Synthesis of New Organo-Inorgano-Clay Materials Based on Metal Ions, CTMAB, and Bentonite. Application for Removal of Acid Dye

The present study focuses on the synthesis of pillared bentonite materials prepared by intercalating solutions of aluminum, chromium, iron, and. cetyltrimethylammonium bromide (CTMAB) into natural bentonite. Six solids were obtained and applied as adsorbents to remove acid-yellow E-4G dye from aqueous solutions. Different characterization methods, such as chemical composition, X-ray diffraction, and specific surface area, were used for that purpose. The efficiency of dye removal was studied as a function of pH, initial dye concentrations, contact time, and temperature. The efficiency of dye removal by CTMA-Al intercalated bentonite was found higher than that of inorgano-bent, under similar conditions. The results obtained showed that the maximum adsorption capacity for dye by modified bentonite was reached within the pH range from 1 to 2. Indeed,  the maximum adsorption capacity was estimated to be 385 mg/g at room temperature. The results of the kinetic study regarding the removal of E-4G dye by modified bentonites was found to fit the pseudo-second-order model. Moreover, it turned out that the adsorption isotherm data obtained fit well the Freundlich model, which is not the case for the Langmuir and D-R models tested. Calculated thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic with bentonite intercalated by aluminum and iron (B-AlFe) and is exothermic in the case of inserted bentonite by cetyltrimethylammonium and chromium (B-C-AlCr).