Kinetics of phosphate adsorption from aqueous solution into organobentonite by cationic polymer grafted bentonite

Abstract

Natural clays are abundantly available low-cost natural resource which is nontoxic to ecosystem. Over the recent years, research on the modification of clay to increase their adsorbent capacity to remove contaminants from aqueous solution. In this study, natural bentonite was modified with polydimethyldiallil tetraammonium chloride (PDMDMAC) and Hexadecyltrimethylammonium bromide (HDTMAB). Bentonite, PDMDMA-Bt and HDTMA-Bt were then characterized using XRD, XRF, SEM, FT-IR, elemental analysis and Brunauer-Emmett-Teller (BET) surface area techniques. The HDTMA+ and PDMDMA+ cations were found to be located on the surface and enters the interlayer spaces of smectite according to the XRD and SEM results. FT-IR spectra indicated the existence of HDTMA PDMDMA functional groups on the bentonite surface. The BET surface area significantly decreased after the modification due to the coverage of the pores of natural bentonite. After the characterization, the kinetics adsorption of phosphate ions (PO4-3) onto betonies, HDTMAB-Bt and PDMDMA-Bt was investigated. On kinetic data representation, pseudo-first, pseudo-second order and intraparticle diffusion models were used, with the pseudo-second-order model gave better correlation which indicates chemisorption between adsorbent and adsorbate molecules.