Mechanistic study of selective adsorption and reduction of Au (III) to gold nanoparticles by ion-imprinted porous alginate microspheres

Abstract In this paper, a novel technique combining ion-imprinting and direct templating was applied to synthesize Au (III) imprinted epicholorohydrin/thiourea modified porous alginate adsorbent. The adsorbent has demonstrated outstanding selectivity towards Au (III) from multi-metallic solutions, and the porous structure generated from urea hydrolysis has provided fast adsorption kinetics. The maximum uptake capacity of Au (III) is 184.82 mg/g at 323 K, which is outstanding as a recyclable polysaccharide-based adsorbent. Photo-reduction of Au (III) to gold particles was observed in the adsorption process under UV light exposure, while visible light is not capable of stimulating electrons from the synthesized adsorbent. FT-IR, XPS, and DFT calculation have proved that hydroxyl, carboxyl, and –N-C=S functional groups were involved in the adsorption-photoreduction of Au (III).