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SCI和EI收录∣中国化工学会会刊
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Table of Content
28 June 2020, Volume 28 Issue 6
    Reviews
    Advanced development in upstream of petroleum industry using nanotechnology
    Sedigheh Sadegh Hassani, Maryam Daraee, Zahra Sobat
    2020, 28(6):  1483-1491.  doi:10.1016/j.cjche.2020.02.030
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    Nowadays, energy supply is one of the most important issues due to limitation of oil, gas and coal sources. Because of rapid population, civilization and energy consumption growth, the improved technologies to make optimal use of the sources, solving related problems and finding new energy sources are important. More than 10 years ago, nanotechnology as one of the most important technologies has also been applied to progress in the oil and gas industry (upstream, midstream and downstream). The experience of these years has shown that application of nanotechnology in the oil industry improves the exploration of crude oil and natural gas (underground or deep water), drilling and bringing the crude oil or raw natural gas to the surface, as well as transportation, storage, processing and purifying methods. Nanoparticles with high specific surface area, pore volume and small size show unique physical and chemical properties, which could be applied in several applications. In this regard, many researchers have been focused on various nanoparticles for upstream industries and studied their potential in oil exploration, drilling, production and enhanced oil recovery (EOR). Also, in downstream and midstream which involve refining of crude oil, processing and purifying of raw natural gas, transportation and storage of crude or refined petroleum products, the nanomaterials have been used to improve the quality of oil and make it appropriate for the environment. Lowering sulfur gasoline, enhancing the octane number and coating the transportation system are among the goals that have been achieved successfully using nanotechnology. In this work, various types of nanoparticles such as metallic, metal oxide, hybrid nanoparticles, carbon nanomaterials, nano-composites and their applications in oil upstream industry are reviewed. Also, their usage in different types of oil upstream processes is discussed.
    Detection mechanism and classification of design principles of peroxidase mimic based colorimetric sensors: A brief overview
    Ali Reza Hormozi Jangi, Mohammad Reza Hormozi Jangi, Saeed Reza Hormozi Jangi
    2020, 28(6):  1492-1503.  doi:10.1016/j.cjche.2020.01.020
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    Synthesis and characterization of enzyme mimics with characteristic stability and high catalytic efficiency is an interesting field for researchers. Especially, with the development of nanoscience and introducing of Fe3O4 magnetic nanoparticles as peroxidase mimics in 2007, various nanomaterials such as noble metals, metal oxides, and carbon materials were introduced as enzyme mimics (nanozymes). Various nanomaterials exhibit peroxidaselike activity, hence, most of the nanozymes are peroxidase mimetics. Although the nanozyme based sensors were previously classified, the classifications have been focused on the type of nanozyme action. Therefore, the nanozyme based sensors were classified as peroxidase, hydrolase, and urease mimic-based sensors. However, heretofore, these sensors are not classified based on the detection mechanism and principles of system design. The aim of this review is the focus on the peroxidase mimic based colorimetric sensors as the most common nanozyme-based sensors and their classification based on principles of sensor design and review of the detection mechanism of the current mimic peroxidase based sensors. Moreover, some current challenges and future developments in this field are discussed.
    Fluid Dynamics and Transport Phenomena
    Determining axial dispersion coefficients of pilot-scale annular pulsed disc and doughnut columns
    Xiong Yu, Han Zhou, Qiang Zheng, Shan Jing, Wenjie Lan, Shaowei Li
    2020, 28(6):  1504-1513.  doi:10.1016/j.cjche.2020.03.024
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    In this study, a computational fluid dynamics (CFD) method was adopted to calculate axial dispersion coefficients of annular pulsed disc and doughnut columns (APDDCs). Passive tracer was uniformly injected by pulse input at the continuous phase inlet, and its concentration governing equation was solved in liquid-liquidtwo-phase flow fields. The residence time distributions (RTDs) were obtained using the surface monitoring technique. The adopted RTD-CFD method was verified by comparing the axial dispersion coefficient between simulation and experimental results in the literature. However, in pilot-scale APDDCs, the axial dispersion coefficients predicted by the CFD-RTD method were approximately three times larger than experimental results determined by the steady-state concentration profile method. This experimental method was demonstrated to be insensitive to the variation of the axial dispersion coefficient. The CFD-RTD method was more recommended to determine the axial dispersion coefficient. It was found that the axial dispersion coefficient increased with an increase in pulsation intensity, column diameter, and plate spacing, but was little affected by the throughput.
