Frontiers of Chemical Science and Engineering

ISSN 2095-0179

ISSN 2095-0187(Online)

CN 11-5981/TQ

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Nanocomposite materials in orthopedic applications
Mostafa R. Shirdar, Nasim Farajpour, Reza Shahbazian-Yassar, Tolou Shokuhfar
Front. Chem. Sci. Eng.    2019, 13 (1): 1-13.   https://doi.org/10.1007/s11705-018-1764-1
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This chapter is an introduction to nanocomposite materials and its classifications with emphasis on orthopedic application. It covers different types of matrix nanocomposites including ceramics, metal, polymer and natural-based nanocomposites with the main features and applications in the orthopedic. In addition, it presents structure, composition, and biomechanical features of bone as a natural nanocomposite. Finally, it deliberately presents developing methods for nanocomposites bone grafting.

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Recent research and development of PLGA/PLA microspheres/nanoparticles: A review in scientific and industrial aspects
Feng Qi, Jie Wu, Hao Li, Guanghui Ma
Front. Chem. Sci. Eng.    2019, 13 (1): 14-27.   https://doi.org/10.1007/s11705-018-1729-4
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Poly(D,L-lactic-co-glycolic acid) (PLGA)/poly(lactic acid) (PLA) microspheres/nanoparticles are one of the most successful drug delivery systems (DDS) in lab and clinic. Because of good biocompatibility and biodegradability, they can be used in various areas, such as long-term release system, vaccine adjuvant, tissue engineering, etc. There have been 15 products available on the US market, but the system still has many problems during development and manufacturing, such as wide size distribution, drug stability issues, and so on. Recently, many new and modified methods have been developed to overcome the above problems. Some of the methods are easy to scale up, and have been available on the market to achieve pilot scale or even industrial production scale. Furthermore, the relevant FDA guidance on the DDS is still incomplete, especially for abbreviated new drug application. In this review, we present some recent achievement of the PLGA/PLA microspheres/nanoparticles, and discuss some promising manufacturing methods. Finally, we focus on the current FDA guidance on the DDS. The review provides an overview on the development of the system in pharmaceutical industry.

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Dendritic BiVO4 decorated with MnOx co-catalyst as an efficient hierarchical catalyst for photocatalytic ozonation
Jin Yang, Xuelian Liu, Hongbin Cao, Yanchun Shi, Yongbing Xie, Jiadong Xiao
Front. Chem. Sci. Eng.    2019, 13 (1): 185-191.   https://doi.org/10.1007/s11705-018-1713-z
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An appropriate co-catalyst can significantly promote the photocatalytic efficacy, but this has been seldom studied in the visible-light photocatalysis combined with ozone, namely photocatalytic ozonation. In this work, a dendritic bismuth vanadium tetraoxide (BiVO4) material composited with highly dispersed MnOx nanoparticles was synthesized, and its catalytic activity is 86.6% higher than bare BiVO4 in a visible light and ozone combined process. Catalytic ozonation experiments, ultra-violet-visible (UV-Vis) diffuse reflectance spectra and photoluminescence spectra jointly indicate that MnOx plays a triple role in this process. MnOx strengthens the light adsorption and promotes the charge separation on the composite material, and it also shows good activity in catalytic ozonation. The key reactive species in this process is ·OH, and various pathways for its generation in this process is proposed. This work provides a new direction of catalyst preparation and pushes forward the application of photocatalytic ozonation in water treatment.

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Anodization of titanium alloys for orthopedic applications
Merve İzmir, Batur Ercan
Front. Chem. Sci. Eng.    2019, 13 (1): 28-45.   https://doi.org/10.1007/s11705-018-1759-y
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In recent years, nanostructured oxide films on titanium alloy surfaces have gained significant interest due to their electrical, catalytic and biological properties. In literature, there is variety of different approaches to fabricate nanostructured oxide films. Among these methods, anodization technique, which allows fine-tuning of oxide film thickness, feature size, topography and chemistry, is one of the most popular approaches to fabricate nanostructured oxide films on titanium alloys, and it has been widely investigated for orthopedic applications. Briefly, anodization is the growth of a controlled oxide film on a metallic component attached to the anode of an electrochemical cell. This review provides an overview of the anodization technique to grow nanostructured oxide films on titanium and titanium alloys and summarizes the interactions between anodized titanium alloy surfaces with cells in terms of cellular adhesion, proliferation and differentiation. It will start with summarizing the mechanism of nanofeatured oxide fabrication on titanium alloys and then switch its focus on the latest findings for anodization of titanium alloys, including the use of fluoride free electrolytes and anodization of 3D titanium foams. The review will also highlight areas requiring further research to successfully translate anodized titanium alloys to clinics for orthopedic applications.

