Comparative assessment of pesticide adsorption capacity and antioxidant activity of Silver Dodecatungstophosphate/HΒEA zeolite composites

Abstract

Composite materials consisting of the silver salt of dodecatungstophosphoric acid and HBEA zeolite are developed in order to give materials of superior adsorption properties for aqueous pesticide removal. Two-step impregnation and an ion-exchange method with variable constituent mass ratios were employed as synthesis procedures. One of the study goals was to optimize the composite preparation for efficient elimination of glyphosate pesticide and to investigate the modulation of antioxidant activity in the presence of pesticide. Based on comprehensive results, we propose mechanisms for simultaneous glyphosate removal and antioxidant activity. Spectroscopic analysis shows that the applied two-step impregnation method results in advanced composite materials with evenly distributed active sites for glyphosate adsorption and radical-scavenging activity. The original Krishnamurti isotherm is successfully used to fit pesticide adsorption data, pointing to co-operative adsorption of glyphosate on partly saturated adsorbents sites. The amount of glyphosate adsorbed from water suspension was 378 mg per gram of composite material, the highest value reported for glyphosate removal to date.