    Influences of top clearance and liquid throughput on the performances of an external loop airlift slurry reactor integrated mixing and separation
    Hongyan Liu, Zhuo Li, Shujun Geng, Fei Gao, Taobo He, Qingshan Huang
    2020, 28(6):  1514-1521.  doi:10.1016/j.cjche.2020.03.027
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    A new developed external loop airlift slurry reactor, which was integrated with gas-liquid-solid three-phase mixing, mass transfer, and liquid-solid separation simultaneously, was deemed to be a promising slurry reactor due to its prominent advantages such as achieving continuous separation of clear liquid from slurry and cyclic utilization of solid particles without any extra energy, energy-saving, and intrinsic safety design. The principal operating parameters, including gas separator volume, handling capacity, and superficial gas velocity, are systematically investigated here to promote the capabilities of mixing, mass transfer, and yield in the pilot external loop airlift slurry reactor. The influences of top clearance and throughput of the clear liquid on flow regime and gas holdup in the riser, liquid circulating velocity, and volumetric mass transfer coefficient with a typical high solid holdup and free of particles are examined experimentally. It was found that increasing the gas separator volume could promote the liquid circulating velocity by about 14.0% at most. Increasing the handling capacity of the clear liquid from 0.9 m3·h-1 to 3.0 m3·h-1 not only could increase the output without any adverse consequences, but also could enhance the liquid circulating velocity as much as 97.3%. Typical operating conditions investigated here can provide some necessary data and guidelines for this new external loop airlift slurry reactor to upgrade its performances.
    Hydrothermal performance analysis of various surface roughness configurations in trapezoidal microchannels at slip flow regime
    Davood Toghraie, Ramin Mashayekhi, Mohammadreza Niknejadi, Hossein Arasteh
    2020, 28(6):  1522-1532.  doi:10.1016/j.cjche.2020.03.028
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    The effects of various surface roughness geometrical properties including roughness height (5%, 10%, 15%), number (3, 6), and shape (rectangular and triangular) on the flow and heat transfer of slip-flow in trapezoidal microchannels were investigated. The effects of mentioned parameters on the heat transfer coefficient through the microchannel, average Nusselt number and pressure drop for Reynolds number of 5, 10, 15 and 20 were examined. The obtained results showed that increasing the roughness height and number increases the pressure drop due to higher stagnation effects before and after roughness elements and decreases the Nusselt number due to higher recirculation zones effects than obstruction effects. The most reduction in Nusselt number and the most increment in pressure drop occur at the roughness height of 15%, roughness number of 6 and Reynolds number of 20 by about 10.6% and 52.8% than the smooth microchannel respectively.
    Numerical study on the hydrodynamics of agglomerates at intermediate Reynolds numbers
    Huanpeng Liu, Shaowei Wang, Chenyu Yang, Taiping Chen
    2020, 28(6):  1533-1541.  doi:10.1016/j.cjche.2020.03.032
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    The flow pattern and hydrodynamics of a heterogeneous permeable agglomerate in a uniform upward flow at intermediate Reynolds numbers (1-40) are analyzed from three-dimensional (3D) computational fluid dynamics simulations. Different from the homogeneous or stepwise-varying permeability models used in previous papers, a continuously radially varying permeability model is used in the present study. The effects of two dimensionless parameters, the Reynolds number and the permeability ratio, on the flow field and the hydrodynamics were investigated in detail. The results reveal that unlike the solid sphere, a small recirculating wake initially forms inside the agglomerate. The critical Reynolds number for the formation of the recirculating wake is lower than that of the solid sphere and it decreases with the increase of permeability ratio. A correlation of drag coefficient as a function of the Reynolds number and permeability ratio is proposed. Comparisons of drag coefficients obtained by different permeability models show that at intermediate Reynolds numbers (1-40), the effect of radially varying permeability on the drag coefficient must be considered.
    Numerical study on non-uniform heat transfer deterioration of supercritical RP-3 aviation kerosene in a horizontal tube
    Yanhong Wang, Yingnan Lu, Sufen Li, Ming Dong
    2020, 28(6):  1542-1557.  doi:10.1016/j.cjche.2020.03.037
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    The convective heat transfer of supercritical-pressure RP-3 (Rocket Propellant 3) aviation kerosene in a horizontal circular tube has been numerically studied, focusing mainly on the non-uniform heat transfer deterioration along the circumferential direction. The governing equations of mass, momentum and energy have been solved using the pressure-based segregated solver based on the finite volume method. The re-normalization group (RNG) k-ε turbulence model with an enhanced wall treatment was selected. Considering the heat conduction in the solid wall, the mechanism of heat transfer deterioration and the buoyancy effect on deteriorated heat transfer were discussed. The evolution of secondary flow was analyzed. Effects of the outer-wall heat flux, mass flux, pressure and tube thermal conductivity on heat transfer were investigated. Moreover, the buoyancy criterion and the heat transfer correlation were obtained. Results indicate that the poor flow performance of near-wall fluid causes the pseudo-film boiling, further leads to the heat transfer deterioration. The strong buoyancy has an effect of enhancing the heat transfer at the bottom of tube, and weakening the heat transfer at the top of tube, which results in the non-uniform inner-wall temperature and heat flux distributions. Decreasing the ratio of outer-wall heat flux and mass flux, increasing the pressure could weaken the heat transfer difference along the circumferential direction, while the effect of thermal conductivity of tube on the circumferential parameters distributions is more complicated. When the buoyancy criterion of (Grq/Grth)max ≤ 0.8 is satisfied, the effect of buoyancy could be ignored. The new correlations work well for non-uniform heat transfer predictions.
