The 50 most-cited articles in Industrial & Engineering Chemistry Research, 2016

Increasing environmental awareness coupled with more stringent regulation standards has triggered various industries to challenge themselves in seeking appropriate wastewater treatment technologies. Coagulation–flocculation process is regarded as one of the most important and widely used treatment processes of industrial wastewaters due to its simplicity and effectiveness. This paper provides a critical review on recent studies of coagulation–flocculation treatment processes of various industrial wastewaters. The limitations and challenges for the coagulation–flocculation process such as the toxicity and health hazard posed by inorganic coagulants, production of large amount of toxic sludge, ineffectiveness in removing heavy metals and emerging contaminants, increase in effluent color, inefficient pollutant removal using natural coagulants, and complexity of scaling up procedure are presented. In addition, an overview on the influence of process parameters on treatment efficiency is included in this review. Finally, this review concludes with recommendations for improvements and new…

In recent years, the progress of efficient green chemistry approaches for the fabrication of commercially viable noble metallic nanoparticles has become a major focus of researchers. The present review has focused on the various plant-mediated nanoparticle fabrication approaches, with brief discussions on the categories of various plant-mediated synthesis approaches and mechanistic aspects of plant-mediated nanoparticle synthesis. The review also focused on the commercial applications of plant-mediated noble metal nanoparticles. Significant remarks on the limitations of plant-mediated fabrication approaches with prospective future direction are also examined.

Abstract Process optimization often has two or more objectives which are conflicting. For such situations, multiobjective optimization (MOO) provides many optimal solutions, which are equally good from the perspective of the given objectives. These solutions, known as Pareto-optimal front and as nondominated solutions, provide deeper insights into the trade-off among the objectives and many choices for implementation. In the past 20 years, researchers have applied MOO to numerous applications in chemical engineering. However, selection of an optimal solution from the set of nondominated solutions has not received much attention in the chemical engineering literature. In the present study, 10 methods for selecting an optimal solution from the Pareto-optimal front are carefully chosen and implemented in an MS Excel-based program. Then, they are applied to the selection of an optimal solution in many benchmark or mathematical problems and chemical engineering applications, and their effectiveness and similarities are analyzed. Results of analysis indicate that, among the 10 methods…

Direct air capture (DAC) removes CO 2 from the atmosphere and can therefore address sizable nonpoint sources emissions of CO 2 such as those from transportation. We propose a five-step temperature vacuum swing adsorption process for direct air capture using solid adsorbents coated as films on monolithic contactors using steam as the stripping agent during desorption. We perform a modeling study and economic assessment for DAC using two metal organic frameworks, MIL-101(Cr)-PEI-800 and mmen-Mg 2 (dobpdc), for which we have experimentally demonstrated film growth on monolith structures. The results indicate minimum energy requirements, and cost estimates are 0.145 MJ/mol-CO 2 and $75–140/t-CO 2 for MIL-101(Cr)-PEI-800, and 0.113 MJ/mol-CO 2 and $60–190/t-CO 2 for mmen-Mg 2 (dobpdc), respectively. The overall DAC cost is sensitive to adsorbent purchase cost and lifetime as well as cycle parameters such as adsorption and desorption times. We conclude that mmen-Mg 2 (dobpdc) has better performance compared to MIL-101(Cr)-PEI-800 in terms of energy requirements because of its higher…

The current work emphasizes the preparation, characterization, recyclability, stability, and mechanistic study of nanosized Fe 3+ -doped TiO 2 photocatalyst. The structural, optical, and photocatalytic properties of undoped and doped TiO 2 were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N 2 absorption–desorption, UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS), Raman and UV–visible spectroscopy. XRD analysis showed that prepared powders with different iron content (200, 100, 50, and 25 molar ratios) consisted of only anatase phase. FTIR study confirmed the chelation of acetate with titanium precursor through the bidentate bridge mode; as a result, the condensation pathways are effectively altered by the acetate ligands favoring the formation of the anatase phase, this result gives further confirmation to the XRD analysis. A decrease in charge carrier recombination rate and the presence of oxygen vacancies and related Ti 3+ centers in the prepared…

Membrane distillation (MD) uses a microporous hydrophobic membrane to separate dissolved molecules from a liquid stream. Notwithstanding the great potential, membrane distillation is not applied on an industrial level yet, because of the lack of specifically developed membranes, modules, and techno-economic data at full scale. This review gives a comprehensive overview of the optimal membrane properties and can serve as a guideline for the development of new membranes, specifically for membrane distillation. Optimization of the membrane is needed to sufficiently resist wetting. Generally, a pore diameter of 0.3 μm is recommended to balance between a high liquid entry pressure and flux. Since vacuum membrane distillation is more sensitive to wetting, a smaller pore diameter could be appropriate for this configuration to avoid membrane wetting. An optimal membrane thickness is found between 10 and 700 μm, depending on process conditions, balancing between mass transport and energy loss. To improve the mass transfer and energy efficiency, membrane porosity should preferably be as high…

Alkali-activated materials (AAMs) have high potential as alternative binder to ordinary portland cement (OPC), because of their high performance beside lower CO 2 emissions. While there is a general consensus about their strength advantages over OPC, there is a widespread debate regarding their durability. Some groups believe that the availability of wide scientific/technical background, together with the already-known OPC durability problems, are sufficient for their commercialization; however, others consider the durability of AAMs to be an unproven issue. This controversy represents one of the limitations facing their bulk applications. The present work provides an overview of the latest developments on durability of fly ash/slag-based AAMs with the aim to update recent findings regarding their behavior under aggressive conditions (sulfates, freeze–thaw, chloride, carbonation, acid, efflorescence). This review will provide a better understanding of the durability issues of AAMs, which will stimulate further research to develop the appropriate testing methods and help to promote…

