Mitigation of laundering-induced microplastic fiber release from polyester fabric via plasma-assisted chemical surface modification

Microplastic fiber (MPF) release from polyester textiles during laundering is a recognized pathway contributing to aquatic contamination and potential human exposure. In this study, atmospheric-pressure plasma activation followed by chemical surface modification was evaluated as an at-source strategy to mitigate MPF shedding from a 100% polyester (PET) fabric. Fabrics were plasma activated and subsequently treated with sodium hydroxide (NaOH) or chitosan at two concentrations (0.6% and 1.2% w/v). MPF release was quantified using an EN ISO 4484-1:2023-based laboratory washing protocol (Gyrowash) over five sequential wash cycles with procedural blanks used to correct background contamination. Released MPFs were assessed using complementary metrics, including filter mass gain (gravimetry), image-based MPF counting, MPF length distribution, and scanning electron microscopy (SEM) of fabric surfaces and collected MPFs. All surface-treated samples exhibited lower MPF counts than the untreated fabric. The strongest mitigation was observed for 0.6% chitosan (-63.0 ± 4.2%), followed by 1.2% chitosan (-40.1 ± 11.0%), while NaOH treatments showed intermediate reductions (-32.4 ± 5.4% to -34.8 ± 7.1%). Length distribution analysis showed treatment-dependent shifts in emitted MPF size, with 1.2% NaOH increasing the relative contribution of short MPFs (<1.0 mm), whereas chitosan treatments increased the proportion of MPFs ≥1.0 mm. SEM observations supported these trends by revealing differences in surface disruption after washing and abrasion, as well as corresponding differences in MPFs retained on filters. Overall, plasma-assisted chitosan finishing-particularly at 0.6%-showed the strongest mitigation among the tested conditions, indicating that combined plasma-chemical modification is a promising at-source strategy for reducing laundering-induced MPF shedding from polyester.