Magnetic and pH responsive composite hydrogel-based on poly(2-(diethylamino)ethyl methacrylate)/chitosan for fipronil removal from aqueous medium

Abstract Herein, a novel magnetic and pH responsive composite hydrogel-based on poly(2-(diethylamino)ethyl methacrylate)/chitosan (Fe3O4/SiO2/PDEAEMA/CS) was synthetized and investigated as an adsorbent for fipronil removal from aqueous medium. After characterizations by different techniques and studies of Fe3O4/SiO2/PDEAEMA/CS properties, experiments were performed in batch process in function of pH, contact time and concentration, and kinetic models and isothermal models were used to describe the adsorption mechanism. The best results were found at pH 4, 25 mg of adsorbent and stirring for 60 s, in which the material exhibited adsorption around 80%. The fipronil adsorption was well interpreted by the pseudo-second order kinetic model (R2 = 0.928; qecal = 6.01 mg g−1) and dual-site Langmuir-Freundlich isotherm model (R2 = 0.984; Qmax = 82.50 mg g−1). Fipronil was desorbed in different buffer phosphate solutions, acetonitrile, methanol and then Fe3O4/SiO2/PDEAEMA/CS was successfully regenerated and reused several times, without loss in adsorption efficiency. The results suggest that the adsorbent have great potential in the fipronil removal or other organic/inorganic compounds found in wastewater.