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Liwei Ren,Honghua Jia,Min Yu,Wenzhong Shen,Hua Zhou,Ping Wei 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.5
Candida rugosa lipase (CRL) is one of the most widely used lipases. To enhance the catalytic abilities of CRL in both aqueous and non-aqueous phases, hollow silica microspheres (HSMSs) with a pore size of 18.07 nm were used as an immobilization support, and aldehydecontaining dextrans were employed to further cross-link the adsorbed CRL. In the experimental ranges examined,the loading amount of lipase linearly increased to 171 ±3.4 mgprotein/gsupport with the CRL concentration and all the adsorption equilibriums were reached within 30 min. After simple cross-linking, the tolerance to pH 4.0 ~ 8.0 as well as the thermal stability of immobilized CRL at 40 ~ 80oC were both substantially increased, and 82 ± 2.1% activity remaining after the sixth reuse. The immobilized CRL was successfully applied to the resolution of racemic ibuprofen in non-aqueous phase. The initial reaction rate increased by 1.4- and 3.6-fold compared with the rates of adsorbed and native lipases, respectively. Furthermore, the R-ibuprofen was obtained at ee > 93%, and the enantiomeric ratio reached E > 140 at the conversion of 50 ± 1.5% within 48 h.
Nitrogen-doped carbon nanosheets from polyurethane foams and removal of Cr(VI)
Jiaqi Duan,Baohua Zhang,Huailin Fan,Wenzhong Shen,Shijie Qu 한국탄소학회 2017 Carbon Letters Vol.22 No.-
Nitrogen-doped carbon nanosheets with a developed porous structure were prepared from polyurethane foams by hydrothermal carbonization following ZnCl2 chemical activation. Scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, solid state 13C nuclear magnetic resonance (NMR) spectra and X-ray photoelectron spectroscopy were used to characterize the nitrogen-doped carbon nanosheet structure and composition. The removal of Cr(VI) by the N-doped carbon nanosheets was investigated. The results showed that the maximum removal capacity for chromium of 188 mg/g was found at pH=2.0 with PHC-Z-3. pH had an important effect on Cr(VI) removal and the optimal pH was 2.0. Moreover, amino groups and carboxyl groups in the nitrogen-doped carbon nanosheet played important roles in Cr(VI) removal, and promoted the reduction of Cr(VI) to Cr(III).
Wei Jiang,Guosong Ni,Pingping Zuo,Shijie Qu,Yunmei Li,Hongxian Niu,Wenzhong Shen 한국탄소학회 2019 Carbon Letters Vol.29 No.5
Isotropic pitch-based carbon fiber was successfully prepared from tetrahydrofuran-soluble fraction of coal tar pitch cocarbonization with petrolatum by air-blowing. The effects of reaction temperature and time, amount of petrolatum added on the composition and spinning properties of resultant pitches were investigated. It indicated that petrolatum could effectively improve the softening point, aromaticity, hydrogen content and molecular weight of the resultant pitches by promoting cross-linking and dehydrogenation polymerization reactions at low air-blowing temperature. Moreover, more aliphatic and naphthenic structures had been introduced into resultant pitches as addition of petrolatum and also inhibited the generation of quinoline-insoluble particles. The obtained green fibers were facile to be stabilized and carbonized and the resultant carbon fibers showed fully isotropic and finer, uniform diameter with smooth surface and higher tensile strength of up to 0.92 GPa. It provided a facile chemical modification method for isotropic pitch-based carbon fiber production.
Jiang Wei,Ni Guosong,Zuo Pingping,Qu Shijie,Li Yunmei,Niu Hongxian,Shen Wenzhong 한국탄소학회 2019 Carbon Letters Vol.29 No.5
Isotropic pitch-based carbon fiber was successfully prepared from tetrahydrofuran-soluble fraction of coal tar pitch co-carbonization with petrolatum by air-blowing. The effects of reaction temperature and time, amount of petrolatum added on the composition and spinning properties of resultant pitches were investigated. It indicated that petrolatum could effectively improve the softening point, aromaticity, hydrogen content and molecular weight of the resultant pitches by promoting cross-linking and dehydrogenation polymerization reactions at low air-blowing temperature. Moreover, more aliphatic and naphthenic structures had been introduced into resultant pitches as addition of petrolatum and also inhibited the generation of quinoline-insoluble particles. The obtained green fibers were facile to be stabilized and carbonized and the resultant carbon fibers showed fully isotropic and finer, uniform diameter with smooth surface and higher tensile strength of up to 0.92 GPa. It provided a facile chemical modification method for isotropic pitch-based carbon fiber production.