Showing papers in "Industrial & Engineering Chemistry Research in 2016"

Recent Advancement of Coagulation–Flocculation and Its Application in Wastewater Treatment

Abstract: 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 revie...

Noble Metal Nanoparticles: Plant-Mediated Synthesis, Mechanistic Aspects of Synthesis, and Applications

Abstract: 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.

Toward the Development and Deployment of Large-Scale Carbon Dioxide Capture and Conversion Processes

Abstract: In light of the depletion of fossil fuels and the increased daily requirements for liquid fuels and chemicals, CO2 should indeed be regarded as a valuable C1 additional feedstock for sustainable manufacturing of liquid fuels and chemicals. Development and deployment of CO2 capture and chemical conversion processes are among the grand challenges faced by today’s scientists and engineers. Very few of the reported CO2 capture and conversion technologies have been employed for industrial installations on a large scale, where high-efficiency, cost/energy-effectiveness, and environmental friendliness are three keys factors. The CO2 capture technologies from stationary sources and ambient air based on solvents, solid sorbents, and membranes are discussed first. Transforming CO2 to liquid fuels and chemicals, which are presently produced from petroleum, through thermochemical, electrochemical, photochemical, and biochemical routes are discussed next. The relevant state-of-the-art computational methods and tools a...

Synthesis of a Novel P/N/S-Containing Flame Retardant and Its Application in Epoxy Resin: Thermal Property, Flame Retardance, and Pyrolysis Behavior

Abstract: 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 1H and 31P 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.

How To Optimize the Membrane Properties for Membrane Distillation: A Review

Abstract: 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 ...

Fe3+-doped Anatase TiO2 with d–d Transition, Oxygen Vacancies and Ti3+ Centers: Synthesis, Characterization, UV–vis Photocatalytic and Mechanistic Studies

Abstract: The current work emphasizes the preparation, characterization, recyclability, stability, and mechanistic study of nanosized Fe3+-doped TiO2 photocatalyst. The structural, optical, and photocatalytic properties of undoped and doped TiO2 were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 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 p...

Silica Nanofluids in an Oilfield Polymer Polyacrylamide: Interfacial Properties, Wettability Alteration, and Applications for Chemical Enhanced Oil Recovery

Abstract: 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 (SiO2) 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 ...

Hierarchical Microspheres of MoS2 Nanosheets: Efficient and Regenerative Adsorbent for Removal of Water-Soluble Dyes

Abstract: This study demonstrates fast and efficient removal of dyes from the wastewater using nanostructural MoS2 as a regenerative adsorbent. The hierarchical microspheres of MoS2 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 MoS2 nanosheets were examined by XPS, FTIR, XRD, FESEM, and HRTEM. The adsorption of a series of organic dyes using MoS2 nanosheets was systematically investigated. The kinetic study illustrated that adsorption of methylene blue dye onto the MoS2 nanosheets followed the pseudo-second-order model. The adsorption isotherm at the equilibrium was supported by the Freundlich model. The hierarchical microspheres of MoS2 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 hi...

Extracting Uranium from Seawater: Promising AF Series Adsorbents

Abstract: A new family of high-surface-area polyethylene fiber adsorbents named the AF series was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series adsorbents were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/comonomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154–354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44 M KOH at 80 °C followed by screening at ORNL with sodium-based synthetic aqueous solution, spiked with 8 ppm uranium. The uranium adsorption capacity in simulated seawater screening ranged from 170 to 200 g-U/kg-ads irrespective of %DOG. A monomer/comonomer molar ratio in the range of 7.57–10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at ...

Continuous Oil–Water Separation Using Polydimethylsiloxane-Functionalized Melamine Sponge

Abstract: 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/cm3 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 ...

A Review on the Durability of Alkali-Activated Fly Ash/Slag Systems: Advances, Issues, and Perspectives

Abstract: Alkali-activated materials (AAMs) have high potential as alternative binder to ordinary portland cement (OPC), because of their high performance beside lower CO2 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 fur...

Cellulose Nanocrystals and Polyanionic Cellulose as Additives in Bentonite Water-Based Drilling Fluids: Rheological Modeling and Filtration Mechanisms

Abstract: This research aims to develop low cost, sustainable, environmentally friendly, and high performance water-based drilling fluids (WDFs) using bentonite (BT), polyanionic cellulose (PAC), and cellulose nanocrystals (CNCs). The effect of concentration of BT, PAC, and CNCs on the rheological and filtration properties of PAC/CNC/BT-WDFs was investigated. Eight empirical rheological models were applied to fit quantitatively the fluid properties. Results showed that the presence of PAC, CNCs, and BT improved the rheological and filtration properties of the WDFs. Among the eight empirical rheological models, the Sisko model performed the best in simulating the rheological behavior of the fluids. At the same concentration level of PAC and CNCs, CNCs had more impact on the rheological properties, whereas PAC had more influence on the filtration property. The incorporation of PAC resulted in very low permeable filter cakes, leading to the excellent filtration property. The combined use of PAC and CNCs yielded better...

Phase Equilibria of Confined Fluids in Nanopores of Tight and Shale Rocks Considering the Effect of Capillary Pressure and Adsorption Film

Abstract: 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 Ea...

Phosphorus and Nitrogen-Containing Polyols: Synergistic Effect on the Thermal Property and Flame Retardancy of Rigid Polyurethane Foam Composites

Abstract: 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.

