Please wait a minute...
[an error occurred while processing this directive]
Table of Content
28 October 2020, Volume 28 Issue 10
    Recent progress in enzymatic functionalization of carbon-hydrogen bonds for the green synthesis of chemicals
    Zheyu Wang, Yupei Jian, Yilei Han, Zhongwang Fu, Diannan Lu, Jianzhong Wu, Zheng Liu
    2020, 28(10):  2499-2506.  doi:10.1016/j.cjche.2020.06.040
    Abstract ( 291 )   PDF (2125KB) ( 220 )  
    References | Related Articles | Metrics
    Enzymatic reactions take place with high chemo-, regio-, and stereo-selectivity, appealing for the direct functionalization of abundant and inexpensive compounds with C-H bonds to make fine chemicals such as high-value intermediates and pharmaceuticals. This review summarizes recent progress in the enzymatic functionalization of C-H bonds with an emphasis on heme enzymes such as cytochrome P450s, chloroperoxidase and unspecific peroxygenases. Specific examples are discussed to elucidate the applications of the molecular and process engineering approaches to overcome the challenges hindering enzymatic C-H functionalization. Also discussed is the recent development of the chemo-enzymatic cascade as an effective way to integrate the power of metal catalysis and enzymatic catalysis for C-H functionalization.
    Fluid Dynamics and Transport Phenomena
    Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing
    Yazhao Liu, Zhi hao Li, Guangwen Chu, Lei Shao, Yong Luo, Jianfeng Chen
    2020, 28(10):  2507-2512.  doi:10.1016/j.cjche.2020.06.038
    Abstract ( 350 )   PDF (1075KB) ( 158 )  
    References | Related Articles | Metrics
    A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid-solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid-solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid-solid mass transfer coefficient (kLS) have been investigated. The correlation for predicting kLS was proposed, and the deviation between the experimental and predicted values was within ±12%. The liquid-solid volumetric mass transfer coefficient (kLSaLS) ranged from 0.04-0.14 1-1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.
    Separation Science and Engineering
    Effects of a novel bimetallic catalytic biofilter-based pretreatment technique on the form of ultrafiltration membrane fouling
    Songze Hao, Xuehui Zhao, Hongwei Zhang, Yun Wu, Cheng Fang, Xujia Wang
    2020, 28(10):  2513-2522.  doi:10.1016/j.cjche.2020.03.015
    Abstract ( 190 )   PDF (4216KB) ( 71 )  
    References | Related Articles | Metrics
    Pretreatments of influents using bimetallic catalytic biofilter (BC-biofilter) can help reduce transmembrane pressures. For ultrafiltration membranes coupled with a conventional biofilter pretreatment, the cake layer resistance accounts for 25.0% of the total resistance. However, for those coupled with BC-biofilter pretreatment, the cake layer resistance accounts only for 12.5% of the total resistance. Confocal laser scanning microscopy is employed to determine the porosity of cake layer. It is found that ultrafiltration membranes with BC-biofilter pretreatment show a cake layer porosity of up to 0.56 or greater, whereas those with a conventional biofilter pretreatment exhibit a cake layer porosity of only 0.36. This is because micro-flocculation occurs in the effluents of BC-biofilter. The flocs generated through flocculation deposit on membrane surfaces to create highly porous cake layer. Moreover, catalytic reduction can increase the zeta potentials of the biofilter effluents. This makes the deposition of colloidal particles and flocs on membrane surfaces difficult under electrostatic repulsion. Simultaneously, micro-flocculation after BC-biofilter pretreatment can remove colloidal particles with particle sizes of 200-350 nm in water. This can effectively prevent the blockage of ultrafiltration membrane pores. Furthermore, compared to conventional biofilter, BC-biofilter pretreatment can more effectively reduce the number of colloidal particles and the van der Waals forces of ultrafiltration membranes. They can also change the action directions of electric double layers and thereby mitigate ultrafiltration membrane fouling.
    Gas-liquid-liquid extraction in a novel rotating microchannel extractor
    Rui Ma, Chunxin Fan, Yubin Wang, Jianhong Luo, Jun Li, Sridhar Komarneni
    2020, 28(10):  2523-2532.  doi:10.1016/j.cjche.2020.05.025
    Abstract ( 175 )   PDF (7249KB) ( 115 )  
    References | Related Articles | Metrics
    In this work, a novel rotating microchannel extractor (RME) is designed and further used for the extraction of chromium (III) from water. Unexpectedly, the micro-extraction had the same effect as carrying out 2.9-stage cross-flow extractions. Various factors, including the gas intake methods, gas intake quantity (Qg), distance between inner rotor and outer wall (D), rotational inner rotor speed (R) and volumetric flow rate (Qa, Qo), were selected to investigate their effect on the extraction efficiency (η) thoroughly. The relation map of η with Wea and Weo-g for RME provides a comprehension for the gas-liquid-liquid extraction process in this RME system.
