Conversion of "Waste Plastic" into Photocatalytic Nanofoams for Environmental Remediation

Plastic debris is a major environmental concern, and to find effective ways to reuse polystyrene (PS) presents major challenges. Here, it is demonstrated that polystyrene foams impregnated with SnO₂ are easily generated from plastic debris and can be applied to photocatalytic degradation of dyes. SnO₂ nanoparticles were synthesized by a polymeric precursor method, yielding specific surface areas of 15 m²/g after heat treatment to 700 °C. Crystallinity, size, and shape of the SnO₂ particles were assessed by X-ray diffraction (XRD) and transmission electron microscopy (TEM), demonstrating the preparation of crystalline spherical nanoparticles with sizes around 20 nm. When incorporated into PS foams, which were generated using a thermally induced phase separation (TIPS) process, the specific surface area increased to 48 m²/g. These PS/SnO₂ nanofoams showed very good efficiency for photodegradation of rhodamine B, under UV irradiation, achieving up to 98.2% removal. In addition the PS/SnO₂ nanofoams are shown to retain photocatalytic activity for up to five reuse cycles.