Micro-galvanic driven selective leaching and pulsed electrodeposition of silver from multi-metallic waste systems and...

Silver is a strategic metal that plays an indispensable role in electronics, healthcare and new energy sectors. Developing green technologies to recover silver from secondary sources can alleviate environmental risks induced by waste accumulation or improper disposal while mitigating primary resource scarcity. Conventional recycling methods suffer from high reagent/energy consumption, severe secondary pollution, and ineffective treatment of low-grade resources. Leveraging the polymetallic nature of waste-streams, we apply micro-galvanic selective leaching and pulsed electrodeposition for efficient, green and energy-saving silver recycling. Firstly, multi-metals form a micro-galvanic network in HNO₃, enabling metallic selective leaching by galvanic corrosion under relatively low operational intensity with leaching efficiencies over 95 %. Subsequent pulsed electrodeposition (transient potentiostatic excitation alternating with prolonged relaxation) achieves 98.98 % silver recovery efficiency from low-concentration leachate. Mechanistic studies reveal that the pulsed potential strategy maintains sustained interfacial reaction activity and efficient kinetics by alternately activating electrochemical/chemical reduction process. The proposed process is expected to reduce CO₂ emissions by 46.7 t/t waste, conserve 38.11 % of energy consumption, lower environmental toxicity by 121 %, and generates a net profit of $5992.3/t waste-streams. It delivers an efficient and energy-efficient strategy for metal recycling from low-grade resources and contributes to the circular economy.