Innovative recycling of end-of-life photovoltaic panels with the aim of polymer degradation and valuable chemical production

Recycling end-of-life photovoltaic (PV) panels is challenging, as multiple-layer structure makes separation and material recovery processes complex and resource-intensive. This study embarks on an innovative chemical recycling technique based on the liquefaction of organic fractions of PV panels in an oxidative environment. Thermogravimetric analysis (TGA) of virgin PV waste showed the mass loss in three stages, with residual mass left in the range of 32–40 %. During oxidative liquefaction following a well-constructed experimental (Central Composition and Fractional Factorial) design effects of three different parameters, including temperature ranging from 200 to 300 °C, hydrogen peroxide serving as an oxidant (30–60 % overall volume of liquid), and the waste-to-liquid ratio of 12.5–37.5 %, were studied. Total polymer degradation (TPD) was calculated in the range of 20–100 %. The liquid fraction obtained after the process was analyzed through gas chromatography with flame ionization detection (GC-FID), to quantify the yield of oxygenated chemical compounds (OCCs). Fourier transform infrared spectroscopy (FTIR) analysis identified various structural modifications and the degradation of polymeric components. An inverse analysis of the process heating behavior was performed to identify the temperature span over which degradation of polymers occurs and specify the nature of the reaction (exothermic or endothermic). An analysis of variance ANOVA was performed to identify the optimal values of parameters supporting maximum TPD and OCCs yield against the minimum energy consumption, a meaningful input for a potential scale-up of the PV panel recycling technique.