Methyl Tin Mercaptide Wastewater Treatment Process Optimization And Mechanism Studies

Because of the excellent thermostability, photostability and intersolubility, Organotin be deemed to the most important heatstabilizer of polyvinyl chloride (PVC), its general uses also includes pesticides and paint etc. With the use of organic tin increasing, Organictin wastewater inevitablee into the environment. Ecological environment is threatened seriously. According to investigation, organictin compounds that human add to water environment is one of the most poisonous chemicals. It is the metal compounds Which is the only known endocrine interfering substances. So that pollution problem has gradually attracted people's attention.This experiment study of mercaptan methyltin Manufacturing process produces condensation wastewater. It has more complicated constitution and strong pungent odour, the main content is ammonia nitrogen and organic pollutant. Belong to high concentration, toxic, hard-degradation organic wastewater. Its chemical oxygen demand (COD) content and NH4+-N content is about 7300mg/L and 26700mg/L, using biochemical treatment will cause microbial cell death and biochemical device normal operation be damaged. So, at present, our country mainly adopts pretreatment reducing the pollutant concentration of mercaptan methyl tin wastewater, and then carry on biological treatment. but this process complex, microbial domesticated difficulties. Based on the nature characteristics and problems of mercaptan methyl tin wastewater, this paper puts forward a method of direct treat the mercaptan methyltin wastewater, expect to obtain a simple, high pollutant removal rate water-treatment technology.Through the three stages of flocculation, distillation and carbocoal adsorption to treat the wastewater. The response surface methodology is taken to study the influences of flocculation pH, flocculation dosage, flocculation stirring rate, the dosage of carbocoal, adsorption time and adsorption pH on the removal rate of COD and NH4+-N, On the base of variance analysis, the multiple regression and the model fitting's foundation, the optimun technological parameter is obtained. The experi- mental data were analyzed by the pseudo second order kinetics model, obtaining the initial sorption rate and rate constants. The results showed that the pseudo second order kinetics model fit the experimental data well. Under the experimental conditions, it was found that the controlling step of adsorption COD from mercaptan methyl tin wastewater by carbocoal were all film diffusion controlling processes.The optimum parameters was as following:flocculation dosage 4g/L,ageing time 2h, flocculation pH9, Flocculation stirring rate 606r/min, the dosage of carbocoal 80g/L, adsorption time 54 min and adsorption pH 6.6. The result show that, Through the three stages to complete wastewater treatment, COD is less than 170 mg/L and NH4+-N is less then 50mg/L, Achieve GB8978-1996 requirements.Compared with other processing method, The process has the advantages of short flow, high Pollutants removal rate and easy to construct.