Production of biodiesel from soybean oil catalyzed by attapulgite loaded with C4H5O6KNa catalyst

Fengxian Qiu,Bin Ye,Yihuai Li,Chuanjia Sun,Zhenyu Zhao,Teng Ma,Dongya Yang 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.7

Biodiesel is a green, safe, renewable alternative fuel, which is of great significance to solving the problem of energy shortage and environmental pollution. A series of solid base catalysts were prepared with the support of attapulgite (ATP), the load of C4H5O6KNa by impregnation method, and were used to catalyze transesterification of soybean oil with methanol to biodiesel. The activities of prepared catalysts were investigated compared to pure ATP. The optimal conditions for the catalyst preparation were investigated: molar ratio of Na : ATP was 1.7 : 1 and calcination temperature was 400 oC. The prepared catalysts were characterized by several techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption measurements,X-ray diffraction and the Hammett indicator method. The prepared solid base catalyst can be separated from reaction system effectively and easily. The effects of the molar ratio of methanol to oil, reaction temperature and amount of catalyst on the biodiesel yield were investigated. The experimental results showed that a 22 : 1 molar ratio of methanol to oil, 10.0% of catalyst amount, 65 oC of reaction temperature and 3.0 h of reaction time gave the best results. The catalyst has longer lifetime and maintained sustained activity after being used for five cycles.

Preparation and characterization of L-phenylalanine-derivatized β-cyclodextrin-bonded silica and its application on chiral separation of alanine acid racemates

Fengxian Qiu,Kaichen He,Jiao Qin,Jie Yan,Dongya Yang 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.11

A chiral adsorption material, L-phenylalanine-derivatized β-cyclodextrin-bonded silica (L-Phe-CD/SiO2),was prepared and characterized by Fourier transform infrared (FT-IR), elemental analysis, field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) measurements. Langmuir and Freundlich isotherm models were employed to simulate the equilibrium data. The results showed that the equilibrium data were well represented by Langmuir isotherm model. Experimental data were analyzed using pseudofirst order and pseudo-second order kinetic models and the obtained results indicated that kinetics followed a pseudosecond order equation. The static adsorption experiments indicated that L-Phe-CD/SiO2 had significantly higher adsorption capacity for L-alanine (L-Ala) compared with D-alanine (D-Ala); and the selectivity coefficient is 2.53. The result shows that the prepared L-Phe-CD/SiO2 could be applied to chiral separation of the racemic alanine acid solution.

A facile hydrothermal synthesis, adsorption kinetics and isotherms to Congo Red azo-dye from aqueous solution of NiO/graphene nanosheets adsorbent

Xinshan Rong,Fengxian Qiu,Jiao Qin,Hao Zhao,Jie Yan,Dongya Yang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.26 No.-

A series of NiO/graphene nanosheets adsorbents (NGNS) were synthesized by a facile hydrothermal method, and characterized by UV–vis, XRD, TG, TEM, HRTEM, Raman, SAED and XPS methods. The NGNS was applied to deal with wastewater solution containing Congo Red (CR); and adsorption efficiency attained 99.56% at optimum condition. The adsorption kinetic and isotherm of adsorbent toward CR were investigated. The results indicated that pseudo second-order kinetic model and the equilibrium data were well fitted by Redlich–Peterson model. The adsorbent can be separated from system effectively and easily. The prepared adsorbent has potential application for the wastewater treatment containing CR azo-dye.

Selective adsorption of L-TA/D-TA by β-cyclodextrin derivative modified with l-tryptophan: Isotherm, kinetic and thermodynamics studies

Kaichen He,Fengxian Qiu,Jiao Qin,Jie Yan,Dongya Yang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

b-Cyclodextrin derivative modified with L-tryptophan (L-Trp-CD) was prepared for recognitive chiral separation of tartaric acid enantiomers from ethanol solution. Kinetic properties were successfully investigated by pseudo-first-order model and pseudo-second-order model. Equilibrium data were described by the Langmuir and Freundlich isotherm models. The thermodynamics parameters (positive values of DH8 and DS8, negative values of DG8) indicated that binding system for L-Trp-CD was endothermic, entropy gained and spontaneous. Selective adsorption result of L-tartaric acid (L-TA)/Dtartaric acid (D-TA) by L-Trp-CD indicated that L-Trp-CD has significantly higher adsorption capacity for L-TA compared with D-TA, and the selectivity coefficient is 3.36.

