Novel method for sustainable and selective separation of PVC and PET by the homogeneous dissociation of H2O2 using ultrasonication

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 H2O2 using ultrasonication

Nguyen Thi Thanh Truc1  · Hung Anh Le1

 · Duy Trinh Nguyen2

 · Thanh‑Dong Pham3

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 H2O2/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 H2O2/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 H2O2 and ultrasonic irrigation

obtains 100% purity and recovery of the PVC separation under the optimum conditions. The optimized separation conditions

are H2O2 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 H2O2 is also feasible to save cost and environmental benefts. The combination

of ultrasonication and H2O2 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/cm3

of PET and

1.42 g/cm3

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

[email protected]

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