Oil production from matured crude oil reservoirs is still associated with low recovery factors. Chemical enhanced oil recovery (EOR) is one of the techniques which can significantly improve the recovery factor of the trapped oil. This is mainly achieved by lowering the interfacial tension (IFT) of the crude oil–brine/aqueous chemical and increasing the viscosity of the injected fluid. Nanofluids have demonstrated potential in this respect, and we thus examined how such nanofluids behave when formulated with standard oilfield polymers, with a particular focus on their EOR efficiency. In this work, silica (SiO 2 ) nanofluids with (NSP) or without (NP) surfactant (sodium dodecyl sulfate) added and with varying nanoparticle concentration were formulated with polyacrylamide (PAM) and characterized by DLS and ζ-potential measurements. These nanofluids were then tested in EOR core-flood experiments. Various studies involving the stability and viscosity of nanofluids, interfacial tension of the nanofluid-crude oil system, their effect on wettability alteration, and efficiency for EOR…

The combination of DOPO and 2-aminobenzothiazole (ABZ) was designed to develop P/N/S-containing flame retardant DOPO-ABZ, and its chemical structure was confirmed by HRMS, FTIR, and 1 H and 31 P NMR. The reduced thermal stability of EP/DOPO-ABZ formulations was found through DSC and TGA, as compared to that of EP. Fire properties were evaluated by LOI, UL-94, and cone calorimeter tests, respectively. The results indicated that DOPO-ABZ imparted flame retardance to EP, and that EP/7.5 wt % DOPO-ABZ passed the V-0 rating, and acquired a LOI value of 33.5%; moreover, when the loading of DOPO-ABZ increased to 10 wt %, it could further suppress the heat release and smoke release of the curved epoxy resin. Finally, the flame-retardant mechanism was studied by TG-FTIR and py-GC/MS, disclosing that DOPO-ABZ exerted predominant gaseous-phase activity of fire inhibition via generating phosphorus-containing free radicals and nitrogen/sulfur-containing volatiles.

This study demonstrates fast and efficient removal of dyes from the wastewater using nanostructural MoS 2 as a regenerative adsorbent. The hierarchical microspheres of MoS 2 nanosheets were prepared by a one-step facile and scalable hydrothermal route using polyethylene glycol as a templating material. Chemical and morphological features of hierarchical microspheres of MoS 2 nanosheets were examined by XPS, FTIR, XRD, FESEM, and HRTEM. The adsorption of a series of organic dyes using MoS 2 nanosheets was systematically investigated. The kinetic study illustrated that adsorption of methylene blue dye onto the MoS 2 nanosheets followed the pseudo-second-order model. The adsorption isotherm at the equilibrium was supported by the Freundlich model. The hierarchical microspheres of MoS 2 nanosheets showed adsorption capacity as high as 297, 204, 216, 183, 146 mg g –1 for methylene blue, malachite green, rhodamine 6G, fuchsin acid, and congo red dyes, respectively. The high adsorption capacity was attributed to the hierarchical arrangement of MoS 2 nanosheets in the microscopic spheres,…

Lignocelluloses have been the focus of much attention, because of their conversion to fermentable sugars for cellulosic ethanol production, both from the viewpoint of energy and the environment. Pretreatment plays a crucial rule in biomass conversion, to overcome the chemical and structural difficulties, which have evolved in lignocelluloses, and to produce a cost-effective fermentable sugar via enzymatic saccharification. Among the developed pretreatment approaches, alkali-based pretreatment technology, which can utilize the equipment and chemical recovery system in the pulping industry, has been considered one of the most promising pretreatment methods, mainly because of its high efficiency in delignification and high final total sugar yields. This paper reviews the classification, mechanism, advantages, disadvantages, and the progress of alkali-based pretreatment technologies, in order to better understand the fundamental principles of alkali-based pretreatments. This is of vital importance for the process improvement and commercial production of alkali-based pretreatment for…

In recent years, the prospective recovery of uranium from seawater has become a topic of interest owing to the increasing demand for nuclear fuel worldwide and because of efforts to find sustainable alternatives to terrestrial mining for uranium. To date, the most advanced and promising method of extracting and concentrating uranium from seawater involves the use of polymeric sorbents containing the amidoxime binding moiety. Among a number of different moieties investigated, glutaroimide-dioxime is the most promising one, forming very stable complexes with U(VI) even in the presence of carbonate. To properly assess the affinity of uranium toward the amidoxime substrates, a comprehensive knowledge of the aqueous chemical equilibria of uranium is required. With this aim, in this paper we review the chemical equilibria of uranium (as UO 2 2+ ) in seawater, focusing on the solution equilibria leading to the formation of the stable complexes, M m (UO 2 )(CO 3 ) 3 (2 m –4) (aq) (M = Ca or Mg, m = 0–2). These binary and ternary species dominate the chemistry of uranium in seawater and have…

Because of the effect of nanoscale confinement, the phase behavior of fluids confined in nanopores differs significantly from that observed in a PVT cell. In this paper, the cubic Peng–Robinson equation of state (EOS) is coupled with capillary pressure equation and adsorption theory to investigate and represent the phase equilibria of pure components and their mixtures in cylindrical nanopores. The shift of critical properties is also taken into account. Because of the effect of an adsorption film, an improved Young–Laplace equation is adopted to simulate capillarity instead of the conventional equation. For the adsorption behavior, the experimental data of the adsorbent of silicalite are used to represent the adsorption behavior of hydrocarbons in nanopores. Then a prediction process for the behavior of methane, n -butane, n -pentane, n -hexane and their mixtures are performed. Furthermore, the results are compared against the available experimental data to validate the accuracy of this scheme. An actual Eagle Ford oil is also used to examine the performance of our scheme. Results…

