Green separation and decomposition of crystalline silicon photovoltaic module's backsheet by using ethanol

The treatment and recycling of discarded crystalline silicon photovoltaic modules (c-Si PV modules) has become a research focus, but few research have paid attention to the standardized treatment of c-Si PV module's fluorinated backsheet. Improper management of fluorinated backsheet can pose ecological and human health risks. Therefore, this study presents a novel method for processing the backsheet. The proposed approach entailed the utilization of ethanol (CH₃CH₂OH) to separate the backsheet from the PV module. Subsequently, the separated backsheet underwent decomposition using an alkaline ethanol (NaOH-CH₃CH₂OH) solution. Finally, the backsheet was recovered in the form of terephthalic acid (TPA) with a purity of 97.47 %. This recovered TPA can then serve as a valuable raw material for producing new backsheets, fostering a closed-loop material circulation. Experimental results demonstrate that immersing the PV module in a 75 % CH₃CH₂OH-H₂O solution at a temperature of 343 K for 30 min achieved 100 % separation of the backsheet. Furthermore, subjecting the separated backsheet to a 60 min reaction in an NaOH-CH₃CH₂OH solution with a temperature of 343 K and a NaOH concentration of 1.0 mol/L achieved complete decomposition. The reaction mechanism was analyzed through characterization methods such as SEM/EDS, NMR, FTIR and XRD. This method is efficient, non-toxic organic reagent-free and environmentally friendly, so it holds significant potential for further development in the field of c-Si PV module recycling.