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Structural engineering of transition metal-based nanostructured electrocatalysts for efficient water splitting
Yueqing Wang, Jintao Zhang
Front. Chem. Sci. Eng.    2018, 12 (4): 838-854.   https://doi.org/10.1007/s11705-018-1746-3
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Water splitting is a highly promising approach for the generation of sustainable, clean hydrogen energy. Tremendous efforts have been devoted to exploring highly efficient and abundant metal oxide electrocatalysts for oxygen evolution and hydrogen evolution reactions to lower the energy consumption in water splitting. In this review, we summarize the recent advances on the development of metal oxide electrocatalysts with special emphasis on the structural engineering of nanostructures from particle size, composition, crystalline facet, hybrid structure as well as the conductive supports. The special strategies relay on the transformation from the metal organic framework and ion exchange reactions for the preparation of novel metal oxide nanostructures with boosting the catalytic activities are also discussed. The fascinating methods would pave the way for rational design of advanced electrocatalysts for efficient water splitting.

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Effect of hierarchical ZSM-5 zeolite crystal size on diffusion and catalytic performance of n-heptane cracking
Shuman Xu, Xiaoxiao Zhang, Dangguo Cheng, Fengqiu Chen, Xiaohong Ren
Front. Chem. Sci. Eng.    2018, 12 (4): 780-789.   https://doi.org/10.1007/s11705-018-1733-8
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Hierarchical ZSM-5 zeolite aggregates with different sizes of nanocrystals were synthesized using different amounts of the mesoporogen 3-aminopropyltriethoxysilane. The effect of the crystal size on the catalytic cracking of n-heptane was investigated and the Thiele modulus and effectiveness factor were used to determine the reaction rate-limiting step. The crystal size affected the textual properties of the catalysts but not the acidic properties of the catalysts. The reaction rate was first order with respect to the n-heptane concentration. Cracking over hierarchical zeolites with nanocrystal sizes larger than about 50 nm took place under transition-limiting conditions, whereas the reaction over hierarchical zeolites with nanocrystal sizes of 15 or 30 nm proceeded under reaction control conditions. Hierarchical ZSM-5 zeolite aggregates with smaller nanocrystals had better selectivity for light olefins which can be ascribed to the shorter diffusion path lengths and lower diffusion resistance in these catalysts. Furthermore, these catalysts had lower coking levels which can be attributed to the substantial number of mesopores which prevent the formation of coke precursors.

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Recent advances on metal-free graphene-based catalysts for the production of industrial chemicals
Zhiyong Wang, Yuan Pu, Dan Wang, Jie-Xin Wang, Jian-Feng Chen
Front. Chem. Sci. Eng.    2018, 12 (4): 855-866.   https://doi.org/10.1007/s11705-018-1722-y
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With the development of carbon catalysts, graphene-based metal-free catalysts have drawn increasing attention in both scientific research and in industrial chemical production processes. In recent years, the catalytic activities of metal-free catalysts have significantly improved and they have become promising alternatives to traditional metal-based catalysts. The use of metal-free catalysts greatly improves the sustainability of chemical processes. In view of this, the recent progress in the preparation of graphene-based metal-free catalysts along with their applications in catalytic oxidation, reduction and coupling reactions are summarized in this review. The future trends and challenges for the design of graphene-based materials for industrial organic catalytic reactions with good stabilities and high catalytic performance are also discussed.

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Multivalent manganese oxides with high electrocatalytic activity for oxygen reduction reaction
Xiangfeng Peng, Zhenhai Wang, Zhao Wang, Yunxiang Pan
Front. Chem. Sci. Eng.    2018, 12 (4): 790-797.   https://doi.org/10.1007/s11705-018-1706-y
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A noble-metal-free catalyst based on both Mn3O4 and MnO was prepared by using the dielectric barrier discharge technique at moderate temperature. The prepared catalyst shows a higher electrocatalytic activity towards the oxygen reduction reaction than the catalyst prepared by using the traditional calcination process. The enhanced activity could be due to the coexistence of manganese ions with different valences, the higher oxygen adsorption capacity, and the suppressed aggregation of the catalyst nanoparticles at moderate temperature. The present work would open a new way to prepare low-cost and noble-metal-free catalysts at moderate temperature for more efficient electrocatalysis.

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Bismuth oxide-related photocatalysts in green nanotechnology: A critical analysis
Andrea P. Reverberi, P.S. Varbanov, M. Vocciante, B. Fabiano
Front. Chem. Sci. Eng.    2018, 12 (4): 878-892.   https://doi.org/10.1007/s11705-018-1744-5
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A survey addressing the uses of bismuth oxide in photocatalysis is presented. The richness of literature on such a specific topic proves the growing importance of this compound as a valid tool in pollution abatement and environmental decontamination. Many research groups have focused their activity on how to improve the photocatalytic properties of this semiconductor and several solutions have been adopted in the synthesis method, often based on wet-chemical processes. The impressive development of nanoscience helped in understanding and identifying process variables and operative conditions aiming at optimizing the yield of this promising photocatalytic material in the utilization of solar energy.

