Electron Spin Resonance Tests Research Articles

A stable Zn-MOF with anthracene-based linker for Cr(VI) photocatalytic reduction under sunlight irradiation

The highly desired goal is to employ visible light for the photocatalytic reduction of toxic Cr(VI) to environmentally friendly Cr(III). Metal-organic frameworks (MOFs) are considered one of the most promising materials for the photoreduction of Cr(VI). Nevertheless, developing MOFs with high stability and activity is still challenging. Herein, we report a stable Zn-based MOF (named DZU-64) with an anthracene functionalized ligand, and its reduction of Cr(VI) under sunlight irradiation was investigated. DZU-64 exhibits excellent chemical stability in pH range of 2−14 aqueous solution, and remarkable thermal stability to 570 °C. For the photoreduction of Cr(VI) under visible light irradiation, DZU-64 gives a record rate constant of 0.467 min−1 and a high Cr(VI) reduction rate of 6.68 mg Cr(VI) g−1cata min−1 at pH 2. Moreover, under real solar light, DZU-64 can also efficiently reduce Cr(VI) to Cr(III) while retaining its catalytic activity throughout 5 cycles without any notable decline, further demonstrating its great application prospect. By combining the photovoltaic performance tests and electron spin resonance test, the possible photoreduction of Cr(VI) mechanism in DZU-64 was analyzed.

Electro-activation of peroxymonosulfate using a carbon fiber membrane anode for high-efficient degradation of antibiotic wastewater: The dominant role of singlet oxygen

A flow-through peroxymonosulfate (PMS) electro-activation system with a polyacrylonitrile-based carbon fiber (PCF) membrane anode (denoted as E-PCF-PMS system) was developed. The introduction of the PCF membrane anode enabled the flow-through electrocatalytical system to achieve a remarkable tetracycline (TC) removal of 96.0 ± 0.2 % within 15 min, with a degradation rate of 0.273 min−1. Scavenging investigations revealed that singlet oxygen (1O2) was the dominant reactive oxygen species for TC degradation in the E-PCF-PMS system, and this finding was confirmed by electron paramagnetic resonance tests. Potential degradation pathways of TC were identified according to the detected intermediates and calculations of density functional theory, and a decreasing trend in the toxicity of TC intermediates was discovered. Thanks to the 1O2-dominated pathway, the constructed E-PCF-PMS system could achieve efficient TC degradation under different concentrations of several common anions (Cl−, NO3−, HPO42−, and HCO3−) and humic acid (HA). General applicability and reusability tests demonstrated the excellent practicability of the proposed system. The PMS electro-activation system offers a potential technique for high-efficient degradation of contaminants in water and wastewater.

Boosting the recyclability of flame-made Bi2O3 via insitu immobilization in cellulose acetate nanofibers for efficient photocatalytic degradation of rhodamine B dye

Flame spray pyrolysis is a novel fast-process for producing functional metal oxides. However, these functional nanomaterials are challenged with poor recyclability in water treatment from pollutants such as dyes. Herein, Bi2O3 nanoparticles were produced by flame spray pyrolysis and spun together with eco-friendly cellulose acetate polymer into nanofiber membrane via electrospinning technique. The results reveal that cellulose acetate (CA) has good interaction with the particles, leading to reduced band gap, retardation of fast recombination of carriers and good electron transportation on the surface of the nanofiber membrane. The Bi2O3/CA nanofiber membrane records similar photocatalytic performance to that of flame-made Bi2O3 nanoparticles, that is about 95% dye degradation at 90 min, which was far better than CA and Bi2O3/polyacrylonitrile nanofiber membranes. The electron spin resonance test and free radical scavenger test reveal that abundant hydroxyl radicals serve as the most active species that enhance photocatalytic degradation of dye on Bi2O3/CA nanofiber membrane. The flexible Bi2O3/CA nanofiber membrane also demonstrates easy recyclability after several runs with no significant decline in performance. This study pins the effectiveness of using eco-friendly cellulose acetate in obtaining inorganic-organic composite to concurrently achieve good photocatalytic performance and recyclability.

