Method for purifying tannic acid

The invention relates to a method for purifying tannic acid. Low-purity tannic acid is used as a raw material, and an acidic solution is used as a purifying agent; dissolving tannic acid in water to form a tannic acid aqueous solution; the method comprises the following steps: adding a low-temperature acidic solution into a low-temperature tannic acid aqueous solution according to a liquid-liquid volume ratio of 0.1-10, fully mixing, and separating out tannic acid in the solution to form flocculent precipitate; and carrying out liquid-solid separation, cleaning and drying to obtain the tannic acid with higher purity. The method has the characteristics of simple process, high efficiency and outstanding purification effect. 本发明涉及一种单宁酸提纯的方法。以低纯度的单宁酸为原料，以酸性溶液为提纯剂；将单宁酸溶解于水中形成单宁酸水溶液；将低温的酸性溶液加入低温的单宁酸水溶液中，液液体积比为0.1~10，充分混合，溶液中的单宁酸析出形成絮状沉淀；再经液固分离、清洗、干燥，即可获得纯度较高的单宁酸。本发明具有工艺简单、效率高和提纯效果突出的特点。