CO2 Capture by Temperature Swing Adsorption: Use of Hot CO2-Rich Gas for Regeneration

Abstract: Temperature swing adsorption (TSA) is an attractive technology for CO2 removal from gas streams. CO2 capture by a TSA process in which the recovered CO2 product is heated and used as regeneration purge gas has been examined. Our study is based on cyclic experiments performed on a single adsorption column packed with the commercially available zeolite NaUSY adsorbent. The commercial Aspen adsorption simulator was used to simulate the experimental system, where the model predictions agreed quite well with experimental results in terms of breakthrough and results for cycle designs based on indirect heating followed by hot product gas purge. The validated model was used to simulate the case of regeneration using only hot product gas purge, which was difficult to examine experimentally due to constraints of the experimental system used. With a three-step cycle of (1) adsorption, (2) hot gas purge, and (3) cooling, this case yielded product purities of >91% CO2 and maximum recoveries of 55.5, 76.2, and 83.6% at...

Review of Alkali-Based Pretreatment To Enhance Enzymatic Saccharification for Lignocellulosic Biomass Conversion

Abstract: 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 pro...

Well-Defined Core–Shell Fe3O4@Polypyrrole Composite Microspheres with Tunable Shell Thickness: Synthesis and Their Superior Microwave Absorption Performance in the Ku Band

Abstract: Highly regulated core–shell Fe3O4@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/Fe3O4 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 Fe3O4–PPy composites, Fe3O4@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 Fe3O4 cores. Therefore, regulated core–shell Fe3O4@polypyrrole com...

Synthesis, Characterization, and Activity Pattern of Ni–Al Hydrotalcite Catalysts in CO2 Methanation

Abstract: 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 (H2-TPR and CO-TPD). Catalytic activity of the analyzed samples was investigated toward hydrogenation of CO2 at atmospheric pressure by varying reaction temperature between 250 and 400 °C. The maximum CO2-to-CH4 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, re...

Preparation of Superhydrophobic Magnetic Cellulose Sponge for Removing Oil from Water

Abstract: 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 (Fe3O4) was coated on cellulose sponge surface via codeposition method, and subsequently magnetic cellulose sponge was modified with hexadecyltrimethoxysilane, which could react with Fe3O4 or hydroxyl groups of cellulose. The purpose of coating Fe3O4 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.

On Tuning and Practical Implementation of Active Disturbance Rejection Controller: A Case Study from a Regenerative Heater in a 1000 MW Power Plant

Abstract: 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 i...

Antibacterial Activities and UV Protection of the in Situ Synthesized Titanium Oxide Nanoparticles on Cotton Fabrics

Abstract: In situ synthesis of titanium oxide nanoparticles (TiO2NPs) 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 TiO2NPs. Characterization of TiO2NPs was performed using SEM-EDX, XRD, FTIR, TEM, particle size analyzer, and zeta potential. The results obtained signify the following features. TiO2NPs 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, TiO2NPs-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 TiO2NPs. Cotton fabrics coated with TiO2NPs display excellent UV protection before and after washing.

Scientific Basis for Efficient Extraction of Uranium from Seawater. I: Understanding the Chemical Speciation of Uranium under Seawater Conditions

Abstract: 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 UO22+) in seawater, focusing on the solution equilibria leading to the formation of the stable complexes, Mm(UO2)(CO3)3(2m–4)(aq) (M = Ca or Mg, m = 0–2). These binary and terna...

Experimental and Quantum Chemical Evaluation of 8-Hydroxyquinoline as a Corrosion Inhibitor for Copper in 0.1 M HCl

Abstract: 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 ΔGads0 value an...

Optimal Process Operations in Fast-Changing Electricity Markets: Framework for Scheduling with Low-Order Dynamic Models and an Air Separation Application

Abstract: 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 reduce...

Synthesis of Functionalized Graphene/Polyaniline Nanocomposites with Effective Synergistic Reinforcement on Anticorrosion

Abstract: 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 cor...

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)-co-chlorinated Poly(vinyl chloride) (PVC-co-CPVC) Fiber

Abstract: 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 (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligands (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[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 ...

Multiobjective Robust Possibilistic Programming Approach to Sustainable Bioethanol Supply Chain Design under Multiple Uncertainties

Abstract: In this article, a multiobjective mixed-integer linear programming (MILP) model is proposed to address the optimal design and planning of a lignocellulosic bioethanol supply chain (LBSC) considering a sustainable supply chain optimization framework including economic, environmental, and social objectives. The proposed model is capable of determining strategic decisions, including biomass sourcing and allocation, locations, capacity levels, and technology types of biorefinery facilities, as well as the tactical decisions, including inventory levels, production amounts, and shipments among the network. Eco-indicator 99, which is a well-known life-cycle-assessment- (LCA-) based environmental impact assessment method, is incorporated into the model to estimate the relevant environmental impacts. To handle the inherent uncertainty of the input data in the problem of interest, a novel multiobjective robust possibilistic programming (MORPP) approach is developed. The performance of the model is demonstrated thro...

Separation Performance of Graphene Oxide Membrane in Aqueous Solution

Abstract: 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 d...

Enhanced CO2 Absorption and Desorption by Monoethanolamine (MEA)-Based Nanoparticle Suspensions

Abstract: In this study, three different nanoparticles—SiO2, TiO2, and Al2O3—were employed to enhance the CO2 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 CO2 absorption rate of >10%. On the other hand, nanoparticles exhibit much more attractive impact on CO2 desorption. Under the same desorption extent, solvent with 0.1 wt % TiO2 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.

Large-Scale Ultrasonic Fabrication of White Fluorescent Carbon Dots

Abstract: 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.