Fenton treatment for flotation separation of polyvinyl chloride from plastic mixtures

Abstract

Abstract The generation of waste plastics has been radically promoted by large-scale consumption and rapid upgrading of plastic products in the last decades, which brings serious threats to environment and management. Combined with Fenton treatment, froth flotation was evaluated to separate polyvinyl chloride (PVC) from waste plastics for recycling. The floatability of polystyrene (PS) and polycarbonate (PC) has a dramatic decrease after Fenton treatment, while the floatability of PVC is not affected. Contact angle, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were conducted to ascertain the mechanism of Fenton treatment. The reduction of PS and PC floatability is attributed to the increase of surface wettability confirmed by contact angle measurement. FT-IR and XPS analysis confirmed that hydrophilic oxygen-containing groups were introduced on PC and PS surface. SEM images indicated that Fenton treatment considerably increased the surface roughness of PC and PS. With respect to flotation separation PVC from plastic mixtures, optimum conditions are molar ratio (H 2 O 2 /Fe 2+ ) 7500, H 2 O 2 concentration 0.2 M/L, treatment 2 min, temperature 25 °C, pH 5.8, frother concentration 15 mg/L and flotation time 4 min. Particle size, mass fractions and reuse of plant effluent were also investigated. After Fenton treatment under optimum conditions, floatation separation of PVC from plastic mixtures was accomplished with high purity and recovery. The purity and the recovery of PVC are up to 99.26% and 100% respectively. The purity and the recovery of other plastics are up to 100% and 97.20% respectively. Consequently, flotation combined with Fenton treatment is a simple, environmental friendly and cost-effective method for separation of PVC from plastic mixtures.