Electron Spin Resonance Tests Research Articles

A cobalt-modified covalent organic framework enables highly efficient degradation of 2,4-dichlorophenol in high concentrations through peroxymonosulfate activation.

The development of covalent organic frameworks (COFs) which can rapidly degrade high concentrations of 2,4-dichlorophenol is of great significance for its practical application. In this work, we report a cobalt-doped two-dimensional (2D) COF (JLNU-307-Co) for the ultra-efficient degradation of high concentration 2,4-dichlorophenol (2,4-DCP) by activating peroxymonosulfate (PMS). The JLNU-307-Co/PMS system takes only 3 min to degrade 100% of 50 mg L-1 2,4-DCP and shows excellent catalytic stability in real water. The superoxide radical (O2˙-) and singlet oxygen (1O2) play a major role in the system through capture experiments and electron spin resonance (ESR) tests. Compared to most previously reported catalysts, JLNU-307-Co/PMS showed the highest efficiency to date in degrading 2,4-DCP. This work not only demonstrates the potential of COFs as a catalyst for water environmental treatment, but also provides unprecedented insights into the degradation of organic pollutants.

Ti-MOF-derived Ti3+-TiOx/CdIn2S4 heterojunction with a hollow structure for enhanced photocatalytic activity under visible light

The removal of refractory organic contaminants in the environment is vital, but developing highly active catalysts with a simple synthesis process remains a challenge. Herein, NH2-MIL-125(Ti) (Ti-MOF) as a template, Ti3+-TiOx clusters of different quantities were embedded in the CdIn2S4 nanosheets to construct Ti3+-TiOx/CdIn2S4 (TiCIS) heterojunction by an in-situ self-assembly strategy, which had a hollow structure, strong visible light absorption, high separation rate of carriers, and more active sites. During the degradation experiment of Rhodamine B (RhB), TiCIS25 exhibited the best photocatalytic performance, and 98.0% of RhB was degraded within 60 min of visible irradiation. The intermediates in the RhB degradation and their ecotoxicity were analyzed, which revealed that RhB degradation was a detoxification process. The radical trapping experiments and electron spin resonance (ESR) tests indicated that e-, 1O2, and ·O2- are the main active species for RhB degradation. Moreover, a possible photocatalytic mechanism was proposed based on electrochemical tests. The photodegradation performance of the as-prepared TiCIS catalyst under different reaction parameters (authentic water matrices, initial pH, coexisting anions, organic matter concentration, actual sunlight, reaction temperature, and multiple pollutants) and circulating experiments, as well as the photo-reduction process CO2, reflected that TiCIS25 possessed excellent practicability, cyclic stability, and universal applicability. Above all, TiCIS25 exhibited great potential in photocatalytic processes, and the work provided a feasible strategy for designing high-performance photocatalysts.

Carbon-coated copper nanocrystals with enhanced peroxidase-like activity for sensitive colorimetric determination of 2,4-dinitrophenylhydrazine.

Carbon-coated copper nanocrystals (CuNCs) with peroxidase-like activity were hydrothermally prepared by using copper acetate, citric acid (CA) and histidine (His) as the precursors. Various shaped CuNCs, including urchin-like, slab-like and spherical appearance were facilely prepared by addition of different amount of NaNO2 in the precursor solutions. When 3,3',5,5'-tetramethylbenzidine (TMB) was used as the substrate, the CuNCs with urchin-like appearance have greatest peroxidase-like activity and their Michaelis-Menten constant (Km) and the maximum rate constant (νmax) are respectively 8.8 and 1.2 times higher than that obtained from horseradish peroxidase (HRP). The production of reactive oxygen species (ROS) was confirmed by radical quenching and electron spin resonance (ESR) tests. Subsequent studies have found that the CuNCs catalyzed color reaction of TMB can be selectively quenched by the environmental pollutant 2,4-dinitrophenylhydrazine (2,4-DNPH). Thus a new colorimetric method for the determination of 2,4-DNPH with a linear range of 0.60-20µM was developed and a limit of detection (LOD) as low as 0.166µM was achieved. The results obtained not only reveal the tunability of the peroxidase-like activity of Cu-based nanomaterials, but also provide a new method for the sensitive determination of environmental contaminate.