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Biomimetic mineralization and cytocompatibility of nanorod hydroxyapatite/graphene oxide composites
Peizhen Duan, Juan Shen, Guohong Zou, Xu Xia, Bo Jin
Front. Chem. Sci. Eng.    2018, 12 (4): 798-805.   https://doi.org/10.1007/s11705-018-1708-9
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Nanorod hydroxyapatite (NRHA)/graphene oxide (GO) composites with weight ratios of 0.4, 1.5, and 5 have been fabricated by a facile ultrasonic-assisted method at room temperature and atmospheric pressure. The chemical structure properties and morphology of the composites were characterized by field emission source scanning electron microscope, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the NRHA/GO composites have an irregular surface with different degree wrinkles and are stable, and NRHA are well combined with GO. In addition, the biomimetic mineralization mechanism of hydroxyapatite on the NRHA/GO composites in simulated body fluid (SBF) is presented. The presence of a bone-like apatite layer on the composite surface indicate that the NRHA/GO composites facilitate the nucleation and growth of hydroxyapatite crystals in SBF for biomimetic mineralization. Moreover, the NRHA-1.5/GO composite and pure GO were cultured with MC3T3-E1 cells to investigate the proliferation and adhesion of cells. In vitro cytocompatibility evaluation demonstrated that the NRHA/GO composite can act as a good template for the growth and adhesion of cells. Therefore, the NRHA/GO composite could be applied as a GO-based, free-template, non-toxic, and bioactive composite to substitute for a damaged or defect bone.

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Sodium cellulose sulfate: A promising biomaterial used for microcarriers’ designing
Qing-Xi Wu, Yi-Xin Guan, Shan-Jing Yao
Front. Chem. Sci. Eng.    2019, 13 (1): 46-58.   https://doi.org/10.1007/s11705-018-1723-x
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Due to a worldwide focus on sustainable materials for human health and economy services, more and more natural renewable biomass are regarded as promising materials that could replace synthetic polymers and reduce global dependence on petroleum resources. Cellulose is known as the most abundant renewable polymer in nature, varieties of cellulose-based products have been developed and have gained growing interest in recent years. In this review, a kind of water-soluble cellulose derivative, i.e., sodium cellulose sulfate (NaCS) is introduced. Details about NaCS’s physicochemical properties like solubility, biocompatibility, biodegradability, degree of substitution, etc. are systematically elaborated. And promising applications of NaCS used as biomaterials for microcarriers’ designing, such as micro-cell-carriers, micro-drug-carriers, etc., are presented.

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Methyl acetate–methanol mixture separation by extractive distillation: Economic aspects
Elena Graczová, Branislav Šulgan, Samuel Barabas, Pavol Steltenpohl
Front. Chem. Sci. Eng.    2018, 12 (4): 670-682.   https://doi.org/10.1007/s11705-018-1769-9
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Methyl acetate is considered low toxicity volatile solvent produced either as a by-product during methanol carbonylation or via acetic acid esterification with methanol. In both cases, pure methyl acetate has to be isolated from the reaction mixture. Simulation of methyl acetate separation from its mixture with methanol by extraction distillation was carried out in ASPEN+ software. In total three case studies were assumed using two different extraction solvents and two solvent regeneration strategies. In case A, novel extraction solvent 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid, was considered. Raw material separation was achieved in an extraction distillation column while the solvent regeneration was accomplished in a second distillation column in this case. In case study B, the same extraction solvent was used; however, its regeneration was carried out in a single-effect evaporator. Dimethyl sulfoxide was the second extraction solvent selected. Its use in methyl acetate-methanol separation is presented in case study C. As high purity of dimethyl sulfoxide was required for the methyl acetate-methanol azeotrope breaking, its regeneration was carried out in the second distillation column only. To simulate the ternary methyl acetate–methanol–extraction solvent mixtures separation, vapor–liquid equilibrium was predicted based on the NRTL equation. Further, unknown properties of the considered ionic liquid and variation of these properties with temperature were predicted and introduced into the ASPEN+ components properties database. Based on these data, optimum operation parameters of the respective separation equipment were established. In all case studies, the same condition had to be fulfilled, namely minimum methyl acetate content in the distillate from the extraction distillation column of 99.5mol-%. Results of simulations using the respective optimum operation parameters were employed in the economic evaluation of the three separation unit designs studied. It was found that the least energy-demanding design corresponds to the case study B in terms of both capital as well as operation expenses.

