查看更多>>摘要：Suspension hydrodynamics of poly(2-hydroxyethyl methacrylate)-based anion-exchange cryogel beads in stirred-tank bioreactors were investigated by high-speed imaging and the scale-up suspension behaviors were simulated by computational fluid dynamics methods. Lactobacillus paracasei cell-loaded cryogel beads were prepared and employed as biocatalysts for biotransformation of phenylalanine to phenyllactic acid (PLA). The results showed that with the increase of agitation rate, the cryogel beads underwent the transition from partial to complete suspension and finally to uniform suspension. The experimental and simulated just suspended impeller speeds were in good agreement with Zwietering's correlation at the cryogel-bead concentrations from 1% to 8%. Non-uniform suspension behaviors and more heterogeneous turbulent flow fields especially in regions near impellers, baffles and bottom wall occurred in the simulated scaling-up of the bioreactors from the working volume of 5-200 L. The yield and productivity of PLA increased with the increase of the fraction of cell-loaded cryogel beads. The maximum PLA concentration of 202 mg L~(-1) and the productivity of 7.1 mg L~(-1) h~(-1) were obtained for 8% cell-loaded cryogel beads in 100 mM phosphate containing 1 mg mL~(-1) of phenylalanine and 2 mg mL~(-1) glucose at the agitation rate of 80 rpm and temperature of 35 °C, indicating that cell-loaded cryogel beads could be new biocatalysts for direct conversion of cheap substrate phenylalanine to high-value product, PLA. ? 2021 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.
Sumaiya Zainal AbidinHerma Dina SetiabudiDai-Viet N. Vo
1页
查看更多>>摘要：The International Symposium of Reaction Engineering, Catalysis & Sustainable Energy (RECaSE2021) was the first symposium organized by Reaction Intensification & Sustainable Energy (RISE) Research Group, Faculty of Chemical and Process Engineering Technology, Universiti Malaysia Pahang, Malaysia. With the theme "New Frontiers in Green Chemistry for Sustainable Energy", the event was successfully hosted in a virtual platform on April 6, 2021. This one-day virtual symposium provided an opportunity for academics, researchers, scientists, practitioners, and students to generate and present novel ideas in a diverse selection of topics.
查看更多>>摘要：Patchy particles, which comprise a core particle of one material partially covered by a thin layer of another, offer great promise for tailored particle-based materials and devices in the future. This study concerns the investigation and improvement of a potentially gram-scalable continuous flow process based on a cascade of two T-mixers for the synthesis of thin, conformal silver patches on colloidal silica particles. The starting point of the work is the observation that on seemingly random occasions the process results in patches having undesired spiky protrusions. Through a systematic study of reagent ageing supported by scanning electron microscopy, optical spectroscopy and chemical equilibrium calculations it can be ascertained that the desired product morphology is only obtained through carbon dioxide absorption by the dilute ammonia solution used in the reaction. It is shown that the ageing process can be emulated for fresh reagents by addition of ammonium nitrate or nitric acid.
Joao R. PachecoHugo G.D. VillardiRaquel M. Cavalcante
18页
查看更多>>摘要：Supercritical biodiesel production has the potential to process cheaper raw materials and reduce separation costs. It did not proved to be competitive with the traditional homogeneous alkaline process so far because of the associated higher capital and energy costs. However, the literature provides enough knowledge about three non-conventional supercritical technologies that have not yet been studied for industrial application: inter-esterification with methyl acetate (Route 1); reaction with acetic acid and esterification with methanol (Route 2); and reaction with dimethyl carbonate (Route 3). They have the additional advantage of not generating low profitable glycerol, replacing it by other more valuable by-products: triacetin and glycerol dicarbonate. This article presents the economic assessment of these three routes in an industrial scale, showing that Routes 1 and 3 are economically feasible as long as 58-89% of triacetin and 26-28% of glycerol dicarbonate can be sold, respectively. It makes Route 3 the most attractive route, requiring 34% less capital for the same (1% lower) production cost as Route 1 in the best scenarios. Route 2 requires still more development to become feasible regardless of the market, as the byproduct revenues do not compensate its 68% higher capital cost and 21% higher production cost (compared to the best scenario of Route 3).
查看更多>>摘要：Titanium dioxide is widely used as a pigment in industrial processes and life, and the mechanical strength of the coating of titanium dioxide is of vital importance for its quality. The content of iron impurities in aluminum sulfate coatings directly affects their quality; therefore, the removal of iron from aluminum sulfate solutions is of paramount importance. In this study, an aluminum sulfate solution containing iron (18 mg/L) was used as a raw material to explore a composite process to reduce iron content to < 5 mg/L for coating high-quality titanium dioxide products. A novel process consisting of sodium diethyldithiocarbamate (DDTC) complexation-precipitation, flocculation by cationic polyacrylamide, and ultrafiltration have been proposed in this study. The reactant structure and thermodynamic equilibrium were determined by quantum chemical calculations to clarify the mechanism of selective iron removal using organic precipitants. The effects of DDTC dosage, reaction temperature, reaction time, stirring speed, and ultrafiltration membrane specifications on iron removal were systematically investigated. The physical and chemical properties of the precipitated particles were analyzed by zeta potential, scanning electron microscopy (SEM), and atomic force microscopy (AFM) before and after the addition of flocculants. Before adding the flocculant, the surface zeta potential of the precipitated particles was negative, and the cationic flocculant was added to neutralize the surface charge, eliminate the electrostatic repulsion, and promote the flocculation of precipitated particles for growth; this is beneficial for ultrafiltration. Furthermore, the experimental conditions were optimized to achieve the lowest iron content of 3.8 mg/L in the solution. Finally, the reaction mechanism of the organic precipitation-cationic flocculation-ultrafiltration complex was elucidated.
