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37. Pervaporation of benzene/cyclohexane mixtures through mixed matrix membranes of chitosan and Ag+/carbon nanotubes.

Author

Shen, Jiang-nan, Chu, Yue-xia, Ruan, Hui-min, Wu, Li-guang, Gao, Cong-jie, and Van der Bruggen, Bart

Subjects
*PERVAPORATION, *BENZENE, *CYCLOHEXANE, *ARTIFICIAL membranes, *CHITOSAN, *CARBON nanotubes, *SILVER ions
Abstract

Abstract: Functionalized multiwalled carbon nanotubes (MWNTs) were incorporated into a chitosan membrane for separation of benzene/cyclohexane mixtures by pervaporation. The pristine MWNTs were treated by mixed acid (H2SO4/HNO3=3/1) and then functionalized with isonicotinic acid. Ag+ was grafted to the pyridine ring on the MWNTs by a complexation reaction. Membranes made of chitosan and Ag+/carbon nanotubes were prepared with polysulfone membranes as support. The surface structure of modified MWNTs was examined by FT-IR, TEM, EDS and XPS to assess its morphology. The swelling and pervaporation characteristics of the membranes for separation of benzene/cyclohexane mixtures were investigated. The swelling degree of the membranes in benzene was more than 2.5 times that of the pristine chitosan membrane. The swelling degree was found to increase with the content of the MWNTs–Ag+ in the membrane and the benzene content in the feed. Pervaporation results also showed that the MWNTs–Ag+/chitosan hybrid membrane separation performance is better than MWNTs/chitosan hybrid membrane and pristine chitosan membrane. The permeation flux of the membrane increased, the selectivity increased firstly and then decreased with the increase in the content of MWNTs–Ag+. The selectivity reached 7.89 and the permeate flux was 357.96g/m2 h (the mass ratio of benzene was 50%, the temperature was 20°C) when the percentage by weight of the MWNTs–Ag+ to chitosan was 1.5%. The Arrhenius activation parameter of 1.5% MWNTs–Ag+/chitosan (CS) hybrid membrane is 4.28kJ/mol while 1.5% MWNTs/CS membrane is 10.6kJ/mol in 50% benzene concentration in feed. [Copyright &y& Elsevier]

Published
2014
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38. Comparison Study of PVDF-HMn2O4 and PES-HMn2O4 Membrane-Type Adsorbents for Lithium Adsorption/Desorption

Author

Yang, Shan Shan, Liu, Xiong, Shen, Jiang Nan, and Gao, Cong Jie

Abstract

Much attention has been paid to membrane-type lithium adsorbents to overcome the shortages of the leakage of powder, poor permeability and difficult recycle for powder lithium adsorbents. In this work, a series of membrane-type adsorbents of spinel-type manganese oxides were converted from lithium manganese oxide precursor membranes by acid treatment. Precursor membranes were prepared by solvent exchange method using polyvinylidene fluoride (PVDF) and Polyether sulphone (PES) respectively as binders, powder LiMn2O4 as the precursor and N,N-dimethyl acetamide (DMAc) as the solvent. The preparation conditions were investigated by changing the binder and the concentration of powder LiMn2O4. The surfaces and morphology of membrane-type adsorbents were observated by scanning electron microscope. The comparation of the capacities of lithium desorption from precursor and adsorption for membrane-type adsorbents based on different binders shows that PVDF is more suitable to be the binder than PES with liquid film thickness of 0.25mm, and the proper concentration of PVDF and powered LiMn2O4 are respectively 12% and 60%.

Published
2014
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39. Preparation of PMAM-B-PNVP and its Hydrolysate by RAFT Polymerization: Structure Characterization and its CO2 Permeation Performance

Author

Shen, Jiang Nan, Li, Juan, Jiang, Ting Ting, and Ruan, Hui Min

Abstract

Macromolecules chain transfer agents (MCTA) were synthesized through the reversible addition fragmentation chain transfer polymerization (RAFT) by using S-l-Dodecyl-S′-(α, α′-dimethyl-α-acetic acid) trithiocarbonate(MTTCD), S, S′-bis (2-hydroxyethyl-2′-dimethylacrylate) trihiocarbonate (BDATC), 2-cyanoprop-2-yl dithiobenzoate (CPDB) as the chain transfer agents, methacrylamide (MAM) as the first polymerization monomer. The results showed that the structures of the end-group of dithiocarbamates had significant effects on the activity of dithiocarbamates for the polymerization of PMAM. The derived block copolymer (PMAM-b-PNVP) was prepared by using the above mentioned polymer as macromolecular RAFT agent and NVP as the second polymerization monomer. N-vinyl-γ-sodium aminobutyrate-sodium methacrylate copolymer (VSA-MSA) containing -NH2 and -COOH as the CO2 facilitated carrier, a kind of new fixed carrier membrane material for CO2 separation, was synthesized by hydrolysis of the resulted PMAM-b-PNVP. The chemical composition and structure of PMAM-CTA, PMAM-b-PNVP, MSA-VSA were analyzed by FTIR, 1HNMR and DSC, the molecular weight and polydispersity index were analyzed by GPC. The Relative molecular mass of polymer was controllable. The polydispersity index (1.2~1.3) of the obtained polymer was narrow via using MTTCD and BDATC. The VSA-MSA/PS composite membranes were prepared. The CO2 and N2 permeation performance were tested at different pressure. The results showed that the resulted composited membrane had a CO2 permeation rate of 1.2×10-4 cm3 (STP) cm-2s-1cmHg-1 and a N2 permeation rate of 8.57×10-7 cm3 (STP) cm-2s-1cmHg-1 and an ideal CO2/ N2 selectivity of 140.02 at a feed gas pressure of 7.6 cmHg and 30 ℃.

Published
2013
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40. Comparative Analysis of HPDC Process of an Auto Part with ProCAST and FLOW-3D

Author

Duan, Hui Zhen, Shen, Jiang Nan, and Li, Yan Ping

Abstract

The high pressure die casting (HPDC) process of an ADC12 aluminum alloy auto part is researched by the software ProCAST and FLOW-3D, respectively. The possible HPDC defects of the auto part are analyzed. The difference of the filling process with the same technological parameter is studied. Compared with the simulation result of ProCAST, FLOW-3D software simulation result is closer to the die casting of the actual production.

Published
2012
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