Rationally regulating reaction mechanisms in Fenton-like reactions by tuning the properties of catalysts is of great significance, but still challenging. Herein, we synthesized various active center size-dependent catalysts to realize the switching of reaction mechanisms and pollutant degradation routes in peroxymonosulfate (PMS) activation systems. The results illustrated that the reaction mechanism transformed from radical oxidation (51.64%) to nonradical oxidation (89.92%) with the decrease of active center size from nanoparticle (CoNP-NC) to single atom (CoSA-NC). The evolution of reactive species switched the degradation intermediates and pathway of sulfisoxazole (SIZ). The generation of singlet oxygen (1O2) in CoSA-NC/PMS tends to selectively attack electron-rich site of SIZ, while reaction between radicals and SIZ prefers non-selective oxidation in CoNP-NC/PMS system. Besides, the toxicity tests indicated that the conversion from non-selective to selective oxidation resulted in lower toxicity of effluent after reaction, which can further reduce environmental risks of effluent.

The porous defective MIL-88B(Fe) with abundant oxygen vacancies and Fe-N sites was fabricated to accomplish nearly zero peroxydisulfate (PDS) consumption for persistent bisphenol A (BPA) degradation via electron-transfer pathway (ETP). Interestingly, the generated sulfates during ETP were oxidized to yield the confined sulfate radicals and to accomplish the peroxydisulfate regeneration in the fine-tuned MIL-88B(Fe), which was verified by series experiments and DFT calculations. Further studies suggested that the optimal De-MIL-88B(Fe)-1.25 catalyst achieved the persistent nonradical reactions for BPA decomposition under visible light irradiation with both low input and low consumption of PDS. It was the first case to achieve nearly zero PDS consumption for emerging pollutants elimination, which provided new strategy to design and tune defective metal-organic frameworks for the purpose of reducing the stoichiometry between PDS and contaminants for nearly zero PDS consumption.

Excess phosphorus (P) in water can lead to eutrophication and upset ecological balance. In this study, biochar with ultrathin two-dimensional nanosheets from the natural mesocarp of shaddock was chosen as the carrier. The highly dispersed and small particle size of La(OH)3 on the surface of the nanosheets (MSBL3) was successfully achieved using chemical impregnation for the adsorption of P in aqueous solution, and the maximum adsorption capacity was 260.0 mg P g−1 [La]. The differences in surface crystallization of La(OH)3 on biochar at different La loadings were analyzed using the high-precision characterization methods. After six adsorption–desorption cycles, MSBL3 retained 76.7% of its initial performance in terms of the P adsorption capacity. The preparation of 1 g of MSBL3 costs about RMB 1, and it could reduce the P concentration in 2.6 ton of Laoyu River water to below the eutrophication threshold; and the inhibitory effect of MSBL3 on the eutrophication of water bodies was confirmed by the growth state of water hyacinth. Furthermore, 0.1 M MSBL3 could inhibit Escherichia coli and Staphylococcus aureus up to 98.7% and 85.0%, respectively, which indicates that MSBL3 can be used to recover P from water and also to improve water quality. In addition, the growth of the maize seedlings verified that the P-absorbed MSBL3 waste is a good soil fertilizer and can solve the problem of post-treatment of the adsorbent. In conclusion, MSBL3 prepared in this study is a promising P sorbent for application.

MnFe Prussian blue analogues (MnFe PBAs) were fabricated for acetamiprid degradation with peroxymonosulfate (PMS) as an oxidant. MnFe PBAs (200) are the most active facets for PMS activation due to the superior chemisorption affinity and electron-transfer ability. Density functional theory calculation verified that Mn(III) served as an electron donor and acceptor to adjust the electron density between Fe and Mn, which played a crucial role in the high activation performance of MnFe PBAs (200). PBA lattice (−C═N) did not exhibit direct PMS activation capability in this system, which differed from previously reported Fenton counterparts. Based on the electronic localization function calculation and probe experiments, the O–O of HSO5– was broken, and the bonds of PBA could be restored during the activation reaction, leading to the continuous generation of reactive oxygen species in the MnFe PBAs/PMS system. Transformation product studies indicated that the oxidized products were primarily the result of aromatic hydroxylation, N–C bond cleavage, azo reaction, and so forth, achieving the mineralization and ecotoxicity mitigation of acetamiprid efficiently. Findings in this study provided new insights into developing advanced facet-dependent catalysts to activate PMS for the efficient degradation of emerging contaminants in the aqueous environment.

