Investigation of environmental burden for waste plastic flotation recovery

For the target of reaching carbon peak and neutrality, plastic recycling is essential nowadays. Flotation is a novel technique but has been proven efficient. The core mechanism of plastic flotation is modifying the surface characteristic to be hydrophobic. Thus, diverse methods are tried for high recovery and purity. Since the initiative of plastic recycling is to protect the environment, it is necessary to explore the environmental footprint of different methods and ensure that recycling could benefit the environment rather than the opposite way. Through the life cycle assessment, this study evaluated the environmental footprint eight methods of polyvinyl chloride (PVC) flotation. The results of the eight methods could be separated into three groups, with high, middle, and low environmental burdens, respectively. Although all methods provided a similar recovery and purity, their performance differed significantly. In climate change, for recovering 1 kg PVC, method 1 needs to emit 5.28 kg CO2-eq, while method 5 would emit only 0.18 kg CO2-eq. Methods 1 and 7 further show the highest environmental burden in climate change, eutrophication, water use, and ozone depletion. Meanwhile, methods 4 and 5 show the lowest environmental in all impacts. Therefore, on the premise of similar recovery, methods 4 and 5 are recommended for recovering the PVC, while methods 1 and 7 are not suggested. In the future, an ideal PVC flotation could be designed based on this study.