    Separation Science and Engineering
    Simultaneous recovery of phosphorus and nitrogen from liquid digestate by vacuum membrane distillation with permeate fractional condensation
    Boya Qiu, Senqing Fan, Xiaoyu Tang, Bufan Qi, Liangwei Deng, Wenguo Wang, Jingyun Liu, Yuyang Wang, Zeyi Xiao
    2020, 28(6):  1558-1565.  doi:10.1016/j.cjche.2020.01.019
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    A vacuum membrane distillation (VMD) process with permeate fractional condensation on membrane downstream has been developed for simultaneous recovery of phosphorus and nitrogen from liquid digestate. The polytetrafluoroethylene (PTFE) membrane flux could reach 6000 g·m-2·h-1 with the rejection efficiency of total phosphorus (TP) over 0.99, under the condition of flowrate being 120 L·h-1 and temperature being 40℃. Membrane fouling occurred with a film of organics and microorganism deposited on the surface of the membrane. Membrane flux could be reversed after the membrane was rinsed by water. Higher feed temperature and flowrate could improve the membrane flux, while hardly affect the rejection efficiency of total phosphorus. The concentration of TP could reach 1600 mg·L-1 after membrane distillation, which is about 5 times of that in initial liquid digestate. On the downstream of the membrane, some of the permeate vapor was condensed under the vacuum condition and most of water was collected here. The remaining vapor enriched with total nitrogen (TN) was compressed and pumped to the atmospheric condition to condense. The TN concentration in atmospheric condensate was as high as 7000 mg·L-1 with the process separation factor for ammonia being enhanced to 114.
    Preparation of hydrophobic flat sheet membranes from PVDF-HFP copolymer for enhancing the oxygen permeance in nitrogen/oxygen gas mixture
    Bahador Akbari, Asghar Lashanizadegan, Parviz Darvishi, Abdolrasoul Pouranfard
    2020, 28(6):  1566-1581.  doi:10.1016/j.cjche.2020.02.018
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    In this study, poly(vinilydene fluoride-co-hexafluoropropylene) (PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion (NIPS) technique. PVDF-HFP copolymer with concentrations of 10 wt% and 12 wt% was prepared to investigate the effect of polymer concentration on pore structure, morphology, hydrophobicity and performance of prepared membranes. Besides, the use of two coagulation baths with the effects of parameters such as coagulant time, polymer type and concentration, and the amount of nonsolvent were studied. The performance of prepared membranes was evaluated based on the permeability and selectivity of oxygen and nitrogen from a gas mixture of nitrogen/oxygen under operating conditions of feed flow rate (1-5 L·min-1), inlet pressure to membrane module (0.1-0.5 MPa) and temperatures between 25 and 45℃. The results showed that the use of two coagulation baths with different compositions of distillated water and isopropanol, coagulant time, polymer type and concentration, and the amount of non-solvent additive have the most effect on pore structure, morphology, thickness, roughness and crystallinity of fabricated membranes. Porosity ranges for the three fabricated membranes were determined, where the maximum porosity was 73.889% and the minimum value was 56.837%. Also, the maximum and minimum average thicknesses of membrane were 320.85 μm and 115 μm. Besides, the values of 4.7504×10-7 mol·m-2·s-1·Pa-1, 0.525 and 902.126 nm were achieved for maximum oxygen permeance, O2/N2 selectivity and roughness, respectively.
    Experimental and mathematical modeling of Cr(VI) removal using nano-magnetic Fe3O4-coated perlite from the liquid phase
    Ismail M. Ahmed, Mostafa M. Hamed, Sayed S. Metwally
    2020, 28(6):  1582-1590.  doi:10.1016/j.cjche.2019.12.027
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    Modification of perlite using nano-magnetic iron oxide was implemented to produce nano-magneticFe3O4-coated perlite composite (Fe3O4/Perlite). The prepared composite was characterized using Scanning Electron Microscopy, Fourier-Transform Infrared spectroscopy and Powder X-ray Fluorescence. The potentiality of both perlite and Fe3O4/Perlite composite to eliminate Cr(VI) from the environmentally relevant water was investigated. The influence of main factors which could affect the adsorption was studied including; pH of medium, shaking time and Cr(VI) ions concentration. The experimental outcome demonstrated that the modification of perlite by nano-magnetic Fe3O4 showed a significantly enhanced Cr(VI) removal efficiency relative to that of unmodified perlite. From the kinetic studies, the experimental data fitted well with the pseudo-second-order model. Moreover, it proposes that Langmuir isotherm is more adequate than the Freundlich isotherm for both perlite and modified perlite. The results recommended that Fe3O4/Perlite composite had a great potential as an economic and efficient adsorbent of Cr(VI) from contaminated water, which has huge application potential.
