Peroxymonosulfate Research Articles

Efficient ofloxacin degradation via peroxymonosulfate activation using an S-scheme MoS2/Co3O4 heterojunction composite under visible light: Performance and mechanistic insights

Sulfate-radical-mediated photocatalysis technology peroxymonosulfate (PMS) activation via visible light irradiation shows great promise for water treatment applications. However, its effectiveness largely depends on the bifunctional performance of photocatalysis and PMS activation provided by the catalysts. In this study, we successfully synthesized a novel S-scheme MoS2/Co3O4 (MC) heterojunction composite by a hydrothermal method and employed it for the first time to activate PMS for ofloxacin (OFX) degradation under visible light irradiation. The MC-5/PMS/Vis system achieved an impressive 85.11% OFX degradation efficiency within 1 min and complete OFX removal within 15 min under optimal conditions, with an apparent first-order kinetics rate constant of 0.429 min−1. Reactive species trapping experiments and electron spin resonance analysis identified 1O2, h+, and •O2− as the primary active species responsible for OFX degradation. Photoelectrochemical analyses and density functional theory calculations indicated the formation of a built-in electric field between MoS2 and Co3O4, which enhanced the separation and migration of photoinduced carriers. Additionally, the Co–Mo interaction further increased the yield of dominant reactive species, thereby boosting photocatalytic activity. This work underscores the potential of visible-light-assisted PMS-mediated photocatalysis using Co3O4-based catalysts for effective pollutant control.

Heterogeneous degradation of chloramphenicol antibiotic by peroxymonosulfate activated by FeS and FeS2: Mechanism and effects of catalysts dosage and pH

Antibiotics in the environmental waters pose long-term threat to ecological safety because of their persistent and potential toxic nature. FeS and FeS2 were proved to be efficient catalysts for the activation of peroxymonosulfate (PMS) and the generation of sulfate radical generation for refractory pollutant degradation. However, their performance for antibiotic degradation has not yet been comparatively and comprehensively investigated. Herein, the FeS/PMS and FeS2/PMS systems were developed to explore chloramphenicol (CAP) degradation under equal conditions. The results show that CAP was efficiently degraded in both two systems, with a removal efficiency exceeding 90 % within 120 min using 6 mM PMS and 0.6 g/L catalysts.Acceleration in degradation rate was observed in the FeS2/PMS system when the catalyst dosage ranged from 0.1 g/L to 1.0 g/L (constant PMS concentration) with a reaction rate constant (kobs) of 2.1-fold higher than that in the FeS/PMS system. However, the kobs were comparable with the PMS concentration range (constant catalyst dosage) in the two systems, suggesting that the catalysts were the rate-limiting step in CAP degradation process. The initial pH strongly affected CAP degradation in the FeS/PMS system but had little effect on that in the FeS2/PMS system. Surface Fe2+ played a dominant role in PMS activation, and S22−/S2− facilitated Fe2+ regeneration. Further, both FeS and FeS2 had stable activity for PMS activation during long-term use. This study proves the effectiveness of FeS and FeS2 for PMS activation for antibiotic degradation and differentiates their catalytic qualities, which will provide alternative heterogeneous catalysts for practical application.

The surface functional groups-driven fast and catalytic degradation of naproxen on sludge biochar enhanced by citric acid

In this work, a sludge biochar (CA-SBC-300) with efficient activation of peroxymonosulfate (PMS) was prepared by citric acid modification. CA-SBC-300 achieved efficient degradation of naproxen (NPX) (95.5%) within 10 min by activating PMS. This system was highly resilient to common disruptive factors such as inorganic anions, humic acid (HA) and solution pH. The results of XPS and Raman showed that the content of oxygenated functional groups (OFGs) and the degree of defects on the sludge biochar increased after citric acid modification, which may be an important reason for the enhanced catalytic performance of SBC. In the CA-SBC-300/PMS system, 1O2 and O2•− made the main contributions to the degradation of NPX. XPS analysis and DFT calculations demonstrated that C=O/C−O and pyridine N on CA-SBC-300 were the crucial active sites for PMS activation. According to the results of UPLC-MS analysis, three possible pathways for NPX degradation were inferred. This study provided a feasible strategy for sludge resource utilization combined with efficient catalytic degradation of toxic organic contaminants in wastewater.