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Preparation of lignin/TiO2 nanocomposites and their application in aqueous polyurethane coatings
Dongjie Yang, Shengyu Wang, Ruisheng Zhong, Weifeng Liu, Xueqing Qiu
Front. Chem. Sci. Eng.    2019, 13 (1): 59-69.   https://doi.org/10.1007/s11705-018-1712-0
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A simple method using a water soluble lignin quaternary ammonium salt (LQAS) and TiO2 has been developed for the preparation of lignin/TiO2 nanocomposites in an aqueous medium under mild conditions. The LQAS/TiO2 nanocomposites contain well-dispersed small particles with excellent ultraviolet (UV) shielding abilities and good compatibilities with waterborne polyurethane (WPU). When the LQAS/TiO2 nanocomposites were blended with WPU, the UV absorbance and the tensile ductility of the WPU increased significantly. The composite WPU hybrid film containing 6 wt-% LQAS/TiO2 nanocomposite had the highest visible light transmittance and had excellent ultraviolet aging properties. After 192 h of UV light irradiation, the tensile strength of the composite film was above 8 MPa and the elongation at break was 800%. This work highlights new possibilities for the utilization of alkali lignin.

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Self-assembled bright luminescent hierarchical materials from a tripodal benzoate antenna and heptadentate Eu(III) and Tb(III) cyclen complexes
Aramballi J. Savyasachi, David F. Caffrey, Kevin Byrne, Gerard Tobin, Bruno D'Agostino, Wolfgang Schmitt, Thorfinnur Gunnlaugsson
Front. Chem. Sci. Eng.    2019, 13 (1): 171-184.   https://doi.org/10.1007/s11705-018-1762-3
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The europium heptadentate coordinatively unsaturated (Eu(III)) and the terbium (Tb(III)) 1,4,7,10-tetraazacyclododecane (cyclen) complexes 1 and 2 were used in conjunction with ligand 3 (1,3,5-benzene-trisethynylbenzoate) to form the supramolecular self-assembly structures 4 and 5; this being investigated in both the solid and the solution state. The resulting self-assemblies gave rise to metal centered emission (both in the solid and solution) upon excitation of 3, confirming its role as a sensitizing antenna. Drop-cased examples of ligand 3, and the solid forms of 4 and 5, formed from both organic and mixture of organic-aqueous solutions, were analyzed using Scanning Electron Microscopy, which showed significant changes in morphology; the ligand giving rise to one dimensional structures, while both 4 and 5 formed amorphous materials that were highly dense solid networks containing nanoporous features. The surface area (216 and 119 m2·g1 for 4 and 5 respectively) and the ability of these porous materials to capture and store gases such as N2 investigated at 77 K. The self-assembly formation was also investigated in diluted solution by monitoring the various photophysical properties of 3–5. This demonstrated that the most stable structures were that consisting of a single antennae 3 and three complexes of 1 or 2 (e.g., 4 and 5) in solution. By monitoring the excited state lifetimes of the Eu(III) and Tb(III) ions in H2O and D2O respectively, we showed that their hydration states (the q-value) changed from ~2 to 0, upon formation of the assemblies, indicating that the three benzoates of 3 coordinated directly to the each of the three lanthanide centers. Finally we demonstrate that this hierarchically porous materials can be used for the sensing of organic solvents as the emission is highly depended on the solvent environment; the lanthanide emission being quenched in the presence of acetonitrile and THF, but greatly enhanced in the presence of methanol.

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Efficient production of D-1,2,4-butanetriol from D-xylose by engineered Escherichia coli whole-cell biocatalysts
Shewei Hu, Qian Gao, Xin Wang, Jianming Yang, Nana Xu, Kequan Chen, Sheng Xu, Pingkai Ouyang
Front. Chem. Sci. Eng.    2018, 12 (4): 772-779.   https://doi.org/10.1007/s11705-018-1731-x
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We have developed a whole-cell bioconversion system for the production of D-1,2,4-butanetriol (BT) from renewable biomass. A plasmid pETduet-xylB-yjhG-T7-adhP-T7-mdlC was constructed and transformed to Escherichia coli BL21(DE3) to obtain the whole cells of E. coli BL21-XYMA capable of bioconversion D-xylose to BT. Then, the factors including carbon sources, nitrogen sources, metal ions, and culture conditions (pH, temperature, IPTG) were identified, and their effects on the whole-cell activity for BT production were investigated. To obtain the highest whole-cell activity, the optimal cultivation parameters are: 15 g·L1 yeast extract, 5 g·L1 sucrose, 3 g·L1 KH2PO4, 5 g·L1 NaCl, 3 g·L1 NH4Cl, 0.25 g·L1 MgSO4∙7H2O and 1 mL·L1 the mixture of trace elements. With the optimized whole cells of E. coli BL21-XYMA, 60 g·L1 of xylose was converted to 28 g·L1 BT with a molar yield of 66.0%, which is higher than those reported in the biotechnological system.

