Sorption Of Isofenphios-methyl On Hexadecyltrimethylammonium Modified Organic Clay

With the vast use of organic man-made pesticide,the pollution of the remnant gradually goes serious.Various techniques have been used to remove pesticide from waste water,including active carbon adsorption,catalyse oxidation,chemical coagulation and activated sludge process.This paper emphasizes the modification techniques of common clay minerals—kaolin and diatomite and the adsorption to the isofenphos-methyl.In this paper,Hexadecyltrimethylammonium(HDTMA) was used to modify kaolin and diatomite.The influence of synthetic conditions on the isofenphos-methyl adsorption of modified clays was investigated.The experimental results indicated that the organic kaolin prepared at room temperature,pH of 4,dosage of HDTMA at the proportion of 0.6 CEC and react time of 15 minutes showed the best adsorption performance,while the appropriate condition to make organic diatomite was:room temperature,the pH value was 7,the dosage of HDTMA was 0.5CEC,the react time was 15 minutes.The properties and optimal conditions for organic clays to adsorb isofenphos-methyl were investigated under static state in the laboratory and also the effects of the initial concentration,adsorption time,adsorbent concentration,the pH value and salt were discussed.Through the test,made the static adsorption isotherms of organic kaolin and diatomite,the research results indicated that the adsorption rate of isofenphos-methyl with the two kinds of sorbent was rapid.About 80%removal of isofenphos-methyl could be achieved within 40 minutes at the initial concentration of 30 mg/L,dosage of modified kaolin at 10 g/L in the natural water pH range of 5 to 9, while the removal rate by organic diatomite could reach to 34.0%within 20 minutes at room temperature,initial concentration of 30 mg/L,adsorbent concentration of 10 g/L in the pH range of 4-10.Besides,the addition of salt could obviously improve the adsorption capability of organic kaolin and diatomite.The adsorption isotherms of isofenphos-methyl with the two kinds of sorbent all fitted the Freundlich equation.Through the dynamic adsorption,made the penetrating curves of organic kaolin and diatomite,also has conducted the experimental study to the influence factors, such as the mass ratio of organic clays and soil and the pH value.The results showed that the optimal removal rate of isofenphos-methyl by 40 g soil and 80 g organic kaolin might reach to 94.1%,however,that of 30 g soil and 30 g organic diatomite was only 66.6%.The removal effect was improved with increase in proportion of organic diatomite in adsorption layer.Furthermore,the pH value played a trifling role to the adsorption effect.