Photo-assisted oxygen-rich vacancy copper oxide catalyst to activate peroxymonosulfate (PMS) for efficient degradation of fulvic acid

In this study, novel copper oxide particles-activated peroxymonosulfate (CuO-S/PMS/UV) were employed to degrade fulvic acid(FA). Under the optimal treatment condition, the FA removal of the CuO-S/PMS/UV process was up to 97.74%. The removal rates of SUVA254, UVA365 UVA280 UVA463 and TOC within 40 min in the UV/CuO-S/PMS process were 23.4%, 95.6%, 63.2%, 100% and 40.8% respectively. The three-dimensional fluorescence spectrum analysis of FA during the degradation process revealed the disappearance of FA-associated functional structures. Furthermore, the impact of common anions in the water matrix on the degradation process was investigated, demonstrating that the system remains effective containing low concentrations of anions. Subsequently, mechanism studying showed that SO4•−, 1O2, h+, and •OH species were primarily involved in the degradation of FA, while O2•− has a limited effect in the degradation process. This study can provide valuable insights for the degradation of humic pollutants in the water environment.

In situ anchoring of bimetal (Cu, Fe) sulfides featured by sulfur vacancy and phosphorus doping within porous carbon nanocubes derived from Prussian blue analogs to activate peroxymonosulfate for the efficient degradation of organic pollutants

In this work, Prussian blue analogues (CuFe-PBA) derived copper-iron sulfides/N-doped porous carbon composite (CuFe-NC-SP-x) was prepared as an effective peroxymonosulfate (PMS) activator to degrade sulfadiazine (SDZ). A strategy that kills two birds with one stone was proposed to construct CuFe-NC-SP-x, i.e., S-etched CuFe-PBA (CuFe-PBA-S) was annealed with NaH2PO2 in N2 atmosphere to simultaneously introduce sulfur vacancy (Sv) and phosphorus doping. 40 μM SDZ was completely removed by CuFe-NC-SP-2/PMS in 20 min (0.2 g/L catalyst and 0.5 mM PMS). The kobs value obtained by CuFe-NC-SP-2 (0.48 min−1) was nearly 33 and 17 times higher than that of CuFe-PBA (0.014 min−1) and CuFe-PBA-S (0.028 min−1), respectively. Quenching tests, electron paramagnetic resonance (EPR) analysis indicated that PMS activation in the system involved radical pathway (26.1 % OH and 22.7 % SO4–) and non-radical pathway (17.8 % 1O2 and 33.4 % electron transfer process). OH, SO4– and 1O2 were mainly produced by S enhanced metal sites for PMS activation. The synergistic effect of Sv and P doping enabled the powerful electron transfer mechanism. Electrochemical tests and DFT calculations demonstrated that Sv existing in CuFe-NC-SP-x improved the electron donor ability and increased the adsorption energy toward PMS, and phosphorus doping accelerated the electron transport from SDZ to PMS. This work not only provides a novel strategy to synthesize a high effective PMS activator by introducing Sv and phosphorous doing in one step, but also manages to comprehensively understand the electron transfer activation mechanisms of PMS facilitated by Sv and phosphorous doping.

Insights into the efficient removal and mechanism of NiFeAl-LDH with abundant hydroxyl to activate peroxymonosulfate for sulfamethoxazole wastewater

Layered double hydroxide (LDH) material with abundant OH was successfully prepared by co-precipitation method, and a water purification system of Ni2Fe0.25Al0.75-LDH activated peroxymonosulfate (PMS) was constructed to rapidly degrade sulfamethoxazole (SMX) pollutants. The optimal conditions for the degradation of SMX in the system were as follows: 0.30 g/L Ni2Fe0.25Al0.75-LDH, 0.30 mM PMS, pH = 7 and 90 % SMX was removed in 10 min and almost completely in 40 min, which was consistent with the predicted results of response surface methodology (RSM) analysis. The abundant OH in Ni2Fe0.25Al0.75-LDH could form M(O)OSO3 complexes with PMS, accelerating the generation of reactive oxygen species (ROS) and promoting the removal of SMX. Quenching experiments and electron paramagnetic resonance (EPR) spectra showed that SO4−, OH, O2− and 1O2 also existed in the system. The surface-bound SO4− and O2− contributed greatly to the removal of SMX and the electron transfer between metals was also conducive to the production of active substances. The possible degradation pathways and intermediates of SMX were proposed. The toxicity assessment software tool (T.E.S.T) and total organic carbon (TOC) results indicated that the Ni2Fe0.25Al0.75-LDH/PMS system could reduce the overall environmental risk of SMX to some extent. This study provided a new strategy for the practical application of heterogeneous catalysts in sewage treatment.

