Improvement of glyphosate adsorption using new composites based on Ghassoul and chitosan: Kinetics and equilibrium study

Abstract

Clay materials combined with other compounds are intensely used in several fields. The present study focuses on the synthesis of organoclays and nanocomposites based on the intercalation of surfactant and biopolymer into swelling Moroccan clay. The produced materials were used in the removal of glyphosate from the aqueous medium. The organoclay was obtained by the intercalation of cetyltrimethylammonium bromide (CTAB) in the interlamellar space of stevensite, and the nanocomposite was fabricated by the direct interaction between the stevensite and chitosan. These materials were characterized by mean X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy (FTIR), Thermal Analysis and Transmission Electron Microscopy (TEM). The results showed that the stevensite is the dominant clay mineral of Ghassoul and confirmed that the nanocomposite has an intercalated clay structure. The batch mode was accomplished to quantify the glyphosate removal capacity from aqueous solution by these materials. The enhancement of hydrophobic properties has promoted the retention of the herbicide. The pseudo-second-order kinetic model of adsorption was the most suitable to describe the process of adsorption and the Freundlich isotherm equation fitted satisfactory the adsorption isotherm data. The capacity of adsorption was more outstanding for the nanocomposite chitosan/Ghassoul and reached a significant value of 159.10 mg.g-1. The nanocomposites based on chitosan/Ghassoul could be considered as promising materials for treatments of pesticide-contaminated water.