Microplastics and organic contaminants: Investigation of the sorption process on different polymer types

The presence of microplastics (MPs) in aquatic environments raises major concerns due to their ability to sorb and transport Emerging Contaminants (ECs). In this work, a sorption study was carried out, using MPs of polyester (PES), polyamide (PA), polyvinyl chloride (PVC), polypropylene (PP), high-density polyethylene (HDPE) and low-density polyethylene (LDPE), in the size range of 63 to 250 μm. Five emerging contaminants (ECs) were selected for this evaluation: Ametryn (AMT), atrazine (ATZ), bisphenol A (BPA), progesterone (PGT) and pyraclostrobin (PCT). The MPs were previously characterized by different analytical techniques and presented results in good agreement with the literature. Sorption experiments presented a predominance in the interaction of the most nonpolar ECs (PCT and PGT), with all six polymers. In general, under the evaluated conditions, the highest sorption percentages were obtained for: PA > PP > LDPE > PVC > HDPE > PES, for 24 h of contact time, that could be considered as the apparent equilibrium time, and the increase in the mass of MPs contributed for the enhancement in the sorption process, probably due to the greater availability of interaction sites. Also, the variation in ionic strength and pH caused no significant effect between the sorption of most ECs and the MPs. The results indicate a greater interaction between MPs and nonpolar contaminants, revealing that MPs play a limited role in the transport of more polar compounds in the aquatic medium.