Efficient and selective gold recovery using a quaternary phosphonium functionalized chitosan based self-standing electrode

With the fast-growing accumulation of precious metals, especially gold ions, in wastewater and electronic waste, achieving rapid and selective gold ions capture from water while maintaining high adsorption capacity is of vital importance to the environment and economy. Herein, a self-standing, quaternary phosphonium functionalized chitosan-based electrode (MTP-CS-CC) is proposed and fabricated via coating functional materials on carbon cloth for the electrochemical capture of Au(III) ions. Abundant quaternary phosphonium sites as nanotraps in MTP-CS-CC under the action of electric field deliver a fast extraction rate with high Au(III) removal efficiency (>99.5 %), a competitive uptake capacity (2114 mg g −1 ), superior selectivity, and long-term recycling stability. In-depth exploration of relevant mechanism by multiple characterizations and density functional theory (DFT) calculations illustrates that the capture of Au(III) ions by MTP-CS-CC electrode involves the electrosorption and electroreduction processes. In addition, when used as electrodes to recover gold from real e-waste leaching solution, the purity of recovered gold from computer central processing unit (CPU) boards reaches up to 23.8 Karat (99.17 % pure). Our work puts forward a facile strategy for preparing chitosan-based electrodes that can be innovatively used for the precious metal recovery and circular economy for recycling resources.