Development Of Special Filter Media For Disinfection By-products In Drinking Water And Its Removal Mechanism

Excessive concentrations of trace disinfection by-products in drinking water are one of the widespread concerns about the safety of drinking water.At this stage,chlorination is still the mainstream disinfection process in waterworks,and the small amount of natural organic matter contained in the raw water is transformed into chlorinated organic matter such as trichloromethane during the chlorination process,which are potentially hazardous to human health and are therefore known as disinfection by-products.Therefore,the effective removal of disinfection by-products in drinking water without affecting the quality of drinking water and without significantly increasing costs is one of the major needs to ensure the safety of drinking water and improve the quality of life of the population.Activated carbon adsorption is considered the most suitable technology for the removal of disinfection by-products from drinking water,however,most commercially available activated carbon has a small adsorption capacity and low rate for disinfection by-products as the molecular polarity of chlorinated organics is greater than that of ordinary organics.This thesis focuses on the development of high performance disinfection by-products filter media and the removal mechanism,the main studies and results are as follows:（1）The structural properties such as iodine and phenol adsorption values,contact angle,pH_pzc,surface acid-base functional group content and pore structure of eight commercially available activated carbon materials and their static adsorption capacity and dynamic adsorption rate of trichloromethane were investigated separately,and the correlation between them was investigated by Spearman’s rank correlation analysis.（2）Targeted chemical modification of existing activated carbons to improve their adsorption performance on trichloromethane.The study showed that the average pore size of the mesopores of the activated carbon was significantly increased by nitrogen high temperature roasting,and the static adsorption capacity of trichloromethane increased from 3080μg/g to 4942μg/g.The modification by urea impregnation followed by nitrogen high temperature roasting increased the average pore size of the mesopores and the number of basic sites on the surface,and the adsorption capacity of trichloromethane was further increased to 5800μg/g.The surface modification by esterification increased the surface contact angle of the activated carbon and increased the dynamic removal rate of trichloromethane from 55.8%to90.5%.（3）It was found that the adsorption capacity and removal rate of the activated carbon were increased after modification by a combination of high-temperature roasting with nitrogen followed by surface esterification;however,the adsorption capacity was significantly increased by modification with urea impregnation followed by high-temperature roasting followed by surface esterification,but the dynamic adsorption rate of the activated carbon was reduced compared with that of the single surface esterification modification due to the increased hydrophilicity of the activated carbon surface caused by the introduction of a large number of alkaline functional groups.The static adsorption capacity of the modified activated carbon was5760μg/g for a raw water concentration of 352.1μg/L of trichloromethane,and the dynamic removal rate was 80.8%for 30 h over 200 L of water.