Study On Production Of Sodium Citrate Through Double Decomposition Method With Calcium Citric And Sodium Carbonate

Sodium citrate is a kind of white cubic crystal or powder with salty flavor. It can be easily dissolved with water, but not with ethanol. It is stable under usual conditions, however, become into the anhydrous after heated to 150℃. According to the rule of ADI, sodium citrate is innocuity. The sodium citrate has the following applications: (1) It is used as food additive largely, such as the flavor, cushion agent, emulsification agent etc. It is often used to produe jelly, fruit juice milk, cake, and cheese with citric acid. (2) It has been used to produce washing powders instead of sodium phosphate since it has the properties including water dissolving, decontamination, and demineralization and so on. With the development of environmental protection industry, the sodium citrate process will speed up to meet the new requirements for washing powders.At present, the main processes producing sodium citrate include citric acid + caustic soda, citric acid + saleratus and so on. However, these processes all have some flaws, such as high cost, long process period, bad quality and the useless by-product of calcium sulphate etc. While the double decomposition procedure to produce sodium citrate using calcium citrate and sodium carbonate as reactants has some merits including short production period, lower cost, simple operation ect. Moreover, the pollution of waste residue existing in the traditional process also can be solved by this procedure. So the process is worthy of studying for citric acid and environment industry.In this paper, the double decomposition procedure for the production of sodium citrate has been researched in detail. The process conditions were optimized as follows:(1) The ratio of calcium citrate to sodium carbonate should be kept 1:3;(2) The optimization temperature of the reaction is 75℃;(3) The optimization pH of reaction should be 10.0-10.5;(4) Appropriate concentration of sodium carbonate should be 25%;(5) The optimization time of reaction should be 30 min;(6) Appropriate consumption of active carbon should be 5% of sodium carbonate. Additionally, the scaling up experiment and pilot were also done, and the results showed that the quality of product can meet the rule of FCC-IV (USA) and GB6782-86. The coversion ratio of calcium citrate was up to 98% and the yield of sodium citrate was up to 97% under optimized conditions.