Stefani KocevskaGiovanni Maria MaggioniSteuen H. Crouse
22页
查看更多>>摘要：Raman spectroscopy is a valuable in-situ technique for many applications. The concentrations of species in complex ionic mixtures of nuclear waste can be estimated using Raman measurements. However, it has been experimentally observed that ion interactions can cause a modification of Raman peak intensities and positions. The present work explores the nonlinear behavior associated with the nitrate anion, NO3~-, which is present in abundance in low activity nuclear waste. We examine changes in the main Raman peak of the nitrate anion in the presence of other ions. A wide range of concentrations are covered, including those expected during direct-feed low-activity waste (DFLAW) processing at the Hanford site in the State of Washington. The experiments showed that the ions interact and associate to form ion pairs, which results in a blue shift (i.e., a shift towards higher wavenumbers) in the main Raman peak of nitrate. The results indicate that cation concentration is a better predictor of the peak shift, compared to ionic strength, both for binary and multicomponent mixtures. These findings have direct implications on the development of spectra-to-composition models for the DFLAW system, since they show deviations from the linearity assumptions used in common chemometric models.
查看更多>>摘要：Zeolitic imidazolate framework (ZIF-8) was functionalized by polyethyleneimine (PEI) and subsequently decorated with ionic liquid (IL) - [P(3)HIm][Tf2N], ZIF-8-PEI@IL/Pebax~R 2533 mixed matrix membranes (MMMs) were fabricated to enhance the CO2 capture performance of Pebax membranes. The amino groups and IL in ZIF-8-PEI improved the gas separation performance of the MMMs due to the additional CO2 transporting pathways by using the reversible reaction with amino groups and the high affinity between IL and CO2. The modified ZIF-8 particles demonstrated enhanced interfacial interactions and compatibility between fillers and polymer matrix due to the presence of amino groups and IL, confirmed by the enhanced gas separation performance, improved elongation at break, and tensile strength of MMMs. Comparing with the pristine membranes, CO2 permeability of MMMs containing 15 wt% ZIF-8-PEI@IL increased by 123% to 285 Barrer, and the CO2/N2 and CO2/CH4 ideal selectivity increased from 17 and 12 to 76 and 25, respectively.
K. Gireesh BaijuMahendra N. NandanwarK. Jayanarayanan
11页
查看更多>>摘要：In this paper, we report a mathematical model developed to study thermal characteristics of heat sink assisted elevated temperature sintering of TiO2 coated polymer photoelec-trode used for the fabrication of high-performance flexible dye sensitized solar cells (FDSSCs). Thermal sintering of TiO2 film deposited indium tin oxide coated polyethylene terephthalate (ITO PET) is usually restricted by the polymer serviceability temperature limit (~ 150 °C), but the heat sink assisted sintering process increases sintering temperature without affecting the polymer integrity, produces effectively sintered TiO2 film on the polymer surface and boosts the photovoltaic performance of FDSSCs. The developed model involves simultaneous heat transfer and coolant flow within the system which is dynamically coupled with an external coolant reservoir. Using this model, effects of various parameters such as coolant flow rate, heat sink material, heat sink geometry, and sintering duration on the thermal characteristics of TiO2 sintered on polymer substrate are studied. Also, the FDSSCs fabricated using this sintering method have shown power conversion efficiency increased significantly because of the rise in sintering temperature is controlled by the heat sink thermal parameters. Besides, possibilities of scaling-up of this sintering system for the fabrication of large area FDSSCs are investigated.
查看更多>>摘要：Over the last few decades, antifouling, protein rejection, and oil-water separations have become a challenge to technologists and environmentalists. In view of this, the proposed work reports formulation, characterization of facile hydrophilic chitosan-graphene oxide modified sustainable non-woven fabric-based sieve membranes (NWF@Cs/Gx) along with their application for antifouling, protein rejection, and multigrade oil-water emulsions separation studies. The surface morphology, diameter size of the fibers, and elemental analysis of the same were characterized with high-resolution microscopes (SEM), EDAX, and spectroscopically. The hydrophilicity of these membranes was investigated using contact angle and water uptake studies that exhibited pure water flux up to 165 L.m~(-2).h~(-1). These studies further confirmed the multigrade oil/water emulsions separation with 98% efficiency and more than 96% protein (Bovine Serum Albumin) rejection. These studies suggest that the formulated membranes may find application in the field of environmental, biological, and petroleum-based industries.
Francisco Javier Lopez-FloresEusiel Rubio-CastroJose Maria Ponce-Ortega
14页
查看更多>>摘要：This paper proposes a methodology for efficient, accurate, and sustainable waste heat recovery, where the energy needs of an industrial plant allow the installation of thermal engines. In this methodology, pinch analysis, mathematical equations, machine learning models, and an optimization algorithm are combined for the first time. To satisfy the industrial requirements, the selected thermal engines are the steam Rankine cycle, the organic Rankine cycle, and the absorption refrigeration cycle, which are modeled by using multilayer perceptron neural networks. The Non-dominated Sorting Genetic Algorithm-III is used to solve the optimization problem. Moreover, multi-objective trade-offs between economic, environmental, and social aspects are studied. A case study is presented to show the applicability of the proposed methodology. The multilayer perceptron models of the thermal engines were created with high accuracy. Furthermore, the results show that with this methodology it is possible to find the optimal operating conditions of thermal engines and solutions that allow the use of different fuels to fulfill the three objective functions.
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