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Dynamic changes of protein corona compositions on the surface of zinc oxide nanoparticle in cell culture media
Vo-Van Giau, Yoon-Hee Park, Kyu-Hwan Shim, Sang-Wook Son, Seong-Soo A. An
Front. Chem. Sci. Eng.    2019, 13 (1): 90-97.   https://doi.org/10.1007/s11705-018-1766-z
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The potential applications of nanomaterials used in nanomedicine as ingredients in drug delivery systems and in other products continue to expand. When nanomaterials are introduced into physiological environments and driven by energetics, they readily associate proteins forming a protein corona (PC) on their surface. This PC could result in an alteration of the nanomaterial’s surface characteristics, affecting their interaction with cells due to conformational changes in adsorbed protein molecules. However, our current understanding of nanobiological interactions is still very limited. Utilizing a liquid chromatography–mass spectroscopy/mass spectroscopy technology and a Cytoscape plugin (ClueGO) approach, we examined the composition of the PC for a set of zinc oxide nanoparticles (ZnONP) from cell culture media typically and further analyzed the biological interaction of identified proteins, respectively. In total, 36 and 33 common proteins were investigated as being bound to ZnONP at 5 min and 60 min, respectively. These proteins were further analyzed with ClueGO, a Cytoscape plugin, which provided gene ontology and the biological interaction processes of identified proteins. Proteins bound to the surface of nanoparticles that may modify the structure, therefore the function of the adsorbed protein could be consequently affect the complicated biological processes.

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Techno-economic evaluation of a biogas-based oxidative coupling of methane process for ethylene production
Alberto T. Penteado, Mijin Kim, Hamid R. Godini, Erik Esche, Jens-Uwe Repke
Front. Chem. Sci. Eng.    2018, 12 (4): 598-618.   https://doi.org/10.1007/s11705-018-1752-5
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This contribution is a preliminary techno-economic assessment of a biogas-based oxidative coupling of methane (OCM) process. Biogas is frequently utilized as a renewable energy source within small scale combined heat and power plants or as a natural gas substitute. The activation of methane also enables its utilization as a feedstock to produce chemicals. In this sense, the OCM process allows for the direct conversion of methane into ethylene, which is a major building block for the chemical and polymer industries. Biogas resulting from the anaerobic digestion of vinasse, a liquid effluent from bioethanol industry, is treated for contaminant removal and its methane content is converted into ethylene, which is then purified as the main product. The biogas cleaning process is assessed based on literature data, while an experimentally validated simulation model is used to assess the OCM process. A techno-economic evaluation is then performed through a Monte Carlo simulation, wherein uncertain parameters take random values between reasonable bounds. The net present value results positive in 74% of the cases, indicating that the project is profitable under a wide range of scenarios. Some performance improvement opportunities have been identified and highlighted to guide future studies in the topic.

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Purification and concentration of gluconic acid from an integrated fermentation and membrane process using response surface optimized conditions
Parimal Pal, Ramesh Kumar, Subhamay Banerjee
Front. Chem. Sci. Eng.    2019, 13 (1): 152-163.   https://doi.org/10.1007/s11705-018-1721-z
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A response surface method was used to optimize the purification and concentration of gluconic acid from fermentation broth using an integrated membrane system. Gluconobacter oxydans was used for the bioconversion of the glucose in sugarcane juice to gluconic acid (concentration 45 g∙L−1) with a yield of 0.9 g∙g−1. The optimum operating conditions, such as trans-membrane pressure (TMP), pH, cross-flow rate (CFR) and initial gluconic acid concentration, were determined using response surface methodology. Five different types of polyamide nanofiltration membranes were screened and the best performing one was then used for downstream purification of gluconic acid in a flat sheet cross-flow membrane module. Under the optimum conditions (TMP= 12 bar and CFR= 400 L∙h−1), this membrane retained more than 85% of the unconverted glucose from the fermentation broth and had a gluconic acid permeation rate of 88% with a flux of 161 L∙m−2∙h−1. Using response surface methods to optimize this green nanofiltration process is an effective way of controlling the production of gluconic acid so that an efficient separation with high flux is obtained.

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Steps of fronts in chemical engineering: An overview of the publications of FCSE
Xiaowen Zhu, Yaodong Huang, Jing-Kang Wang
Front. Chem. Sci. Eng.    2018, 12 (4): 593-597.   https://doi.org/10.1007/s11705-018-1789-5
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Accounting for local features of fouling formation on PHE heat transfer surface
Petro Kapustenko, Jiří J. Klemeš, Olga Arsenyeva, Olexandr Matsegora, Oleksandr Vasilenko
Front. Chem. Sci. Eng.    2018, 12 (4): 619-629.   https://doi.org/10.1007/s11705-018-1736-5
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The fouling phenomena can create significant operational problems in the industry by deteriorating heat recuperation, especially in heat exchangers with enhanced heat transfer. For a correct prediction of fouling development, the reliable fouling models must be used. The analysis of existing fouling models is presented. The chemical reaction and transport model developed earlier for a description of fouling on intensified heat transfer surfaces is used for modeling of plate heat exchanger (PHE) subjected to fouling. The mathematical model consists of a system of differential and algebraic equations. The integration of it is performed by finite difference method with developed software for personal computer. For countercurrent streams arrangement in PHE the solution of two-point boundary problem is realized on every time step. It enables to estimate local parameters of heat transfer process with fouling formation and its development in time with the growth of deposited fouling layer. Two examples of model application in cases of PHEs working at sugar factory and in district heating network are presented. The comparison with experimental data confirmed the model validity and the possibility of its application to determine the performance of PHE subjected to fouling.

