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Frontiers of Chemical Science and Engineering >> 2011, Volume 5, Issue 3 doi: 10.1007/s11705-010-1104-6

Separation of epigallocatechin-3-gallate from crude tea polyphenols by using Cellulose diacetate graft

Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029, China

Available online:2011-09-05

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Abstract

This study demonstrates a new Cellulose diacetate graft -cyclodextrin (CDA- -CD) copolymer asymmetric membrane prepared by a phase inversion technique for the separation of (-)-epigallocatechin-3-gallate (EGCG) from other polyphenols in crude tea. The graft copolymer, CDA- -CD, was synthesized by prepolymerization of cellulose diacetate (CDA) and 1,6-hexamethylene-diisocyanate (HDI), which was then grafted with -cyclodextrin ( -CD). Surface and cross-section morphologies of the CDA- -CD membranes were analyzed by using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FT-IR) indicated that the -CD was grafted onto the CDA by chemical bonding. The influences of the HDI/CDA mass ratio and the catalyst mass fraction on the -CD graft yield were investigated. The optimum conditions of a HDI/CDA mass ratio of 0.35 g·g and a catalyst mass fraction of 0.18 wt-% produced a -CD graft yield of 26.51 wt-%. The effects of the -CD graft yield and the concentration of the polymer cast solution on the separation of EGCG were also investigated. Under optimum conditions of a -CD graft yield of 24.21 wt-% and a polymer concentration of 13 wt-%, the purity of EGCG increased from 26.51 to 86.91 wt-%.

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