Preparation And Characterization Of Cellulose Acetate-graft-β-Cyclodextrin Membrane

Cellulose Acetate (CA) is a good membrane material, which has high selectivity, large water permeability and simple process.β-cyclodextrin (β-CD) has been used extensively in separation science due to its hydrophilic surface and hydrophobic cavity. In this study, CA graftingβ-CD copolymers (CA-g-β-CD) were synthesized by two-step reactions. CA-g-β-CD membrane was prepared to separate puerarin (PU) and Epigallocatechin-3-gallate (EGCG). The main results are as follows:1. Synthesized of cellulose acetate graftingβ-cyclodextrin copolymersSome influential parameters on graft yield, includingβ-CD/CA mass ratio, cross-linking agent (HDI)/CA mass ratio and catalyst type and mass fraction were investigated. Under the optimum conditions ofβ-CD/CA mass ratio 1.5g.g-1, HDI/CA mass ratio 0.4g.g-1, dibutyl tin dilaurate mass fraction 0.18wt%, theβ-CD graft yield was 26.51wt%.2. Separation of Epigallocatechin-3-gallate (EGCG) from crude tea polyphenols by CA-g-β-CD membraneSome parameters on tea polyphenols rejection, membrane adsorption capacity for EGCG and purity of EGCG includingβ-CD graft yield, polymer concentration of cast solution and additives were investigated. Under optimum conditions ofβ-CD graft yield 24.21wt%, polymer concentration 13wt%, addition of 5wt% PVPK30, tea polyphenols rejection reached the maximum of 85.84%, the purity of EGCG increased from 26.51% to 87.29% and membrane adsorption capacity reached maximum of 33.294mg.g-1.3. Separation of puerarin from crude pueraria flavonid by CA-g-β-CD membraneSome parameters on puerarin purity includingβ-CD graft yield, polymer concentration of cast solution, additives, filtration time and batch were investigated. Under optimum conditions ofβ-CD graft yield 24.21wt%, polymer concentration 13wt%, no additive and filtering 16h, the purity of puerarin increased from 52.62% to 65.77%. The membrane was used for best 3 batchs.The results also showed that, compared to CA membrane, CA-g-β-CD membrane had lack in number of pore quantity, small pore volume and pore diameter.