In-situ fabrication of MOF-derived MnO-C modified graphite felt for electro-activation of peroxymonosulfate toward degradation of tetracycline: Performance, mechanism and degradation pathway

Peroxymonosulfate (PMS) activation by synergy of electrochemistry and catalyst has emerged as a promising technique for the degradation of organic contaminants. Herein, manganese oxide-carbon modified graphite felt (MnO-C/GF) electrodes are successfully synthesized by pyrolyzing Mn-MOF/GF composite. MnO-C/GF is employed as an anode to remove tetracycline (TC) in a process of PMS activation with the assistance of electrochemistry (EC). Under optimal conditions (50 mg/L TC, 10 mA·cm−2, pH 7, 0.80 mM PMS,0.05 M Na2SO4, 25 °C), MnO-C800/GF electrode (pyrolysis at 800 °C) achieves remarkable degradation efficiency of 90.48 % for TC after 60 min in EC-PMS system. The reaction rate constant (k) of MnO-C800/GF increases by 4.54 and 2.38 times compared to bare GF and MnO/GF in EC-PMS system, respectively. In addition, quenching test and electron paramagnetic resonance test reveal that ·OH, SO4−, O2− and 1O2 are involved in the degradation process at MnO-C800/GF-EC-PMS system. According to the results of density functional theory and liquid chromatography-mass spectrometry, the degradation of TC mainly includes hydrogenation, demethylation, deamidation, dehydroxylation and ring-opening reactions. This work demonstrates that the combination of electrochemistry and metal oxide-activated PMS is a highly efficient approach for the degradation of antibiotic contaminant.

Three-dimensional porous La(OH)3/g-C3N4 adsorption-photocatalytic synergistic removal of tetracycline.

La(OH)3/g-C3N4 composites were successfully synthesized via one-step calcination using urea, melamine, and La(NO3)3·nH2O as raw materials, and applied to UV-induced photocatalytic tetracycline (TC) removal. Comprehensive characterization by an X-ray diffraction (XRD), Fourier transform infrared reflection (FT-IR), high-resolution transmission electron microscope (HRTEM), and other techniques analyzed effects of La3+ doping, especially N vacancies and cyano groups as active sites. Compared to pure g-C3N4 and La(OH)3, synthesized La(OH)3/g-C3N4 composites exhibited a three-dimensional porous nanosheet structure with specific surface area of 83.62 m2/g and equilibrium TC adsorption capacity up to 285.59 mg/g; La(OH)3 doping significantly improved composite structure. After dispersing 10 mg La-CN-0.5 photocatalyst in 60 mL 40 mg/L TC solution, TC removal reached 91.08% in 30 min under UV irradiation, exhibiting excellent performance. Additionally, La-CN-0.5 showed significant adsorption-photocatalytic synergism, with the quasi-primary kinetic constant increased by 1.83-fold. The efficiency of high tetracycline (TC) concentration treatment through adsorption photocatalytic degradation by La-CN-0.5 was confirmed by the utilization of free radical trapping and electron spin resonance (ESR) tests. The significant involvement of ∙O2-, ∙OH, and h+ in this process was observed. These findings propose that the prepared La-CN-0.5 material exhibits a unique capability for adsorption photocatalysis, providing a promising approach for the efficient removal of high TC concentrations.

Efficient peroxymonosulfate activation by nanoscale zerovalent iron for removal of sulfadiazine and sulfadiazine resistance bacteria: Sulfidated modification or not

Whether it’s necessary to extra chemical synthesis steps to modify nZVI in peroxymonosulfate (PMS) activation process are worth to further investigation. The 56 mg/L nZVI/153.65 mg/L PMS and 56 mg/L sulfidated nZVI (S-nZVI) (S/Fe molar ratio = 1:5)/153.65 mg/L PMS) processes could effectively attain 97.7% (with kobs of 3.7817 min−1) and 97.0% (with kobs of 3.4966 min−1) of the degradation of 20 mg/L sulfadiazine (SDZ) in 1 min, respectively. The nZVI/PMS system could quickly achieve 85.5% degradation of 20 mg/L SDZ in 1 min and effectively inactivate 99.99% of coexisting Pseudomonas. HLS-6 (5.81-log) in 30 min. Electron paramagnetic resonance tests and radical quenching experiments determined SO4•−, HO•, 1O2 and O2•− were responsible for SDZ degradation. The nZVI/PMS system could still achieve the satisfactory degradation efficiency of SDZ under the influence of humic acid (exceeded 96.1%), common anions (exceeded 67.3%), synthetic wastewater effluent (exceeded 90.7%) and real wastewater effluent (exceeded 78.7%). The high degradation efficiency of tetracycline (exceeded 98.9%) and five common disinfectants (exceeded 96.3%) confirmed the applicability of the two systems for pollutants removal. It’s no necessary to extra chemical synthesis steps to modify nZVI for PMS activation to remove both chemical and biological pollutants.

