Preparation of HDTMA-bentonite: Characterization studies and its adsorption behavior toward dibenzofuran

Abstract

Bentonite is one of the most commonly used raw materials in the water treatment processes because of its low cost, easily availability and high mechanical and chemical stability. In this study, natural bentonite was modified with a large organic surfactant, which is hexadecyltrimethyl ammonium (HDTMA) bromide. The modified bentonite was called organobentonite. The surface characterization of natural bentonite and HDTMA-bentonite was examined by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry(XRD), Brunauer-Emmett-Teller (BET) and thermogravimetric(TG) analysis. FTIRspectroscopy showed the existence of HDTMA functional groups on bentonite surface. XRD results revealed randomly lateral-monolayer arrangements of the intercalated alkylammonium cation. The BET surface area significantly decreased after the modification due to the coverage of the pores of natural bentonite. Differences in the differential thermogravimetric (DTG) peaks for natural-and HDTMA-bentonite were observed and interpreted. HDTMA-bentonite was then tested as an adsorbent for the removal of organic compounds such as dibenzofuran (DBF) from aqueous solutions. The amount of adsorption for HDTMA-bentonite was found to be around 20 times higher than that of natural bentonite in 10 mg dm(-3) DBF solution at 20 degrees C. The adsorption kinetics of DBF onto HDTMA-bentonite was also studied at 20, 30 and 40 degrees C and thermodynamic parameters were calculated. The overall adsorption process was exothermic and physical in nature. The results indicate that HDTMA-bentonite is an effective and a low-cost adsorbent for the removal of heterocyclic aromatic compounds such as DBF. Copyright (C) 2010 John Wiley & Sons, Ltd.