利用醋酸和硝酸混合废液制备食品级醋酸钙

Preparation of Food Grade Calcium Acetate using Liquid Wastes containing Acetic Acid and Nitric Acid

以醋酸和硝酸混合废液为原料,首先与碳酸钙、氢氧化钙反应,再通过蒸发结晶得到醋酸钙晶体。研究了反应终点pH、结晶温度、搅拌速度和洗涤方式对晶体品质的影响。在碳酸钙反应终点pH=2.5、氢氧化钙反应终点pH=7.5、结晶温度65℃、搅拌速度200rpm、饱和醋酸钙打浆洗涤5min的优化条件下,醋酸钙晶体纯度在98%以上。醋酸钙晶体重新溶解后,将溶液pH调至7以下,通过喷雾干燥即可制成食品级醋酸钙。

Liquid wastes containing acetic acid and nitric acid was processed into calcium acetate (CA) by reaction with calcium carbonate and calcium hydroxide in sequence. The effects of pH value of reaction end point, crystallization temperature, agitation speed and the way of crystal washing on the purity of calcium acetate were investigated respectively. The results show that the purity of calcium acetate crystal (CAC) was above 98 % at the optimal conditions as the reaction end point with calcium carbonate at pH=2.5 and with calcium hydroxide at pH=7.5, crystallization temperature of 65℃, agitation speed of 200 rpm, beating and washing crystal for 5 min by saturated calcium acetate solution. The calcium acetate crystal was dissolved, the pH of the solution was adjusted below 7, and then the food grade calcium acetate was prepared by spray drying.