Removal of malachite green from the contaminated water using a water-soluble melamine/maleic anhydride sorbent

Xinshan Rong,Fengxian Qiu,Jiao Qin,Jie Yan,Hao Zhao,Dongya Yang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

A novel water-soluble adsorbent (S-Me/MA) was prepared from melamine and maleic anhydride by two steps. The structure of material was characterized by FT-IR spectroscopy, SEM, and 1H NMR. The S-Me/MA was applied to deal with wastewater solution containing malachite green (MG). The influences of adsorbent dose, temperature, pH and contact time were investigated. At the same time, the adsorption kinetic and isotherm of S-Me/MA toward malachite green were investigated. The results indicated that the adsorption of malachite green was in line with pseudo-second order kinetics equation. Langmuir isotherm equation can be a fine description of the removal process.

Preparation of Carbon Nanotubes/Polyurethane Hybrids as a Synergistic Absorbent for Efficient Oil/Water Separation

Tao Zhang,Bin Gu,Fengxian Qiu,Xiaoming Peng,Xuejie Yue,Dongya Yang 한국섬유공학회 2018 Fibers and polymers Vol.19 No.10

Polyurethane (PU) hybrid materials have attracted a great deal of attention as oil-absorbents in oil/water separation because they combine the surface properties of nanomaterials and the excellent absorption properties of PU. Herein, we report a facile two-step process to synthesize the oil-absorbing hybrid materials by integrating carbon nanotubes (CNTs) into porous PU foam architectures. First, the multi-walled carbon nanotubes (MWCNTs) were modified by oxidation in binary H2SO4-HNO3 mixed acid, followed by grafting the silane coupling agent (KH 570) on the on surfaces of MWCNTs. Then, the MWCNTs/PU hybrid materials were synthesized using isocyanate and polyether polyol as monomers for polymerization and surface modified MWCNTs as inorganic components. The physical and chemical properties of hybrid materials were validated by XRD, TEM, SEM, N2 sorption and contact angle analysis. The surface grafted MWCNTs possess superhydrophobic properties with the maximum water contact angle of 153 o. The SEM results indicate that the WCNTs/PU hybrid materials consisted of spherical structures with microscale holes, which can separate oils from oil/water mixtures with high absorption properties and high selectivity. Effects of the various MWCNTs contents on the oil absorption behavior of the WCNTs/PU hybrid materials were investigated. The results show that the modified MWCNTs significantly improves the oil absorption properties with the optimal MWCNTs content of 3 %. By combining the structural features of WCNTs and PU foams, the hybrid materials not only exhibit excellent absorption properties for various types of oils and organic solvents, but also show excellent oil recoverability and absorbent regenerability. The as-synthesized WCNTs/PU hybrid have significant potential as oil absorbents for efficient separation of oils and organic solvents from water.

Structural evolution of hierarchical porous NiO/Al2O3 composites and their application for removal of dyes by adsorption

Jian Rong,Tao Zhang,Fengxian Qiu,Mingliang Chen 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1

Hierarchical porous NiO/Al2O3 composites were successfully prepared by two-steps. First, the core-shell structured Al2O3 microspheres were prepared via a template-free hydrothermal route using KAl(SO4)2·12H2O and Al2(SO4)3·18H2O as aluminum source. Then, the NiO/Al2O3 composites with micro- and nano-hierarchical structures were prepared by a hydrothermal method combining the subsequent calcination process. The obtained characterization result presented that the morphology of hierarchical Al2O3 microsphere tuned to irregular platelets by simply varying Ni/Al ratios. The BET analysis showed that the special surface area from 52.12m2 g−1 to 214.8m2 g−1 after two hydrothermal complex process. Effects of Ni/Al ratio, adsorbent dosage, Congo red (CR) concentration, coexisting ions, adsorption time and temperature were investigated. The obtained results indicated that NiO/Al2O3 composite had the high adsorption efficiency (99.6%) and great adsorption capacity (186.9mg g−1) under the optimum conditions. The adsorption isotherm and kinetics data were found to be well fitted and in good agreement with the Langmuir isotherm model and pseudo-second order model, respectively. The hierarchical porous NiO/Al2O3 composites presented remarkably higher adsorption efficiency during five recycling, which showed their potential as the highly efficient adsorbent for removal of CR in wastewater.