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A free-standing superhydrophobic film for highly efficient removal of water from turbine oil
Fan Shu, Meng Wang, Jinbo Pang, Ping Yu
Front. Chem. Sci. Eng.    2019, 13 (2): 393-399.   https://doi.org/10.1007/s11705-018-1754-3
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A free-standing superhydrophobic film is prepared by sequentially dip-coating a commercially available filter paper with nano SiO2 suspension, epoxy emulsion, and octyltrimethoxysilane solution. A surface with micro- or nano-roughness is formed because SiO2 nanoparticles are uniformly and firmly adhered on the backbone of the filter paper by the cured epoxy resin. Furthermore, the surface energy is significantly reduced because of introducing octytrimethoxysilane. Such a surface structure makes the prepared film a superhydrophobic material. Due to its free-standing nature, this superhydrophobic film can be used to remove water from turbine oil by filtration. The efficiency of water removal is high (up to 94.1%), and the filtration process is driven solely by gravity without extra energy consumption. Because of the facile fabrication process and the high efficiency of water removal, this free-standing superhydrophobic film may find application in power industry.

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Effect of adding a smart potassium ion-responsive copolymer into polysulfone support membrane on the performance of thin-film composite nanofiltration membrane
Meibo He, Zhuang Liu, Tong Li, Chen Chen, Baicang Liu, John C. Crittenden
Front. Chem. Sci. Eng.    2019, 13 (2): 400-414.   https://doi.org/10.1007/s11705-018-1757-0
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Thin-film composite (TFC) nanofiltration (NF) membranes were fabricated via the interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricarbonyl trichloride on polysulfone (PSf) support membranes blended with K+-responsive poly(N-isopropylacryamide-co-acryloylamidobenzo-15-crown-5) (P(NIPAM-co-AAB15C5)). Membranes were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, scanning electron microscope, contact angle, and filtration tests. The results showed that: (1) Under K+-free conditions, the blended P(NIPAM-co-AAB15C5)/PSf supports had porous and hydrophilic surfaces, thereby producing NF membranes with smooth surfaces and low MgSO4 rejections; (2) With K+ in the PIP solution, the surface roughness and water permeability of the resultant NF membrane were increased due to the K+-induced transition of low-content P(NIPAM-co-AAB15C5) from hydrophilic to hydrophobic; (3) After a curing treatment at 95 °C, the improved NF membrane achieved an even higher pure water permeability of 10.97 L·m−2·h−1·bar−1 under 200 psi. Overall, this study provides a novel method to improve the performance of NF membranes and helps understand the influence of supports on TFC membranes.

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Intrinsic kinetics and external diffusion of catalytic steam gasification of fine coal char particles under pressurized and fluidized conditions
Xuantao Wu, Jie Wang
Front. Chem. Sci. Eng.    2019, 13 (2): 415-426.   https://doi.org/10.1007/s11705-018-1725-8
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Catalytic steam gasification of fine coal char particles was carried out using a self-made laboratory reactor to determine the intrinsic kinetics and external diffusion under varying pressures (0.1–0.5 MPa) and superficial gas flow velocities (GFVs) of 13.8– 68.8 cm∙s−1. In order to estimate the in-situ gas release rate at a low GFV, the transported effect of effluent gas on the temporal gasification rate pattern was simulated by the Fluent computation and verified experimentally. The external mass transfer coefficients (kmam) and the effectiveness factors were determined at lower GFVs, based on the intrinsic gasification rate obtained at a high GFV of 55.0 cm∙s–1. The kmam was found to be almost invariable in a wider carbon conversion of 0.2–0.7. The variations of kmam at a median carbon conversion with GFV, temperature and pressure were found to follow a modified Chilton-Colburn correlation: Sh=0.311Re2.83Sc13(PP0)2.07 (0.04<Re<0.19), where P is total pressure and P0 is atmospheric pressure. An intrinsic kinetics/external diffusion integrating model could well describe the gasification rate as a function of GFV, temperature and pressure over a whole gasification process.

