Removal of chlorobenzene by adsorption from aqueous solutions on the HDTMA-bentonites as a function of HDTMA/CEC ratio

Abstract

In this work an Algerian natural bentonite was used in the preparation of new adsorbents by impregnation with different mass ratios of hexadecyltrimethylammonium bromide (HDTMA) surfactant. The HDTMA-bentonites adsorbents were prepared according to the HDTMA/bentonite cation exchange capacity (CEC) ratios (HDTMA/CEC). Five HDTMA/CEC ratios (25%, 50%, 100%, 150% and 200%) were used to investigate the effects on the physicochemical characteristics and the adsorptive power of these clays. The characteristics of these adsorbents were studied by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The adsorptive power of these clays was studied by batch adsorption of chlorobenzene from aqueous solutions. FTIR and TGA spectra confirm the modification of bentonites by intercalation with HDTMA. XRD spectra of these adsorbents exhibited interlayer spacings from 13 to 20 Å, with maximum interlayer spacing of 20 Å corresponding to the adsorbent with 100% HDTMA/CEC ratio. Adsorption experiments of chlorobenzene indicate that pseudo first order model was suitable for describing the kinetic results. Regarding the equilibrium results, both Langmuir and Freundlich isotherms were fitted well. The adsorbent impregnated with 100% HDTMA/CEC ratio, shows a high percentage of chlorobenzene removal compared to the other adsorbents.

Keywords

• Adsorption
• Bentonites
• HDTMA
• Chlorobenzene
• Cation exchange capacity (CEC)