A Fe-doped CeO2 was fabricated for catalytic ozonation of Amoxicillin (AMX), and the catalytic mechanisms were explored in this study. Under optimal conditions (the initial solution pH of 7.0, FC-0.3 dosage of 0.5 g/L, O3 dosage of 4 mg/min), the AMX and TOC removal by the optimal material (FC-0.3, at Fe/Ce atomic ratio of 0.3) reached 98.1% at 24 min and 55.2% at 36 min, respectively. Improved the AMX mineralization efficiency by 3.7 times. The experiments and theoretical calculation reveal the mechanisms of promoted catalytic ozonation by FC-0.3: 1) Highly abundant surface-active sites (i.e., -OH) enabled the adsorption of H2O and O3, which was favorable to the generation of reactive oxygen species (ROS) and improved the reaction probability for ROS and contaminants. 2) The synergistic effect between Ce4+/Ce3+ and Fe3+/Fe2+ redox couples accelerated the electron transfer and formation of ROS. More than 42% of •OH was generated in the presence of FC-0.3, and the •OH, •O2− and 1O2 were the main ROS that contributed to AMX degradation. The surface OH groups played a key role in the catalytic ozonation. The oxygen vacancies (OVs) played an important role in electron transfer, Ce and Fe were the active sites of electrons transfer following the sequence of (Ce3+ + Fe2+) → (Ce4+ + Fe3+) → (Ce3+ + Fe2+) redox reaction. The degradation pathway investigation and toxicity evaluation revealed that some more toxic intermediates were generated during the ozonation process, and sufficient mineralization is required to meet safe discharge. This study provides reference for the synthesis of new catalysts and insight into the reaction mechanisms in the heterogeneous catalytic ozonation process.

Interfacial modulation of catalysts for constructing active sites can greatly promote its catalytic activity, while the mechanism on reactive species production at different interfaces still needs to be revealed. In this study, Zr-S4 active sites were usefully constructed on ZnIn2S4 nanosheets, which effectively modulated the reaction interface and band structure, thus boosting the photocatalytic activity. The optimized material (Zr1.2-ZIS) showed a ∼3-fold kinetic rate constant for photocatalytic degradation of tetracycline compared with the pristine ZnIn2S4. Moreover, TC underwent a different degradation pathway over the modified catalyst due to regulation of reactive species after photo-activation. The Zr-S4 centers were energetically favorable for activating O2 into •O2- and •OH, as a more reactive d-band electron was obtained and the adsorption of •O2- as well as its further conversion into •OH was promoted. Theoretical calculations on Fukui index and toxicity also confirmed the dramatical toxicity reduction during TC degradation by Zr1.2-ZIS.

A novel PbO2 electrode modified with rare earth elements (La, Ce, Gd and Er) doping (named as Re-PbO2) was prepared by electrodeposition in the present study. The micro-morphology and crystal structure of Re-PbO2 were characterized by scanning electronic microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Their electrochemical properties were determined by linear sweep voltammetry (LSV), cyclic voltammetry (CV), accelerated life test and hydroxyl radicals (•OH) formation analysis. Electrochemical oxidation of p-nitrophenol (p-NP) by Re-PbO2 compared with un-doped PbO2 has been investigated and the degradation rate followed the order of Er-PbO2 > Gd-PbO2 > La-PbO2 > Ce-PbO2 > PbO2. Especially for Er-PbO2, the pseudo-first order kinetic for p-NP (kp-NP) degradation was 0.41, which was only 0.19 for un-doped PbO2. Rare earths elements doping improved the oxidation ability of Re-PbO2 mainly through reducing grain size, increasing oxygen evolution potential, enlarging electrochemical active surface area and enhancing •OH formation ability. In addition, existing formation of oxygen species on PbO2 electrode surface was investigated by XPS. For Re-PbO2, percentage of lattice oxygen species (Oads) were higher than that on the un-doped one. These results demonstrated that rare earth elements can enhance the oxidation ability of PbO2 electrode significantly.