We first used oligomer polyamide resin as carbon source to prepare carbon dots (CDs) that can emit white fluorescence via one step ultrasound at room temperature. We have had a further understanding in the surface morphology and chemical characteristics of the CDs by performing TEM, XPS, XRD, FT-IR, and Raman spectroscopy. It has been found that such carbon dots have good dispersion, low crystallinity, rich surface functional groups, and easy large-scale production. The quantum yield of the white fluorescent CDs was further enhanced from 3.3% to 28.3% by adding a silane coupling agent as a co-passivating agent and conducting ultrasonic treatment. We successfully prepared white-light-emitting diodes using these carbon dots as light conversion materials. To further broaden the applications of white fluorescent carbon dots, we employed the as-prepared CD solution as ink to prepare luminescent patterns, along with favorable versatile effect.

The development of absorbent materials with high selectivity for oils and organic solvents is of great ecological importance for removing pollutants from contaminated water sources. We have developed a facile solution-immersion process for creating polydimethylsiloxane (PDMS)-functionalized sponges for oil–water separation. Sponge materials with densities ranging from 8 to 26 mg/cm 3 were investigated as candidate skeletons. After functionalization, the lowest-density melamine sponge exhibits superior superhydrophobic and superoleophilic properties, absorption capacity, oil–water selectivity, and absorption recyclability. Via suction through such a functionalized sponge, we have experimentally demonstrated that various kinds of oils can be continuously separated from immiscible liquid mixtures without any water uptake. The widely available raw materials (melamine sponge and PDMS solution) and simple synthesis steps yield a cost-effective and scalable process for fabrication of absorbent materials that can be readily adopted for the cleanup of oil spills and industrial chemical…

In this work, the investigation mainly focused on the synergistic effect of phosphorus-containing polyol (BHPP) and nitrogen-containing polyol (MADP) in improving the flame retardancy of EG/rigid polyurethane foam (RPUF). BHPP and MADP were synthesized through dehydrochlorination and Mannich reaction, respectively. The influence of the weight ratio of BHPP and MADP was studied by thermogravimetric analysis and limiting oxygen index (LOI) tests. The results demonstrated that the optimal weight percentage of BHPP and MADP in flame-retarding RPUF was 1/1. In addition, the incorporation of expandable graphite (EG) into the RPUF/BHPP/MADP system could greatly improve the flame-retardant properties of RPUF composites. When the content of EG was 15 wt %, LOI value of RPUF composites reached 33.5%. Furthermore, the value of the peak of the heat release rate was reduced by 52.4% compared to that of pristine RPUF. Based on the analysis and discussion, a condensed flame-retardant mechanism was primarily proposed.

Various type iron oxides of FeO, Fe 2 O 3, and Fe 3 O 4 were used for carbon dioxide (CO 2 ) capture at room temperature and pressure by studying its adsorption–desorption properties. Several interactions of carbonate species were detected on its surface. The morphology of carbonate formation shows different structures on FeO (grooves-like), Fe 2 O 3 (fine sharp particles), and Fe 3 O 4 (aggregated nanoparticles). CO 2 chemisorption discovered a potential adsorbent of Fe 2 O 3 with an adsorption capacity of 3.95 mg CO2 /g adsorbent . The adsorption capacity increased up to 62.8% by using concentrated 99.9% CO 2 for adsorption. At higher concentration of CO 2 exposure, it partially turns to red color which indicated the less stable Fe 3 O 4 was easily oxidized to Fe 2 O 3 after CO 2 regeneration with temperatures up to 500 °C. Hence, Fe 2 O 3 possessed the highest basicity strength (1.26 cm 3 /g), and the adsorption capacity after four cycles was not significantly reduced by 8.6% indicating an effective chemical or physical adsorption in CO 2 capture.

Abstract Spinning of cellulose nanofibrils (CNF) offers promising opportunities to develop renewable fibers and filaments with strong, aligned structure. This review introduces recent findings on the relationship between the properties of CNF hydrogels, the spinning conditions and the performance of filaments obtained by dry- and wet-spinning. For example, the filament Young’s modulus correlates with CNF structural factors, such as slenderness and crystallinity. Furthermore, high shear rates and extensional flow strengthen the filament, mainly by improving structural uniformity and partly by effectively orienting the fibrils. However, other less obvious factors, such as those associated with coagulation and drying, play critical roles in filament performance. These and other details related to this timely application of CNF are presented here for the benefit of researchers and users of fibers and filaments for composites, textiles and others.

Two nickel–aluminum hydrotalcite samples (HTLCs) were prepared by a coprecipitation method at different pH values and investigated as catalysts for the hydrogenation of carbon dioxide. The newly synthesized samples have been compared with a reference alumina supported nickel-based commercial catalyst, with equal nickel content. The as-prepared and commercial samples were characterized by BET analysis, atomic adsorption spectroscopy (AAS), X-ray diffraction (XRD), and temperature-programmed techniques (H 2 -TPR and CO-TPD). Catalytic activity of the analyzed samples was investigated toward hydrogenation of CO 2 at atmospheric pressure by varying reaction temperature between 250 and 400 °C. The maximum CO 2 -to-CH 4 conversion value achieved by hydrotalcyte was ≈86% at 300 °C. The superior performance of HTLCs has been put in relationship with the major catalysts reducibility nature and with the higher metal surface area and metal dispersion. The stability of the HTLCs was investigated through long-term tests, resulting in good stability in the reported reaction conditions.

