Domino Polymerization toward Microporous Polythioureas for Selective Gold Recovery from Electronic Waste

Abstract

The recovery of gold from electronic waste by absorption is a sustainable process owing to its easy operation, low cost, and negligible energy consumption. Thiourea groups demonstrate a strong affinity toward Au(III); therefore, microporous polythioureas (PTUs) are believed to be emerging absorbents and advantageous over other porous materials. Motivated by the successful preparation of porous organic polymers (POPs) via domino polymerization in our recent report, the one-pot strategy is introduced to the synthesis of microporous PTUs. During the polymerization process, thiourea knots are formed between the reaction of amino and diisothiocyanate monomers and integrated into networks by the simultaneous self-cross-linkage of alkynyl, acetyl, or double-bond groups on the amine monomers. Eventually, the family of POPs exhibits a maximum surface area of 561 m² g^–1. The thiourea groups and microporous structures endow the products with high Au(III) adsorption capacities (maximum: 1159 mg g^–1) and remarkable adsorption selectivity. Even in actual electronic waste, where the concentration of Au(III) (0.18 mg L^–1) is much lower than that of other interference ions (approximately 200 mg L^–1), 100% removal efficiency is accomplished. This achievement not only verifies the versatility of the domino polymerization methodology for the construction of POPs but also sheds light on the potential application of high-performance gold adsorbents in real scenarios.