Investigation On Electrodialysis Technology Application In Glycine Synthesis

Glycine is an important intermediate product, and extensively applied in the medicine, pesticide, food, fertilizer, animal feed and related industries. With the increase of market demand for glycine, more and more attention was paid to its production process and purification techniques. China is one of the main countries producing glycine. The main producing technology is through the ammoniation of chloroacetic acid. The key problem existing in the industrial producing process is the separation of glycine from ammonium chloride by the diluents crystallization with methanol. The main disadvantages of this separation technology include the high cost of methanol, the vent of wastewater, the serious pollution, the high consumption of energy and reactant, which will cause the high producing costs and the low competitive position.In this paper, the reaction mechanism was studied and the influence of the key elements, such as temperature and pH, on the synthesis process of glycine was investigated. By improving the traditional producing technology of glycine, an advanced synthesis and separation technology was introduced. Liquid ammonium was replaced by ammonium bicarbonate as stuffs, so steel cylinder was not needed for liquid ammonia and erosion and irritation was not appeared in the course of production. It was benefit for storing, transporting and producing .the reaction between them was carried out in the common saturated solution of glycine and ammonium chloride.This thesis developed a new technology of purifying glycine by electrodialysis on the base of summarizing several glycine-producing technology. Separation of glycine from the reaction mixture including ammonium chloride and glycine was emphasized. Effects of operation parameters such as flux of raw solution and limited current on the yield and quality of product were discussed. The results showed that a yield of glycine exceeds 96% with 99%purification can be achieved. Compared to the current technology, the proposed technology offers higher yield, less pollution, significantly lower production costs.