Effect of Organic Modification on Adsorption Behaviour of Bentonite

摘要

A natural Kutch bentonite was modified using hexadecyl trimethyl ammonium (HDTMA) bromide and di- octadecyl dimethyl ammonium (DODMA) chloride to obtain two different types of organo bentonites viz., HDTMA- bentonite and DODMA-bentonite to study their sorption capacities for sorption of organic contaminants. The natural bentonite and the modified clays were characterized by X-ray diffraction, Fourier transform spectroscopy, thermal analysis, and BET-surface area techniques. The studies revealed that the organic cations in both the modified bentonites are inter- calated and assumed pseudo tri layer configuration. The dif- ferential scanning calorimetry studies have established that the modified clays are thermally stable up to about 200 °C. The adsorption capacity, in terms of total organic carbon (TOC), increases with increase in the concentration of the organic contaminant up to 500 mg/1 for both the modified clays. However the maximum sorption capacity for DODMA- bentonite was found to be higher and reached a maximum value of about 9.0 mg/g whereas and it was 7.8 mg/g for HDTMA-bentonite. The TOC sorption capacity of unmodi- fied bentonite was far less and was about 1 mg/g. Even though the TOC sorption efficiencies were similar for both the organo bentonites, they were not in direct proportion to the amount of organic carbon attached to the clay.