A Co3O4-activated chlorite (Co3O4/chlorite) process was developed to enable the simultaneous generation of high-valent cobalt species [Co(IV)] and ClO2 for efficient oxidation of organic contaminants. The formation of Co(IV) in the Co3O4/chlorite process was demonstrated through phenylmethyl sulfoxide (PMSO) probe and 18O-isotope-labeling tests. Both experiments and theoretical calculations revealed that chlorite activation involved oxygen atom transfer (OAT) during Co(IV) formation and proton-coupled electron transfer (PCET) in the Co(IV)-mediated ClO2 generation. Protons not only promoted the generation of Co(IV) and ClO2 by lowering the energy barrier but also strengthened the resistance of the Co3O4/chlorite process to coexisting anions, which we termed a proton enhancement effect. Although both Co(IV) and ClO2 exhibited direct oxidation of contaminants, their contributions varied with pH changes. When pH increased from 3 to 5, the deprotonation of contaminants facilitated the electrophilic attack of ClO2, while as pH increased from 5 to 8, Co(IV) gradually became the main contributor to contaminant degradation owing to its higher stability than ClO2. Moreover, ClO2– was transformed into nontoxic Cl– rather than ClO3– after the reaction, thus greatly reducing possible environmental risks. This work described a Co(IV)-involved chlorite activation process for efficient removal of organic contaminants, and a proton enhancement mechanism was revealed.

Peracetic acid combined ultraviolet (UV/PAA) process has garnered growing attention as a promising advanced oxidation process (AOP) for wastewater treatment, but the corresponding transformation of ubiquitous dissolved organic matter (DOM) under this AOP remains unknown. This study systematically investigated the changes in characteristics and composition of DOM under UV/PAA, as well as the underlying mechanisms by multiple spectroscopic analyses and Fourier transform ion cyclotron resonance mass spectrometry. UV/PAA treatment dramatically decreased aromaticity, apparent molecular weight, and fluorescent abundance of DOM with the production of more oxidized and saturated compounds. The reactive species (i.e., ·OH and CH3C(O)O·/CH3C(O)OO·) in UV/PAA contributed primarily to DOM changes but showed different reaction selectivity and mechanisms. ·OH reacts with DOM components and mainly yields oxygenation products via a radical addition pathway. Comparatively, the electron transfer route is more likely to occur in CH3C(O)O·/CH3C(O)OO·-induced DOM transformation. Aside from oxygenation products, electron transfer could exclusively generate decarboxylation products and distinguishes CH3C(O)O·/CH3C(O)OO·-based AOPs from ·OH-based AOPs. These findings significantly improve knowledge of DOM alterations under UV/PAA AOP at both the bulk and molecular levels.

Halogenated pharmaceuticals exhibit high toxicity if released to natural environment, and dehalogenation is a key process for their degradation. In this study, a reductive and directional dehalogenation technique, heterogenous formic acid (HCOOH) catalytic activation system, was proposed for diclofenac (DCF) dechlorination and detoxification. A functional material of Pd nanocluster decorated graphitic carbon nitride (Pd/g-C3N4) was developed for HCOOH activation. Although the optimized material (Pd1/g-C3N4) showed lower HCOOH decomposition rate (k1 = 0.287 ± 0.017 min−1) than the pristine Pd particles (k1 = 0.401 ± 0.031 min−1), it processed higher DCF degradation efficiency (97.9% within 30 min) than Pd particles. The enhancement mechanism was revealed by both experiments and theoretical calculations. Firstly, the six-fold cavities of g-C3N4 acted as anchor sites, which offered strong coordination environment for Pd nanoclusters. Secondly, the strong coordination environment of Pd led to upshifted d-band center of Pd 4d with enhanced bonding state, and then promoted HCOOH adsorption on Pd/g-C3N4, thus facilitating HCOOH decomposition through formate pathway rather than carboxyl pathway. Thirdly, Pd/g-C3N4 ensured HCOOH selectively decomposed as dehydrogenation reaction, which generated more H* (adsorbed H on Pd) than the dehydration reaction. The H* was proved to be the dominant reductive species for DCF hydrodechlorination. Moreover, the toxicities of DCF dechlorination products were greatly reduced.