Unraveling the transition of ZIF-67-on-ZIF-8 core–shell structured dodecahedron formed by an oriented attachment mechanism from type II to step-scheme for enhanced photocatalytic degradation of oxytetracycline hydrochloride

A composite photocatalyst comprising ZIF-67 and ZIF-8 was synthesized using a hydrothermal method. The process entailed the crystallization of ZIF-67 on the ZIF-8 dodecahedron backbone, eschewing the utilization of ligands. The photocatalytic efficiency of the composite ZIF-67-on-ZIF-8 was evaluated through the degradation of oxytetracycline hydrochloride (OTC) under visible and UV light. The results indicated superior OTC degradation compared to pure ZIF-8 and ZIF-67, which might be attributed to the energy level and lattice alignment between ZIF-8 and ZIF-67. This facilitated the separation and transfer of photogenerated electron-hole pairs, thereby suppressing electron-hole complexation. The activation of ZIF-67-on-ZIF-8 with peroxymonosulfate (PMS) resulted in a further enhancement in the degradation efficiency of OTC under both visible and UV light conditions. The optimal effect was observed with the addition of 0.6 mmol of PMS, which resulted in a degradation rate of 95.7 % at 60 min under visible light and 97.01 % at 30 min under UV light. The acceleration of the degradation process and the reduction in the required time were the result of a change in configuration. The study’s originality led to the transformation of the conventional type II heterojunction model into the S-scheme heterojunction model through the modification of the light source, thereby offering a novel perspective for heterojunction design.

Enhanced peroxymonosulfate activation for emerging contaminant degradation via defect-engineered interfacial electric field in FeNC

Peroxymonosulfate (PMS) activation technology has important application value in treating emerging contaminant (ECs), but it still faces challenges in achieving efficient electron transfer and metal valence cycling. In this study, the interfacial electric field characteristics of FeNC catalysts were adjusted by introducing NC defects to affect the electron transfer process, thereby enhancing the catalytic performance of PMS. It is found that in the FeNC structure, the shift of the charge generates an interfacial electric field, which can promote the directional transfer of electrons. Through quantitative structure–activity relationship (QSAR) analysis, it was confirmed that the defect played a decisive role in regulating the interfacial electric field and improving the catalytic reaction efficiency. The interfacial electric field-mediated superexchange interaction realizes the electron donor effect of organic pollutants and the effective electron transfer between the Fe site, accelerates the electron cycling of the Fe site, and realizes the rapid and stable catalysis of PMS. The increase of the occupancy state distribution of d orbitals near the Fermi level provides favorable conditions for electron transitions and catalytic activation of PMS. ECs can be converted into environmentally friendly, non-toxic and harmless substances through. This defect-controlled interface electric field strategy realizes rapid electron directional transfer, which provides a new solution for improving the catalytic efficiency of PMS and the safe treatment of ECs in water.

Strategically engineered multifunctional graphene oxide hybrid nanomaterials for efficient catalytic degradation and emerging contaminants treatment

