An efficient method for clay modification and its application for phenol removal from wastewater

A new type of modified clay was produced from a Ca-bentonite treated with hydrochloric acid as a surface modifier agent and then with hexadecyltrimethylammonium bromide (HDTMA) as a surfactant to produce an organophilic adsorbent. The specific surface area of the modified clays was 40% higher than the specific surface area of bentonite treated only with HDTMA. A series of kinetic and equilibrium tests was carried out to study the effectiveness of the modification method to improve the bentonite ability to remove phenol from aqueous solutions. The adsorption capacity of modified bentonite was 10 times greater than the natural bentonite. Phenol adsorption was fast and reached equilibrium in 30 min. Adsorption was physical and exothermic and was described with Henry and Freundlich isotherms.