Role of Substituents in the Removal of Emerging Fluorinated Liquid Crystal Monomer Pollutants under the UV/Peroxydisulfate Treatment

Abstract

Fluorinated liquid crystal monomers (LCMs) have been identified as emerging persistent and bioaccumulative chemicals with non-negligible environmental concentrations. Herein, 12 fluorinated LCMs including highly detected 4-ethoxy-2,3-difluoro-4′-(trans-4-propylcyclohexyl)biphenyl (EDPB) were selected as target fluorinated LCMs to investigate their structure–reactivity relationships by the ultraviolet/peroxydisulfate (UV/PDS) treatment. EDPB with biphenyl and ethoxy showed the highest first-order degradation rate constant of 1.93 h–1, while that of fluorinated LCMs with ethoxy (1.10–1.26 h–1) and biphenyl (0.45–0.56 h–1) and without biphenyl or ethoxy (0.27–0.30 h–1) decreased sequentially. HO• and SO4 •– were identified as the main oxidative species in the UV/PDS treatment. Theoretical calculation suggested that biphenyl and ethoxy can significantly alter the electron distribution of LCM molecules, providing more attackable sites for HO• and SO4 •– on LCMs with biphenyl or ethoxy. Oxalic acid, cyclohexane, and bicyclohexane were the main degradation products of fluorinated LCMs even though their degradation pathways were determined by their different molecular structures. Toxicity estimation revealed that fluorinated LCMs with high acute toxicity and developmental toxicity could be decomposed into some final products with less toxicity. This study is expected to fill knowledge gaps in the structure–activity relationships of fluorinated LCMs by the UV/PDS treatment.

Enhanced Persulfate Activation and Micropollutants Decontamination by In Situ Generated MnO2 in Carbon Nanotubes/Permanganate System

“…Typically, SO 4 •– and HO • are viewed as the major reactive species in oxidation processes based on PDS, but other nonradical mechanisms have also been highlighted . Experiments on the quenching of ROS and EPR measurements were used together to probe the reaction mechanism of the flow-through CNT/PM/PDS systems.…”

Efficiently Predicting Reaction Rates and Revealing Reactive Sites with a Molecular Image-Vision Transformer and Fukui Function Validation

“…Specifically, hydroxyl radicals ( · OH), widely distributed in various ecosystems such as aquatic, atmospheric, and biological environments, serve as highly reactive oxygen species (ROS) . Their ability to oxidize biogenic compounds and environmental contaminants plays a crucial role in regulating the carbon and nitrogen cycles, thereby exerting a profound impact on environmental health and sustainability. This includes the degradation of persistent organic pollutants, alteration of rainwater acidity, and modulation of physiological functions in living organisms .…”