Vol.:(0123456789) 1 3 Journal of Material Cycles and Waste Management https://doi.org/10.1007/s10163-019-00861-1 ORIGINAL ARTICLE Novel method for sustainable and selective separation of PVC and PET by the homogeneous dissociation of H 2 O 2 using ultrasonication Nguyen Thi Thanh Truc 1  · Hung Anh Le 1  · Duy Trinh Nguyen 2  · Thanh‑Dong Pham 3 Received: 29 November 2018 / Accepted: 5 April 2019 © Springer Japan KK, part of Springer Nature 2019 Abstract This paper presents a one-step selective separation of polyvinyl chloride (PVC) from PVC/PET mixture based on hydrophi- licity building on the PVC surface using H 2 O 2 /ultrasonication. After the combined treatment, the decrease of PVC contact angle (from 87.2° to 71.5°) is consistent with the increase in hydrophilic functional groups that is evidenced by Fourier transform infrared and X-ray photoelectron spectroscopy results on the PVC surface. The H 2 O 2 /ultrasonic treatment gener- ates oxidizing agent and increases hydrophilicity on the PVC surface, which allows to selectively separate the treated PVC by its submerging on the reactor bottom. Meanwhile, the treated PET is easily foated of because it is not afected by the combined treatment and still maintains the hydrophobic surface. The combined treatment of H 2 O 2 and ultrasonic irrigation obtains 100% purity and recovery of the PVC separation under the optimum conditions. The optimized separation conditions are H 2 O 2 concentration 3%, ultrasonic irrigation time 30 min and temperature 30 °C, foating agent concentration 0.4 mg/L and intermittent mixing at 50 rpm. Reusing of H 2 O 2 is also feasible to save cost and environmental benefts. The combination of ultrasonication and H 2 O 2 is an efective and inexpensive method for PVC separation to improve plastic recycling quality. Keywords PVC · PET · Hydrophilization · Froth fotation · Ultrasonic treatment · Waste plastics recycling Introduction The enlargement of plastic used in modern industries has led to the increase in plastic waste volume, which poses seri- ous difculties in their proper management and disposal [1, 2]. The most widely used method for the new plastic pro- duction from waste material is mechanical recycling. This mechanical recycling process involves the plastic separa- tion into individual types, with high purity products in high demand [3, 4]. In general, the diferent plastics cannot be recycled together due to chemical incompatibilities as well as diferences in their melting points and thermal stabili- ties. Thus, the mixture recycling can limit the quality of the recycled plastic products [5, 6]. In addition, with energy recycling, PVC-free plastics are more practicable because the incineration of PVC can generate the environmentally hazardous chlorinated compounds such as hydrochloric acid, polychlorinated benzo para dioxin, polychlorinated dibenzofuran, chlorofuorocarbon, and polycyclic aromatic hydrocarbons [7–9]. Therefore, the selective PVC separa- tion from mixed plastic waste is more important than the mechanical recycling/reusing or the minimization of the adverse environmental efects caused during combustion which can afect the quality of the secondary product result- ing in degrading value or market price of recycled goods [10, 11]. In the current recycling process, the recovery ratio of PVC is low because of the contamination of polyethylene terephthalate (PET) with the similar properties of natural hydrophobicity and heavy density (1.38 g/cm 3 of PET and 1.42 g/cm 3 of PVC) [12–15]. Currently, many studies of selective PVC separation from plastic mixture have been developed by including manual sorting, dry gravity method, and triboelectrostatic sorting [16–18]. Other methods typi- cally have expensive polymer identifcation systems based * Nguyen Thi Thanh Truc nguyenthithanhtruc_vmt@iuh.edu.vn 1 Institute for the Environmental Science, Engineering and Management, Industrial University of Ho Chi Minh City, No. 12 Nguyen Van Bao, Ward 4, Go Vap District, Ho Chi Minh City, Vietnam 2 NTT Hi-Tech Institute, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam 3 VNU Key Laboratory of Advanced Materials for Green Growth, University of Science, Vietnam National University, Hanoi, Vietnam