with hydrogen (H 2 -SCR) has been regarded as a promising technology for NO x abatement under lean-burn conditions. In this review, we discuss the recent progress in the development and understanding of H 2 -SCR catalysts. The various mechanisms that have been proposed in the literature are reviewed first. The influence of the catalyst chemical components (noble metals, supports, promoters, and perovskites) and their roles in H 2 -SCR are then analyzed. Non-noble metal catalysts and the new strategy of alloying Pt with transition metals (Ni, Fe, Co, and Cu) are of particular interest and discussed. From a practical viewpoint, the effects of exhaust gas composition on H 2 -SCR is also addressed. Finally, we propose potential opportunities and challenges in the area of H 2 -SCR.

In this work, the main results of a thermodynamic and kinetic study of glycerol ketalization to produce solketal in the presence of a solvent are presented. A catalyst and a solvent screening was carried out leading to the selection of Amberlyst-35 ion-exchange resin and ethanol as the most suitable materials for this reaction. A parametric study allowed one to determine reaction equilibrium and kinetic parameters in a batch reactor in the absence of external mass-transfer limitations. Regarding reaction thermodynamic equilibrium, a standard enthalpy of −20.1 ± 1.1 kJ mol –1 and a Gibbs free energy of 1.4 ± 0.3 kJ mol –1 were obtained. Reaction kinetics was studied assuming different reaction rate laws to fit the experimental data obtained: Pseudo-Homogeneous (PH), Langmuir–Hinshelwood–Hougen–Watson (LHHW), and Eley–Rideal (ER). The experimental results revealed that the reaction kinetics behavior could be accurately described by the LHHW reaction rate law, considering the presence of internal mass-transfer resistances. The activation energy for the overall reaction was found to be…

Over the past few decades, reversible responsive polymer materials have received interest conjointly from academia as well as industry owing to their ability to adapt to the surrounding environment, change adhesion and wettability of copious species upon extraneous stimulus, and regulate transportation of molecules and ions. Stimuli-responsive polymers or macromolecules also exhibit the ability to convert biochemical and chemical signals into mechanical, thermal, optical, and electrical signals, and vice versa, for which they are utilized in an array of applications like “smart” optical systems, drug delivery, diagnostics, and tissue engineering, in conjunction with coatings, textiles, biosensors, and microelectromechanical systems. Extensive exploration on reversible responsive polymeric systems for a variety of engineering functionalities has been done; however, no collection of all the information is available as such. This Review consolidates profuse studies of reversible responsive polymers utilized in an assorted array of functions, inclusive of sensors, drug delivery, smart…

Nowadays persistent perfluorohexanoic acid (PFHxA) ubiquity in the environment is a result of its increasing use as substitute of longer chain perfluorocarboxylic acids. In this study, five nanofiltration (NF270, NF90) and reverse osmosis (XLE, BW30 and SW30XLE) membranes were analyzed in the separation of PFHxA at elevated concentrations (100 mg L –1 ) relevant in industrial effluents of the production of fluorinated polymers. Experiments assessed the influence of the operation pressure, pH, and ionic strength. The NF270 membrane achieved the highest permeate flux, although PFHxA rejection was typically the lowest of all membranes and was negatively affected in the acidic pH range. The NF90, XLE, and BW30 membranes achieved PFHxA observed rejections over 99%, but only NF90 and XLE membranes attained suitable water permeability. Finally, both XLE and NF90 membranes were selected to provide the lowest PFHxA concentration in the permeate (0.2 mg L –1 at 10 bar). However, when the ionic strength was further increased the electrostatic repulsion to perfluorohexanoate was weakened and…

The increasing awareness of the environmental impact of fluorinated gases (F-gases) used in refrigeration is instigating the development of technologies to recover and recycle them. With this goal in mind, single-component absorption equilibrium isotherms at 303.15 K of F-gases in different ionic liquids (ILs) were determined using a gravimetric method. The selected F-gases are the most used in domestic refrigeration (R-32: difluoromethane, R-125: pentafluoroethane, and R-134a: 1,1,1,2-tetrafluoroethane). The results show that ILs containing a fluorinated alkyl side chain with four carbon atoms, that is, fluorinated ILs (FILs), have higher gas absorption capacity than conventional fluoro-containing ILs. All studied ILs showed ideal selectivity toward R-134a. Conventional fluoro-containing ILs showed better selectivities for the separation of the binary mixtures R-134a/R-125 and R-32/R-125, and FILs showed better selectivities for the R-134a/R-32 mixture. These results provide fundamental knowledge of the behavior of these new alternative solvents and key information for their…