    TiO2-incorporated polyelectrolyte composite membrane with transformable hydrophilicity/hydrophobicity for nanofiltration separation
    Yahua Lu, Zhenping Qin, Naixin Wang, Hongxia Guo, Quanfu An, Yucang Liang
    2020, 28(10):  2533-2541.  doi:10.1016/j.cjche.2020.06.029
    Abstract ( 154 )   PDF (5387KB) ( 54 )  
    References | Related Articles | Metrics
    The wettability of the membrane surface has shown obvious influent on the separation performance of the membrane. In this work, a hydrophilic PDA-[PDDA/TiO2]+Cl- membrane was prepared by a one-step codeposition of poly(diallyldimethylammonium chloride) (PDDA) polyelectrolyte solution containing positively charged TiO2@ PDDA nanoparticles with the assistance of dopamine (DA). Such positively charged membrane can be transformed into a hydrophobic membrane PDA-[PDDA/TiO2]+PFO- via the counterion exchange between Cl- and PFO- (perfluorooctanoate). The transformation between hydrophilicity and hydrophobicity is reversible. For both hydrophilic and hydrophobic membranes, the nanofiltration performances were respectively investigated by the aqueous solution and ethanol solution of dyes including methyl blue (MB), Congo red (CR) and Evans blue (EB), and as well metal salt aqueous solution. The consecutive running stability and anti-fouling performance of both hydrophilic and hydrophobic membranes were explored. The results revealed that both membranes showed high nanofiltration performances for retention of dyes in (non)aqueous solution. For the hydrophilic membrane, the rejection of salts in a sequence is MgSO4 > Na2SO4 > MgCl2 > NaCl. Moreover, both
    Catalysis, Kinetics and Reaction Engineering
    Highly dispersed metal incorporated hexagonal mesoporous silicates for catalytic cyclohexanone oxidation to adipic acid
    Wenjuan Yan, Wenxiang Zhang, Qi Xia, Shuaishuai Wang, Shuxia Zhang, Jian Shen, Xin Jin
    2020, 28(10):  2542-2548.  doi:10.1016/j.cjche.2020.04.013
    Abstract ( 228 )   PDF (1645KB) ( 111 )  
    References | Related Articles | Metrics
    Adipic acid is a dicarboxylic acid of great industrial importance, mainly used in the production of nylon-6,6 and polyurethane. The use of nitric acid as an oxidant in the industrial production of adipic acid poses significant carbon footprint to the environment. Clean adipic acid synthesis methods using a heterogeneous catalyst with H2O2 as oxidant and water as solvent have potential advantages of low catalyst cost, easy synthesis and recovery, cleanness and environmental protection. In this work, hexagonal mesoporous silicate materials were synthesized by a sol-gel method and evaluated for cyclohexanol/cyclohexanone oxidation to adipic acid. The physical and chemical properties of Fe-HMS were characterized by XRD, HR-TEM, BET and UV-Vis. The experimental results showed that Fe-HMS materials show pore sizes ranging from 2-3 nm. W- and Mo-based polyoxometalates were also evaluated and compared to the Fe-based HMS catalysts. To improve the adipic acid yield, the influence of the transition metal as well as the effect of metal loading, reaction temperature and catalyst amount on the catalytic performances of Fe-HMS have been investigated in details. When Si/Fe atomic ratio = 100, Fe-HMS catalyst shows the highest activity, with a cyclohexanone conversion of 92.3% and adipic acid selectivity of 29.4%. The reaction pathway of cyclohexanone oxidation was further proposed based on experimental data.
