Furfural-bridged silsesquioxane-based hybrid network rich in heteroatoms for selective adsorption and reduction of Au(III) in the aqueous phase

Abstract

Gold-containing wastewater is generated during the refining of gold ores and the production of electronic products. There is urgent need for efficient methods to recover gold from these effluents. In this work, a hybrid network (PCS-OF) was successfully synthesized via amino-aldehyde condensation and possible amine-ene reaction/hydrogen bonding interactions of octa(aminophenyl)silsesquioxane (OAPS) with furfural (PCS-OF). The hydrophilic nature, excellent dispersion, and abundant heteroatoms (O, N) in the PCS-OF network make it highly suitable for the adsorption and reduction of gold ions. The material can achieve rapid adsorption of gold ions, and the adsorption capacity of gold ions can reach 1361.8 mg g⁻¹ within 40 min. The final adsorption capacity can reach 2022.4 mg g^–1 at 293 K. Its adsorption isotherm and adsorption kinetic are in line with the Temkin model and pseudo-second-order model respectively, PCS-OF has excellent selectivity for Au(III) in the presence of different metal ions, and can be applied in a wide range of pH and temperature. XPS analysis demonstrated that many Au(III) ions are reduced in situ to Au(0) particles, which are evenly distributed across the surface of PCS-OF, providing catalytic sites. It was demonstrated that PCS-OF could catalyse the reduction of nitroaromatics with high efficiency.