In this study, three different nanoparticles—SiO 2, TiO 2, and Al 2 O 3 —were employed to enhance the CO 2 gas absorption by monoethanolamine (MEA) solvent. It is observed that, with increased solids loading, the total mass-transfer enhancement has a tendency to be dominated by the bubble breaking effect. It is concluded that nanoparticles result in an increased CO 2 absorption rate of >10%. On the other hand, nanoparticles exhibit much more attractive impact on CO 2 desorption. Under the same desorption extent, solvent with 0.1 wt % TiO 2 nanoparticles saved 42% desorption time, compared to that without nanoparticles. Under higher heat flux density, more input heat would be supplied to the heat of desorption, rather than the heat of water evaporation, which is due to the enhancement of desorption rate by nanoparticles. The issue of particle aggregation was also investigated by analyzing the size distribution of nanoparticle clusters and zeta potential of MEA solvents.

Different samples of graphite oxide (GrO) were prepared by modification of the Improved Hummers Method reported in the literature. Graphite was used as the raw material and KMnO 4 and H 2 SO 4 were used as chemical reagents. GrO samples were analyzed by Raman spectroscopy, SEM, TEM, elemental analysis, X-ray diffraction, N 2 adsorption–desorption, and thermogravimetric analysis. The results indicate that, after optimizing the synthesis method, the oxidation time was reduced from 12 to 3 h, coagulation step was removed, wash step was halved, use of H 3 PO 4 during the oxidation step was no longer necessary, the production of graphite oxide per batch was increased, and the amount of graphite that could be processed was increased five times. Therefore, synthesis costs were significantly lower than those related to the published Improved Hummers Method. An economic assessment for the industrial scale demonstrated that this process could be viable from the third year after its implementation.

The corrosion inhibition properties of 8-hydroxyquinoline (8-HQ) in 0.1 M HCl for copper have been investigated by using experimental (electrochemical impedance spectroscopy (EIS), dynamic electrochemical impedance spectroscopy (DEIS), and potentiodynamic polarization) and theoretical methods complemented by surface morphological examination with the aid of scanning electron microscopy (SEM) and electron dispersive X-ray spectroscopy (EDAX). Results obtained from all of these applied techniques are in agreement and demonstrate that 8-HQ inhibited copper corrosion in 0.1 M HCl solution significantly and the inhibition efficiency varies directly with 8-HQ concentration. Potentiodynamic polarization results show that 8-HQ behaved like a cathodic-type inhibitor in the studied system. EDAX results reveal that 8-HQ is most stable and effective at 10 h of immersion time. Inhibition of Cu corrosion by 8-HQ is due to electrostatic interaction between the Cu surface and salt of 8-HQ according to the Δ G ads 0 value and FTIR results. E HOMO, E LUMO, and Δ E values support the proposed…

We report the large-scale synthesis of porous graphitic carbon nitride (g-C 3 N 4 ) in a direct heat treatment process by controlling the thermal condensation temperature of the low-cost urea precursor. An excellent linear relation between the yield of the urea-derived porous g-C 3 N 4 (U-g-C 3 N 4 ) and the input urea was experimentally demonstrated, and consequently, a large-scale yield >50 g in a batch was readily achieved. A series of morphology and structure characterizations revealed the actual evolutionary process of the temperature-dependent porous architecture of U-g-C 3 N 4 and its inherent superiority. Furthermore, we demonstrated the extraordinary visible-light-driven photodegradation activity of large-scale U-g-C 3 N 4 toward organic pollutants such as rhodamine B, safranine T, and α-naphthol. Such superior photodegradation performance and long-term photocatalytic stability, together with a scalable preparation method, may render as-fabricated U-g-C 3 N 4 as a promising candidate for practical application in environmental remediation.

In situ synthesis of titanium oxide nanoparticles (TiO 2 NPs) on cotton fabrics was innovatively studied. The synthesis involved the use of titanium isopropoxide (TIP) as a source of titanium hydroxide and urea nitrate as a peptizing agent responsible for conversion of titanium hydroxide to TiO 2 NPs. Characterization of TiO 2 NPs was performed using SEM-EDX, XRD, FTIR, TEM, particle size analyzer, and zeta potential. The results obtained signify the following features. TiO 2 NPs are deposited in the form of coating on the surface of cotton fibers. They are composed of aggregated nanoparticles with an average size dimension that does not exceed 50 nm. On the other hand, TiO 2 NPs-loaded cotton fabrics exhibit a bacterial reduction of more than 95%, which is sustainable even after 20 washing cycles; the bacterial reduction increases by increasing the urea nitrate concentration used in the synthesis of TiO 2 NPs. Cotton fabrics coated with TiO 2 NPs display excellent UV protection before and after washing.

