Abstract: Purification of tannin from Chinese gall nut was studied through treatment with granulated Fuller'earth and activated carbon. The results indicated that the sample with purity of tannin ≥98%, color 0.6 (Lovibond total color), content of main metal ions ≤0.5 μg/g was obtained respectively by extracting Chinese gall nut solution by 95% alcohol at 60℃, 30 mL/min flow rate with combined columns of granulated Fuller'earth and activated carbon.

Key words: gall nut tannin, granulated Fuller'earth, active carbon, physical absorption method, food grade tannin