Semiconducting minerals (such as iron sulfides) are highly abundant in surface water, but their influences on the natural photochemical process of contaminants are still unknown. By simulating the natural water environment under solar irradiation, this work comprehensively investigated the photochemical processes of anthracene (a typical Polycyclic Aromatic Hydrocarbons) in both freshwater and seawater. The results show that the natural pyrite (NP) significantly promotes the degradation of anthracene under solar illumination via 1) NP induced photocatalytic degradation of anthracene, and 2) Fenton reaction due to the NP induced photocatalytic generation of H2O2. The material characterization and theoretical calculation reveal that the natural impurity in NP enlarges its band gap, which limits the utilization of solar spectra to shorter wavelength. The contribution of generated reactive intermediates on anthracene degradation follows the order of 1O2 > OH > O2− in freshwater and O2− > 1O2 > OH in seawater. The photochemically generated H2O2 is a vital source for OH generation (from Fenton reaction). The steady-state concentration of OH, 1O2 and O2− in freshwater were monitored as 3.0 × 10−15 M, 1.1 × 10−13 M, and 4.5 × 10−14 M, respectively. However, the OH concentration in seawater can be negligible due to the quenching effects by halides, and the 1O2 and O2− concentrations are higher than that in freshwater. An anthracene degradation kinetic model was built based on the experimentally determined reactive intermediates concentration and its second order rate constant with anthracene. Moreover, the anthracene degradation pathway was proposed based on intermediates analysis and DFT calculation, and its toxicity evolution during the photochemical process was assessed by quantitative structure-activity relationship (QSAR) based prediction. This finding suggests that the natural semiconducting minerals can affect the fate and environmental risks of contaminants in natural water.

Concurrently elevating the degradation efficiency of pollutants and realizing the reduction of iron sludge in Fe-based catalytic ozonation is important but still challenging. Herein, we developed an electrocatalytic ozonation (ECO) system with iron plate cathode and graphite felt anode (ECO-Fe-cathode), which was free from added chemical reagents. Unlike the iron plate as a sacrificial anode in the ECO (ECO-Fe-anode) system, this delicately designed system shows a much higher degradation rate of ibuprofen (kobs = 1.490 min−1) than that of the ECO-Fe-anode system (kobs = 0.345 min−1). Simultaneously, the effluent was totally limpid without the corrosion of iron plates and the formation of iron sludge in the ECO-Fe-cathode system. Unexpectedly, the generation of singlet oxygen (1O2) which is indirectly generated by the single-electron transfer derived from superoxide ion (O2•-) is the primary reactive oxygen species (ROS) in the ECO-Fe-cathode system, which is different from the ECO-Fe-anode system with hydroxyl radicals (•OH). Moreover, linear sweep voltammetry (LSV) was applied to reveal the oxygen evolution reaction (OER) performance of the iron plate and graphite felt, and the results showed that graphite felt as anode has better electrocatalytic performance. The electrochemical analysis and density functional theory (DFT) calculation revealed that ozone adsorbed on the iron plate surface is more conducive to facilitating and triggering subsequent reactions. Finally, the different degradation pathways of ibuprofen in both systems were proposed. This work represents a fundamental breakthrough toward the design of an efficient and harmless ECO system for wastewater treatment.

Achieving efficient degradation of organic pollutants via activation of sulfite is meaningful but challenging. Herein, we have constructed a heterogeneous catalyst system involving Co3O4 and TiO2 nanoparticles to form the p-n heterojunction (Co3O4/TiO2) to degrade acetaminophen (ACE) through photocatalytic activation of sulfite. Specifically, X-ray photoelectron spectroscopy analysis and theoretical calculations provide compelling evidence of electron transfer from Co3O4 to TiO2 at the heterointerface. The interfacial electron redistribution of Co3O4/TiO2 tunes the adsorption energy of HSO3‒/SO32‒ in sulfite activation process for enhanced the catalytic activity. Owing to its unique heterointerface, the degradation efficiency of ACE reached 96.78% within 10 min. The predominant active radicals were identified as •OH, h+, and SOx•− through radical quenching experiments and electron spin resonance capture. Besides, the possible degradation pathway was deduced by monitoring the generated intermediate products. Thereafter, the enhanced roles of well-engineered compositing interface in photocatalytic activation of sulfite for complete degradation of ACE were unveiled that it can improve light absorption ability, facilitate the generation of active species, and optimize reactive pathways. Considering that sulfite is a waste from flue gas desulfurization process, the photocatalytic activation of sulfite system will open up new avenues of beneficial use of air pollutants for the removal of pharmaceutical wastewater.