    Extraordinary adsorption of acidic fuchsine and malachite green onto cheap nano-adsorbent derived from eggshell
    Atefeh Moosavi, Ali Akbar Amooey, Ali Alinejad mir, Mojtaba Hedayati Marzbali
    2020, 28(6):  1591-1602.  doi:10.1016/j.cjche.2020.02.031
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    Removal of dyestuffs such as Acidic Fuchsine (AF) and Malachite Green (MG) being present in many forms in industries is vital to protect water reservoirs from their catastrophic effects on the ecosystem. This study attempts to effectively eliminate these dyes using a low-cost and eco-friendly material. Eggshell, as a biocompatible by-product, was initially characterized, then some modifications were conducted, and its morphology and chemical structure were then examined through (Atomic force microscopy) AFM, (Fourier-Transform Infrared Spectroscopy) FTIR, (Energy-Dispersive X-ray Spectroscopy) EDS and (Brunauer-Emmett-Teller) BET analyses. They revealed that the modifications on raw material gave rise to a natural nano-adsorbent presenting porous medium appropriate for targeted adsorbate molecules with the average particle size and average pore diameter of 54 and ~2 nm, respectively. Functional groups on the adsorbent surface were also of importance to assist the adsorption of AF and MG. The effect of contact time, adsorbent dose, solution pH and initial concentration was evaluated. Pseudo-second order model accurately correlated the experimental kinetic data for both dyes. Moreover, the participation of intra-particle diffusion along with film diffusion in controlling the process was suggested. Langmuir isotherm model fitted very well to the equilibrium data for both dyes and maximum monolayer adsorption capacity of AF and MG was accordingly calculated to be 5000 and 3333.33mg·g-1 respectively. The inherent characteristics of eggshell make it a potential material to remove contaminants from wastewater in future applications.
    Catalysis, Kinetics and Reaction Engineering
    Effects of iron precursors on the structure and catalytic performance of iron molybdate prepared by mechanochemical route for methanol to formaldehyde
    Lingtao Kong, Shengtao Xu, Xue Liu, Chaofan Liu, Dandan Zhang, Ling Zhao
    2020, 28(6):  1603-1611.  doi:10.1016/j.cjche.2020.03.009
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    Mechanochemical synthesis has been applied for many novel material preparations and gained more and more attention due to green and high-efficiency recently. In order to explore the influences of iron precursors on structure and performance of iron molybdate catalyst prepared by mechanochemical route, three typical and cheap iron precursors have been used in preparation of iron molybdate catalyst. Many characterization methods have been employed to obtain the physical and chemical properties of iron molybdate catalyst. Results indicate that iron precursors have the significant impact on the phase composition, crystal morphology and catalytic performance in the conversion of methanol to formaldehyde. It is hard to regulate the phase composition by changing Mo/Fe mole ratios for Fe2(SO4)3 as iron precursor. In addition, as for Fe2(SO4)3, the formaldehyde yield is lower than that from iron molybdate catalyst prepared with Fe(NO3)3·9H2O due to the reduction in Fe2(MoO4)3 phase as active phase. Based on mechanochemical and coprecipitation method, the solvent water could be a key factor for the formation of MoO3 and Fe2(MoO4) for FeCl3·6H2O and Fe2(SO4)3 as precursors. Iron molybdate catalyst prepared with Fe(NO3)3·9H2O by mechanochemical route, shows the best methanol conversion and formaldehyde yield in this reaction.
    Silver modified Cu/SiO2 catalyst for the hydrogenation of methyl acetate to ethanol
    Zhiheng Ren, Muhammad Naeem Younis, Hui Zhao, Chunshan Li, Xiangui Yang, Erqiang Wang, Gongying Wang
    2020, 28(6):  1612-1622.  doi:10.1016/j.cjche.2020.02.011
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    A series of silver modified Cu/SiO2 catalysts were synthesized with ammonia-evaporation method and applied in vapor-phase hydrogenation of methyl acetate to ethanol. The influence of additive ‘Ag’ on the structural evolution of catalyst was systematically studied by several characterization techniques, such as N2 adsorption-desorption, N2O titration, PXRD, FTIR, in-situFTIR, H2-TPR, H2-TPD, XPS and TEM. Results showed that incorporation of a small amount of Ag could enhance the structural stability, and the strong interaction between Cu and Ag species was conducive to increase the dispersion of copper species and create a suitable Cu+/(Cu0 + Cu+) ratio, which was proposed to be responsible for the improved catalytic activity. The maximum conversion of MA (94.1%) and selectivity of ethanol (91.3%) over optimized Cu-0.5Ag/SiO2 and 120 h on stream without deactivation under optimal conditions demonstrates its excellent stability.
