Leaching of silver from used crystalline silicon PV modules using I2-KI full factorial experimental design

The scale of solar photovoltaic (PV) power generation is growing exponentially. However, the service life of crystalline silicon photovoltaic modules is typically around 25 years, primarily due to light-induced degradation (LID) and related degradation mechanisms. Waste solar crystalline silicon (c-Si) PV modules are a kind of hazardous waste, and green recycling of precious metals in waste solar c-Si PV modules needs to be solved urgently. To address the recycling problem, green dismantling of panels and green leaching of cells are used. Freeze cracking method is selected to separate the cell wafers from used crystalline silicon PV panels. Recovery of silver from used crystalline silicon cell wafers was carried out using I2-KI as a green leaching reagent. Full factorial experimental design for leaching rate is carried out using MINITAB software. A regression equation on the leaching rate of silver as a response value is established. Iodine concentration, potassium iodide concentration, solid–liquid ratio, and pH are the influencing factors in the regression equation. The parameters for the optimal solution of silver leaching rate were iodine concentration of 0.3 mol/L, solid–liquid ratio of 1:10, pH of 9.6, and potassium iodide concentration of 0.8 mol/L. The results of the response optimization are verified by three sets of parallel experiments, and the silver leaching rate is obtained as 96.62%.