Hydroisomerization of long chain n -alkanes has been playing an important role in the petroleum industry, in which heavy distillate and residue are converted into value-added products such as gasoline, jet fuel, other middle distillates and lubricant oils. Herein, 10-ring zeolites, including ZSM-22, ZSM-23, ZSM-35, and ZSM-48 were studied for the process. ZSM-35 and ZSM-48 are relatively less studied zeolites as hydroisomerization reaction catalysts though they are expected to display interesting shape selective properties. A higher conversion was obtained over Pt-ZSM-35 and a higher selectivity was obtained over Pt-ZSM-23 at low temperature and short contact time, and a higher selectivity was obtained over Pt-ZSM-48 at high temperature and long contact time, while the mixed catalysts displayed interesting conversion and selectivity. Small differences in the channel system have a notable influence on the product distribution of hexadecane hydroisomerization over 10-ring zeolites. A combination of the evidence of no absence of multibranched products and the length of hexadecane…

Colloidal silica is used in many applications including catalysis, pharmaceuticals, and coatings. Although naturally formed silica materials are widely available, they are often in forms that are difficult to process or are even harmful to health. Therefore, uniform colloidal silicas are generally manufactured using synthetic chemical processes. While established high temperature gaseous synthesis methods fall out of favor in our energy conscious society, liquid synthesis methods are current industrial leaders. The precipitated silica method provides the majority share of commercially produced specialty silicas with its economic advantages predicted to continue to grow in the future. The biomimetic method and microemulsion methods of synthesis provide a superior level of surface chemistry and morphological control than current industrial processes and are the major focus of current silica synthesis research. Movement toward more tailor-made products and ecologically friendly production methods will likely provide incentive for biomimetic methods, in particular, to take more of a…

It is still a challenging global task for oil/water separation. Here we fabricate superhydrophobic magnetic cellulose sponge (SMCE) that can be used to separate free oil/water mixtures and surfactant-stabilized W/O emulsions. The simple modification includes only two steps: a thin layer of ferroferric oxide (Fe 3 O 4 ) was coated on cellulose sponge surface via codeposition method, and subsequently magnetic cellulose sponge was modified with hexadecyltrimethoxysilane, which could react with Fe 3 O 4 or hydroxyl groups of cellulose. The purpose of coating Fe 3 O 4 is to increase the roughness of the surface and recycle the sample by magnetic force. SMCE could separate oil–water mixtures with a high separation efficiency and good reusability. The sample is green, low cost, and environmental friendly, which makes it a promising candidate to be used in oil–water separation.

Composite oxide supported Ni-based catalysts were prepared by a wet impregnation technique and applied to the methanation of carbon dioxide. The composite oxide supports were prepared by an impregnation–precipitation method using commercial γ-Al 2 O 3 powder as a host with variation of the percentage of loading of ZrO 2, TiO 2, and CeO 2 promoters from their respective salt precursors. NH 4 OH was used as the precipitating agent. The as-prepared catalysts were characterized by Brunauer–Emmet–Teller surface area analysis, atomic absorption spectroscopy, X-ray diffraction, temperature-programmed reduction by H 2 (H 2 -TPR), and CO chemisorption. Catalytic activity of the newly synthesized catalysts was investigated toward hydrogenation of CO 2 at atmospheric pressure by varying reaction temperature between 250 and 400 °C (with increasing step equal to 25 °C). Experimental results revealed that the composite oxide supported Ni-based catalysts showed performance superior to that of the γ-Al 2 O 3 only supported Ni-based catalyst (which was synthesized using the same procedure for…

Functionalized graphene (PGO)/polyaniline (PANI) nanocomposites with effective synergistic reinforcement on anticorrosion have been prepared via an in situ redox polymerization–dedoping technique. PGO nanosheets are obtained through the modification of graphene oxide with p -phenylenediamine to improve the dispersion stability in acidic conditions and compatibility with the polymer. Also, PGO/PANI composites are synthesized via the in situ redox polymerization of aniline. The results show that PGO is highly exfoliated and intercalated among the PANI matrix. In potentiodynamic polarization tests, the anticorrosion efficiency of the films with reinforcement of PGO/PANI composites increases from 85.16% to 99.98%. Moreover, the lowest corrosion rate is 1.68 × 10 –4 mm/year, which is much better than that with individual PGO or PANI. Electrochemical impedance spectroscopy, where the Warburg impedance component emerges, further reveals that well-dispersed PGO in the film can retard or defend permeation of the corrosive material from the environment.

Highly regulated core–shell Fe 3 O 4 @polypyrrole composite microspheres have been successfully prepared via chemical oxidative polymerization in the presence of poly(vinyl alcohol) and p -toluenesulfonic acid. The polypyrrole shell thickness can be adjusted from 20 to 80 nm with the variation of the pyrrole/Fe 3 O 4 ratio. Investigations of the microwave absorbing properties indicate that the polypyrrole shell plays an important role, and the maximum reflection loss of composite microspheres can reach as much as −31.5 dB (>99.9% absorption) at 15.5 GHz with a matching layer thickness of 2.5 mm. Compared to the physically blended Fe 3 O 4 –PPy composites, Fe 3 O 4 @polypyrrole composite microspheres not only possess better reflection loss performance but also have a wider absorbing bandwidth of 5.2 GHz (12.8–18 GHz) in the Ku band, which may be attributed to the intensive synergistic effect of dielectric loss from polypyrrole shells and magnetic loss from Fe 3 O 4 cores. Therefore, regulated core–shell Fe 3 O 4 @polypyrrole composite microspheres are postulated to be more promising…

Today’s fast-changing markets often require the granularity of production schedules to be refined to time scales comparable to the time constants of a chemical process. Consequently, the process dynamics must be considered explicitly in production scheduling. High dimensionality, nonlinearity, and the associated computational complexity make incorporating dynamic models in scheduling calculations challenging. We propose a novel scheduling approach based on scheduling-oriented low-order dynamic models identified from historical process operating data. We introduce a methodology for selecting scheduling-relevant variables and identify empirical models that capture their dynamic response to production target changes imposed at the scheduling level. The optimal scheduling calculation is then formulated as a dynamic optimization aimed at minimizing operating cost. We apply these concepts to an industrial-size model of an air separation unit operating under time-sensitive electricity prices. Our approach reduces computational effort considerably while preserving essential information…