    Gas-phase dehydrochlorination of 1, 1, 2, 2-tetrachloroethane over the non-metal supported ionic liquid catalyst
    Pengze Zhang, Yangzhen Jin, Zhaobin Jiang, Guanqun Xie, Qunfeng Zhang, Xiaonian Li
    2020, 28(6):  1623-1627.  doi:10.1016/j.cjche.2020.03.011
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    Developing of non-metallic catalyst to replace metal catalyst is a meaningful and challenging direction. In this work, the non-metallic catalyst was synthetized successfully by loading ionic liquid onto the silica surface, which was applied for the gas-phase dehydrochlorination of 1, 1, 2, 2-tetrachloroethane. The 12%TPPC/SiO2 (wt%) showed the best results with the conversion of 1, 1, 2, 2-tetrachloroethane reaching 100%. The selectivity of 1, 1, 2-trichloroethylene was 100%, and no deactivation was found during the evaluation period. The catalytic mechanism was investigated and possible reaction route was given, which was a reference for fabricating and design of solid base catalyst.
    Promotion effect of Re additive on the bifunctional Ni catalysts for methanation coupling with water gas shift of biogas: Insights from activation energy
    Xinxin Dong, Baosheng Jin, Zhiwei Kong, Yiqing Sun
    2020, 28(6):  1628-1636.  doi:10.1016/j.cjche.2020.03.016
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    The cheap manganese sand was first modified by H2O2 and was further creatively utilized as Ni-based catalyst support. In order to enhance the catalytic performance, Re was added into the Ni-based catalyst and the promotion effect of Re on the methanation coupling with water gas shift of biogas was investigated from the perspective of activation energy. It was found that CH4 and CO2 formation rates, which separately represented the reaction rate of methanation and water gas shift, were both enhanced after Re addition compared to non-added catalyst. Two kinetics models including empirical model and K-model were employed and from the results of calculation, it showed that Re selectively decreased the activation energy of methanation reaction and had little impact on the activation energy of water gas shift. The increased CO2 formation rate was owing to the assistance of accelerated H2O production from methanation rather than the activation energy change in water gas shift.
    Process Systems Engineering and Process Safety
    Kinetic parameter estimation for cooling crystallization process based on cell average technique and automatic differentiation
    Feiran Sun, Tao Liu, Yi Cao, Xiongwei Ni, Zoltan Kalman Nagy
    2020, 28(6):  1637-1651.  doi:10.1016/j.cjche.2020.03.007
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    In this paper, a cell average technique (CAT) based parameter estimation method is proposed for cooling crystallization involved with particle growth, aggregation and breakage, by establishing a more efficient and accurate solution in terms of the automatic differentiation (AD) algorithm. To overcome the deficiency of CAT that demands high computation cost for implementation, a set of ordinary differential equations (ODEs) entailed from CAT based discretized population balance equation (PBE) are solved by using the AD based high-order Taylor expansion. Moreover, an AD based trust-region reflective (TRR) algorithm and another interior-point (IP) algorithm are established for estimating the kinetic parameters associated with particle growth, aggregation and breakage. As a result, the estimation accuracy can be further improved while the computation cost can be significantly reduced, compared to the existing algorithms. Benchmark examples from the literature are used to illustrate the accuracy and efficiency of the AD-based CAT, TRR and IP algorithms in comparison with the existing algorithms. Moreover, seeded batch cooling crystallization experiments of β form L-glutamic acid are performed to validate the proposed method.
    A game theory based method for inter-plant heat integration considering cost allocation
    Yufei Wang, Zehuan Wan, Chenglin Chang, Xiao Feng
    2020, 28(6):  1652-1660.  doi:10.1016/j.cjche.2020.04.007
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    Inter-plant heat integration is an effective way for energy recovery in process industry. Although inter-plant heat integration can significantly reduce energy consumption, it is not widely applied in the multiple stakeholders' situation due to profit or cost distribution problems. Therefore, this work considers both the technique aspects of heat integration and its business aspects between stakeholders simultaneously. The new proposed methodology consists of three steps. Firstly the optimal matching of heat integration between plants is obtained through mathematical programming. Then the cost distribution is decided through game theory. Finally the cost distribution obtained previous is corrected by an ideal expert model. A case study is used to illustrate the effectiveness of the method in the end of the work.