A thermoresponsive smart window that can switch its transmittance to control heating from sunlight is attracting great attention. Such windows made from a hydrogel of a thermoresponsive polymer such as poly( N -isopropylacrylamide) (PNIPAm) or hydroxypropyl cellulose (HPC) have been successful and can switch their transmittance at room temperature. However, such hydrogels occasionally freeze in cold places, degrading their transmittance. Thus, a thermoresponsive hydrogel that can be used in various geographical regions is desired. Here, we produced a thermoresponsive smart window with freezing resistance made from HPC and glycerol. We could adjust its switching temperature by simply changing the amount of added glycerol, letting us easily change it to room temperature for practical use. These smart windows show high cyclic performance, freezing resistance, and heat shielding, demonstrating great potential.

In the current study, a new type of composite adsorbent was synthesized by amine modification of binder-containing zeolite 4A bodies and its potential application in the post-combustion CO 2 capture was evaluated. A wide range of aliphatic straight chain amines such as propylamine (PA), butylamine (BA), pentylamine (PEA), and their respective branched chain amines, iso -propylamine (IPA), iso -butylamine (IBA), and iso -pentylamine (IPEA), were used in a smaller fraction to modify binder-containing zeolite 4A bodies. The synthesized materials were characterized by various spectro-analytical techniques to elucidate the effect of amine modification on physicochemical properties of binder-containing zeolite 4A bodies and its reactivity for CO 2 capture. Among all of the studied hybrid adsorbents, the iso -butylamine-modified binder-containing zeolite 4A bodies (IBA-Z4A) exhibited excellent CO 2 adsorption performance with a maximum adsorption capacity of 2.56 mmol g –1 at 25 °C and 1 bar of pressure. Notably, IBA-Z4A also demonstrated excellent purity (98%) and remarkably high CO 2 /N…

The SAFT and cubic models are often compared in the open literature. Usually, limitations and strengths of both types of equations of state (EoSs) are ascribed to their theoretical foundations. Little attention has been paid until now to the influence of parameterization choices on the performance of these EoSs. By parameterization, it is here meant the way or method used to attribute values to EoS component-dependent parameters. SAFT-type and cubic EoSs for pure compounds use two different parameterization methods: SAFT parameters are generally regressed on vapor pressure and liquid density data, whereas cubic models use as input parameters experimental values of the critical temperature, pressure, and acentric factor and are generally parameterized to exactly reproduce these three properties. As a consequence of these parameterization methods, SAFT EoSs overestimate critical pressures, whereas cubic EoSs fail in reproducing accurately liquid density data. To discuss the influence of parameterization methods on EoS performances, three different parameterization methods are…

A carboxy-functionalized covalent organic framework COOH@COF for efficient removal of Pb 2+ and Hg 2+ ions from water has been prepared. Fourier transform infrared spectroscopy, solid-state 13 C NMR spectra, and elemental analysis indicate that the carboxy function has been grafted to COF materials via the click reaction. Its crystallinity remains unchanged after post-synthetic modification, as confirmed by the powder X-ray diffraction. Scanning electron microscopy images reveal that the COOH@COF possesses the thorn ball structure assembled by numerous nanowires with a diameter of 90 nm. This COOH@COF features excellent adsorption capacities for Pb 2+ (123.8) and Hg 2+ (99.1 mg/g) in water. The adsorption isotherms follow the Langmuir model, and their kinetics adsorption fits the pseudo-second-order model. Particularly, the COOH@COF can be recycled 20 times without loss of the adsorption capacity in water, showing its latent potential for practical application in the future.

The process intensification (PI) can significantly improve energy and process efficiency by enhancing mixing, mass, and heat transfer as well as driving forces. There are several benefits of such improvements, which include energy and cost savings, enhanced safety, smaller reactor size, less waste generation, and higher product quality. This review article focuses on the PI, discussion about its dimensions and structure, what it involves, and recent developments in PI which can be achieved using the technique of cavitation. Recommendations for optimum operating parameters needed for process intensification using cavitation phenomena which has been reported in the literature have been presented along with some of our own work in the area. Some experimental case studies have been presented which highlight the degree of intensification achieved when cavitation is used for different physicochemical transformations. These physicochemical transformations include crystallization, emulsification, extraction, wastewater treatment, depolymerization, and water disinfection.