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Detoxification and concentration of corn stover hydrolysate and its fermentation for ethanol production
Qing Li, Yingjie Qin, Yunfei Liu, Jianjun Liu, Qing Liu, Pingli Li, Liqiang Liu
Front. Chem. Sci. Eng.    2019, 13 (1): 140-151.   https://doi.org/10.1007/s11705-018-1714-y
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Environmental and energy concerns have increased interest in renewable energy sources, particularly biofuels. Thus the fermentation of glucose from sulfuric acid-hydrolyzed corn stover for the production of bioethanol has been explored using a combined acid retardation and continuous-effect membrane distillation treatment process. This process resulted in the separation of the sugars and acids from the acid-catalyzed hydrolysate, the removal of most of the fermentation inhibitors from the hydrolysate and the concentration of the detoxified hydrolysate. The recovery rate of glucose from the sugar-acid mixture using acid retardation was greater than 99.12% and the sulfuric acid was completely recovered from the hydrolysate. When the treated corn stover hydrolysate, containing 100 g/L glucose, was used as a carbon source, 43.06 g/L of ethanol was produced with a productivity of 1.79 g/(L∙h) and a yield of 86.31%. In the control experiment, where glucose was used as the carbon source these values were 1.97 g/(L∙h) and 93.10% respectively. Thus the integration of acid retardation and a continuous-effect membrane distillation process are effective for the production of fuel ethanol from corn stover.

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Automated retrofit targeting of heat exchanger networks
Timothy G. Walmsley, Nathan S. Lal, Petar S. Varbanov, Jiří J. Klemeš
Front. Chem. Sci. Eng.    2018, 12 (4): 630-642.   https://doi.org/10.1007/s11705-018-1747-2
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The aim of this paper is to develop a novel heat exchanger network (HEN) retrofit method based on a new automated retrofit targeting (ART) algorithm. ART uses the heat surplus-deficit table (HSDT) in combination with the Bridge Retrofit concepts to generate retrofit bridges option, from which a retrofit design may be formulated. The HSDT is a tabular tool that shows potential for improved re-integration of heat source and sink streams within a HEN. Using the HSDT, retrofit bridges—a set of modifications that links a cooler to a heater to save energy—may be identified, quantified, and compared. The novel retrofit method including the ART algorithm has been successfully implemented in Microsoft ExcelTM to enable analysis of large-scale HENs. A refinery case study with 27 streams and 46 existing heat exchangers demonstrated the retrofit method’s potential. For the case study, the ART algorithm found 68903 feasible unique retrofit opportunities with a minimum 400 kW·unit−1 threshold for heat recovery divided by the number of new units. The most promising retrofit project required 3 new heat exchanger units to achieve a heat savings of 4.24 MW with a favorable annualised profit and a reasonable payback period.

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Greenhouse gas emissions from thermal treatment of non-recyclable municipal waste
Tomáš Ferdan, Martin Pavlas, Vlastimír Nevrlý, Radovan Šomplák, Petr Stehlík
Front. Chem. Sci. Eng.    2018, 12 (4): 815-831.   https://doi.org/10.1007/s11705-018-1761-4
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This paper analyses factors affecting the production of greenhouse gases from the treatment of residual municipal waste. The analysis is conducted so that the environmentally-friendly decision-making criteria may be later implemented into an optimisation task, which allocates waste treatment capacities. A simplified method of life cycle assessment is applied to describe environmental impact of the allocation. Global warming potential (GWP) is employed as a unit to quantify greenhouse gases (GHG) emissions. The objective is to identify the environmental burdens and credits measured by GWP for the three fundamental methods for treatment of residual waste unsuitable for material recovery. The three methods are waste-to-energy (WTE), landfilling and mechanical-biological treatment (MBT) with subsequent utilization of refuse-derived fuel. The composition of the waste itself and content of fossil-derived carbon and biogenic carbon are important parameters to identify amounts of GHG. In case of WTE, subsequent use of the energy, e.g., in district heating systems in case of heat, is another important parameter to be considered. GWP function dependant on WTE capacity is introduced. The conclusion of this paper provides an assessment of the potential benefits of the results in optimisation tasks for the planning of overall strategy in waste management.

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Preparation of copolymer-grafted mixed-mode resins for immunoglobulin G adsorption
Shenggang Chen, Tao Liu, Ruiqi Yang, Dongqiang Lin, Shanjing Yao
Front. Chem. Sci. Eng.    2019, 13 (1): 70-79.   https://doi.org/10.1007/s11705-018-1745-4
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The mixed-mode resins for protein adsorption have been prepared by a novel strategy, copolymer grafting. Specially, the copolymer-grafted resins CG-M-A with two functional groups, 5-amino-benzimidazole (ABI) and methacryloxyethyltrimethyl ammonium chloride (METAC), have been prepared through surface-initiated activator generated by electron transfer for atom transfer radical polymerization of METAC and glycidyl methacrylate (GMA), followed by a ring-open reaction to introduce ABI. The charge and hydrophobicity of CG-M-A resins could be controlled by manipulating the addition of METAC and GMA/ABI. Besides, METAC and ABI provided positive effects together in both protein adsorption and elution: dynamic binding capacity of human Immunoglobulin G (hIgG) onto CG-M-A resin with the highest ligand ratio of METAC to ABI is 46.8 mg·g1 at pH 9 and the elution recovery of hIgG is 97.0% at pH 5. The separation experiment showed that purity and recovery of monoclonal antibody from cell culture supernatant are 96.0% and 86.5%, respectively, indicating that copolymer-grafted mixed-mode resins could be used for antibody purification.

