Bacterial cellulose hybrid membrane grafted with high ratio of adipic dihydrazide for highly efficient and selective recovery of gold from e-waste

Abstract

To solve metal resource shortage and alleviate environmental issues, it is in urgent need to explore cost-effective and environment-friendly adsorbents for sustainable recovery of valuable gold from e-waste. Herein, bacterial cellulose (BC) hybrid membrane grafted with adipic dihydrazide (ADH) has been fabricated via a facile schiff base reaction strategy for efficient and selective recovery of gold from complex aqueous media. The resulting ADH@BC hybrid membrane features high ratio of hydrazide groups (67% of ADH by mass content) and hierarchical porous structure, ensuring high adsorption capacity (1149 mg/g) and fast adsorption equilibrium time (20 min) toward gold. Meanwhile, the remarkable recovery selectivity of gold is achieved in the simulated e-waste leachate containing a large amount of interfering metal ions. Notably, the captured Au(III) species on ADH@BC hybrid membrane can be directly converted by redox-active hydrazide groups into Au(0) with no need of any external reductant. Furthermore, the developed ADH@BC membrane possesses superior recycling and reusability performance, as reflected by no obvious decrease in gold extraction capability after six cycles. More importantly, the ADH@BC hybrid membrane is capable of extracting almost 100% of gold from actual waste central processing unit (CPU) leachate, yielding high-purity gold (23.7 K) after pyrolysis.