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly(vinyl chloride)- co -chlorinated poly(vinyl chloride) (PVC- co -CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert -butyl acrylate ( t BA), precursors for uranium-interacting functional groups, from PVC- co -CPVC fiber. The [ t BA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from t BA) and uranyl-binding ligands (from AN). The best performing adsorbent fiber, the one with the optimal [ t BA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42–3.24 g/kg in 42 days of seawater…

The Integrated Process Intensification approach is used for the synthesis of ammonia using novel coassembled microporous silica supported nickel catalysts and nonthermal plasma reactors operating at ca. 140 ± 10 °C and ambient pressure. The conversion levels of nitrogen and hydrogen to ammonia are similar to that achieved by the current industrial best practice which is, however, carried out at 100–250 bar and the temperatures 350–550 °C. In order to achieve continuous plasma generation, a novel catalyst, which has a surface area of ca. 200 m 2 /g in the form of lamellae with ca. 2 nm thick plates of nickel catalyst sandwiched between the silica support, has been used in the presence of plasma catalysis promoters in the form of spheres made from high permittivity material. In addition to process variables (flow rate, feed composition, and plasma power input), the effect of the electrode configuration on conversion was investigated. It is shown that the catalyst activity remained constant over a continuous period of 72 h when the reaction was terminated.

This work identifies a benchmark for the performance of a small-scale ammonia synthesis plant powered by wind energy. The energy used is stranded, far from urban centers but near locations of fertilizer demand. The wind energy drives the pressure swing absorption of air to make nitrogen and the electrolysis of water to make hydrogen. These are combined in the small-scale continuous Haber process to synthesize ammonia. The analysis of runs of the small plant presented in this article permits an assessment of how the current production rate is controlled by three resistances: catalytic reaction, ammonia separation by condensation, and recycling of unreacted gas. The measured catalytic reaction rates are consistent with separate experiments on chemical kinetics and with published reaction mechanisms. The condensation rates predicted are comparable with literature correlations. These rate constants now supply a rigorous strategy for optimizing this scaled-down, distributed ammonia plant. Moreover, this method of analysis is recommended for future small-scale, distributed manufacturing…

Conventional carbon capture and sequestration (CCS) in aqueous alkanolamine solutions is an energy-intensive process for power plant flue gas CO 2 treatment. We report a laboratory parametric study on the utilization of CO 2 from simulated natural gas postcombustion effluent by cyclic adsorption and methanation using a single dual functional material (DFM). The DFM is composed of nanodispersed CaO and Ru metal supported on an γ-Al 2 O 3 carrier (5% Ru, 10% CaO/Al 2 O 3 ), respectively functioning as the CO 2 adsorbent and methanation catalyst. The stored H 2 used for methanation is assumed to be produced by water electrolysis using excess alternative wind or solar energy. The effects of DFM preparation methods, Al 2 O 3 carrier materials (with different shapes and properties), and adsorption and methanation conditions (feed compositions, flow rates, and reaction temperatures) were examined. The DFM samples, prepared using chloride precursor salts, showed stable performance under cyclic operating conditions. Reaction conditions were explored for the optimized CO 2 utilization…

A series of 6FDA-Durene-ZIF71 mixed matrix membranes (MMMs) comprising three different ZIF-71 particle sizes (i.e., 30, 200, and 600 nm) have been fabricated to investigate the effects of particle size on the gas separation performance of MMMs. Compared to MMMs containing ZIF-71 particle size > 200 nm, ZIF-71 embedded MMMs with particle sizes of ≤ 200 nm exhibited significantly enhanced gas separation performance. The O 2 and N 2 permeability of MMMs comprising ZIF-71 with particle sizes ≤ 200 nm have higher permeability than the predicted ones using the Maxwell model. By considering the inefficiently packed polymer chain and the sieve-in-a-cage phenomena, the modified Maxwell model displayed comparable permeability over the experimental results suggesting the nonideal nature of MMMs. For the first time, it was found that 200 nm ZIF-71 generated the best MMM for gas separation, particularly for H 2 /CH 4 systems. Therefore, a trade-off between ZIF-71 particle size vs gas separation performance must be taken into account when designing an MMM suitable for industrial gas separation…

In this research work, surface of graphene oxide was functionalized by zirconium and phosphate to form graphene oxide–zirconium phosphate (GO–Zr-P) nanocomposite, which is used for the removal of heavy metals from aqueous solutions. The GO–Zr-P nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), and zeta-potential analysis. The sheets of GO–Zr-P was found to be strongly wrinkled, and the flat and layered structure of GO varied significantly after treatments with zirconium and phosphate. The effects of pH, contact time, and initial concentrations on the removal of heavy metals were studied. The results of batch experiments indicated that, at pH 6, maximum adsorption capacity can be achieved for Pb(II), Cd(II), Cu(II), and Zn(II), as 363.42, 232.36, 328.56, and 251.58 mg g –1, respectively. A removal efficiency of ∼99% was obtained after 20 min, via the dispersion of 150 mg of GO–Zr-P nanocomposite in 100 mL of 50 ppm heavy metals. The…