Construction of NiP/Ni(OH)2/Ag-ZIF photocatalyst with 2-methylimidazole framework for rapid removal of tetracycline

Tetracycline (TC) is a kind of antibiotic that is difficult to be degraded by photocatalysis due to its stable molecular structure, and no ideal photocatalyst has been developed so far, thus developing a photocatalyst that can efficiently remove TC remains a challenge. In this work, a novel ternary photocatalyst of NiP/Ni(OH)2/Ag-ZIF (NNA) with 2 −Methylimidazole framework was constructed via a facile liquid phase reaction, in which the NiP is amorphous with particle size of about 3–5 nm, the Ni(OH)2 is nano-flake crystal with a one-dimensional diameter of about 200 nm, and the Ag-ZIF is a octahedral crystal with a side length of 4 µm. The NiP nano particles covered on the surface of Ni(OH)2 nanosheeps to form NiP/Ni(OH)2 heterojunction with flower-like structure and large BET area of 393.11 m2 g−1, which was further assembled with Ag-ZIF to form NiP/Ni(OH)2/Ag-ZIF composite with double heterojunction. The as-constructed NNA shows high removal capacity for TC, while 10 mg NNA was added into 100 mL 60 mg/L TC solution and exposed in visible light for 60 min, 91.3% of TC was removed. Meanwhile, the NNA shows good stability and reusability, which is attribute to the reversible of adsorption and desorption process of NiP/Ni(OH)2 for TC and the excellent photo-corrosion resistance of Ag-ZIF. The radical trapping and electron spin resonance (ESR) tests manifested that the superoxide radical (O2-) and the hydroxyl radical (·OH) play the key role in the degradation of TC.

2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction for enhanced removal of tetracycline: Performance, toxicity, and mechanism

In this paper, the two-dimensional (2D) layered CoAl LDH (CoAl) was coupled with Bi2MoO6 (BMO) nanoplate and used for tetracycline (TC) degradation. Based on the results of UV–visible diffuse reflectance spectrum (UV–vis DRS), Motty-Schottky curves, and in situ X-ray photoelectron spectroscopy (XPS), a novel 2D/2D Bi2MoO6/CoAl LDH S-scheme heterojunction photocatalyst was built. The photodegradation rate constant of TC by the optimized sample BMO/CoAl30 was 3.637 × 10−2 min−1, which was 1.26 times and 4.01 times higher than that of Bi2MoO6 and CoAl LDH, respectively. The favorable photocatalytic performance of the heterojunction was attributed to the increased interfacial contact area of the 2D/2D structure. Besides, the transfer of photogenerated electrons from Bi2MoO6 to CoAl LDH under the effect of the built-in electric field (BIEF) reduced the recombination of photogenerated carriers and further improved the photocatalytic performance. The reactive species of h+, ·O2−, and 1O2 exhibited critical roles to degrade TC molecules by reactive radicals capture experiments and electron spin resonance (ESR) tests. The intermediate products of TC degradation and toxicity of intermediates were analyzed by liquid chromatography-mass spectrometer (LC-MS) and Toxicity Estimation Software Tool (T.E.S.T). Additionally, the BMO/CoAl composite photocatalysts showed high stability and environmental tolerance during the testing of cycles and environmental impacts with various water sources, organic contaminants, initial pH, and inorganic ions. This work provides a new protocol for designing and constructing novel 2D/2D S-scheme heterojunction photocatalysts for wastewater treatment.

Synthesis of novel ZnIn0.2Ga1.8O4/CaIn2S4 composite material with S-scheme heterojunction for efficient photocatalytic degradation of organic pollutants and hydrogen evolution

Semiconductor photocatalysts that can both photocatalytic evolve hydrogen from water and degrade organic pollutants are very important to solve the problem of energy shortage and environmental pollution. The S-scheme ZnIn0.2Ga1.8O4/CaIn2S4 complex was successfully synthesized using sol–gel and oil bath methods. Characterization technique indicates that chrysanthemum-shaped CaIn2S4 is anchored on the surface of irregular nanoparticles ZnIn0.2Ga1.8O4, forming a closely packed heterostructure. The bandgap values of CaIn2S4 and Zn(In0.1Ga0.9)2O4 were determined as 2.11 eV and 3.61 eV, respectively. Under visible-light irradiation, the ZnIn0.2Ga1.8O4/CaIn2S4-1(ZC-1) photocatalyst exhibited superior performance in degrading an organic pollutant (RhB) and generating hydrogen compared to ZnGa2O4, ZnIn0.2Ga1.8O4, and CaIn2S4 alone. The photocatalytic degradation of RhB using ZC-1 was 1.7, 1.31, and 1.14 times higher than that of ZnGa2O4, ZnIn0.2Ga1.8O4, and CaIn2S4, respectively. Moreover, the photocatalytic hydrogen evolution rate of ZC-1 was 5.8, 3.7, and 13 times higher than that of ZnGa2O4, ZnIn0.2Ga1.8O4, and CaIn2S4, respectively. The formation of S-type heterojunctions in the composite photocatalysts was confirmed through free radical trapping and electron paramagnetic resonance tests, further enhancing hydrogen production and organic pollutant degradation. This study presents a novel approach for developing ZnGa2O4-based composite photocatalysts with S-scheme heterojunctions to address energy shortage and environmental pollution in the future.