The use of functional textiles is growing in all fields of science and technology. Surface functionalization is mainly used to impart conventional textiles with new functionalities and improved performances. In the present study, a cobalt ferrite nanoparticle/graphene oxide (CoFe2O4/GO) coated polyethylene terephthalate (PET) fabric with excellent catalytic and antibacterial properties, has been successfully developed. The PET-coated CoFe2O4/GO samples, ranging from 1 % to 5 % wt. were obtained using a simple dip-coating method in CoFeO/GO solution (1 mg/mL), and were investigated through several physiochemical characterization techniques. CoFe2O4/GO and PET fabric have been shown to establish an interfacial connection by Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) results showed that CoFe2O4/GO coating did not affect the PET crystallinity and that CoFe2O4/GO hybrid was incorporated in the PET samples, which was proved as well by the morphological study through Scanning electron microscopy (SEM). Furthermore, thermogravimetric characterisation (TGA) verified that the coating does not change or impair the quality of the fibre and that the PET@CoFe2O4/GO as made is thermally stable. Tensile strength tests demonstrated that coated fabrics exhibited outstanding mechanical properties in comparison with pristine PET. Moreover, the coated PET@CoFe2O4/GO fabric was used as a model catalytic system for peroxymonosulfate (PMS) activation in the rhodamine B (RhB) degradation reaction. Total Organic Carbon (TOC) measurements showed that TOC removal reached 89.82 % in only 12 min reaction. The results confirmed that the coated fabrics exhibited high catalytic performances, good stability and reusability in consecutive degradation experiments with a degradation rate over 60 % even after 7 degradation cycles; Moreover, it is easily and simply separated from the mixture, by removing the textile sample from the aqueous solution. It is worth mentioning that the PET@CoFe2O4/GO fabrics showed outstanding antibacterial activity against both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria with an inhibition diameter zone of up to 13 mm for PET@CoFe2O4/GO (5 %). Overall, these findings are of great importance as they permit the development of a novel multifunctional textile fabric, combining anti-bacterial activity, catalytic performance and mechanical properties. The study provides a textile-based catalyst with improved catalytic performance, re-usability in consecutive degradation reactions and easy catalyst separation compared to traditional supports. Thus, a huge potential application in several fields such as medicine, heterogeneous catalysis, and wastewater treatment.

High Efficiency Removal Performance of Tetracycline by Magnetic CoFe2O4/NaBiO3 Photocatalytic Synergistic Persulfate Technology.

The widespread environmental contamination resulting from the misuse of tetracycline antibiotics (TCs) has garnered significant attention and study by scholars. Photocatalytic technology is one of the environmentally friendly advanced oxidation processes (AOPs) that can effectively solve the problem of residue of TCs in the water environment. This study involved the synthesis of the heterogeneous magnetic photocatalytic material of CoFe2O4/NaBiO3 via the solvothermal method, and it was characterized using different characterization techniques. Then, the photocatalytic system under visible light (Vis) was coupled with peroxymonosulfate (PMS) to explore the performance and mechanism of degradation of tetracycline hydrochloride (TCH) in the wastewater. The characterization results revealed that CoFe2O4/NaBiO3 effectively alleviated the agglomeration phenomenon of CoFe2O4 particles, increased the specific surface area, effectively narrowed the band gap, expanded the visible light absorption spectrum, and inhibited recombination of photogenerated electron-hole pairs. In the Vis+CoFe2O4/NaBiO3+PMS system, CoFe2O4/NaBiO3 effectively activated PMS to produce hydroxyl radicals (·OH) and sulfate radicals (SO4-). Under the conditions of a TCH concentration of 10 mg/L-1, a catalyst concentration of 1 g/L-1 and a PMS concentration of 100 mg/L-1, the degradation efficiency of TCH reached 94% after 100 min illumination. The degradation of TCH was enhanced with the increase in the CoFe2O4/NaBiO3 and PMS dosage. The solution pH and organic matter had a significant impact on TCH degradation. Notably, the TCH degradation efficiency decreased inversely with increasing values of these parameters. The quenching experiments indicated that the free radicals contributing to the Vis+CoFe2O4/NaBiO3+PMS system were ·OH followed by SO4-, hole (h+), and the superoxide radical (O2-). The main mechanism of PMS was based on the cycle of Co3+ and Co2+, as well as Fe3+ and Fe2+. The cyclic tests and characterization by XRD and FT-IR revealed that CoFe2O4/NaBiO3 had good degradation stability. The experimental findings can serve as a reference for the complete removal of antibiotics from wastewater.

Deciphering iopamidol transformation during the joint disinfection of monochloramine and peroxymonosulfate: A base-catalyzed mutual activation

The joint disinfection of monochloramine (MCA) and peroxymonosulfate (PMS) can combine the advantages of both sides; and the iodine-containing micropollutants are widely present in drinking water. For the first time, the conversion of iopamidol (IPM) was investigated in the MCA/PMS system. For IPM degradation, the observed pseudo-first-order rate constant (kobs) was 0.0076 min−1, and the apparent rate constant (kapp) was 6.14 × 10−7 μM−2.16 min−1. The reaction orders for MCA (m) and PMS (n) were fitted to be 1.14 and 1.02, respectively. The mutual activation of MCA and PMS was a base-catalyzed reaction, which was highly exothermic and thermodynamically favored with a free energy of − 78.74 kcal/mol. It is believed that Cl• and 1O2 contributed to IPM degradation. The kobs value was increased by an alkaline pH and the presence of Cl−, while reduced by the existence of NOM, HCO3− and NH4+. The N in MCA was converted to NH4+-N, NO2−-N and NO3−-N, and 47.0 % of I in IPM was converted to IO3−. In the MCA/PMS system, IPM transformation was mainly via amide hydrolysis, deiodination and substitution reaction by reactive species. The study provides an insight into the fate of iodine-containing micropollutants during the joint disinfection of MCA and PMS.