    An experimental study of electroreduction of CO2 to HCOOH on SnO2/C in presence of alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) and anions (HCO3-, Cl-, Br- and I-)
    Qi Zhang, Xiaolin Shao, Jin Yi, Yuyu Liu, Jiujun Zhang
    2020, 28(10):  2549-2554.  doi:10.1016/j.cjche.2020.04.015
    Abstract ( 240 )   PDF (2302KB) ( 115 )  
    References | Related Articles | Metrics
    It is well-known that the electrolytes can influence the electrochemical reduction of carbon dioxide (ERCO2) in aqueous media. In this work, we explore the effects of alkali metal cations and anions (Li+, Na+, K+, Rb+, Cs+, HCO3-, Cl-, Br-, I-) on the current density and product selectivity for the ERCO2 into formic acid (HCOOH) on the SnO2/carbon paper (SnO2/C) electrode. Results of the ERCO2 experiments show that for the cations, the promotion effects on current density and faradaic efficiencies (FEs) are in the order of Li+ < Na+ < K+ < Cs+ < Rb+. For the anions, the current density values are in the order of NaHCO3 < NaCl < NaBr < NaI and KHCO3 < KCl ≈ KI < KBr, respectively, and that on the FEs for the formation of the HCOOH (FEHCOOH) is HCO3- < Cl- < Br- < I-. Based on this result, the effects of alkali metal cations and anions on ERCO2 are discussed.
    Green bio-synthesis of Ni/montmorillonite nanocomposite using extract of Allium jesdianum as the nano-catalyst for electrocatalytic oxidation of methanol
    Mohammad Hossein Sheikh-Mohseni, Sajjad Sedaghat, Pirouz Derakhshi, Aliakbar Safekordi
    2020, 28(10):  2555-2565.  doi:10.1016/j.cjche.2020.04.017
    Abstract ( 255 )   PDF (6737KB) ( 134 )  
    References | Related Articles | Metrics
    In this work, synthesis of Ni nanoparticles was carried out successfully by water extract of Allium jesdianum as a biochemical reducing agent in the presence of montmorillonite clay (MMT) as a natural solid support for the first time. Then the electrochemical activity of the synthesized nanocomposite was investigated in methanol electrocatalytic oxidation. MMT with high cation exchange capacity and nano layer structure was exposed to ion exchange conditions in nickel solution. Then Ni2+ ion exchanged form was used in this process as a source of ions and also capping agent. Water extract of Allium jesdianum used as a reducing agent due to abundant availability of phenolic and flavonoid contents. The synthesized Ni/MMT nanocomposite was characterized using UV-Vis spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX). The surface of prepared modified electrode has been characterized using SEM to evaluate the morphology, showing uniform dispersion of Ni nanoparticles with mean diameter of 12 to 20 nm. The modified carbon paste electrode was then used in methanol electrocatalytic oxidation reaction. Methanol oxidation on the proposed modified electrode surface occurs at 0.6 V and 0.3 V in alkaline and acidic medium respectively. Also, the results showed the better performance of modified electrode toward methanol electrocatalytic oxidation in comparison with carbon paste electrode that is modified by ion exchanged MMT. Charge transfer coefficients and apparent charge transfer rate constant for the modified electrode in the absence of methanol in alkaline medium were respectively found as: αa = 0.53, αc = 0.37 and ks = 1.6×10-1 s-1. Also, the average value of catalytic rate constant for the electrocatalytic oxidation of methanol by the prepared nano-catalyst was estimated to be about 0.9 L·mol-1·s-1 by chronoamperometry technique. The prepared electrode was also effective for electrocatalytic oxidation of ethanol and formaldehyde in alkaline medium.
    Selective catalytic hydrogenation of naphthalene to tetralin over a NiMo/Al2O3 catalyst
    Xiaoping Su, Pu An, Junwen Gao, Rucheng Wang, Yujuan Zhang, Xi Li, Yangkun Zhao, Yongqi Liu, Xiaoxun Ma, Ming Sun
    2020, 28(10):  2566-2576.  doi:10.1016/j.cjche.2020.05.010
    Abstract ( 282 )   PDF (9992KB) ( 191 )  
    References | Related Articles | Metrics
    The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated. A series of Al2O3 catalysts containing different active metals (Co, Mo, Ni, W) were prepared by incipient wetness impregnation. The effects of different active metals forms (oxidation, reduction, sulfuration) and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD, XPS, BET, NH3- TPD and SEM. Especially, Ni-Mo/Al2O3 was first used in this reactive system. The results show that the oxidative 4%NiO-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin. The conversion of naphthalene and the selectivity of tetralin can reach 95.62% and 99.75% respectively at 200 ℃, 8 h and 6 MPa. Compared with reduced and sulfureted 4%NiO-20%MoO3/Al2O3 catalysts, oxidative 4%NiO-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals, larger pore volume and size, and larger total acidity. NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.
