The fate of microplastics and organic matter leaching behavior during chlorination

As an emerging persistent pollutant, microplastics (MPs) have been detected in the drinking water system and its potential risk in the presence of disinfectants has received little attention. This work aimed to investigate the changes in MPs properties and the organic matter leaching behavior of MPs during chlorination. Physical and chemical changes of the chlorinated MPs were detectable by scanning electron microscope, Micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Polystyrene (PS) was less resistant to chlorination than polyethylene (PE), indicated by changes in Raman peaks and O/C ratio of the XPS spectrum. Organic matter leaching behavior of MPs was explored by dissolved organic carbon (DOC) determination and disinfection byproducts formation potential measurement. The results demonstrated the stimulating effect of chlorination on the organic matters leaching from MPs, with the total leached DOC accounting for ∼0.3‰-0.5‰ of the MPs mass. The leached organic matters exhibited an appreciable potential to form trihalomethanes (THMs) and haloacetonitriles (HANs). The formation potential of THMs and HANs were 54.43-185.08 μg/mg C and 3.65-11.83 μg/mg C, respectively. Compared to PE, organic matter leaching behavior during chlorination was more obvious for PS. This study provides insights into the fate of chlorinated microplastics and the possible risk of organic matters leached from MPs to form disinfection byproducts during chlorination.