Boosting peroxymonosulfate activation via Fe–Cu bimetallic hollow nanoreactor derived from copper smelting slag for efficient degradation of organics: The dual role of Cu

Valorization of iron-rich metallurgical slags in the construction of Fenton-like catalysts has an appealing potential from the perspective of sustainable development. For the first time, copper smelting slag (CSS) was utilized as the precursor to synthesize hollow sea urchin-like Fe–Cu nanoreactors (Cu1.5Fe1Si) to activate peroxymonosulfate (PMS) for chlortetracycline hydrochloride (CTC) degradation. The hyper-channels and nano-sized cavities were formed in the catalysts owing to the induction and modification of Cu, not only promoting the in-situ growth of silicates and the formation of cavities due to the etching of SiO2 microspheres, but also resulting the generation of nanotubes through the distortion and rotation of the nanosheets. It was found that 100 % CTC degradation rate can be achieved within 10 min for Cu1.5Fe1Si, 75 times higher than that of Cu0Fe1Si (0.0024 up to 0.18 M−1‧min−1). The unique nanoconfined microenvironment structure could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of active species. Density functional theory (DFT) calculations show that Cu1.5Fe1Si has strong adsorption energy and excellent electron transport capacity for PMS, and Fe-Fe sites are mainly responsible for the activation of PMS, while Cu assists in accelerating the Fe(II)/Fe(Ⅲ) cycle and promotes the catalytic efficiency. The excellent mineralization rate (83.32 % within 10 min) and efficient treatment of CTC in consecutive trials corroborated the high activity and stability of the Cu1.5Fe1Si. This work provides a new idea for the rational design of solid waste-based eco-friendly functional materials, aiming at consolidating their practical application in advanced wastewater treatment.

Activation mechanism of CoFe2O4 nanocatalysts on different oxidants and degradation efficiency of butyl xanthate

Owing to the technological limitations associated with beneficiation technology, large amounts of flotation reagents remain in mineral processing wastewater, which is extremely detrimental to humans and the environment. In addition, direct reuse of mineral processing wastewater will adversely affect the entire mine water system. Efficient treatment of residual butyl xanthate from tailing wastewater has recently attracted increasing interest. In this study, we compared the degradation efficiencies of cobalt iron oxide (CoFe2O4) nanoparticles assisted by sulfite-activated advanced processes and persulfate (PDS) and peroxymonosulfate (PMS) advanced oxidation processes on butyl xanthate (BX) for the first time and explored possible reaction mechanisms in various systems. We conducted comprehensive experiments on the acid/alkali washed catalysts using oxidizing agents, obtaining catalysts best adapted to three degradation systems. Results of batch experiments indicated that the BX degradation rate for all the three systems exceeded 95 % within 60 min under their respective optimal conditions and that the best total organic carbon content (TOC) removal rate for these systems was 85.79 %. The effects of key factors, such as catalyst dosage, oxidant dosage, solution pH, and coexisting ions, on BX degradation were investigated. Furthermore, the active free radicals that played a major role in each system were detected via electron paramagnetic resonance (EPR). EPR results indicated that SO3·− and ·O2− were the main active species of the CoFe2O4/sodium sulfite system, ·OH and ·O2− participated in the degradation of BX in the CoFe2O4/PDS system, and ·O2− was present in the CoFe2O4/PMS system. Thus, this study promotes the application of CoFe2O4 with magnetism as a catalyst in wastewater treatment and provides new insights into the effective treatment of organic pollutants in tailing wastewater.