In the presence of the difficulties pertinent to the selective oxidation of cyanide and the high-efficient hydrolysis of cyanate, the mineralization of cyanide into nitrogen could not be realized during the traditional processes. Herein, a novel system of electrocatalysis coupled with ultraviolet-based advanced oxidation processes (UV/EC/PS, PS: persulfate) is developed, exhibiting astonishingly high activity and selectivity for cyanide mineralization. The achieved results reveal that adequate active-chlorine species (ClO•/Cl2•−) are generated due to the synergistic effects of electrocatalysis and advanced oxidation processes and these are high-selective for cyanide mineralization. Concurrently, induced by the interconversion between active species, the pH value in the UV/EC/PS system vigorously lessens from 11.5 to 3.3 at a rate of 1.1 × 10-2 min−1, hugely speeding up the hydrolysis of cyanate intermediates. The results display that PS plays a pivotal role in the formation of ClO•/Cl2•− and the self-reduction of pH value in the UV/EC/PS system. Under the action of ClO•/Cl2•− and self-decreased pH value, 0.25 mM of ferricyanide is thoroughly mineralized into nitrogen within 80 min and no HCN evolves. Additionally, the UV/EC/PS system exhibits exceptional feasibility for the practical purifications of cyanide-containing wastewater (CCWW). This study aims to give new insights into developing technologies associated with the mineralization treatment of CCWW.

Herein, electro-catalysis (EC) as the electron donor to accelerate the continuable Fe(III)/Fe(II) cycles in different inorganic peroxides (i.e., peroxymonosulfate (PMS), peroxydisulfate (PDS) and hydrogen peroxide (HP)) activation systems were established. These electro-cocatalytic Fenton-like systems exhibited an excellent degradation efficiency of sulfamethoxazole (SMX). A series of analytical and characterization methods including quenching experiments, probe experiments, and electron paramagnetic resonance spectrometry (EPR) were implemented to systematically sort out the source and yield of reactive oxygen species (ROS). A wide kind of ROS including hydroxyl radical (•OH), singlet oxygen (1O2), and sulfate radical (SO4•−), which contributed 38%, 37%, and 24% were produced in EC/Fe(III)/PMS system, respectively. •OH was the dominant ROS in both EC/Fe(III)/PDS and EC/Fe(III)/HP processes. According to the analysis of SMX degradation routes and biotoxicity, abundant degradation pathways were identified in EC/Fe(III)/PMS process and lower environmental impact was achieved in EC/Fe(III)/HP process. The diversiform ROS of EC/Fe(III)/PMS system makes it exhibit greater environmental adaptability in complex water matrixes and excellent low-energy consumption performance in many organic pollutants degradation. Continuous flow treatment experiments proved that the three systems have great sustainability and practical application prospect. This work provides a strong basis for constructing suitable systems to achieve different treatment requirements.

Hydroxyl radical (•OH) and sulfate radical (SO4•−) produced in advanced oxidation processes (AOPs) have been widely studied for organic contaminants degradation, however, the different radical characteristics and reaction mechanisms on organics degradation are still needed. In this study, a homogeneous Co(II)/peroxymonosulfate activation system was established for caffeine (CAF) degradation, and pH was controlled to regulate the radicals production. The different attack routes driven by SO4•− and •OH were deeply explored by transformation products (TPs) identification and theoretical calculations. Specifically, a method on dynamic electronic structure analysis of reactants (R), transition state (TS) and intermediates (IMs) during reaction was proposed, which was applied to elucidate the underlying mechanism of CAF oxidation by •OH and SO4•− at the molecular orbital level. In total, SO4•− is kinetically more likely to attack CAF than •OH due to its higher oxidation potential and electrophilicity index. Single electron transfer reaction (SET) is only favorable for SO4•−due to its higher electron affinity than •OH, while only •OH can react with CAF via hydrogen atom abstraction (HAA) route. Radical adduct formation (RAF) is the most favorable route for both •OH and SO4•− attack according to both kinetics and thermodynamics results. These findings can significantly promote the understanding on the degradation mechanism of organic pollutants driven by •OH and SO4•− in AOPs.

