Modify Bentonite And Study On The Adsorption Of BTEX In Wastewater By Modification Bentonite

Bentonite is a kind of clay mineral that is abundant in our country. It has unique samdwich structure and powerful adsorption ability. Modification of bentonite can improve its adsorption ability greatly and so makes it adsorb the contaminants such as heavy metal ions and organic substances in wastewater more effectively. Bentonite has lots of advantages in the treatment of wastewater, such as simple process, high efficiency and low cost. Above all we studied the raw bentonite by means of XRD and XRF, refined it, determined its basic physicochemical properties, and made modification experiment on it. Moreover, we systematically studied the factors that affect the adsorption of BTEX from the wastewater on bentonite surface and the best conditions for treatment were determined by experiments. We also discussed the adsorption mechanism of BTEX on the modified bentonite.The experiments resulted in two modified methods under the best preparation conditions. Na-bentonites reaction time was 1h, pH=8, T=60℃, sodium reagent dosage was 4% of bentonite. Organic bentonite: reaction time was 1.5h, pH=8, T=60℃, modified reagent dosage was 50%.The adsorption experiments using the organic bentonite were carried out and the best adsorption conditions of BTEX were given. Organic bentonite: solid-fluid ratio was 20g/L, adsorption time was 1h,T=40℃, pH=8, removing rate of benzene, toluene, xylene achieved 88%,95%,98%.Finally, the properties and mechanisms for CTMAB-bentonite to adsorb benzene, toluene and xylene in water were investigated in detail. Data of linear regression indicates that the adsorbing process of benzene, toluene and xylene fits the Langmuir and Freundlich isotherm. The adsorption mechanism was also studied by octanol-water partition coefficients of organic compounds. The above findings have certain theoretical and practical significances for using the adsorption performance of bentonites to treat wastewater, especially the BTEX-containing wastewater. Simultaneously a new way to enhance the application value of bentonite in our country has been developed.