Quantification of textile microfibers from laundry wastewater using the Rock-Eval® device: Difference between natural and synthetic microfiber origin

Synthetic textiles constitute a significant emission source of microplastics into the environment release by mechanical abrasion during laundering. Only a portion of these microfibers is retained in wastewater treatment plants, and major issues to identify and quantify microfibers remain because of their nature, shape, and size. Most widespread natural (cotton, linen) and synthetic (polyester PET, nylon polyamide PA, viscose) textiles were first analyzed using a pyrolysis and oxidation based-method: the Rock-Eval® device. In this study, a novel procedure based on Rock-Eval® parameters was carried out for relative mass quantification of textile microfibers emitted from washing machines. Specific linear regressions of Rock-Eval® parameters were first defined for each investigated natural and chemical fibers. Furthermore, it was verified that Rock-Eval® results are not affected by the polymer shape (fiber vs. pellet) and the nature of the fiber (cotton vs. polyester). Results also confirm that the Tpeak parameter can be considered as a useful characteristic to distinguish between natural (cotton, linen) and chemical (polyester PET, nylon PA, viscose) fibers. Finally, the proposed method was successfully applied and able to evaluate the relative mass concentration of natural and synthetic fibers in several real case laundry wastewaters pre-filtered on a silica membrane.