Measurement And Research Of Solid-liquid Equilibrium For Nts Salt In Water-organic Solvent

4-nitrotoluene-2-sulfonic acid (NTS) is an important raw material in chemical industry and the organic intermediate for synthesis DSD acid. In order to improve the process of DSD acid, solubilities of NTS salt in different alcohol aqueous solutions were determined. This work provides the basis data for NTS acid purification and also for enhancement product yield of NTS acid oxidation process.According to the industrial process of NTS acid oxidation,, the binary mixtures, methanol-water,ethanol-water,propanol-water,2-methoxyethanol-water,ethylene glycol-water were choosen as solvents. Solubilities of NTS salt in the single or mixed solvent with different alcohol mole fraction (from 0.2000 to 1.0000) were measured by the dynamic method with a laser monitoring observation technique over a temperature range from 288 K to 351 K. The solubilities data were compared for different systems in order to find some useful information. The result showed that the solubilities of NTSNa in solvent augmented as the temperature increased. Comparing with others, the solubilities of NTSNa in 2-methoxyethanol-water is the biggest. It is consistent with the report that 2-methoxyethanol-water can be used as the solvent of NTS acid oxidation reaction.Because the NTS salt belongs to the electrolyte system, the electrolyte solution and phase equilibrium calculation methods of solid-liquid-liquid ternary system were summarized and discussed in this article. The fitting result in each pure solvent group using the empirical equation is good. The root-mean-square deviation was 0.72 K in 2-methoxyethanol. The result also showed that the comparison between the experimental and the calculated solubilities of NTSNa+methanol+water using the E-NRTL equation was reasonable.The model of solid-liquid equilibrium established in this work could provide the direction to the industrial process of NTS acid. The root-mean-square deviations for NTSNa+ methanol+water was 0.94 K.The root-mean-square deviations for NTSNa+ethanol+water was 3.94 K. It is somewhat dissatisfactory compared with the NTSNa+methanol+water system.