Synthesis of Bi4O5I2 coupled with Sb2WO6 boosts the photocatalytic degradation of tetracyclines under simulated sunlight

For this study, a Sb2WO6/Bi4O5I2 composite material was successfully prepared via a precipitation-calcination method. The Sb2WO6/Bi4O5I2 heterostructure enhanced the light absorption and facilitated the separation of charge carriers. Under simulated sunlight exposure, the removal rates of tetracycline (TC) and doxycycline hyclate (DOX·HCl) reached 88.2% and 83.9%, respectively, over an optimized SWB2 composite (theoretical mole ratio of Sb2WO6: BiOI was 1.5:10). Further, the total organic carbon (TOC) removal rates were 37.6% and 33.7%, respectively. The experiments explored various parameters including catalyst dosage, initial concentrations of TC and DOX·HCl, solution pH, and common inorganic ions. The TC and DOX·HCl degradation pathways were speculated. Furthermore, SWB2 demonstrated remarkable stability and cyclability under simulated sunlight. Trapping experiments and electron paramagnetic resonance (EPR) tests revealed that •O2- played a major role as a free radical in the photocatalytic process, while h+ and •OH also had significant contributions. Based on in-situ XPS, trapping experiments, EPR test, band bending analysis, and SPV tests, the formation of S-scheme heterojunction between Sb2WO6 and Bi4O5I2 was inferred. This study provides insights into the design strategy of S-scheme heterojunctions between Aurivillius-type compounds and bismuth-rich halide bismuth oxide, which is informative for the development of advanced environmental remediation concepts.

Activation of periodate by chalcopyrite for efficient degradation of tetracycline hydrochloride

Activation of periodate (PI) has been widely recognized as an efficient and economical technique for the elimination of contaminants. In this study, a novel system with PI triggered by chalcopyrite (CuFeS2) was applied in the decomposition of tetracycline hydrochloride (TC). Effects of CuFeS2 dosage, PI concentration, pH value, inorganic anions, valence state change of Iodine ions (I-) were tested. The experimental findings demonstrated that the CuFeS2/PI system could successfully decompose TC in water under mild alkaline conditions (89.5 %, pH = 8). Compared with the other catalysts and the other CuFeS2/peroxide systems, CuFeS2/PI system exhibited more superior decontamination performance. Involvement of multiple reactive oxygen species such as superoxide radical (·O2–), hydroxyl radical (*OH) and singlet oxygen (1O2) in TC decomposition was confirmed by Electron spin resonance (ESR) tests and quenching experiment, and the interactions between Cu(Ⅱ)/Fe(III) and Cu(I)/Fe(Ⅱ) was confirmed. Based on a calculation using the density functional theory (DFT), the active sites of CuFeS2 for PI activation were revealed. Additionally, the analysis of degradation intermediates was conducted, with the toxicity of the intermediates analyzed. The CuFeS2/PI system was then applied in the treatment of real water samples, and the reusability of CuFeS2 was also investigated. This research presents a novel strategy as well as a theoretical foundation for CuFeS2 triggered PI to remove antibiotic contaminants.