    Chemical Engineering Thermodynamics
    Experimental data and modeling for excess enthalpies of 2-Pentanol with n-alkanes (C7-C9) at T=(293.15, 298.15 and 303.15) K
    Dongwei Wei, Mengying Li, Jing Ma, Baohe Wang
    2020, 28(6):  1661-1669.  doi:10.1016/j.cjche.2020.03.029
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    Excess molar enthalpies, HE, for the binary mixtures of 2-pentanol with n-alkanes(n-heptane, n-octane, and n-nonane) have been determined at three different temperatures T=(293.15, 298.15 and 303.15) K and normal atmospheric pressure over the entire composition range using a Calvet microcalorimeter. All mixtures show endothermic mixing with the maximum values of the excess enthalpies occurring in the n-alkane-rich region. The HE data are smoothed using Redlich-Kister equation. The applicability of the Treszczanowicz-Benson, ERAS, Renon-Prausnitz and Chen-Bagley models to correlate HE of studied mixtures is tested, and the agreement between experimental and theoretical results is satisfactory. Each model includes a self-association equilibrium constant that represents hydrogen bonding and an adjustable parameter that reflects physical interactions.
    Biotechnology and Bioengineering
    Hydrodeoxygenation of vegetable oil in batch reactor: Experimental considerations
    Alexis K. Noriega, Alexis Tirado, Cecilia Méndez, Gustavo Marroquín, Jorge Ancheyta
    2020, 28(6):  1670-1683.  doi:10.1016/j.cjche.2019.12.022
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    The generation of reliable experimental data in any experimental scale requires proper procedures not only for the reaction step but also for the feed preparation, separation, and characterization of products as well as calculations of conversion and product yields. Batch reactor is the most used experimental setup for carrying out exploratory studies for catalyst screening and development. This work is focused on describing and discussing a step-by-step methodology for conducting experiments for catalytic hydrotreating of vegetable oils in batch reactor. The proposed methodology considers literature and own experiences on advantages and disadvantages of different feed types, catalysts, experimental setup and procedures, effect of reaction parameters, separation and characterization of products, and calculations.
    Energy, Resources and Environmental Technology
    Comprehensive evaluation and sensitivity analysis of regeneration energy for acid gas removal plant using single and activated-methyl diethanolamine solvents
    Ammar Ali Abd, Samah Zaki Naji, Ahmed Barifcani
    2020, 28(6):  1684-1693.  doi:10.1016/j.cjche.2019.12.004
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    The absorption of acid gas using reactive amines is among the most widely used types of capturing technologies. However, the absorption process requires intensive energy expenditure majorly in the solvent regeneration process. This study simultaneously evaluated the regeneration energy of MDEA and PZ/MDEA solvents in terms of heat of absorption, sensible heat, and vaporization heat. Aspen Hysys version 8.8 simulation tool is applied to model the full acid gas removal plant for the chemical absorption process. The new energy balance technique presents around the absorption and desorption columns to bring a new perspective of energy distribution in the capturing of acid gas plants. Sensitivity analysis of regeneration energy and its three contributors is performed at several operation parameters such as absorber and stripper pressures, lean amine circulation rate, solvent concentration, reflux ratio, and CO2 and H2S concentrations. The results show that the heat of absorption of PZ/MDEA system is higher than that for MDEA system for the same operating conditions. The sensible heat is the main contributor in the required regeneration energy of MDEA solvent system. The simulation results have been validated against data taken from real plant and literature. The product specifications of our simulation corroborate with real plant data in an excellent approach; additionally, the profile temperature of the absorber and the stripper columns are in good agreement with literature. The overall results highlight the direction of the effects of each parameter on the heat of absorption, sensible heat, and vaporization heat.
    CO2-hierarchical activated carbon prepared from coal gasification residue: Adsorption equilibrium, isotherm, kinetic and thermodynamic studies for methylene blue removal
    Yuhong Kang, Xianyong Wei, Guanghui Liu, Miao Mu, Xiangrong Ma, Yong Gao, Zhimin Zong
    2020, 28(6):  1694-1700.  doi:10.1016/j.cjche.2019.12.017
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    Mineral matter in a residue (RCG) from coal gasification (CG) was removed by two-stage acid leaching. Hierarchical activated carbon (HAC) was prepared by activating RCG with CO2. The performance of HAC on removing methylene blue (MB) from an aqueous solution was investigated. HAC was characterized by N2 adsorption-desorption isotherm, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results show that HAC exhibits hierarchical pore structure with high specific surface area (862.76 m2·g-1) and total pore volume (0.684 cm3·g-1), and abundant organic functional groups. The adsorption equilibrium data of MB on HAC are best fitted to the Redlich-Peterson. The kinetic data show that the pseudo-first-order model is more suitable at low MB concentration, while the advantages of the pseudo-second-orderand the Elovich models are more obvious as the concentration increases. According to the thermodynamic parameters, the HAC-MB adsorption process is spontaneous and endothermic.