Integration of single-atom photothermal catalysts with surface-localized high temperature in peroxymonosulfate-based Fenton-like systems for enhanced antibiotics degradation

This study delves into integrating single-atom catalysts with photothermal effect in peroxymonosulfate (PMS)-based Fenton-like systems for enhanced pollutant degradation. A single-atom photothermal catalyst (Co/PMCNs) was designed using mesoporous carbon spheres as both a single-atom support and a photothermal material. Near-infrared (NIR) light was employed due to its superior thermal effect and penetration capacity in water. It was found that Co/PMCNs could generate surface-localized high temperatures for accelerating PMS activation and reducing energy gap of activation reactions, leading to improved degradation performance. Surface-localized high temperatures were demonstrated as key in distinguishing photothermal heating from external heat sources for PMS activation. Moreover, this system performed well across various operating conditions and water matrices, with Co/PMCNs showing promising recyclability. This study highlights the impact of surface-localized high temperatures on heterogeneous catalysis under NIR irradiation, and underscores the potential of integrating single-atom catalysts with photothermal effects into advanced oxidation processes for effective water pollution control.

Synergistic degradation of p-nitrophenol using peroxymonosulfate activated with a bimetallic Mn3O4–Cu2O catalyst: Investigation of strong interactions between metal oxides

The use of efficient, eco-friendly catalysts is essential for activating peroxymonosulfate (PMS) to degrade organic contaminants in aqueous media. In this study, we developed a novel approach to fabricating bimetallic MnCu catalysts (Mn:Cu molar ratios: 10:1, 5:1, 3:1, and 2:1) comprising tetragonal Mn3O4 and cubic Cu2O. MnCu-5:1 exhibited superior catalytic activity for the degradation of p-nitrophenol (PNP) using PMS because of the synergistic interplay between Mn and Cu. Experimental and density functional theory (DFT) calculation data revealed that the mixed valence states and strong interactions between Mn and Cu in the MnCu-5:1 system increased the electron transfer efficiency and promoted electron transfer to PMS. The results of quenching experiments elucidated a primary radical mechanism and minor nonradical pathway for the PNP degradation over the MnCu-5:1/PMS system. DFT calculations confirmed a relatively high adsorption energy of the Mn3O4–Cu2O (MnCu) composite, indicating enhanced catalytic performance. The superior reactivity of the composite was verified by analyzing its density of states and electrostatic difference potential. Our findings offer fresh perspectives for harnessing the synergistic potential of less toxic mixed metal oxides for controlling catalytic properties and help achieve a better understanding of the activation mechanism for contaminant degradation over MnCu catalysts.

Magnesium incorporation-mediated formation of oxygen vacancies in zinc ferrite for PMS activation toward effective photocatalytic 4-nitrophenol degradation

Developing highly effective heterogeneous photocatalysts for activating peroxymonosulfate (PMS) in the photodegradation of chemical effluents remains challenging. In this study, ZnFe2O4 (ZFO) nanoparticles (NPs) incorporated with different magnesium ratios were prepared using a cost-effective microwave process. The resulting Mgx:ZFO catalysts were characterized by several analysis techniques, and the effect of Mg incorporation on the photocatalytic 4-nitrophenol (4-NP) degradation was studied. The results revealed that incorporating Mg into the ZFO structure substantially improved the photocatalytic removal efficiency of 4-NP from 62 % to 89 %. Compared with pure ZFO, Mg:ZFO contained more surface oxygen vacancies (SOVs), which can facilitate the generation and transfer of photocarriers, promote PMS activation, and improve photocatalytic performance. The ZFO catalysts exhibited larger surface areas after Mg incorporation, which provided more active sites for 4-NP removal. Finally, the bandgap energy of ZFO was widened from ∼ 1.67 eV to ∼ 1.80 eV after Mg incorporation, which could reduce photocarrier recombination and result in higher photocatalytic removal efficiency.

Advanced activation of peroxymonosulfate by NiFe-LDH/CeO2 heterostructure photocatalysts toward medical wastewater remediation

The great harm of antibiotic residues in medical wastewater to the ecological environment and human health has become the focus of social attention. Herein, we designed a new peroxymonosulfate (PMS) activation system by in-situ anchoring NiFe-LDH nanosheets into CeO2 (NFC) as a heterogeneous photocatalyst to degrade pollutants. The NFC/PMS/Vis system showed excellent and rapid degradation effect on tetracycline (TC) under the synergistic effect of photocatalysis and PMS activation, and the removal rate of TC was about 98.8 % within 40 min. The chemical compositions, microstructures, and optical properties of synthesized photocatalysts were studied by a series of characterization methods such as XRD, XPS, SEM, TEM and UV-DRS. The effects of various reaction systems and operating parameters such as initial concentration, catalyst dosage, and PMS concentration on the degradation efficiency of TC over optimized NFC-4 composite were investigated. The active species in the reaction system and the dominant SO4− were confirmed by quenching tests and electron paramagnetic resonance (EPR) measurements, and a plausible photocatalytic mechanism for PMS activation and pollutant remediation was further proposed.