    Direct synthesis of hydrogen peroxide over Pd nanoparticles embedded between HZSM-5 nanosheets layers
    Guozhu Liu, Hairui Liang, Yajie Tian, Bofeng Zhang, Li Wang
    2020, 28(10):  2577-2586.  doi:10.1016/j.cjche.2020.05.013
    Abstract ( 177 )   PDF (2970KB) ( 62 )  
    References | Related Articles | Metrics
    Direct synthesis of hydrogen peroxide (DSHP) was studied over Pd loaded on HZSM-5 nanosheets (Pd/ZN). Pd nanoparticles with average size of ca. 4.3 nm were introduced into the adjacent nanosheet layers (thickness of ca. 2.9 nm) by impregnation method. Pd/ZN with theoretical Si/Al molar ratio of 25 showed the highest selectivity for H2O2 among the prepared catalysts, together with highest formation rate of H2O2 (38.0 mmol·(g cat)-1·h-1), 1.9 times than that of Pd supported on conventional HZSM-5 zeolite (Pd/CZ-50). Better catalytic performance of nanosheet catalysts was attributed to the promoted Pd dispersion which promoted H2 dissociation, more Brønsted acid sites and stronger metal-support interaction which inhibited the dissociation of O-O bond in H2O2. The embedded structure sufficiently protected the Pd nanoparticles by space confinement which restrained the Pd leaching, leading to a better catalytic stability with 90% activity retained after 3 cycles, which was almost 3 times than that of Pd/CZ-50 (30.4% activity retained).
    Industrial TiO2 based nacreous pigments as functional building materials: Photocatalytic removal of NO
    Jue Li, Li Wang, Chunqiu Han, Fengyun Su, Yumin Leng, Liqun Ye
    2020, 28(10):  2587-2591.  doi:10.1016/j.cjche.2020.05.029
    Abstract ( 247 )   PDF (2559KB) ( 73 )  
    References | Related Articles | Metrics
    In this paper, the photocatalytic activity of industrial titanium dioxide (TiO2) based nacreous pigments was researched as functional building materials for photocatalytic NO remove. Three industrial TiO2 based nacreous pigments were selected to estimate the photocatalytic activity for NO remove. This study is a good proof that pearlescent pigments can eliminate NO, and its performance is positively correlated with its titanium dioxide content. And this research will widen the application of nacreous pigments in functional building materials, and provide a new way to eliminate in door nitric oxide pollution.
    Effect of Zr-doping on Pd/CexZr1-xO2 catalysts for oxidative carbonylation of phenol
    Lichao Zhou, Gang Feng, Xiaojing Liu, Zhimiao Wang, Fang Li, Wei Xue, Yanji Wang
    2020, 28(10):  2592-2599.  doi:10.1016/j.cjche.2020.05.034
    Abstract ( 316 )   PDF (2338KB) ( 115 )  
    References | Related Articles | Metrics
    Ce-Zr solid solution (CexZr1-xO2, CZO) was prepared by the citric acid sol-gel method. The CZO was then used as a support for Pd/CZO catalysts for the oxidative carbonylation of phenol to diphenyl carbonate. The Pd/CZO catalyst showed enhanced activity and diphenyl carbonate selectivity compared with the Pd/CeO2 catalyst. The catalytic performance of Pd/CZO was influenced by the calcination temperature of the CZO support. X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption measurements, X-ray photoelectron spectroscopy and H2 temperature-programmed reduction measurements were used to investigate the effects of Zr doping and calcination temperature. The catalytic performance of Pd/CZO and Pd/CeO2 for the oxidative carbonylation of phenol was affected by several factors, including the specific surface area, Ce3+ and/or oxygen vacancy content, oxygen species type and Pd(II) content of the catalyst. All these properties were influenced by Zr doping and the calcination temperature of the CZO support.
