膜分离技术制备高纯单宁酸的研究

Study on Preparation of High-purity Tannic Acid by Membrane Separation

工业单宁酸经改性活性炭预处理后,用超滤和纳滤技术纯化的方法制备高纯度单宁酸。重点考察了料液质量分数、操作压力差、料液温度对膜分离效果的影响。确定的最佳工艺条件是:料液质量分数15%、截留相对分子质量为6 000的超滤膜和截留相对分子质量为600的纳滤膜的操作压力差分别为0.10 MPa和0.08 MPa、料液温度40℃。同时探讨了颗粒活性炭通过硝酸氧化改性增强其吸附性能的方法。分析结果表明,膜分离技术有效地实现了不同分子质量的物料分级和截留,精品单宁酸的含量为97.3%,收率为84.7%。

High-purity tannic acid was prepared from industrial tannic acid by the methods of membrane separation and modified activated carbon pretreatment. Effects of factors such as solution concentration, operation pressure difference, solution temperature on result of membrane separation were studied. Optimum conditions are as follows： solution concentration 15 % （mass fraction） ,operation pressure difference 0.1 MPa for ultrafihration membrane （ molecular mass cut-off 6 000） and 0.08 MPa for nanofiltration membrane （MMCO 600） , solution temperature 40 ℃. In order to enhance activated carbon absorption properties, modification of granular activated carbon with nitric acid was also explored. Experimental results showed that technology of membrane separation promoted the content and yield of tannic acid significantly, which reached 97.3 % and 84.7 % respectively.