[Effect of Ageing on the Adsorption of Triclosan by Microplastics of Different Types and Particle Sizes]

In order to investigate the effect of aging on the adsorption of triclosan （TCS） by microplastics （MPs） of different types and particle sizes， the physicochemical properties of polyamide （PA）， polybutylene terephthalate （PBT）， polylactic acid （PLA）， and polyvinyl chloride （PVC） with particle sizes of 50 μm and 200 μm， as well as their adsorption of TCS， were analytically determined under aging at 0， 30， and 90 d. The results showed that the surface roughness of MPs increased significantly. The results showed that aging significantly increased the surface roughness of the MPs. After 90 d of aging， the surface oxygen percentage of all MPs except PVC50 increased compared with that before aging， with the increase being more significant for the small-sized MPs. Further， the hydrophilicity of PBT showed a tendency of increasing and then decreasing with aging time， but the hydrophilicity of the rest of the MPs was enhanced with the increase in aging time. At the same aging level， the adsorption property of PA was stronger than that of other MPs. At 30 d of aging， the adsorption property of MPs on TCS was increased compared with that before aging. However， after 90 d of aging， the adsorption property of PBT and PLA showed a decreasing trend compared with that at 30 d of aging. MPs with smaller particle size had higher adsorption capacity due to more available adsorption sites， while the growth rate of adsorption of larger particle size PA， PLA， and PVC was higher than that of smaller particle size after aging compared with that before aging， whereas PBT had the opposite trend. The study confirms that material properties， surface functional group evolution， and hydrophilic interaction-dominated adsorption mechanism jointly affect the MPs-TCS interaction， and the results provide theoretical support for the risk assessment of MPs-TCS composite contamination.