    Phenol hydrogenation to cyclohexanone over palladium nanoparticles loaded on charming activated carbon adjusted by facile heat treatment
    Chunhua Zhang, Guangxin Yang, Hong Jiang, Yefei Liu, Rizhi Chen, Weihong Xing
    2020, 28(10):  2600-2606.  doi:10.1016/j.cjche.2020.06.005
    Abstract ( 194 )   PDF (1622KB) ( 146 )  
    References | Related Articles | Metrics
    Selective phenol hydrogenation is a green approach to produce cyclohexanone. It still remains a big challenge to prepare efficient supports of the catalysts for the phenol hydrogenation via a simple and cost-effective approach. Herein, a facile approach was developed, i.e., direct calcination of activated carbon (AC) under argon at high temperature, to improve its structure and surface properties. The modified AC materials were supported with Pd nanoparticles (NPs) to fabricate the Pd/C catalysts. The as-prepared Pd/C600 catalyst exhibits superior catalytic performance in the phenol hydrogenation, and its turnover frequency (TOF) value is 199.2 h-1, 1.31 times to that of Pd/C-raw. The Pd/C600 catalyst presents both better hydrophobicity and more structural defects, contributing to the improved dispersibility in the reaction solution (phenol-cyclohexane), the better Pd dispersion and the smaller Pd size, which result in the enhancement of the catalytic performance. Furthermore, the as-prepared Pd/C600 catalyst shows a good recyclability.
    Process Systems Engineering and Process Safety
    A modified active disturbance rejection control for a wastewater treatment process
    Wei Wei, Pengfei Xia, Zaiwen Liu, Min Zuo
    2020, 28(10):  2607-2619.  doi:10.1016/j.cjche.2020.06.032
    Abstract ( 174 )   PDF (1426KB) ( 123 )  
    References | Related Articles | Metrics
    Waste water treatment process (WWTP) control has been attracting more and more attention. However, various undesired factors, such as disturbance, uncertainties, and strong nonlinear couplings, propose big challenges to the control of a WWTP. In order to improve the control performance of the closed-loop system and guarantee the discharge requirements of the effluent quality, rather than take the model dependent control approaches, an active disturbance rejection control (ADRC) is utilized. Based on the control signal and system output, a phase optimized ADRC (POADRC) is designed to control the dissolved oxygen and nitrate concentration in a WWTP. The phase advantage of the phase optimized extended state observer (POESO), convergence of the POESO, and stability of the closed-loop system are analyzed from the theoretical point of view. Finally, a commonly accepted benchmark simulation model no. 1. (BSM1) is utilized to test the POESO and POADRC. Linear active disturbance rejection control (LADRC) and the suggested proportion-integration (PI) control are taken to make a comparative research. Both system responses and performance index values confirm the advantage of the POADRC over the LADRC and the suggested PI control. Numerical results show that, as a result of the leading phase of the total disturbance estimation, the POESO based POADRC is an effective and promising way to control the dissolved oxygen and nitrate concentration so as to ensure the effluent quality of a WWTP.
    Chemical Engineering Thermodynamics
    Experimental measurement and correlation of solubility of β-carotene in pure and ethanol-modified subcritical water
    Hadi Share Mohammadi, Ali Haghighi Asl, Maryam Khajenoori
    2020, 28(10):  2620-2625.  doi:10.1016/j.cjche.2020.07.006
    Abstract ( 157 )   PDF (1134KB) ( 173 )  
    References | Related Articles | Metrics
    For the first time, the solubility of β-carotene in pure and ethanol-modified subcritical water (SW) using the static method was determined. The experimental runs were performed at a temperature ranging from 298.15 to 403.15 K and 0-10% (w/w) of ethanol as a modifier at a constant pressure of 5 MPa. Samples were analyzed by UV-vis spectrophotometer. The solubility of β-carotene was found to range from 1.084×10-8 to 227.1×10-8 mol fractions in the subcritical water in above mentioned conditions. The obtained β-carotene solubility data were correlated using the linear model and modified Apelblat model. The obtained results showed the modified Apelblat model was better for estimating the solubility of β-carotene in SW. The values of the rootmean-square deviation (RMSD) between experimental and correlated data were calculated and used as the index of validity and accuracy for the model. Also, thermodynamic properties of the solution such as the Gibbs free energy of solution, enthalpy, and entropy of solution were estimated.
    Preferential solvation of pomalidomide, an anticancer compound, in some binary mixed solvents at 298.15 K
    Mohsen Padervand, Shima Naseri, Hadi Chahiyan Boroujeni
    2020, 28(10):  2626-2633.  doi:10.1016/j.cjche.2020.07.010
    Abstract ( 301 )   PDF (1700KB) ( 55 )  
    References | Related Articles | Metrics
    Preferential solvation of pomalidomide (PMD) was explored in dimethyl sulfoxide (DMSO)-dimethylformamide (DMF), DMSO-tetrahydrofuran (THF), DMSO-methanol (MeOH), DMSO-isopropanol, DMSO-water, water-DMF, water-THF, water-MeOH, and water-isopropanol binary mixed solvents at 298.15 K. Bosch-Rose model was utilized to determine the electronic transition energies (ET) and other preferential solvation parameters, describing solute-solute and solute-solvent interactions. We found that λmax situation shifted with dielectric constant of the pure solvents meaningfully. According to the obtained results, ET enhanced and λmax shifted to the lower wavelengths as the percentage of DMSO decreased in the binary mixtures, remarking the important role of DMSO for stabilizing the excited state (π*) of PMD chromophore via efficient intermolecular solute-solvent interactions. In addition, the aqueous binary systems showed an optimum point for the ET values as the percentage of water changed in the solutions. The local mole fraction of the solvents in the cybotactic region was also estimated to describe the specific and non-specific interactions in the systems.
