Tao Yang,Xiujuan Kong,Ge Zeng,Maoju Jiang,Linqian An,Peng Su,Qixiao Lv,Jun Ma,Juan Li
Bromine (HOBr and OBr - ) can be rapidly formed in chlorine-involved processes in the presence of bromide (Br - ), and it significantly affects chlorine chemistry. The activation of chlorine by ultraviolet light A via light emitting diode (UVA-LED) is promising for disinfection and removal of organic contaminants in water treatment, while the bromine behavior therein remains unclear. In this study, the activation of bromine by UVA-LED (UVA-LED/bromine) was investigated to understand the bromine chemistry by selecting ibuprofen (IBP) and benzoic acid (BA) as the representatives. Bromine was readily decomposed into Br - and bromate by UVA photolysis with Br - being the major product. The apparent quantum yield of HOBr (0.589 ± 0.017 mol Einstein −1 ) and OBr - (0.0190 ± 0.0015 mol Einstein −1 ) kept stable at bromine concentrations of 20 – 200 μM, while it decreased as pH increased from 6.0 to 10.0. IBP and BA were rapidly degraded by the UVA-LED/bromine process under different conditions, and it could be well simulated by a kinetic model. Reactive bromine species (RBS, mainly Br• and Br 2 •- ) instead of hydroxyl radical (•OH) contributed predominantly therein. The efficiency of the UVA-LED/bromine process decreased in real waters, mainly due to negative effects of background constituents such as chloride, bicarbonate, and humic acid, as evidenced by both experiments and kinetic modeling. Brominated disinfection byproducts (DBPs) were generated during IBP and BA degradation, while their concentrations were within the regulation limit of drinking water. The results advance the bromine chemistry, and shed light on the UVA-LED photolyzed chlorine process in the presence of Br - .
Advanced oxidation processes (AOPs) based on sulfite (S(IV)) activation are gaining recognition as a promising Fenton-like strategy, primarily due to their ability to generate potent radicals (e.g., SO 4 − and HO ). However, the existence and role of a non-radical-driven oxidation pathway in the S(IV)-mediated degradation of contaminants remain under debate. Herein, a magnetic iron-carbon composite (FeO x @C) was fabricated using the MOF-templated method and utilized as a stable photocatalyst to activate S(IV) under UVA light, achieving >93.6 % degradation of 20 μM ofloxacin (OFL) with a high degradation rate constant of 0.073 min −1 within 45 min. The catalyst’s porous carbon structure facilitated the transport of substrates to active sites and shortened the diffusion distance between reactive species and contaminants. Adsorbed S(IV) donated one electron to photo-generated holes and exposed Fe(III) sites with the formation of SO 5 − , which then followed two distinct pathways to produce radicals (SO 4 − ) and non-radicals (Fe(IV) and 1 O 2 ) responsible for OFL degradation. By leveraging the synergy of both radicals and non-radicals, this innovative oxidative system showcased robust anti-interference capacities and exceptional performance in degrading contaminants from complex water matrices. This study provides new insights into the significant role of non-radical species in S(IV)-mediated decontamination processes.
In this study, we fabricate magnetic–fluorescent responsive Janus photonic crystal beads (JPCBs) based on poly(styrene-methyl methacrylate-acrylic acid) (p(St-MMA-AA)) colloidal nanoparticles, Fe3O4, and photobase generators used for self-destructive anti-counterfeiting. We synthesize two kinds of photobase generators that can react with fluorescamine to produce various fluorescence colors. A microfluidic method is used to obtain the Janus photonic crystal beads. The upper portions of the JPCBs are photonic crystals assembled with colloidal spheres, whereas the Fe3O4 settles down to the bottom of the JPCBs due to its higher density. Photobase generators are distributed in photonic crystal gaps. Because of the magnetism of the Fe3O4, the JPCBs could be flipped from one side to the other in the presence of a magnet. After being exposed to UVC light and fluorescamine, the JPCBs can fluoresce under UVA light. Then, we create Janus microbeads arrays with various types of beads and apply them to the visitor card, bracelet, and box label to provide irreversible and self-destructive anti-counterfeiting. The JPCBs are capable of being encoded and angle-independently displayed, which are crucial to their applications in anti-counterfeiting, information coding, and array display.
危险品化学品经营许可证（带存储）