Preparation of a Novel Ag/CFOOVs Composite Catalyst and Efficient Degradation of Phenol in a H2O2-based Fenton-like System

Although CuFe2O4 has been widely used in the field of Fenton-like wastewater treatment, its ability to activate H2O2 still needs to be further improved. In this context, a novel Agx/CFOOVs (x represents the theoretical mass percentage of Ag) composite catalyst was prepared by the tartaric acid reduction method for the first time, and its degradation performance and degradation mechanism of Phenol in a H2O2-based Fenton-like system were investigated. Through a series of characterizations, the successful preparation of the catalyst was confirmed. The degradation experiment showed that the degradation rate of 50mg/L Phenol by Ag2/CFOOVs/H2O2 system was 98.55% within 15min, which was a significant improvement in the degradation efficiency compared with that of CuFe2O4 and CFOOVs. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) confirmed the successful introduction of oxygen vacancies (OVs). Electrochemical impedance spectroscopy (EIS) showed that Ag2/CFOOVs had the lowest impedance, and the synergistic effect of OVs and Ag effectively enhanced the degradation capability of the catalysts for Phenol. The capture experiments of active species and ESR tests showed that the main active species of the Ag2/CFOOVs/H2O2 system were 1O2 and •OH. This study provides a new reference for the introduction of OVs and Ag in Fenton-like catalysts and their application to wastewater treatment.

Enhanced tribocatalytic degradation performance of organic pollutants by Cu1.8S/CuCo2S4 p-n junction

Tribocatalysis research, leveraging the triboelectric effect, presents significant potential for environmental water pollution control. However, there is a notable scarcity of studies pertaining to tribocatalysis involving heterojunctions, particularly in the context of p-n junction tribocatalysis. In this study, we employed a one-step solvothermal method to synthesize a Cu1.8S/CuCo2S4 p-n junction composite catalyst. Subsequently, we explored the tribocatalytic degradation performance of organic pollutants facilitated by the Cu1.8S/CuCo2S4 catalyst. The findings reveal that, under simple magnetic stirring conditions, the degradation rates achieved by the Cu1.8S/CuCo2S4 catalyst for tetracycline (TC), methylene blue (MB), and methyl orange (MO) are remarkably high, reaching 99.9 %, 99.7 %, and 94.0 %, respectively. This underscores the broad applicability of the Cu1.8S/CuCo2S4 catalyst for the tribocatalytic degradation of diverse organic pollutants. Experimental evidence establishes that friction occurring between the polytetrafluoroethylene (PTFE) magnet rod, the beaker, and the catalyst induces charge transfer at their interfaces, generating highly oxidized active species that effectively decompose pollutants. Through free radical capture and electron spin resonance (ESR) tests, it was empirically determined and validated that the principal active species involved in tribocatalytic degradation are holes (h+) and superoxide radicals (O2–). Incorporating insights from the experimental characterization of p-n junctions and density functional theory (DFT) theoretical calculations, we propose a plausible tribocatalytic mechanism for Cu1.8S/CuCo2S4. This research not only contributes novel findings but also serves as a reference for the exploration of innovative heterojunction tribocatalysts.

Thermal evolution of biochar in nature: A potential mode to enhance the self-cleaning of environmental DOC

Biochar often undergoes multiple thermal processes. Thermal evolution is described in this study as the process by which biochar in the environment changes again in a thermal environment. In this study, the thermal evolution process of biochar was studied by characterization test. The results showed that the oxygen content in biochar increased after thermal evolution, mainly due to functional groups such as O-H and C-O, while the functional groups of CO did not change significantly. Micro-pores will be generated in biochar after thermal evolution, which will increase the surface area and significantly enhance the adsorption capacity. The biochar was added to natural water to observe how biochar enhanced the removal of dissolved organic carbon (DOC). The concentration of DOC was reduced by about 6.68 mg/L by SB 800, and most of the components were humus, which indicated that the thermal evolution of biochar promoted the removal of DOC. The Electron spin resonance (ESR) test shows that after thermal evolution, biochar has more oxygen-containing carbon center persistent free radicals due to the increase of C-O functional groups in biochar. Under visible light, persistent free radicals in oxygen center are formed by electron transition, which can undergo a variety of reactions with water to form reactive oxygen species.

Synergistic interface engineering in n-p-n type heterojunction Co3O4/MIL/Mn-STO with dual S-scheme multi-charge migration to enhance visible-light photocatalytic degradation of antibiotics

