Green flotation of polyethylene terephthalate and polyvinyl chloride assisted by surface modification of selective CaCO_3 coating

摘要

Plastic flotation was a promising separation method for efficient recycling of waste plastics. Aiming to avoid the destruction of original surface and secondary pollution, a novel flotation process based on calcium carbonate (CaCO3) coating was proposed for separation of polyvinyl chloride (PVC) and polyethylene terephthalate (PET). The mechanism of CaCO3 coating was researched via scanning electron microscope (SEM), Xeray photoelectron spectroscopy (XPS), Xeray diffraction (XRD), zeta potential, Fourier transformed infrared spectroscopy (FTeIR), and solution chemistry analysis. High polarity of C eCl on PVC surface resulted in selective adherence of Ca2+ on PVC surface, and Ca2+ was a bridge between plastic surface and CaCO3 particles. The separation of PVC and PET was optimized by response surface methodology (RSM) combining BoxeBehnken design (BBD). Optimal pretreatment conditions for flotation separation of PVC and PET were 0.11 g CaCO3, temperature 50.6 degrees C, treatment time 20 min, and pH 10.1. The purity and recovery of PVC could be 100% and 99%, respectively. (c) 2019 Elsevier Ltd. All rights reserved.