Characterization and adsorption of phenol by organophilic clays

Nowadays, increasing concern about pollution of groundwater by organic chemicals led to research on the use of various adsorbents. They can be applied to provide a barrier to the escape of organic contaminants from storage tanks and stabilization lagoons. This study investigated, experimentally, the adsorption of phenol by six organoclays, using phenol in aqueous solution. This is the way that wastewater is discharged. The organoclays were prepared with two different clays, a bentonite from the Brazilian State of Paraiba (SVC), sodium exchanged in laboratory and a Wyoming, bentonite (SWy) with three Brazilian quaternary ammonium salts. The cations exchanged were dialkyl dimethyl with the alkyls groups dodecyl (DADM), distearyl dimethyl (DSDM) and octadecyl trimethyl (ODTM). Through this technique the hydrophilic character is transformed into hydrophobic. Adsorption of phenol followed the order of ODTM-SVC > DADM-SVC > DSDM-SVC > DADM-SWy > DSDM-SWy > ODTM-SWy. Isotherms for DSDM-SVC, DSDM-SWy, DADM-SVC, DADMA-SWy, ODTM-SVC and ODTM-SWy followed a convex up pattern. The equilibrium curves obtained are well represented by the Freundlich isotherm model. The adsorption data showed that the prepared materials were effective to adsorb phenol, being the Brazilian clay the most efficient of the three materials.