Fabrication of 3D porous network structure chitosan/thiourea/graphene oxide aerogel for efficient and selective adsorption of Au(III) in aqueous solution

Abstract

It is of great significance to remove Au(III) in industrial wastewater for alleviating environmental pollution and resource waste. According to the hard-soft-acid-base theory, the adsorbents containing N or S atoms are conducive to the treatment and recovery of Au(III). In this work, a three-dimensional (3D) porous network structure chitosan/thiourea/graphene oxide (CS/TU/GO) aerogel was successfully constructed under optimal conditions by orthogonal experiments using simple chemical cross-linking by adding crosslinker at room temperature and freeze-drying. The CS/TU/GO aerogel has a designable macroscopic size for easy separation and recovery. TU containing N and S groups, has low cost and toxicity, and recyclability. In addition, CS as a promising aerogel matrix with N groups could further improve the adsorption capacity of Au(III). And GO could settle the instability and brittleness of CS aerogel matrix in acidic media. Moreover, GO could form 3D network structure by self-assembly. The CS/TU/GO aerogel adsorbed Au(III) selectively and efficiently by cooperative interaction, electrostatic interaction and redox reaction. Au(III) was mainly reduced to Au(0) and Au(I) during the adsorption process. The maximum adsorption capacity of the CS/TU/GO aerogel for Au(III) was 2202.83 mg/g. This study can provide a potential adsorbent for the treatment of precious metal ions in wastewater.