Selective Removal of Aluminum and Impurity Metals from End-of-Life Photovoltaic Panels Using Hydrochloric Acid Pretreatment: Optimization Through Response Surface Methodology

The rapid growth of photovoltaic panels installations has led to a dramatic increase in the end-of-life (EoL) panels, creating an urgent need for efficient recycling strategies. In the present study, a pretreatment system consisting of hydrochloric acid was developed to remove impurity metals such as aluminum and iron from EoL PV panel powder prior to the precious metals leaching step. Response surface methodology (RSM) based on a central composite design (CCD) was employed to optimize the effects of main operational parameters, i.e., HCl concentration, leaching time, and solid-to-liquid (S/L) ratio on the dissolution of Al, Fe, Pb, Sn, and Cu. Thermodynamic analysis with the help of HSC Chemistry® 10 software, confirmed the feasibility of dissolution of the Al, Fe, Pb, Sn, and Cu in chloride media. Experimental results demonstrated that the dissolution rate of Al and Fe under optimal conditions were 86.05 and 91.77 percent, respectively. In all of the tests, copper dissolution remained negligible (<4%), and no silver was detected which confirms the selectivity of the pretreatment. The optimized conditions (1.5 M HCl, 198 min, 20% S/L) enabled effective impurity removal while preserving silver in the solid residue. This study highlights the importance of selective pretreatment in enhancing downstream silver recovery and provides a practical approach for the hydrometallurgical recycling of end-of-life PV waste.