Activation of Peroxymonosulfate by Fe, O Co-Embedded Biochar for the Degradation of Tetracycline: Performance and Mechanisms

In recent years, pollution stemming from pharmaceuticals has garnered widespread global concern, which exacerbates the ecological risk to both surface and groundwater. In the current study, Fe and O co-embedded biochar (Fe-O-BC) was synthesized through a one-step pyrolysis procedure with corncob serving as the feedstock. The fabricated Fe-O-BC catalysts were characterized by various techniques and were employed for the activation of peroxymonosulfate (PMS) to degrade tetracycline (TC). TC was rapidly degraded within 40 min, with a degradation rate of 0.1225 min−1, which was much higher than those for O-BC/PMS (0.0228 min−1) and Fe-BC/PMS (0.0271 min−1) under the same conditions. The effects of PMS dosage, Fe-O-BC dose, initial pH value and coexisting anions for TC degradation were investigated. Finally, the mechanism of TC oxidation in the catalytic system was implored through experiments of determining the active sites and radical scavenging experiments. The C-O-Fe bond in the catalyst was confirmed to be the dominant active sites accelerating TC degradation. Free diffused HO•, the surface-bound HO• and SO4•− and O2•−participated in the reaction and absorbed SO4•−, and HO• predominantly contributed to TC degradation. This study provides an efficient and green alternative for pharmaceutical wastewater treatment by Fe and O co-doped catalyst-induced heterogeneous process.

Mechanistic Investigation of Rapid Catalytic Degradation of Acetaminophen Using Electrochemical-Induced CoFe2O4 by Activation of Peroxymonosulfate

Advanced oxidation technology based on PeroxyMonoSulfate (PMS) has become a research hotspot in the field of water treatment. To improve the activation efficiency of PMS, electrochemically assisted spinel type catalyst CoFe2O4 was used to activate PMS and achieve effective degradation of acetaminophen. The influence of single factor on degradation was explored to determine the best degradation process parameters of E/CoFe2O4/PMS system. Results show that under the optimum reaction conditions (DC voltage is 6[Formula: see text]V, the initial mass concentration of acetaminophen is 10[Formula: see text]mg[Formula: see text]L[Formula: see text], the dosage of CoFe2O4 is 0.3[Formula: see text]g[Formula: see text]L[Formula: see text], and the mass concentration of PMS is 1.5[Formula: see text]g[Formula: see text]L[Formula: see text]), the degradation rate of acetaminophen reaches up to 95% within 20[Formula: see text]min. CoFe2O4 catalyst showed a good stability, with only a 12% decrease in acetaminophen degradation after three cycles. Radical quenching tests show that [Formula: see text] and [Formula: see text] played predominant roles in the advanced oxidation process. This work provides a new strategy for more efficiency in PMS activation.

Peroxymonosulfate activated by CoMn@CNT nanocomposite for moxifloxacin degradation

As a fourth quinolone drug, the efficient and rapid degradation of moxifloxacin (MOX) remain a rigorous problem. Peroxymonosulfate (PMS)-based oxidation method poses a promising application prospect for refractory antibiotic wastewater with an excellent degradation efficiency. Herein, the Co/Mn doped-carbon nanotube catalyst (CoMn@CNT) was successfully synthesized by a two-step pyrolysis method and applied to activate PMS for MOX degradation. The degradation efficiency of MOX could reach 89.7 % in 30 min with relatively low concentrations of PMS (100 mg/L) and CoMn@CNT (30 mg/L). The effects of catalyst dosage, PMS dosage, initial pH, reaction temperature, and co-existing ions for the degradation of MOX were investigated. The CoMn@CNT/PMS system possessed wide pH application range (3.0–11.0). Sulfate radical (SO4−) was verified as the dominant reactive species responsible for degradation of MOX by quenching experiment. Finally, the possible MOX degradation pathways were also proposed. Overall, this study could provide some inspirations of the CoMn@CNT/PMS as a new system which applied to wastewater treatment of antibiotics.