Turning danger into opportunity: Ultraviolet (UV) irradiation-surface reconstruction effect of hydrophilic plastics and its application in plastic flotation separation

Plastic flotation shows a good application prospect in the field of waste plastic recycling. Nevertheless, surface reconstruction effect is highly likely to worsen the effect of plastic flotation separation. In order to avoid the fluctuation of plastic flotation separation process, it is urgent to explore the role of environmental factors on the reconstruction of hydrophilic and hydrophobic groups. Among various environmental factors, ultraviolet (UV) irradiation is one of the most important environmental factors affecting surface reconstruction effect. In view of this, in this work, we first used two common plastic modification methods, Fenton aging and polyaluminum chloride (PAC) modification, to hydrophilize six common plastics, namely PS, PVC, ABS, PMMA, PC, and PET. Then we studied the UV irradiation-surface reconstruction effect of hydrophilic plastics using flotation experiments. The results showed that UV irradiation can significantly enhance the surface reconstruction effect of hydrophilic plastics. More importantly, the wettability of plastic surfaces can be regulated by changing lighting conditions. Based on this, a novel UV irradiation-flotation process to separate PVC, ABS, and polyester (PMMA, PC, and PET) was successfully developed in this study. This work not only provides ideas for the further application of plastic flotation technology, but also lays a certain foundation for the development of novel and efficient UV irradiation-flotation processes.