Study On The Crystallization Kinetics Of Chlorothalonil

Chlorothalonil(CTL)is a high efficient and low poisonous broad-spectrum germicide, which is mostly used to defend crop from epiphyte; and it is also used as a repellent for industrial mildew inhibitor, fruit antistaling agent, germicide, coating and binder. Recently, pure CTL is demanded in the world, but the purity of CTL produced inland can't satisfy the requirements of the world market, especially the occident market. This paper focused attention on the research and analysis of the crystallization of CTL as temperature drop. The basic thermodynamic and kinetic data of CTL crystallization were tested, and we also regressed the crystallization kinetic equation which provides kinetic base for the optimization of the CTL crystallization.In this paper we chose several potential solvents based on the characters of CTL and the principles of solvent choosing, and then the solubility of CTL in these solvents were measured by laser and the purified effects were determined too, finally ethanol-(m-xylene) was selected as crystallization solvent. The solubility curve and metastable zone of CTL in ethanol-(m-xylene) were set out and the solubility and supersolubility equations were regressed from the experimental data.The CTL crystal nucleation and growth kinetic data were measured by means of batch dynamic method in the laboratory, and the regressive parameters of crystal nucleation and growth kinetic model were obtained through the data. In this paper we also analyzed the influence of the temperature, suspend density and supersaturation on the crystal nucleation and growth rate in the crystallization of CTL. According to the character of CTL crystallization kinetics the crystal size distribution could be improved by choosing suitable operating conditions.