Constructing an effective multi-heterojunction photocatalyst with maximum charge carrier separation remains challenging. Herein, a high-efficient Co3O4/MIL-88A/Mn–SrTiO3 (Co3O4/MIL/Mn-STO) n-p-n heterojunction photocatalyst was successfully prepared by a simple hydrothermal method for the photodegradation of sulfamethoxazole (SMX). The combination of MIL and Co3O4/Mn-STO established an internal electric field and heterojunction, accelerating the separation of carriers, and thus improved photocatalytic performance. In the Co3O4/MIL/Mn-STO photocatalytic system, 95.5 % of SMX was degraded in 90 min. The photocatalytic kinetic removal rate of Co3O4/MIL/Mn-STO reached 0.0337 min−1, 8 times of Co3O4 (0.0041 min−1), 5.2 times of Mn-STO (0.0062 min−1), 4.6 times of MIL (0.0078 min−1), and 3.6 times of MIL/Mn-STO (0.0095 min−1). Remarkably, superoxide radicals (•O2−) and holes (h+) have been recognized as the main active species in the degradation process through reactive species elimination experiments and electron spin resonance (ESR) tests. The experimental and theoretical proved the in-built interfacial contact and synergistic effect between the photocatalyst accomplished with low bandgaps, high specific surface area, more reaction sites, high electron-hole pair separation, and maximum solar-light utilization. The molecular structure and possible degradation routes with intermediate products in the photocatalytic system were investigated using a liquid chromatography-mass spectrometer (LC-MS) and DFT calculations. This work provided new insight into the guidelines of rational design/growth of new multicomponent photocatalysts to remove antibiotics and other emerging contaminants in wastewater.

Synergistic removal of organic and inorganic composite pollutants from water by zero-valent iron activated calcium peroxide

Agricultural non-point source pollution has received widespread attention in recent years due to its characteristics of dispersion, uncertainty, extensiveness and high difficulty in control. Among them, components such as fertilizers, heavy metals and herbicides constitute complex inorganic–organic composite pollution, which poses great threat to agricultural water ecosystem. Therefore, in this study, phosphate (P), lead (Pb) and atrazine (ATZ) as typical pollutants from agricultural non-point sources were investigated to remove collaboratively by constructing an environmentally friendly zero-valent iron (ZVI)-activated calcium peroxide (CaO2) system. At unadjusted initial pH 2.86, with the mass ratio of ZVI/CaO2 1:1, the removal efficiencies of P, Pb and ATZ were 95.3%, 97.4%, and virtually 100%, respectively. The main active species in the ZVI/CaO2 system was identified as hydroxyl radicals (·OH) by quenching experiment, electron spin resonance test and probe experiment. The characterization results showed that P was mainly precipitated in the form of Ca-P and Fe-P species. Pb was mainly adsorbed and reduced by ZVI and precipitated in solution. ATZ was mainly degraded into ten by-products, and the overall toxicity showed a decrease. The influence of pH on the removal efficiencies of pollutants was reflected in the fact that high pH promoted the removal of P and Pb but inhibited the degradation of ATZ. The ZVI/CaO2 system performed well under the influence of humic acid and typical anions. Therefore, this work provides a promising technology for the organic–inorganic co-polluted water treatment.

Electrocatalytic degradation of p-nitrophenol on metal-free cathode: Superoxide radical (O2•−) production via molecular oxygen activation

Although metal-free electrodes in molecular oxygen-activated Fenton-like wastewater treatment technologies have been developed, the reactive oxygen species (ROS) generation mechanisms are still not sufficiently clear. As a typical example of refractory phenolic wastewater, p-nitrophenol (PNP) has been widely studied. This study demonstrated the critical role of superoxide radicals (O2•−) in PNP degradation by metal-free electrodes through electron spin resonance (ESR), ROS quenching, and density functional theory (DFT) tests. The most superior metal-free electrode exhibited a mass activity of approximately 133.5 h−1 gcatalyst−1. Experimental and theoretical studies revealed the mechanism of O2•− generation via oxygen activation, including one- and three-electron transfer pathways, and found that O2•− mainly attacked the nitro group of PNP to degrade and transform the pollutant. This study enhances the mechanistic understanding of metal-free materials in the electrochemical degradation of refractory pollutants.

Interfacial oxygen vacancy modulated ZIF-8-derived ZnO/CuS for the photocatalytic degradation of antibiotic and organic pollutants: DFT calculation and degradation pathways