Residential segregation and employment stability among China’s migrant population, and related intergenerational differences—analysis based on propensity score matching

Jinxin Yao,Xingfu Lu,Fengxian Qiu 서울시립대학교 도시과학연구원 2022 도시과학국제저널 Vol.26 No.4

China’s migrant workers, the majority of whom are residents of rural China, have poured in to urban centres. Despite this influx, migrant workers have not integrated into urban society; rather, rural migrant life in cities is characterized by residential segregation and widespread social exclusion. This study explores the effect of residential segregation on the employment stability of China’s migrant population and investigates the intergenerational differences in this effect. Data were obtained from China’s 2014 special investigation on the social interactions and mental health of migrant workers and covered 6,805 and 3,237 people from the new generation (born in 1980 or later) and first-generation (born before 1980) migrant populations, respectively. Propensity score matching was employed to match those living in and outside of residentially segregated areas. Residential segregation had a significant adverse effect on the total sample’s employment stability. The negative effect of residential segregation on employment stability among the first-generation migrant population was found to be nonsignificant, but was significant for the new generation of migrants.

Fabrication of hydrophobic and oleophilic polyurethane foam sponge modified with hydrophobic Al2O3 for oil/water separation

Liying Kong,Yang Li,Fengxian Qiu,Tao Zhang,Qing Guo,Xiaoying Zhang,Dongya Yang,Jicheng Xu,Mengwei Xue 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.58 No.-

In current work, hydrophobic and oleophilic polyurethane (Al2O3/PUF) foam sponge was prepared by foaming technology. The material was characterized by XRD, TEM, BET, SEM and water contact angles (CA). The Al2O3/PUF was applied to removal of oil or organic solvent from oil/water system. Water contact angle of Al2O3/PUF could exceed 140°. The absorption capacity of Al2O3/PUF could be obtained 37 g/g and found to be reusable up to 10 cycles while maintaining its high absorption capacity. The result indicated that prepared foam sponge has good potential application in oil–water separation.

In situ fabrication dynamic carbon fabrics membrane with tunable wettability for selective oil–water separation

Xuejie Yue,Tao Zhang,Dongya Yang,Fengxian Qiu,Yao zhu,Jiasheng Fang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-

Achieving reversible wetting properties of separation membrane for on-demand separate oil/water mixture remains challenging, especially for the oil/water mixtures with complex impurities. Herein, hierarchical porous dynamic separation membranes involving primary fiber membrane and secondary nanostructures are fabricated by in situ growth ZnO nanowires on the surface of carbon fibers. Based on the effect of oxygen-related defects of ZnO nanowires coating, the as-fabricated dynamic separation membrane is capable of switching wetting property between high-hydrophobicity and superhydrophilicity via simply annealing alternatively under vacuum and air environment, achieving the switching between oil-removing mode and water-removing mode according to the type of oil/water mixtures. Moreover, the dynamic separation membrane can be extended to separate the oil/water mixtures containing suspended solids using the reconstruction of ZnO dynamic coating. Through removing the ZnO dynamic coating via soaking the clogged membrane in the hydrochloric acid–ethanol and refabricating the ZnO-dynamic coating, the membrane blocked by impurities could be readily re-formed, which effectively expand its scope of application and enhance its anti-fouling property. This work not only provides a simple and on-demand solution for pure oily wastewater, but also extends the separation membrane to separate oil/water mixtures containing suspended solids.