Tungsten oxide nanowires (WO3−x) with rich oxygen vacancies (OVs) were fabricated through a facile hydrothermal method, which had both high adsorptive capability and photocatalytic activity. 95.1% of total U(VI) (C0 = 10 mg/L) was removed by WO3−x at pH 5, and 79.9% was transformed to U(IV) to achieve reductive immobilization after photocatalysis under simulated solar light. Band structure and optical characterizations indicated WO3−x had narrower band gap energy, but higher charger carrier separation and transfer rates compared with conventional WO3. Density functional theory (DFT) calculations further demonstrate the spin polarization state electrons of W 5d in WO3−x due to the construction of OVs, thus greatly inhibiting recombination of electron-hole pairs. In addition, the electron density increases in WO3−x and the photogenerated e– in the conduction band of WO3−x has higher reduction ability than WO3, leading to more efficient electron transfer from WO3−x to UO22+ after photo-excitation for U(VI) reduction.

In this work, an excitonic energy transfer (EET) based non-radical mechanism was proposed for the degradation of organic pharmaceuticals by graphitic carbon nitride (g-C3N4) under visible light irradiation. Using diclofenac (DCF) as a model molecule, the competition between single electron transfer (SET) and EET was studied through modulating the exciton binding energy of g-C3N4. The different mechanisms of SET and EET for DCF degradation were predicted by DFT calculation, and further confirmed by their different degradation pathways. When EET played an important role, the rationality of some very popular radical scavengers, such as p-BQ, TEMPOL and furfuryl alcohol must be reconsidered. In addition, humic acid (HA) had a distinct effect on EET and SET. Specifically, HA enhanced the EET process through photosensitization, but suppressed SET through radical quenching effect. The effect of HA on DCF degradation depended on the contribution ratio of SET and ET.

Sulfate radical (SO4•–)-based heterogonous advanced oxidation processes (AOPs) show promising potential to degrade emerging contaminants, however, regulating the electron structure of a catalyst to promote its catalytic activity is challenging. Herein, a hybrid that consists of Co3O4−x nanocrystals decorated on urchin-like WO2.72 (Co3O4−x/WO2.72) with high-valence W and rich oxygen vacancies (OVs) used to modulate the electronic structure of Co-3d was prepared. The Co3O4−x/WO2.72 that developed exhibited high catalytic activity, activating peroxymonosulfate (PMS), and degrading sulfamerazine (SMR). With the use of Co3O4−x/WO2.72, 100 % degradation of SMR was achieved within 2 min, at a pH of 7, with the reaction rate constant k1 = 3.09 min−1. Both characterizations and density functional theory (DFT) calculations confirmed the formation of OVs and the promotion of catalytic activity. The introduction of WO2.72 greatly regulated the electronic structure of Co3O4−x. Specifically, the introduction of high-valence W enabled the Co-3d band centre to be closer to the Fermi level and enhanced electrons (e–) transfer ability, while the introduction of OVs-Co in Co3O4−x promoted the activity of electrons in the Co-3d orbital and the subsequent catalytic reaction. The reactive oxygen species (ROS) were identified as •OH, SO4•–, and singlet oxygen (1O2) by quenching experiments and electron spin resonance (EPR) analysis. The DFT calculation using the Fukui index indicated the reactive sites in SMR were available for an electrophilic attack, and three degradation pathways were proposed.

In this work, the different selectivity of SO4•- and •OH towards municipal solid waste incineration leachates (MSWILs) was studied by a comparative study of UV/persulfate (PS) and UV/H2O2. Results showed SO4•- preferentially mineralized carbon atoms of higher average oxidation state, while •OH showed a two-stage mechanism of partial oxidation and mineralization successively. Electron spin resonance (ESR) analysis showed SO4•- had superior selectivity towards MSWILs than •OH, and Fe(II) would significantly affect the selectivity via forming Fe-MSWILs complex. As the consequence, Fe(II) showed slightly negative effect on UV/PS, but greatly enhanced the performance of UV/H2O2/Fe(II). High concentration of Cl- affected the degradation of non-fluorescent substances by UV/PS, while SO42- and NO3- showed no effect. In contrast, anions showed no effect on UV/H2O2. In addition, •OH preferentially attacked large molecules, but SO4•- showed no selectivity. This study further revealed the selectivity of SO4•- and •OH in the treatment of hypersaline wastewater, and provided theoretical support for the development of targeted technology.