Current environmental concerns have encouraged the food packaging industry to search for biobased barriers produced from renewable material sources. One candidate for renewable barrier applications is nanocellulose which has been found to possess excellent barrier properties, especially against grease and oxygen. However, most of the research presented so far has been based on small, batch-produced films or coatings of nanocellulose. Reports on continuous processing of nanocellulose into films or coatings, which is required for large-scale, low-cost production, are few. The current work presents a roll-to-roll coating process of cellulose nanofiber (CNF) suspensions on paperboard for renewable barrier applications. The coating apparatus used herein provides a low effective viscosity to enable the processing of the highly viscous nanocellulose suspensions into a coating on a paper web. The impact of various process parameters on the coating quality and runnability are discussed. Strength (tensile and burst) and barrier properties (air permeability, water and heptane vapor…

The Pacific Northwest National Laboratory (PNNL) is evaluating the performance of adsorption materials to extract uranium from natural seawater. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time using flow-through columns and a recirculating flume to determine adsorbent capacity and adsorption kinetics. The amidoxime-based polymer adsorbent AF1, produced by Oak Ridge National Laboratory (ORNL), had a 56-day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material, a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material, and a half-saturation time of 23 ± 2 days. The ORNL AF1 adsorbent has a very high affinity for uranium, as evidenced by a 56-day distribution coefficient between adsorbent and solution of log K D,56day = 6.08. Calcium and magnesium account for a majority of the cations adsorbed by the ORNL amidoxime-based adsorbents (61% by mass and 74% by molar percent), uranium is the fourth most abundant element adsorbed by mass and seventh most abundant by molar percentage. Marine testing at Woods Hole…

CO 2 foam can control the CO 2 mobility and improve the sweep efficiency in reservoirs; however, CO 2 foam stabilized solely by surfactants is not stable. Nanoparticles can improve the performance of CO 2 foam. The synergistic effect of SiO 2 nanoparticles and sodium dodecyl sulfate (SDS) on the CO 2 foam stability was studied in this paper. The experimental results show that the synergistic effect requires an SDS/SiO 2 concentration ratio of 0.1–0.4. The strength of the effect increases as the SDS/SiO 2 concentration ratio increases from 0.1 to 0.17 but then decreases as the ratio further increases from 0.17 to 0.4; thus, a ratio of 0.17 provides the best performance for CO 2 foam. The mechanisms of the synergistic effect of SDS and SiO 2 include modulating the position of nanoparticle adsorption on the CO 2 and liquid interface, improving the interfacial properties of the CO 2 foam, and reducing its liquid discharge and coarsening. SiO 2 nanoparticles can also improve the CO 2 foam performance under high temperatures and pressures. The visual flooding experiment reveals that the…

Active disturbance rejection controller (ADRC) is emerging as a promising approach to deal with uncertainties, which has received many practical applications in motion controls. This paper discusses the issues that should be taken into account when applying ADRC in process industry. First, the strategies of bumpless transfer and anti-windup are introduced to make ADRC applicable for continuous production processes. Second, an automatic tuning tool, based on robust loop shaping, is developed to obtain a group of reasonable parameters that can guarantee the system safety when ADRC is put in loop. For robustness concerns, the maximum sensitivity function is introduced in tuning the bandwidth of the extended state observer (ESO). Third, a quantitative retuning strategy is introduced to avoid the proportional kick in set-point tracking. The simulation and laboratory experiments confirm the effectiveness of the proposed strategies. Finally, it is attempted to apply the ADRC controller to a regenerative heater in an in-service 1000 MW power plant. The field test well demonstrates the…

Graphene oxide (GO) is a type of two-dimensional nanomaterial with a single-atom thickness. GO sheets contain pristine regions, oxidized regions, and a small fraction of holes. By stacking GO sheets together, a GO membrane can be fabricated with sufficient mechanical strength. The interlayer nanocapillary network formed from connected interlayer spaces, together with the gaps between the edges of noninterlocked neighboring GO sheets and cracks or holes of the GO sheet, provides passage for molecules or ions to permeate through the GO membrane in an aqueous solution. The characteristics of molecules or ions (e.g., their size, charge, and the interaction with the GO membrane) affect the separation performance of the GO membrane. The contribution of gaps between neighboring GO sheets for separation can be adjusted by changing the GO sheet size and the GO membrane thickness. The interlayer space of the GO membrane can be adjusted by changing the water pH and modifying or reducing the GO sheets to obtain the desired separation performance. The production of the GO membrane is easily…

Magnetic Prussian blue (PB) nanocomposites were synthesized by binding PB to a core of magnetite (Fe 3 O 4 ) nanoparticles for highly efficient and rapid separation of cesium (Cs + ) from aqueous solution. The average particle size of the magnetic PB nanocomposites was 13.6 nm, and they had a high surface area (322.19 m 2 /g), leading to efficient Cs + adsorption capability. The nanocomposites showed a maximum sorption capacity of 280.82 mg/g at an initial Cs + concentration of 50 mM, pH 7, and 10 °C, which is much higher than those of previously reported PB-based adsorbents for removing Cs + . The adsorption behavior followed pseudo-second-order kinetics and obeyed the Tempkin isotherm. The adsorption capacity of Cs + on magnetic PB nanocomposites remained consistent even at high ionic competition in the simulated seawater. The obtained magnetic PB nanocomposite is a cost-effective adsorbent and can be easily retrieved from an aqueous solution by a magnet after decontamination of cesium. These results showed that the magnetic PB nanocomposite has extensive applicability for the…

