Green and Facile Recovery of Silver and Aluminum from Waste Photovoltaic Modules: A Novel Mechanochemically Driven Pathway

The resource recovery of waste photovoltaic (PV) modules represents a critical pathway for mitigating environmental pollution, alleviating resource scarcity, and enhancing energy security. Among the various components within PV modules, silver (Ag) stands out as one of the most critical and economically significant materials; thus, its efficient recovery serves as a pivotal step in the valorization process of waste PV modules. To address the dual challenges of surging waste PV modules and the looming shortage of high-value Ag supply and to overcome the limitations of traditional hydrometallurgical processes (characterized by procedural complexity, high safety hazards, significant environmental pollution, and high costs), a cleaner and more efficient strategy is urgently needed. Recognizing that Ag is intricately integrated with the aluminum (Al) back grid lines in cells, this work pioneers a mechanochemically driven process for the high-efficiency coextraction of Ag and Al. Unlike conventional leaching, this activation strategy leverages intense mechanical energy to overcome the chemical inertness of the metals. Mechanistic investigations reveal that the mechanochemical action induces the in situ decomposition of ammonium persulphate ((NH₄)₂S₂O₈) to generate hydroxyl radical (^•OH) and sulfate radical (SO₄^•-). These generated species rapidly oxidize Ag and Al, converting them into water-soluble sulfates, thereby rendering the subsequent water leaching process both thermodynamically and kinetically favorable. Under optimized conditions, the extraction efficiencies of Ag and Al reached 98.39 and 91.72%, respectively. This work not only offers a highly efficient and clean pathway for the circular utilization of scarce Ag resources but also underscores the potential of mechanochemistry in the field of waste PV modules, holding significant implications for promoting sustainable development of the photovoltaic industry and resource circularity.