    Determination and correlation solubility of 4-nitroimidazole in twelve pure solvents from 278.15 K to 323.15 K
    Pengbao Lian, Qiang Liu, Lizhen Chen, Cai Cao, Jiaxiang Zhao, Jianlong Wang
    2020, 28(10):  2634-2639.  doi:10.1016/j.cjche.2020.07.022
    Abstract ( 186 )   PDF (895KB) ( 65 )  
    References | Related Articles | Metrics
    In this paper, the solubility of 4-nitroimidazole in twelve pure solvents (toluene, benzene, 1,4-dioxane, acetonitrile, ethyl acetate, acetone, GBL, ethanol, methanol, n-butanol, DMF and NMP) were determined by using the laser monitoring system from 278.15 K to 323.15 K under 101.1 kPa, which are 0.00018-0.00070, 0.00021-0.00073, 0.00034-0.00092, 0.00038-0.00142, 0.00047-0.00120, 0.00126-0.00303, 0.00225-0.00517, 0.00310-0.00724, 0.00467-0.00982, 0.00453-0.01940, 0.01947-0.04652, and 0.04670-0.07452, respectively. At constant temperature, the mole fraction solubility of 4-nitroimidazole were increased as the following order: toluene < benzene < 1,4-dioxane < (ethyl acetate or acetonitrile) < acetone < GBL < ethanol < (methanol or nbutanol) < DMF < NMP, and the solubility of 4-nitroimidazole in (ethyl acetate, acetonitrile) and (methanol, n-butanol) had an intersection point at 297.55 K and 281.85 K, respectively. The solubility of 4-nitroimidazole could be increased with increasing temperature in twelve pure solvents. The ideal model, modified Apelblat equation, polynomial empirical equation, and λh equation were used to correlate the experimental values. The experimental solubility values were employed to calculate the standard dissolution enthalpy, standard dissolution entropy and Gibbs energy. The dissolution of 4-nitroimidazole could be an endothermic process in twelve pure solvents. The determination and fitting solubility of 4-nitroimidazole have important guiding significance for the purification and crystallization of its preparation process.
    Biotechnology and Bioengineering
    Exploring novel cell cryoprotectants based on neutral amino acids
    Xiaojie Sui, Pengguang Chen, Chiyu Wen, Jing Yang, Qingsi Li, Lei Zhang
    2020, 28(10):  2640-2649.  doi:10.1016/j.cjche.2020.07.009
    Abstract ( 194 )   PDF (3906KB) ( 162 )  
    References | Related Articles | Metrics
    Cryoprotectants play a key role in cell cryopreservation because they can reduce cryoinjuries to cells associated with ice formation. To meet the clinical requirements of cryopreserved cells, cryoprotectants should be biocompatible, highly efficient and easily removable from cryopreserved cells. However, integration of these properties into one cryoprotectant still remains challenging. Herein, three biocompatible neutral amino acids, including β-alanine, γ-aminobutyric acid and ε-aminocaproic acid, are first reported to have the potential as such ideal cryoprotectants. The results demonstrate that they can inhibit ice formation and reduce osmotic stress to provide extracellular and intracellular protection, thereby ensuring high cryopreservation efficiency for both anuclear and nucleated cells. More importantly, due to the remarkable osmotic regulation ability, the neutral amino acids can be rapidly removed from cryopreserved cells via a one-step method without causing observable damage to cells, superior to the current state-of-the-art cryoprotectants—dimethyl sulfoxide and glycerol. This work provides a new perspective to develop novel cryoprotectants, which may have dramatic impacts on solvent-free cryopreservation technology to support the cell-based applications, such as cell therapy and tissue engineering, etc.