Fabricating oxygen vacancies (Vo) is an effective approach to enhance photocatalytic performance, but its effect on the interfacial charge transfer pathway remains unelucidated to date. In this study, we used the simple aqueous solution method to create an oxygen-defected ZIF-8-derived CuS/ZnO (CZ) heterostructure, and various characterization techniques were used to investigate the prepared catalysts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to determine the surface defects caused by the CuS nanoparticles in the ZnO matrix generated from ZIF-8. The optimized CuS/ZnO (CZ-2) catalyst exhibited efficient photocatalytic performance by effectively increasing the charge separation rate of the photogenerated electrons. The photocatalytic performances of methylene orange (MO) and ciprofloxacin (CIP) using the CZ heterostructure were 99.76 % and 94.59 %, respectively, with the corresponding rate constants of 0.0695 and 0.0312 min−1 at 40 min. The electron spin resonance and scavenger tests have established that •O2− is the primary oxidative radical species involved in photocatalytic activity. In addition, the density functional theory calculations were performed to determine the degradation mechanism of CIP, and the possible pathways of CIP degradation were investigated using liquid chromatography–mass spectroscopy. This study provides new insights into the development of metal–organic frameworks and metal sulfide-based heterostructures for environmental degradation applications.

Highlight the plasma-generated reactive oxygen species（ROSs）dominant to degradation of emerging contaminants based on experiment and density functional theory

This paper aims to deeply analyze the degradation mechanism of emerging contaminants by dielectric barrier discharge (DBD) plasma through experiments and simulations. It was confirmed that DBD plasma exhibits a high degradation effect on three emerging contaminants by the generated reactive oxygen species (ROSs). Increasing the output power leads to higher ROSs production and higher degradation rates of emerging contaminants. At an input power of 94.6 W, the degradation rates of sulfamethoxazole (SMX), bisphenol A (BPA) and ciprofloxacin (CIP) reach 94.5 %, 92.9 %, and 98.6 %, respectively. Trapping agent experiments were conducted to investigate the role of ROSs (·OH, ·O2–, and 1O2) in emerging contaminants degradation. Notably, capturing of 1O2 led to a decrease of up to 31 % in the degradation rate of BPA. Electron spin resonance (ESR) tests confirmed the involvement of various ROSs, especially 1O2, in the degradation process. Density functional theory (DFT) was employed to further explore the action mechanism of ROSs in the DBD plasma system. For SMX and BPA, the degradation is initiated by the dissociation of annular structures, while for CIP, annular structures are directly opened by ROSs. These findings highlight the importance of 1O2 and ·OH in the degradation process. Finally, the toxicity of intermediates produced by ROSs-dominate to degradation was declined. This work can provide new insights and unique guidance on the plasma degradation mechanism of emerging contaminants.

Improved aquaculture wastewater treatment and concomitant power generation in a photoelectrocatalytic fuel cell equipped with S-scheme Fe2WO6/ZnO nanorod arrays photoanode and NiFe2O4 cathode

The treatment of aquaculture wastewater involved the elimination of refractory organics and total nitrogen (TN) concurrently was one of the towering challenges in wastewater treatment. In this work, aquaculture wastewater comprised of tetracycline (TC) and TN as well as its energy recovery was recuperated in a visible light responsive photocatalytic fuel cell (PFC) system. The S-scheme Fe2WO6 nanoparticle-anchored on ZnO nanorod array (Fe2WO6/ZNA) photoanode and NiFe2O4 nanoflower-loaded on carbon felt (NiFe2O4/CF) cathode spanned photoelectrocatalysis and catalytic chlorination, conducing both contaminant removal and power production. In the presence of optimized conditions (0.5 M Cl−, dual constructed electrodes, solution pH 7), the system exhibited a maximum power density of 1.820 mW cm−2 and removed 100 % and 88.4 % of TC and TN in 120 min, respectively. The yielded small amount of NH4+ and NO3– can also destroy by NiFe2O4/CF cathode because of its large surface area and rapid charge carrier transport. Moreover, the toxicity results testified that the treated aquaculture organic seemed to have no harmful impact on zebrafish model after PFC-chlorine treatment. The mechanism involving S-scheme Fe2WO6/ZNA-NiFe2O4/CF electrodes and PFC-chlorination enabled the core species Cl and OH partook in the photoelectrocatalytic reaction. Based on the trapping agent, electron spin resonance and liquid chromatography mass spectrometry test outcomes, the degradation pathway of TC and its by-product was also postulated.