    Influence of solvent on ion conductivity of polybenzimidazole proton exchange membranes for vanadium redox flow batteries
    Yahui Wang, Kaimin Feng, Liming Ding, Lihua Wang, Xutong Han
    2020, 28(6):  1701-1708.  doi:10.1016/j.cjche.2020.01.009
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    Polybenzimidazole (PBI) is a kind of proton transport membrane material, and its ion conductivity is a key factor affecting its application in vanadium redox flow batteries (VRFBs). The casting solvent of PBI has a significant influence on the acid doping level of PBI membranes which is closely related to ionic conductivity. In this paper, 3,3'-diaminobenzidine (DABz) and 4,4'-Dicarboxydiphenylether (DCDPE) were used as raw materials by solution condensation to prepare the PBI with ether bond groups. The chemical structure of PBI was determined by 1H NMR and FT-IR, and the prepared PBI had good solubility which can be dissolved in a variety of solvents. The PBI proton exchange membranes were prepared by solution coating with 5 different solvents of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), 1-methyl-2-pyrrolidone (NMP), methane sulfonic acid (MSA). The effects of different solvents on the ion conductivity and physicochemical properties were discussed in detail. The results showed that the PBI membrane prepared by using MSA as solvent (the PBI + MSA membrane) exhibits high water uptake, acid doping level and low vanadium ion permeability. The VRFB assembled with the PBI + MSA membrane exhibited higher coulombic efficiency (CE) 99.87% and voltage efficiency (VE) 84.50% than that of the commercial Nafion115 membrane at 100 mA·cm-2, and after 480 cycles, the EE value can still be maintained at 83.73%. The self-discharge time of a single battery was recorded to be as long as 1000 h. All experimental data indicated that MSA is the best solvent for casting PBI membrane.
    Desorption of VOC from polymer adsorbent in multistage fluidized bed
    Jiale Zheng, Wenli Song, Lin Du, Lina Wang, Songgeng Li
    2020, 28(6):  1709-1716.  doi:10.1016/j.cjche.2020.02.001
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    The desorption process of volatile organic compounds (VOC) from a polymer adsorbent in counter-current multistage fluidized bed was studied. And a mathematical model considering the mass transfer dynamics was developed, which was validated from experiment data. The gaseous ethyl acetate mass transfer was discussed, and the limiting step is the intraparticle mass transfer of the desorption process. The value of intraparticle mass transfer coefficient is between 1.85×10-6 and 1.38×10-5 m·s-1 under temperature of 100-160℃. Experiments under different operating conditions were carried out. The effects of operating conditions such as gas-solid flow ratio, gas inlet temperature and total stage number of multistage fluidized bed on outlet VOCs concentration and desorption efficiency were discussed. The maximum outlet VOCs concentration and corresponding desorption efficiency of the multistage fluidized bed desorber was calculated under different gas inlet temperatures and total stage numbers.
    Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries
    Sajjad Haydar, Mehwish Anis, Misbah Afaq
    2020, 28(6):  1717-1724.  doi:10.1016/j.cjche.2020.02.017
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    In developing countries, high cost of conventional wastewater treatment is a major hindrance in its application. Constructed wetlands (CWs) offer low-cost and effective solution to this issue. The current study aimed to evaluate an innovative maneuver of CWs i.e. hybrid flow constructed wetlands (HCWs) for municipal wastewater (MWW). The HCWs included two lab scale CWs; one horizontal and one vertical, in series. Local plant species were used. HCWs were operated in both, batch and continuous mode. Batch mode was used to (1) optimize detention time and (2) find pollutants removal efficiency. Continuous operation (at batch optimized retention time) was carried out for the evaluation of mass removal rate, r (g·m-2·d-1), volumetric rate constant, Kv (per day) and areal rate constant, Ka (m·d-1). Among two local plants tested, Pistia stratiotes gave better removal efficiency than Typha. Optimum detention time in HCWs was found to be 8 days (4 + 4 each). The optimum COD, BOD, TSS, TKN and P removal observed for Pistia stratiotes planted HCWs was 80%, 84%, 82%, 71% and 88% respectively. Effluent standards for COD, BOD and TSS were met at optimum conditions. The values of Ka and Kv demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.
    Materials and Product Engineering
    Flame retardant synergy between interfacial and bulk carbonation in glass fiber reinforced polypropylene
    Yuan Xue, Rongjing Zhao, Ling Zhang, Chunzhong Li
    2020, 28(6):  1725-1732.  doi:10.1016/j.cjche.2020.03.034
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    Glass fiber reinforced polypropylene (GF-PP) composites have high flammability on account of wick effect which leads to accelerated flow of the polymer melt along the glass fibers (GF) surface to the flame zone. In this study, dipentaerythritol (DPER), a charring agent, was adsorbed on the GF surface through the hydrogen bond between silane coupling agent and DPER. DPER has a synergistic effect with the intumescent flame retardants (IFR) added in the composites, which can induce interfacial carbonization on the surface of GF, thus transforming the intrinsic smooth GF surface into roughness one. In this way, the negative effect of the wick effect in flame retardancy is weakened. Moreover, the char residues remained on the surface of GF can bring an improved adhesion between GF and char residues formed in the resin so that a more stable barrier char layer is formed. The PP composites with 20 wt% modified glass fiber (M-GF) and 30 wt% IFR can achieve the UL-94V-0, and its limiting oxygen index (LOI) value increased from 16.5% to 29.5%. Simultaneously, the heat release rate (HRR), total heat release (THR) and total smoke release (TSR) decreased significantly, and the peak of heat release rate (PHRR) reduced 60.6% compared with GF-PP.
