The production of gallic acid by acid method and alkali hydrolysis is the two most commonly used production methods at present. The acid method is to directly hydrolyze the tannins in gallnut with sulfuric acid. Good, but the product contains a small amount of sulfate ions, the production is difficult to control, and it is prone to excessive hydrolysis. The hydrolyzed Gallic Acid Sigma acts to generate pyrogallic acid and other substances, resulting in an increase in the solubility of Gallic Acid Sigma, a darker color, and a decrease in yield. .
Alkaline method: It uses sodium hydroxide to act on the tannins in Galla japonica. The product has low purity, weak Gallic Acid Sigma activity, easily contains unhydrolyzed tannins, and has many auxiliary equipment and a long production cycle. SUMMARY OF THE INVENTION
The technical problem to be solved by the present invention is to provide a Gallic Acid Sigma production technology which can improve the production quality of Gallic Acid Sigma, increase the yield, and solve the defect of unstable product performance in the prior art.
The technical scheme that the present invention solves its technical problem adopts: a kind of buffer solution hydrolysis Gallic Acid Sigma production technique, it is characterized in that: comprise the following steps:
5) pulverize the gall;
6) in the enamel reaction kettle, add NaH PO Solution;
7) Add gall powder under stirring and stir well;
8) slowly add H SO Make pH value 1-2; Add steam 0.15MPA and be warming up to 120 DEG C, regulate and keep the pH=1-2 of mixture. Reaction times 2-4 hours, after reaction finishes cooling crystallization: filter, Dehydration, decolorization, filtration, crystallization, dehydration, and drying are performed to obtain the finished product.
The reaction conditions of the present invention are mild, and can effectively solve the improper control in the hydrolysis process using pure concentrated sulfuric acid, which is prone to excessive hydrolysis, and the problems of carbonization and other impurities. cycle, reduce the loss of gallic acid caused by excessive solid hydrolysis and activated carbon adsorption, improve the yield of Gallic Acid Sigma, and reduce production costs.