Unraveling the contribution of Co(IV) and free radicals in Co2+-activated Peroxymonosulfate process: Reaction mechanism, degradation pathway, and DFT calculation

The Co2+ and Peroxymonosulfate (PMS) reaction is a highly regarded advanced oxidation process (AOP) that has been extensively researched. The consensus regarding the relative contribution of reactive species in the Co2+/PMS system under different pH conditions has not been established. In this study, quenching experiments and electron spin resonance (ESR) tests demonstrated the coexistence of Co(IV), sulfate radical (SO4•-), hydroxyl radical (•OH), and singlet oxygen (1O2), and there fell to CBZ degradation were Co(IV) > SO4•->•OH ≈ 1O2 in the optimal conditions, where almost 100% of CBZ was degraded in the Co2+/PMS system within 30 min. Furthermore, Cl− would suppress the formation of Co(IV), SO4•-, and •OH but enhance the yield of 1O2, thereby showing a trend of inhibiting CBZ degradation. The probe compound used in this study was Methyl Phenyl Sulfoxide (PMSO), while methyl phenyl sulfone (PMSO2) as the indicator of Co(IV), the generation efficiency of PMSO2 (η'[PMSO2]) increased with reaction time and reached 70%–98% at 40 min at all set pH values (3, 4, 6, and 8). These results suggest that Co(IV) played a significant role in the Co2+/PMS system and its importance became more pronounced as the reaction progressed. PMSO probe and SO4•- quantification experiments jointly revealed that Co(IV) had the greatest performance at pH 4, and compared to other pH values, SO4•- had the largest contribution in the initial stage of the reaction at pH 6. The Ecological Structure Activity Relationships (ECOSAR) software was utilized to predict the toxicity of the degradation by-products. Additionally, luminescent bacteria experiments were conducted to assess the acute toxicity of the reaction solution. The results of these experiments demonstrated that the Co2+/PMS process exhibited a remarkable ability to detoxify the solution.

Dual-plasma enhanced 2D/2D/2D g-C3N4/Pd/MoO3-x S-scheme heterojunction for high-selectivity photocatalytic CO2 reduction

The localized surface plasmon resonance (LSPR) effect has shown significant progress in enhancing the efficiency of light absorption and separating photogenerated carriers. Herein, the dual-plasma enhanced 2D/2D/2D g-C3N4/Pd/MoO3-x (CPM) S-scheme heterojunction photocatalysts were synthesized using the method of hydrothermal and electrostatic self-assembly for high-selectivity photocatalytic reduction of CO2 to produce CO. The dual LSPR effect of MoO3-x and ultrathin Pd nanosheets synergistically broadened the optical response range of the CPM composites and successfully improved the photocatalytic activity and near-infrared (NIR) performance. The optimized CPM-30 photocatalysts exhibited CO yields of 18.55 μmol g−1 with a selectivity of 96.3%. In addition, the CO yield reached 3.92 μmol g−1 after 4 h of NIR light photoirradiation. The electron spin resonance (ESR) and ultraviolet photoelectron spectroscopy (UPS) tests showed that the S-scheme heterojunctions were constructed by coupling g-C3N4/Pd nanosheets and MoO3-x. This work will provide a reference for improving product selectivity through the design of two-dimensional composites and the utilization of plasma materials.

Yeast-biotemplate-assisted fabrication of self-phosphorus doped Co3O4@C hollow architecture for ciprofloxacin degradation via peroxymonosulfate activation: Performance, mechanism and toxicity evaluation

Sustainable development of highly active catalysts for peroxomonosulfate (PMS) activation to destruct organic pollutants in wastewater has irreplaceable significance, but remains a challenge. Herein, we report the successful preparation of P-doped Co3O4 integrated porous carbon hollow architecture (Co3O4@PC-HM) using spherical yeast as a natural biological template and cobalt nitrate as a cobalt source. The unique hollow microspherical structure endows Co3O4@PC-HM with large specific surface area for providing copious surface-exposed active sites, and the self-P doping facilitates the electron transfer rate, which concomitantly contribute to boosting the PMS activation for ciprofloxacin (CIP) degradation. Specifically, the Co3O4@PC-HM exhibits an excellent performance for activating PMS to degrade CIP with a removal efficiency of 95% in 20 min. Quenching experiments and electron paramagnetic resonance tests indicate the coexistence of radical and non-radical pathways in the Co3O4@PC-HM/PMS system, among which 1O2 and SO4•− play the dominant roles in CIP degradation. Simultaneously, four possible pathways of CIP degradation with the Co3O4@PC-HM/PMS system are proposed. Toxicity evaluation based on ECOSAR procedure and the growth status of mung bean roots reveal that the degradation process catalyzed by the Co3O4@PC-HM/PMS system efficiently decreases the toxicity of CIP. The natural biological template strategy has guiding significance for the synthesis of other hollow structure for versatile applications.