Layered aerogel embedded with thiourea-resorcinol-formaldehyde resin for efficient adsorption of Au(III)

Abstract

Current adsorbents for Au(III) recovery suffer from high costs, low adsorption capacity, recycling difficulty, as well as small-scale applications, making most of them have no commercialization potential. We report a complex adsorbent SA-TRF in this work. The aerogel made of sodium alginate (SA) serves as the carrier, and TRF resin (a resin composed of thiourea, resorcinol and formaldehyde) is used as the functional element. The thin-layered SA aerogel is evenly embedded with functionalized micron adsorbent (TRF) particles. Owing to the multiple functional groups of TRF, SA-TRF exhibited a high adsorption capacity. TRF was capable of making complete contact with Au (III) in the solution owing to the thin-layered SA aerogel. The SA aerogel's macrostructure makes it simple to collect SA-TRF in solution. The repeating unit of TRF's CS and NH functional groups were identified as being responsible for Au(III) binding, with its sulfhydryl functional group performing as the strongest binding site. The conveniently synthesized SA-TRF outperformed most other adsorbents and demonstrated significant adsorption capacity for Au (III) up to 600.2 mg/g in 70 mg/L Au-spiked water (corresponding removal efficiency is 85.7 %), which makes it particularly promising for industrial applications.