Release of Microplastics from Polyvinyl Chloride Pipes: An Accelerated Aging Study Using Ozonation, Chlorination and Heating

Abstract

Microplastics (MPs) has been found in drinking water and aged plastic pipe could be an important source. In this study, the release of MPs from polyvinyl chloride (PVC) pipe after accelerated aging using ozonation, chlorination and heating was investigated. The release of MPs increased with the enhanced aging and the highest MPs release in 30 mg O3 L-1, 260 mg Cl2 L-1 and 80°C were 1058, 1256 and 1303 # L-1, respectively. The fractions of MPs with a size of 10-50 and > 50 µm increased with the increasing chlorine exposure, while the size distribution of MPs due to ozonation and heating tended to remain constant. The carbonyl index (CI) generally increased with the aging as a result of oxidation. Scanning electron microscope images showed that hole structures < 50 µm developed on the pipe surfaces especially under ozonation and chlorination. The results indicated that MPs < 50 µm could result from surface pitting and those > 50 µm were caused by surface peeling of the outmost layer of the pipe. This study provides essential insights connecting the concentration and size of MPs to surface morphology change after accelerated aging of PVC pipe.

Keywords: Plastic pipe, microplastics, distribution system, Oxidation