    Energy, Resources and Environmental Technology
    Enhanced adsorptive removal of Cr(VI) in aqueous solution by polyethyleneimine modified palygorskite
    Jiahong Wang, Tongtong Sun, Atif Saleem, Yao Chen
    2020, 28(10):  2650-2657.  doi:10.1016/j.cjche.2020.03.019
    Abstract ( 148 )   PDF (2327KB) ( 78 )  
    References | Related Articles | Metrics
    Polyethyleneimine (PEI) modified palygorskite (Pal) was used for the adsorption of Cr(VI) in aqueous solution. The absorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Characterized results confirmed that the Pal has been successfully modified by PEI. The modification of PEI increased the Cr(VI) adsorption performance of the Pal by the adsorption combined reduction mechanism, and amino groups of the adsorbent play the main role in the enhanced Cr(VI) adsorption. The maximum adsorption capacity was 51.10 mg·g-1 at pH 4.0 and 25 ℃. The adsorption kinetics of Cr(VI) on the adsorbent conforms to the Langmuir isotherm model. The maximum adsorption occurs at pH 3, and then the adsorption capacity of PEI-Pal was decreased with the increase of pH values. The adsorption kinetics of Cr(VI) on PEI-Pal was modeled with pseudo-second-order model. The addition of Cl-, SO42- and PO43- reduced the Cr(VI) adsorption by competition with Cr(VI) for the active sites of PEI-Pal. The Cr(VI) saturated PEI-Pal can be regenerated in alkaline solution, and the adsorption capacity can still be maintained at 30.44 mg·g-1 after 4 cycles. The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI) in aqueous solutions.
    Degradation of methotrexate by UV/peroxymonosulfate: Kinetics, effect of operational parameters and mechanism
    Muhammad Imran Kanjal, Majid Muneer, Amal Abdelhaleem, Wei Chu
    2020, 28(10):  2658-2667.  doi:10.1016/j.cjche.2020.05.033
    Abstract ( 276 )   PDF (2775KB) ( 144 )  
    References | Related Articles | Metrics
    Methotrexate (MTX) is one of the most consumed anti-cancer drugs in the pharmaceutical market around the world. The widespread occurrence of MTX in aquatic environment through hospital effluent has attracted increasing concern due to its potential to induce water pollution. In the present study, the degradation of MTX in aqueous medium was investigated by UV-activated peroxymonosulfate (PMS). A significant improvement in degradation rate by increasing UV intensity and PMS concentration while the decrease in degradation efficiency with the increase of solution pH and initial concentration of MTX was observed. The proposed UV/PMS process could achieve more than 90% MTX degradation in 30 min with a good mineralization degree (65%). A pseudofirst order kinetic model was employed and successfully predicted the degradation of MTX. The effect of other operational parameters such as the initial concentration of the targeted compound, dosage of oxidant (PMS), solution pH and UV intensity on the degradation rate were investigated. At the last, the main transform intermediates were identified using LC-MS and possible degradation pathways were proposed. The results show that UV/ PMS can be used as an efficient technology to treat pharmaceuticals such as methotrexate containing water and wastewater.
    Layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers for chemical looping reforming
    Jiangyong Yuan, Yannan Zhao, Haiwen Xu, Chunqiang Lu, Kun Yang, Xing Zhu, Kongzhai Li
    2020, 28(10):  2668-2676.  doi:10.1016/j.cjche.2020.06.035
    Abstract ( 270 )   PDF (3688KB) ( 127 )  
    References | Related Articles | Metrics
    A series of layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers were prepared for co-production of syngas and pure hydrogen via chemical looping steam reforming (CLSR). The presence of magnesium-aluminum layered double oxides (MgAl-LDO) significantly increases the specific surface area of the mixed oxides, reduces the particle size of CeO2-based solid solution and promotes the dispersion of free Fe2O3. When reacting with methane, MgAl-LDO supported oxygen carrier shows much lower temperature for methane oxidation than the pure CeFe-Zr-O sample, indicating enhanced low-temperature reactivity. Among different Ce-Fe-Zr-O(x)/MgAl-LDO samples, the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO sample shows the best performance for the selective oxidation of methane to syngas and the H2 production by water splitting. After a long period of high temperature redox experiment, the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO oxygen carrier still shows high activity for syngas generation. The comparison on the morphology of the fresh and cycled oxygen carriers indicates that the Mg-Al spinel support still forms a stable skeleton structure with high dispersion of active components on the surface after the long-term cycling, which contributes to excellent redox stability of the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO oxygen carrier.
