Study On Technology Of Sodium Citrate Production Through One Step Reaction

Sodium citrate is widely used in industry. For example, it can be used at food, medicine, electroplating, brewage and other trade. It has been needed more and more around the world in recent years, because some countries prescribed that sodium tripolyphosphate should not be used in detergent and sodium citrate has been substituted for it little by little.Sodium citrate was produced traditionally through the following process in industry. Firstly, calcium citrate was treated with vitriol, and then citric acid came out through filtrating, decoloring and exchanging for ions, etc, in turn. Let citric acid react with sodium carbonate to obtain the product of sodium citrate in the end. This technology for sodium citrate has some deficiencies, such as high production cost, long production cycle and environmental pollution from byproduct. A new technology for sodium citrate should be exploited as soon as possible in order to reduce the cost of production, improve the quality of product and so meet the market better. At the same time the byproduct can be utilized availably to avoid polluting the environment. The new technology for sodium citrate produced from calcium citrate and sodium carbonate was studied, and some conclusions were drawn after detailed research on the conditions of experiment:(1) The ratio of calcium citrate to sodium carbonate must be controlled above 1:3.35;(2) The appropriate concentration of sodium carbonate should be 20%;(3) Stop adding calcium citrate when the pH of solution is at the range of 10.30-10.55;(4) Appropriate time of adding calcium citrate should be 20min exactly;(5) Appropriate temperature of the reaction between calcium citrate and sodium carbonate should be 80℃;(6) Appropriate time of the reaction should be 30min; (7) The pH of sodium citrate solution should be adjusted to the range of 6.9-7.2 before concentration; (8) The mass of active carbon should be 1/20 of the mass of sodium carbonate.Both of magnified experiment and experimental production showed that the quality of product could meet the demand of FCC-IV (USA) and GB6782-86. Furthermore, the percentage conversion of calcium citrate was up to 99.7% and the yield percentage of sodium citrate was up to 98.6% at optimum conditions. The new technology of one stage process can solve the pollution of waste residue which existed in the old technology. At the same time, the method of analyzing the content of calcium citrate in material and byproduct was established. At last some principal equipment was designed according to the parameters in experiment.