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Kinetic-compartmental modelling of potassium-containing cellulose feedstock gasification
Attila Egedy, Lívia Gyurik, Tamás Varga, Jun Zou, Norbert Miskolczi, Haiping Yang
Front. Chem. Sci. Eng.    2018, 12 (4): 708-717.   https://doi.org/10.1007/s11705-018-1767-y
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Biomass is of growing interest as a secondary energy source and can be converted to fuels with higher energy density especially by pyrolysis or gasification. Understanding the mechanism and the kinetics of biomass pyrolysis (thermal decomposition) and gasification (conversion of organic material to gases) could be the key to the design of industrial devices capable of processing vast amounts of biomass feedstock. In our work real product components obtained in pyrolysis were took into consideration as well as char and oil as lumped components, and the kinetic constants for a biomass model compound (cellulose) pyrolysis and gasification were identified based on a proposed simplified reaction mechanism within a compartment model structure. A laboratory scale reactor was used for the physical experiments containing consecutive fast pyrolysis and gasification stages using alkali metal (K) containing feedstock, which has a significant effect on the cellulose pyrolysis and gasification. The detailed model was implemented in MATLAB/Simulink environment, and the unknown kinetic parameters were identified based on experimental data. The model was validated based on measurement data, and a good agreement was found. Based on the validated first principle model the optimal parameters were determined as 0.15 mL/min steam flow rate, and 4% K content.

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Effect of incorporating Elaeagnus angustifolia extract in PCL-PEG-PCL nanofibers for bone tissue engineering
Vahideh R. Hokmabad, Soodabeh Davaran, Marziyeh Aghazadeh, Effat Alizadeh, Roya Salehi, Ali Ramazani
Front. Chem. Sci. Eng.    2019, 13 (1): 108-119.   https://doi.org/10.1007/s11705-018-1742-7
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Plants have been used for medicinal purposes for thousands of years but they are still finding new uses in modern times. For example, Elaeagnus angustifolia (EA) is a medicinal herb with antinociceptive, anti-inflammatory, antibacterial and antioxidant properties and it is widely used in the treatment of rheumatoid arthritis and osteoarthritis. EA extract was loaded onto poly(ϵ-caprolactone)-poly(ethylene glycol)-poly(ϵ-caprolactone) (PCL-PEG-PCL/EA) nanofibers and their potential applications for bone tissue engineering were studied. The morphology and chemical properties of the fibers were evaluated using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, contact angle measurements and mechanical tests. All the samples had bead-free morphologies with average diameters ranging from 100 to 200 nm. The response of human cells to the PCL-PEG-PCL/EA nanofibers was evaluated using human dental pulp stem cells (hDPSCs). The hDPSCs had better adhesion and proliferation capacity on the EA loaded nanofibers than on the pristine PCL-PEG-PCL nanofibers. An alizarin red S assay and the alkaline phosphatase activity confirmed that the nanofibrous scaffolds induced osteoblastic performance in the hDPSCs. The quantitative real time polymerase chain reaction results confirmed that the EA loaded nanofibrous scaffolds had significantly upregulated gene expression correlating to osteogenic differentiation. These results suggest that PCL-PEG-PCL/EA nanofibers might have potential applications for bone tissue engineering.

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Fabrication of high-capacity cation-exchangers for protein adsorption: Comparison of grafting-from and grafting-to approaches
Ming Zhao, Run Liu, Jian Luo, Yan Sun, Qinghong Shi
Front. Chem. Sci. Eng.    2019, 13 (1): 120-132.   https://doi.org/10.1007/s11705-018-1730-y
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In this work, we have synthesized two polymer-grafted cation exchangers: one via the grafting-from approach, in which sulfopropyl methacrylate (SPM) is grafted through atom transfer radical polymerization onto Sepharose FF (the thus resulting exchanger is referred as Sep-g-SPM), and another via the grafting-to approach, in which the polymer of SPM is directly coupled onto Sepharose FF (the thus resulting exchanger is called as Sep-pSPM). Protein adsorption on these two cation exchangers have been also investigated. At the same ligand density, Sep-g-SPM has a larger accessible pore radius and a smaller depth of polymer layer than Sep-pSPM, due to the controllable introduction of polymer chains with the regular distribution of the ligand. Therefore, high-capacity adsorption of lysozyme and γ-globulin could be achieved simultaneously in Sep-g-SPM with an ionic capacity (IC) of 308 mmol·L1. However, Sep-pSPM has an irregular chain distribution and different architecture of polymer layer, which lead to more serious repulsive interaction to proteins, and thus Sep-pSPM has a lower adsorption capacity for γ-globulin than Sep-g-SPM with the similar IC. Moreover, the results from protein uptake experiments indicate that the facilitated transport of adsorbed γ-globulin occurs only in Sep-pSPM and depends on the architecture of polymer layers. Our research provides a clear clue for the development of high-performance protein chromatography.

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