Aging of textile-based microfibers in both air and water environments

Textile-based microfibers (MFs) are a predominant source of global microplastics (MPs) pollution. Yet, less is known about the aging of textile-based MFs. This study explored the aging behavior of textile-based polyethylene terephthalate (PET) MFs with white (without pigment) and black (with carbon black as pigment) colors in both air and water environments. Ultraviolet (UV) and plasma aging were carried out to simulate the short- and long-term aging of MFs. Results indicated that white MFs exhibited more pronounced surface changes, formed more -OH bonds, and showed a higher increase in the oxygen-to-carbon(O/C) ratio than black MFs in both air and water environments. For example, in the air environment, the percentage increase of O/C for white MFs was 24.43 %, compared to 16.4 % for black MFs during plasma aging process. Further investigations were conducted to elucidate the mechanisms driving higher degree of aging of white MFs. It was verified that the carbon black in the black MFs could enhance their tensile strength and hardness, thereby countering the aging process. Furthermore, excitation-emission-matrix (EEM) analysis of dissolved organic matter (DOM) released from MFs, combined with the detection of reactive oxygen species (ROS) generated by MFs in the water environment, confirmed that carbon black functioned as an effective anti-aging additive. Its protective role, attributed to UV and plasma shielding and reactive radical-trapping mechanisms, led to higher aging degree in white MFs compared to black MFs. These findings provide insights into predicting the aging behaviors of textile-based MFs with different colors in air and water environments.