The main objective of this study is to evaluate the effect of particle size and surface acidity of synthesized silica gel nanoparticles on the inhibition of formation damage caused by asphaltene precipitation/deposition. Silica gel nanoparticles were synthesized through the sol–gel method, and their characterization was performed via N 2 physisorption at −196 °C, field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS) measurements, and NH 3 temperature-programmed desorption (TPD). The size of the synthesized nanoparticles ranged from 11 to 240 nm. The ability of the nanoparticles to adsorb asphaltenes and to reduce asphaltene self-association was evaluated using batch-mode experiments. The kinetics of asphaltene aggregate growth in the presence and absence of nanoparticles were evaluated using DLS measurements in different Heptol solutions. The smallest nanoparticles (11 nm) had the highest adsorptive capacity for n -C 7 asphaltenes among the nanoparticles studied. Therefore, these nanoparticles were modified using acid, base, and neutral treatments,…

Ammonia production has traditionally been based on large-scale plants. The thrust toward large-scale production to gain economic advantages has overshadowed the benefits that could be derived from small-scale production plants. Additionally, the ammonia industry consumes a major chunk of global fossil fuels, which also burdens the planet with greenhouse gases. To effectively counter these issues, this study investigates the production of ammonia from biomass. Processes based on biomass plants are usually small-scale and are limited by biomass supply. To ensure sustainable ammonia production, this study tries to highlight the techno-economic advantages that result from small-scale ammonia plants based on biomass feedstock. This paper proposes a new process that takes inputs from a relatively old, natural gas based process (leading concept ammonia) specifically designed for small-scale ammonia manufacture and couples it with a recently developed dual fluidized bed technology for biomass feedstock. Two different flowsheet configurations are simulated rigorously and compared to gain a…

Gasification of southern pine using carbon dioxide as an oxidizing medium was carried out in a bench-scale atmospheric bubbling fluidized bed gasifier, and the results were compared with an oxygen gasification study from literature. Evolution of gases (CO, CO 2, H 2, and CH 4 ) was quantified as a function of temperature in the range 700 °C to 935 °C and CO 2 /C ratios in the range of 0.5–1.5 (wt/wt). The main aim of this study was to determine the effect of temperature and CO 2 /C ratios on the output syngas and to understand which reactions were influential within the operational limits of the experimental parameters. Additionally, results from CO 2 gasification and oxygen gasification were thoroughly compared. Statistical analyses were performed to determine the significance of changes in operating parameters on the process. Variation in temperature seemed to have a significant effect on the output, whereas the effects of CO 2 /C ratios were not that profound. The analyses of the gas evolution trends suggested that the Boudouard reaction, char reforming reaction, and free radical…

Three-dimensional (3D) crumpled graphene-based porous adsorbents with highly interconnected networks were synthesized through a facile one-step physical activation method using reduced graphene oxide (RGO) as precursor, for separation of carbon dioxide (CO 2 ) from postcombustion flue gas mixtures. Due to their large surface area (above 1300 m 2 g –1 ), high pore volume (over 1 cm 3 g –1 ), and well-defined bimodal microporous–mesoporous structure, these hierarchical porous graphene-based materials demonstrate rapid, stable, reversible, and high CO 2 uptake of 2.45 mmol g –1 at 25 °C and 1 bar. Importantly, the CO 2 over nitrogen (N 2 ) adsorption selectivity is among the best at partial pressures relevant to capturing CO 2 emanating from postcombustion power plants fueled with either coal or natural gas. Moreover, the isosteric heat of adsorption of only −27.42 kJ mol –1 at zero coverage reflects the ease of adsorbent regeneration with significantly low energy consumption, which in turn might reduce the costs of carbon capture and sequestration.

Ammonia is normally made at high temperature and pressure using a promoted iron catalyst. High temperatures are needed to get fast kinetics; the high pressure is used to ensure high conversion. Alternatively, ammonia can be made at high temperature but lower pressure if the product ammonia is rapidly separated. Here, we have systematically studied the effect of temperature and pressure on the rates of reaction. We then have qualitatively investigated the absorptive separation of ammonia using calcium chloride in a reaction–separation process. Rapid separation reduces the constraint of reversible reaction and enables us to obtain appropriate reaction rates at relatively lower pressure. The effect of different operating conditions—reaction temperature, pressure, absorption temperature, and gas transport—on production rates is carefully measured, and this elucidates the potential and the limits of this type of low-pressure ammonia synthesis.

WS 2 nanosheets–CdS nanorods with heterojunctions were prepared by an ultrasonic/exfoliation method using dimethylformamide as the dispersing agent. CdS nanorods were coupled with small WS 2 nanosheets as a result of exfoliation. An excellent hydrogen production rate of 1222 μmol h –1 (20 mg of catalyst) was achieved over the WS 2 –CdS composite with a WS 2 -to-CdS mass ratio of 1.6:1 under visible-light irradiation (λ ≥ 400 nm). The efficient evolution of hydrogen is attributed to promotion of the separation of photogenerated charge carriers due to the presence of heterojunctions created on the surface.

A facile method to prepare SnO 2 hollow microspheres has been developed by using SiO 2 microspheres as template and Na 2 SnO 3 as tin resource. The obtained SnO 2 hollow microspheres were characterized by X-ray diffraction, scanning electron microscopy, high resolution and transmission electron microscopy, and Brunauer–Emmett–Teller analysis, and their sensing performance was also investigated. It was found that the diameter of SnO 2 hollow microspheres can be easily controlled in the range of 200–700 nm, and the shell thickness can be tuned from 7.65 to 30.33 nm. The sensing tests showed that SnO 2 hollow microspheres not only have high sensing response and excellent selectivity to acetone, but also exhibit low operating temperature and rapid response and recovery due to the small crystal size and thin shell structure of the hollow microspheres, which facilitate the adsorption, diffusion, and reaction of gases on the surface of SnO 2 nanoparticles. Therefore, the SnO 2 hollow microsphere is a promising material for the preparation of high-performance gas sensors.