Abstract

In the present study, the synthesis and characterization of bifunctional organic-inorganic hybrid adsorbent for As(V) extraction in aqueous medium is described. The hybrid adsorbent was synthesized by coupling free radical addition with sol-gel processing, using 1-vinylimidazole (1-VI) as monomer, (3-aminopropyl) trimethoxysilane (APTMS) as amino functional group, vinyltrimethoxysilane as coupling agent, tetraethoxysilane as inorganic precursor and 2,2'-azoisobutyronitrile as radical initiator. Characterization was performed by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and textural analysis (surface area, average pore diameter and pore volume). High As(V) adsorption by hybrid adsorbent was observed in a wide pH range 2-7, which indicates robustness to this parameter. From adsorption kinetic, the As(V) adsorption equilibrium was reached quickly (3 min), indicating a fast mass transfer. The pseudo-second order, Elovich and intraparticle diffusion models showed good adjustments on experimental kinetic data. The maximum adsorption capacity was found to be 15.00 mg g(-1), which has been higher than others observed from natural, mineral and synthetic adsorbents. The Langmuir-Freundlich dual model showed the best fit on experimental isotherm data, indicating the presence of energetically heterogeneous binding sites in the materials, most likely ascribed to the amino and imidazole groups from APTMS and 1-VI, respectively. Upon achieving outstanding adsorption of As(V), it appears that hybrid material may present good performance as an adsorbent for packing mini-column in separation and preconcentration analytical methods.