反萃取降低高纯单宁酸生产中没食子酸残留量的应用

Application of counter extraction in gallic acid reduction during high-purity tannin acid production

为了进一步降低单宁酸中没食子酸残留量,以单宁酸为原料,采取萃取、反萃取等分离技术,以单宁酸中没食子酸残留量为评价指标,对提纯工艺进行优化。其最终优化工艺条件为选择pH 6.8的磷酸钠盐溶液作为反萃剂,单宁酸与乙酸乙酯固液比为1∶5(g∶mL),单宁酸与反萃液固液比为1∶2.5(g∶mL)。在此条件下单宁酸中没食子酸含量可降低到1%以内。

In order to further reduce the residual content of gallic acid in tannic acid, using tannic acid as raw material, by extraction, counter extrac- tion and other separation techniques, the purification technology was optimized using gallic acid residual content in tannic acid as evaluation index. Finally the optimum technology conditions were obtained as sodium phosphates （pH6.8） as stripping agent, tannic acid to ethyl acetate ratio 1：5 （g：ml） and tannic acid to stripping agent ratio 1：2.5 （g：ml）. Under the conditions, the residual content of gallic acid in tannic acid could decrease to less than 1%.