Separation Of Monochloroacetic Acid And Dichloroacetic Acid With TOA Based On Chemical

The monochloroacetic acid enjoys a wide range of applicability as an important organic intermediate, for example, in agricultural idustry, medical industry and daily chemical. The main production process of monochloroacetic acid is acetic acid catalysis and chlorination method, which produces dichloroacetic acid by-product. The traditional purification method is crystallization and the content of monochloroacetic acid is not high. Therefore, it will be of great significance if a new way which can separate the monochloroacetic acid and dichloroacetic acid deeply is available for the system. So complexation extraction has been studied. In this paper, the extraction and back extraction behavior of monochloroacetic acid and dichloroacetic acid with a mass ratio of322:1was investigated with industrial class trioctylamine (TOA) as the extractant and n-hexane as the diluent.The main contents are as follows:1. The composition of aqueous solution was determined by industrial operating. The effects of temperature, pH of aqueous solution and initial concentrations of TOA on distribution coefficient were studied. The extraction conditions were optimized. The mathematical models of the pH of aqueous solution and distribution coefficient of extraction were established. The models could be used in the prediction of effects of pH on distribution coefficient in the suit conditions. And the mathematical models of concentration of TOA and distribution coefficient of extraction both in single acid system and mixture acid system were built up. Based on the apparent basicity of the TOA on extraction, the model in single dichloroacetic acid system was proposed to describe the relationship between dichloroacetic acid and TOA. Further, the models in mixture acid system were proposed based on the synergistic extraction.2. According to the pH swing effect, back extraction by water and sodium hydroxide were investigated. The monochloroacetic acid was recovered and the extractant was regenerated after back extraction. The optimal volume ratio of aqueous solution to organic solution was given. The concentration of TOA in aqueous solution was measured and reduced.3. With the optimal conditions, the industrial applications of complexation extraction and back extraction on monochloroacetic acid and dichloroacetic acid were studied. Monochloroacetic acid was purified (from98wt%to99.8wt%), and the content of dichloroacetic acid was reduced (from0.3wt%to0.09wt%). The economic accounting of the technology was then carried out and proved feasible.