络合沉淀法制备茶多酚工艺中络合剂的循环利用及Fe3+影响

Tea polyphenols（TP） were prepared by a complexing precipitation processs with an aluminium salt as the complexing agent.This study mainly focuses on the recycle of the complex agent,and the effect of Fe3+ content on the product yield was investigated.At 30～50 ℃ and pH 5～6,the TP in 200 g of green tea formed complex with 65 g of hydrous（aluminium） chloride.The precipitate obtained was washed with deionized water thoroughly,acidified with 10% hydrochloric acid, and then extracted with an equivalent volume of ethyl acetate.The ethyl（acetate） solution of TP was concentrated to produce crude TP with a yield of up to 11.94% and a purity of 90%.The experimental data also show great reduction in TP yield when Fe（Ⅲ） was involved in the precipitation process of the aluminium salt.In the absence of ferric iron,the aluminium complex agent can be recycled at least 3 times with TP yields of more than 10% and the purity higher than 88%.