Taurine Preparation And Electrodialysis Desalination Process,

Taurine is one of the vital components of bezoar which is a Chinese traditional medicine that is good for medical treatment and health care. There is a great demand for it. The domestic preparation method for taurine used by most manufacturers is based on the following steps: synthesis of 2-aminoethyl sulfuric ester (AES), following sulfonation with Na2SO3 to get the taurine mother liquid. The paper's work is mainly focused on the above route, but introduces electrodialysis technique into the desalting purifying of taurine. In contrast, this electrodialysis technique has a specific advantage over the domestic technique of hydrochloric acid-ethanol desalting.In the process of esterification to get 2-aminoethyl sulfuric ester (AES), by contrasting, a series of organic solvents are used to finally select n-butanol as a dehydrant. The dehydrant has much goodness over toluene. The esterification conditions of synthesizing AES are optimized and the best material adding sequence, sulfuric acid dropping temperature, refluxing time, material ratio, etc. The purity of product (AES) and the yield both reaches above 97%.In the process of sulfonation, it is found that AES hydrolysis at the reaction conditions doesn't have a large effect on the yield of taurine and it is found that one of the factor causing the low yield is the oxidation of Na2SO3. Protection under nitrogen and deoxygenation of water are adopted to solve the problem. Iodine titration is made to trace the content of Na2SO3, and thus the sulfonation state can be known, and the sulfonation ends over a period of 12h. Increases of concentration of AES and Na2SO3 effect favorably the yield of taurine and the nearly saturated Na2SO3 is better. Kinetics of reaction of AES with Na2SO3 is proposed, and the approximate equation is dx/dt = 0.0241x2-0.0982(a-x)2. SN2 kinetics is supposed for the reaction.Conventional hydrochloric acid-ethanol desalting technique runs on a basis of complex operation, high cost, and some pollution. In our research work, a new technique that adopts electrodialysis membrane separation desalting to purify taurine is introduced. A two-pump electrodialysis device is designed and main parameters of the device are tested. The results show that the two-pump one can overcome somedrawbacks of the existing four-pump device. The electrode potential is reduced, energy is saved, and side-products are decreased. Taurine of high quality is obtained through electrodialysis desalting, distillation, dehydration, drying, crystallization. Experimental voltage is used as a controlling index, which varies at different stage of desalting to control the electrodialysis is working under its utmost electricity. Conductivity is used to represent the content of salt in the taurine product so that the desalting process can be monitored. According to the loss of taurine during electrodialysis, it is found that the content of salt in the taurine mother liquid has a effect on the yield of taurine. The conclusion that high content of salt causes more transfer of taurine into concentrating chamber i.e. more loss of taurine is reached.