Photoaging of Baby Bottle-Derived Polyethersulfone and Polyphenylsulfone Microplastics and the Resulting Bisphenol S Release

This study evaluated the release of bisphenol S (BPS) from polyethersulfone (PES) and polyphenylsulfone microplastics (MPs) derived from baby bottles under UV irradiation. Released BPS fluctuates over time because it undergoes photolysis under UV254 irradiation. Under UV365 irradiation, the highest released concentration at 50 degrees C was 1.7 and 3.2 times that at 35 and 25 degrees C, respectively, as the activation energy of the photochemical reactions responsible for MP decay was reduced at high temperatures. Low concentrations of humic acid (HA, <= 10 mg.L-1) promote BPS release because HA acts as a photosensitizer. A high concentration of HA (10 similar to 50 mg.L-1) decreases the BPS release because HA shields MPs from light and scavenges reactive radicals that are produced via photochemical reactions. For example, under UV irradiation, hydroxyl radicals (center dot OH) attack results in the breakage of ether bonds and the formation of phenyl radicals (Ph center dot) and phenoxy radicals (Ph-O center dot).The center dot OH addition and hydrogen extractions further produce BPS from the decayed MPs. A leaching kinetics model was developed and calibrated by the experimental data. The calibrated model predicts the equilibrium level of BPS release from MPs that varies with the surface coverage density of BPS and leaching rate constants. This study provides groundwork that deepens our understanding of environmental aging and the chemical release of MPs.

Automated summary

This study evaluated the release of bisphenol S (BPS) from microplastics derived from baby bottles under UV irradiation. It found that high temperature and low concentrations of humic acid promote BPS release, while high concentrations of humic acid decrease BPS release. A leaching kinetics model was developed to predict the release of BPS.