Poly(methacrylic acid)/SiO2/Al2O3 based organic-inorganic hybrid adsorbent for adsorption of imazethapyr herbicide from aqueous medium

Abstract

In the present study a newly designed hybrid polymer based on poly(methacrylic acid)/SiO2/Al2O3 synthesized by combination of random free-radical polymerization followed by sol–gel process was evaluated for imazethapyr herbicide adsorption from aqueous medium. The adsorbent material has been characterized by FT-IR, SEM, TGA and X-ray diffraction. The adsorption kinetic properties were obtained by application of kinetic models (pseudo-first order, pseudo-second order and intraparticle diffusion). Although the fit models to experimental data were similar each others, the pseudo-second provided a slight best fit for herbicide adsorption onto hybrid polymer. From binding isotherm adsorption, the dual-site Langmuir-Freundlich model showed the best fit and maximum adsorption capacity of 4.50mgg−1. Thermodynamic parameters seem to indicate that adsorption of herbicide by hybrid material is exothermic, with decreasing in the disorder of the system and spontaneous. From the magnitude of ΔH (−24.68kJmol−1) and the activation energy (12.21kJmol−1), it can be infer that adsorption of imazethapyr by hybrid polymer if of physical nature. From the achieved results, the poly(methacrylic acid)/SiO2/Al2O3 material showed good adsorptive characteristic for imazethapyr and this strategy open a convenient approach for preparation of new hybrid adsorbent materials in the field of separation science.