Au Nanoparticles in Silsesquioxane-Based Hybrid Networks by Simultaneous Recovery and Reduction of Au(III) in Wastewater

The recovery of gold from wastewater or electronic waste is significant due to its enormous value in a variety of fields. An amine-functionalized silsesquioxane (SQ)-based hybrid network (PCS-PAA) was successfully synthesized through the cost-effective, mild amine–ene reaction of acrylate-functionalized SQ with triaminoethylamine (TAA). Hydrophilic PCS-PAA helps to adsorb Au(III) via the coordination with abundant heteroatoms (N and O). The adsorption capacity of PCS-PAA for Au(III) reaches 647 mg/g within 30 min at room temperature and 1235 mg/g at 323 K, respectively. The Langmuir model is more suitable to describe the adsorption process, and the pseudo-second-order model well fits the adsorption kinetic. Surprisingly, most Au(III) ions are in situ reduced to Au(0) particles, which are uniformly distributed on the surface of PCS-PAA. PCS-PAA-Au (PCS-PAA loaded with Au) can reduce 4-nitrophenol to 4-aminophenol with high catalytic activity. More interestingly, PCS-PAA can selectively adsorb Au(III) from e-waste. This work provides a convenient and mild method to recover Au(III) from wastewater or e-waste for multiple purposes.