    Numerical modeling of SiC by low-pressure chemical vapor deposition from methyltrichlorosilane
    Kang Guan, Yong Gao, Qingfeng Zeng, Xingang Luan, Yi Zhang, Laifei Cheng, Jianqing Wu, Zhenya Lu
    2020, 28(6):  1733-1743.  doi:10.1016/j.cjche.2020.03.035
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    The development of functional relationships between the observed deposition rate and the experimental conditions is an important step toward understanding and optimizing low-pressure chemical vapor deposition (LPCVD) or low-pressure chemical vapor infiltration (LPCVI). In the field of ceramic matrix composites (CMCs), methyltrichlorosilane (CH3SiCl3, MTS) is the most widely used source gas system for SiC, because stoichiometric SiC deposit can be facilitated at 900℃-1300℃. However, the reliability and accuracy of existing numerical models for these processing conditions are rarely reported. In this study, a comprehensive transport model was coupled with gas-phase and surface kinetics. The resulting gas-phase kinetics was confirmed via the measured concentration of gaseous species. The relationship between deposition rate and 24 gaseous species has been effectively evaluated by combining the special superiority of the novel extreme machine learning method and the conventional sticking coefficient method. Surface kinetics were then proposed and shown to reproduce the experimental results. The proposed simulation strategy can be used for different material systems.
    High-gravity-assisted green synthesis of rare-earth doped calcium molybdate colloidal nanophosphors
    Yuan Pu, Lifeng Lin, Jun Liu, Jiexin Wang, Dan Wang
    2020, 28(6):  1744-1751.  doi:10.1016/j.cjche.2020.03.023
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    In this work, we report an innovative route for the synthesis of rare-earth doped calcium molybdate (CaMoO4) nanophosphors by using high gravity rotating packed bed (RPB) technology and paraffin liquid as the solvent. The significant intensified mass transfer and micromixing of reactants in the RPB reactor are benefiting for homogeneous doping of rare-earth ions in the host materials, leading to nanophosphors with high quantum efficiency. The use of liquid paraffin as the solvent eliminates the safety risks associated with volatile organic compounds, increasing the potential for clean production of nanophosphors. Under excitation of deep ultraviolet (DUV) light, the CaMoO4:Na+, Eu3+ nanophosphors exhibit red emission at peak wavelength of 615 nm and quantum yield of up to 35.01%. The CaMoO4:Na+,Tb3+ nanophosphors exhibit green emission at peak wavelength of 543 nm with quantum yield of up to 30.66%. The morphologies of the nanophosphors are tunable from nanofibers through nanorods to nanodots and the possible mechanism of controlling the formation of different nanostructures is proposed on the basis of experimental results and theoretical analysis of mesoscience. These nanophosphors are highly dispersible in organic solvents and utilized for fabricating fabrication of flexible, freestanding luminescent films based on silicone resin. We also demonstrate the red LEDs consisting of the hybrid films of CaMoO4:Na+,Eu3+ nanoparticles as color-converting phosphors and DUV LEDs as illuminators, offering strong potential for future nanophosphors-basedsolid-state lighting systems.
    Direct synthesis of single-phase α-CaSO4·0.5H2O whiskers from waste nitrate solution
    Shuang Shao, Baozhong Ma, Yongqiang Chen, Wenjuan Zhang, Bao Liu, Peng Xing, Chengyan Wang
    2020, 28(6):  1752-1754.  doi:10.1016/j.cjche.2020.04.005
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    Single-phase α-CaSO4·0.5H2O whiskers were directly synthesized from waste Ca(NO3)2 solution using a hydrothermal method, and HNO3 was synchronously regenerated. The effects of reaction temperature and Ca2+ concentration on the phase composition and morphology of products were determined by X-ray diffraction and optical microscopy. On the basis of the experimental results, the formation diagram of α-CaSO4·0.5H2O was plotted within the range of 5-35 g·L-1 Ca2+ and 115℃-150℃. In addition, the conditions of the direct synthesis of α-CaSO4·0.5H2O were determined. Well-crystallized, single-phase α-CaSO4·0.5H2O whiskers with high aspect ratios (length, 1785 μm; diameter, 10.63 μm; aspect ratio, 168) and HNO3 (70.25 g·L-1) were obtained at the optimal conditions of 25 g·L-1 Ca2+ and 125℃.