Trace Co(II) triggers peracetic acid activation in phosphate buffer: New insights into the oxidative species responsible for ciprofloxacin removal

Peracetic acid (PAA) emerges as a promising disinfectant and oxidant applied worldwide, and its application has been broadened for advanced oxidation processes (AOPs) in wastewater treatment. Current studies on transition metal-activated AOPs utilized relatively high concentrations of catalysts, leading to potential secondary pollution concerns. This study boosts the understanding of reaction mechanism in PAA activation system under a low-level concentration. Herein, trace levels of Co(II) (1 μM) and practical dosages of PAA (50–250 μM) were employed, achieving noticeable ciprofloxacin (CIP) degradation efficiencies (75.8–99.0%) within 20 min. Two orders of magnitude of the CIP’s antibacterial activity significantly decreased after Co(II)/PAA AOP treatment, which suggested the effective ecological risk control capability of the reaction system. The degradation performed well in various water matrices and the primary reactive species is proposed to be CoHPO4-OO(O)CCH3 complexes with scavenging tests and electron paramagnetic resonance tests. The degradation pathway of fluoroquinolones including piperazine ring-opening (dealkylation and oxidation), defluorination, and decarboxylation, were systematically elucidated. This study boosts a comprehensive and novel understanding of PAA-based AOP for CIP degradation.

Synergistic modulation of oxygen vacancies and heterojunction structure in Pd@CN@TiO2 promotes efficient photocatalytic Suzuki–Miyaura CC coupling reactions

This paper reports a concise strategy for the controlled preparation of Pd@g‐C3N4/TiO2 photocatalysts rich in oxygen vacancies. The scheme forms black TiO2 with oxygen vacancies on a carbon nitride material by in‐situ growth and heat treatment, and then utilizes solvothermal reduction to load metallic palladium into the material. The composites were structurally analyzed using Fourier transform infrared (FT‐IR), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction analysis (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), scanning electron microscopy (SEM), elemental mapping, diffuse reflectance spectroscopy (DRS), and inductively coupled plasma (ICP) analysis. The results show that the oxygen vacancies in the black TiO2 materials prepared by the method reported in this paper can effectively improve the separation efficiency of the photogenerated electron–hole pairs and prolong the lifetime of the charge carriers by inhibiting charge recombination. In addition, the heterojunction structure formed between TiO2 and g‐C3N4 materials also enhances the photocatalytic performance of the materials to some extent. After a simple optimization of the conditions, the Pd@g‐C3N4/TiO2 photocatalyst could promote the Suzuki–Miyaura CC coupling reactions under mild conditions (room temperature, 30 W LED lamp, λ = 455 nm), and good biaryl yields were obtained (optimum yield = 99%). It is very noteworthy that the photogenerated electrons and holes generated by the photoexcited catalyst were confirmed to be the main active species in the photocatalytic process of the catalyst by radical trapping assay and EPR test. The Pd@g‐C3N4/TiO2 material reported in this paper has excellent photocatalytic activity and stability in use, which provides a new reference scheme for wider green synthesis and catalysis.

Emergence of S-scheme-derived Ag decorated CuBi2O4/CNTs/(BiO)2CO3 photocatalyst with enhanced visible light photocatalytic performance

BackgroundDue to advantages like low cost, and high catalytic efficiency, photocatalysis has attracted more and more attention. The present investigation presents a straightforward and cost-effective hydrothermal method for producing Ag-decorated CuBi2O4/CNTs/(BiO)2CO3 composites with varying weight percentages of (BiO)2CO3. MethodsHerein, systematic investigations were conducted to examine the crystal, morphological, and optical properties of the photocatalysts. The investigation focused on evaluating the photocatalytic performance via visible light-assisted photodegradation of methyl orange (MO) and rhodamine B (RhB). Significant findingsFindings revealed that loading of (BiO)2CO3 efficiently improved the photoactivity of the composite. The Ag-CuBi2O4/CNTs/(BiO)2CO3 heterojunction photocatalyst with 15 % loading of (BiO)2CO3 has expressively enhanced photocatalytic performance, estimated around 97.79 % of RhB and 98.29 % of MO photo-degraded within 70 min in visible light irradiation, which was also found much enhanced than that of bare CuBi2O4 and (BiO)2CO3. Re-cyclic experiments indicated that fabricated semiconductor hybrid photo-catalyst own good photo-stability as well as reusability. The involvement of ∙O2- and ∙OH active radical species in the process of increased photo-degradation has been demonstrated using ESR and radical trapping tests. The description of the full photocatalytic mechanism based on the S-scheme was conducted by considering the estimated energy band locations, electron spin resonance (ESR) analysis and reactive oxygen species (ROS) trapping tests. This study presents a pragmatic methodology for the development of wide-bandgap bismuth-derived semiconductors that exhibit effective photo-degradation for environmental remediation.

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.