    Controlled preparation of P-doped g-C3N4 nanosheets for efficient photocatalytic hydrogen production
    Qiachun Lin, Zesheng Li, Tingjian Lin, Bolin Li, Xichun Liao, Huiqing Yu, Changlin Yu
    2020, 28(10):  2677-2688.  doi:10.1016/j.cjche.2020.06.037
    Abstract ( 275 )   PDF (6447KB) ( 182 )  
    References | Related Articles | Metrics
    Hydrogen production by photolysis of water by sunlight is an environmentally-friendly preparation technology for renewable energy. Graphitic carbon nitride (g-C3N4), despite with obvious catalytic effect, is still unsatisfactory for hydrogen production. In this work, phosphorus element is incorporated to tune g-C3N4's property through calcinating the mixture of g-C3N4 and NaH2PO2, sacrificial agent and co-catalyst also been supplied to help efficient photocatalytic hydrogen production. Phosphorus (P) doped g-C3N4 samples (PCN-S) were prepared, and their catalytic properties were studied. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and ultraviolet diffuse reflection (UV-DRS) were used to study their structures and morphologies. The results show that the reaction rate of PCN-S is 318 μmol·h-1·g-1, which is 2.98 times as high as pure carbon nitride nanosheets (CN) can do. Our study paves a new avenue, which is simple, environment-friendly and sustainable, to synthesize highly efficient P doping g-C3N4 nanosheets for solar energy conversion.
    Adsorptive removal of tetracycline from water using Fe (III)-functionalized carbonized humic acid
    Dairui Xie, Hongcheng Zhang, Meng Jiang, Hao Huang, Heng Zhang, Yang Liao, Shilin Zhao
    2020, 28(10):  2689-2698.  doi:10.1016/j.cjche.2020.06.039
    Abstract ( 175 )   PDF (3760KB) ( 93 )  
    References | Related Articles | Metrics
    Humic acid (HA) was carbonized at 300, 400 and 500 ℃ and then functionalized with 1 wt%-12 wt% Fe(III) respectively [CHA300/400/500-Fe(III)]. Adsorption of such Fe(III)-functionalized carbonized HA as adsorbents to aqueous tetracycline (TC: 25 mg·L-1) was studied. The adsorption equilibrium time for CHA400-Fe(III) to TC was 6 h faster and the adsorption removal efficiency (Re) was two times higher than that of HA/CHA. The adsorption R e of CHA400-Fe(III) loaded 10% iron [CHA400-(10%)Fe(III)] to TC could reach 99.8% at 8 h and still kept 80.6% after 8 cycles. The adsorption kinetics were well fitted to the pseudo-second-order equation and the adsorption isotherms could be well delineated via Langmuir equations(R2 > 0.99), indicating that the homogeneous chemical adsorption of TC occurred on the adsorbents. The main adsorption mechanisms of TC were complexation Fe(III) and hydrophobic distribution. Electropositive and electronegative repulsion between TC and CHA400-(10%)Fe(III) at lowly pH(2) and highly pH(8-10) respectively, leaded to the relatively low adsorption capacity and more notable influence of ion concentration. When the pH was between 4 and 8, TC mainly existed in neutral molecules (TCH2), so the influence of ion concentration was not obvious. The dynamic adsorption results showed that the CHA400-(10%)Fe(III) could continuously treat about 2.4 L TC(27 mg·L-1) wastewater with the effluent concentration as low as 0.068 mg·L-1. Our study suggested a broad application prospect of a new, effective, lowcost and environment-friendly adsorbent CHA400-(10%)Fe(III) for treatment of low-concentration TC polluted wastewater.
    FeS2@TiO2 nanorods as high-performance anode for sodium ion battery
    Zhenxiao Lu, Wenxian Wang, Jun Zhou, Zhongchao Bai
    2020, 28(10):  2699-2706.  doi:10.1016/j.cjche.2020.07.011
    Abstract ( 245 )   PDF (6067KB) ( 156 )  
    References | Related Articles | Metrics
    Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na+ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS2 nanoparticles encapsulated in biphase TiO2 shell (FeS2@TiO2), is developed towards the improvement of sodium storage. The diphase TiO2 coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS2 caused by the Na+ insertion. The FeS2 core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS2@TiO2 nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g-1 at 0.2 A·g-1 after 300 cycles, 374.9 mA·h·g-1 at 5.0 A·g-1 after 600 cycles) and outstanding rate capability (222.2 mA·h·g-1 at 10 A·g-1). Furthermore, the synthesized FeS2@TiO2 demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na+ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs.