Enhanced phenol removal from aqueous media by adsorption onto organo-modified bentonite

Abstract

The removal of organic pollutants from contaminated water was the interest of numerous research works, which demonstrated the efficiency of adsorption and organo-modified bentonite-based adsorbents in discharging organic pollution from wastewater. However, the availability and the high cost of those adsorbents have limited further application; this study aims to solve these issues. The intercalation of an organic surfactant, tetraheptylammonium bromide (THPAB) onto the surface of Algerian bentonite from the deposit M'zila we named Ben, yields a new material. The synthesized tetraheptylammonium bentonite (THPA-Ben) underwent characterization before testing its effectiveness as an adsorbent for removing phenol from aqueous solutions. The FTIR, TGA, XRD, and SEM-EDS analysis confirmed successful intercalation of the THPAB onto the Ben surface. The results of adsorption experiment demonstrate the high efficiency of the new adsorbent in removing phenol from aqueous solution. The greatest percentage of the removed phenol was 98.2% when the initial concentration was 5 mg L-1. Adsorbing onto 40 mg of THPA-Ben, the optimum adsorption conditions were: 55 degrees C; pH values of 4.26 and similar to 9; equilibrium was reached after a contact time of 90 min. The modeling of phenol removal results by kinetic equations shows that the pseudo-second-order model is the best to describe the adsorption process (R-2 > 0.9999). The modeled isotherms of phenol adsorption onto the THPA-Ben were well fitted with both the Langmuir and Freundlich isotherm models; the highest phenol adsorption capacity was obtained for the organo-modified bentonite; this indicates that the organo-bentonite THPA-Ben is a promising low-cost adsorbent that enhanced the phenol removal from aqueous media.