Sustainable physical recycling of rigid PVC waste: A biobased solvent approach for the recovery of PVC, TiO2, and CaCO3.

For the first time, rigid polyvinyl chloride (PVC) waste has been successfully recycled using a dissolution-precipitation approach with biobased solvents. Hansen Solubility Parameter, HSP, predictions guided the systematic selection of solvents, while a modified HSP approach was developed to estimate the required non-solvent amounts for efficient polymer precipitation. Among the tested biobased solvents cyrene, γ-valerolactone (GVL) and 2-methyltetrahydrofuran demonstrated excellent dissolution performance, with water, methanol or isopropanol serving as effective non-solvents. The GVL-water system was the most efficient, requiring less than 10% non-solvent to achieve nearly complete separation and recovery of both the polymer and inorganic fraction without inducing polymer degradation. This optimized system was applied to a commercial PVC formulation for window frames, an end-of-life PVC window frame and a rigid PVC tube, achieving over 95% polymer recovery. Additionally, the process successfully removed more than 99% of inorganic fillers, enabling the selective purification and co-valorization of CaCO3 or the valuable TiO2.