Halobenzoquinones (HBQs) are a novel family of unregulated disinfection byproducts (DBPs). Little is known about their phototransformation activities in natural water. Here, five HBQs with various halogenated substituent types, numbers, and structures positions were selected to investigate the kinetics of degradation in aqueous solutions at various concentrations and in the presence of common environmental variables (Cl − , NO 2 − , and humic acid). The results indicated that dichloride and dibromo-substituted HBQs were photolyzed, whereas tetrachloro-substituted HBQs showed little degradation. The photolysis rate constant ( k ) of HBQs decreased with increasing initial concentration. The presence of NO 2 − and Cl − promoted the degradation of HBQs mainly through the formation of hydroxyl radical (•OH), which were confirmed by electron paramagnetic resonance (EPR). In contrast, humic acid played a negative role on HBQs transformation due to the adsorption and quenching reactions. Possible conversion pathways for HBQs were proposed based on the identification of two major photodegradation products, hydroxylated HBQs and halogenated-benzenetriol, as well as reactive free radicals . This study provided meaningful insights into the environmental fates and risk assessments of HBQs in natural aquatic system.
Microplastics (MPs) discharged from wastewater treatment plants (WWTPs) have emerged as serious pollutants in aquatic environments. Herein, a new magnetic filter (MFA) was prepared using an acidification–magnetization method with fly ash (FA) as the base material. The filter specifically targeted the removal of 1-μm polystyrene microspheres (PSMPs) because of the challenges they pose in filtration processes. The findings demonstrated that MFA filter exhibited superior PSMPs removal efficiency, with increases of 219%, 250%, and 288% compared to FA at flow rates of 1, 3, and 5 mL min −1 , respectively. Scanning electron microscopy and other characterizations provided insights into the removal mechanisms of PSMPs using the MFA filter, which combined electrostatic attraction, π–electron conjugation, hydrogen bonding, and complexation. Environmental variables, such as solution pH, ionic strength, and dissolved organic matter, were identified as considerable influences in the removal process of PSMPs. The practical application confirmed that the MFA filter considerably promoted the elimination of MPs from the secondary treatment effluent of WWTPs without having any toxic effects on freshwater fish. Thus, this study provides a new approach to the resource utilization of FA, which would prominently promote its application prospects in MPs immobilization and removal from wastewater effluent.
危险品化学品经营许可证（带存储）