Peroxymonosulfate Research Articles

Enhancing colorimetric efficiency: nanozyme-activated peroxymonosulfate for in situ 3-aminophenol detection.

Anovel colorimetric approach specifically designed to effectively identify the presence of 3-aminophenol (3-AP) in environmental water isintroduced. Briefly, a nitrogen-doped carbon-supported cobalt nanozyme (Co@CN-1) was synthesized and utilized to improve the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of peroxymonosulfate (PMS). Comparative catalytic reactions confirmed that the performance of PMS as an activator exceeds that of hydrogen peroxide catalytically by a factor of 3.5. The catalytic reaction parameters underwent optimization, further resulting in the derivation of a linear detection equation for 3-AP, expressed as inhibition rate (IR%) = 3.35[3-AP]-4.36 (0-20μM, R2 = 0.994) and IR% = 1.43[3-AP] + 31.87 (20-36μM, R2 = 0.992), with the limit of detection (LOD) of 2.84μM. The linear relationship between 3-AP concentration and the conversion of color to grayscale value (GSV) was established by smartphones, expressed as GSV = 1.28[3-AP] + 147.10 (R2 = 0.972). Density functional theory calculations revealed that Co acts as the preferred active site for donating electrons in PMS activation. This work provides a rapid and accurate approach for monitoring 3-AP concentration, enabling real-time analysis and potentially contributing to environmental and ecological studies.

Impact of metal ions on PMS/Cl− disinfection efficacy: Enhancing or impeding microbial inactivation?

Peroxymonosulfate (PMS) is an eco-friendly disinfectant gaining attention. This study examined the influence of metal ions (Co(II), Cu(II), Fe(II)) on PMS disinfection with chloride ions (Cl−) against waterborne microorganisms, encompassing both bacteria and fungal spores. The findings elucidated that metal ions augment the inactivation of bacteria in the PMS/Cl− system while concurrently impeding the inactivation of fungal spores. Specifically, the PMS/Co(II)/Cl− process increased E. coli inactivation rates by 2.25 and 2.75 times compared to PMS/Co(II) and PMS/Cl−, respectively. Conversely, PMS/Me(II)/Cl− generally exhibited a diminished inactivation capacity against the three fungal spores compared to PMS/Cl−, albeit surpassing the efficacy of PMS/Me(II). For instance, the inactivation levels of A. niger by PMS/Cl−, PMS/Cu(II)/Cl−, and PMS/Cu(II) are 4.47-log, 1.92-log, and 0.11-log, respectively. Notably, fungal spores demonstrated a substantially higher resistance to disinfectants compared to bacteria. Differences in microbial susceptibility were linked to cell wall structure, composition, antioxidant defenses, and reactive species generation, such as hydroxyl radicals (•OH), sulfate radicals (SO4•−), and reactive chlorine species (RCS). This study demonstrated the novel and unique phenomenon of metal ions' dual role in modulating the PMS/Cl− disinfection process, which has not been reported before and has important implications for the field of water treatment.

Organically coordinated Cu(II) activated peroxymonosulfate for enhanced degradation of emerging contaminants

Copper ion Cu(II) is generally considered ineffective in activating peroxymonosulfate (PMS). However, our study demonstrates that organically coordinated Cu(II), namely, org-Cu(II) with contaminants such as amoxicillin (AMO), ofloxacin (OFX), sulfadiazine (SDZ), and tetracycline (TET) can efficiently activate PMS under neutral conditions, leading to faster degradation of these emerging contaminants. In contrast, organic contaminants that do not coordinate with Cu(II) do not facilitate PMS activation. Unlike traditional PMS-induced advanced oxidation processes (AOPs), our study identifies trivalent Cu(III) as the primary oxidant intermediate, with monovalent Cu(I) serving as its precursor. In addition, basic conditions was found to be beneficial for the degradation of target pollutants in org-Cu(II)/PMS systems. Moreover, this promotion effect extends to realistic wastewater, suggesting promising application prospects. The potential mechanism of the rate-limiting reduction step from Cu(II) to Cu(I) was further investigated. The interaction strength between the lowest unoccupied molecular orbital (LUMO) of the copper complex formed with organic compounds and the highest occupied molecular orbital (HOMO) of PMS influences the energy of the bonding orbitals. Coordination with organic ligands alters the LUMO of Cu(II), facilitating electron transfer from the HOMO of PMS to copper. This process activates PMS, ultimately leading to the production of Cu(I) and Cu(III). These findings deepen our understanding of PMS-induced AOPs for degrading emerging contaminants and underscore the importance of further research into PMS activation by Org-Cu(II).

Degradation of tetracycline hydrochloride through g-C3N4/TiO2 nanotube arrays for photoelectrocatalytic activation of PMS system: Performance and mechanistic analysis

To enhance the pollutant degradation ability of TiO2 nanotube arrays (TNAs) in a photoelectrocatalytic system (PEC), g-C3N4/TNAs photoanode was synthesized using anodic oxidation-slow evaporation method. Then, peroxymonosulfate (PMS) was incorporated and the resulting PEC-PMS system was applied to degrade tetracycline hydrochloride (TCH). The results from SEM, XRD and UV–vis DRS analyses indicated that g-C3N4 was successfully loaded onto the surface of TNAs, reducing the forbidden bandwidth from 3.10 eV to 2.89 eV. I-t and EIS curves demonstrated that the loading of g-C3N4 increased the electron transfer rate of TNAs. The photoanode prepared with a g-C3N4 solution (concentration of 100 mg L−1) exhibited the best degradation performance for TCH. The degradation rate of TCH by the PEC-PMS system reached 95.69 % at a TCH concentration of 10 mg L−1, pH of 9, PMS dosage of 2 mM, and voltage of 2 V, significantly higher than that of the PEC system without PMS (35.14 %). The contribution of active radicals to the system was in the order of SO4·- > h+ > ·O2- > ·OH. Three possible pathways for TCH degradation were proposed based on the experimental results. In conclusion, this work provides a theoretical basis for the preparation of photoelectrodes responsive to visible light and their application in the degradation of pollutants by the PEC-PMS system.

Upcycling polystyrene microplastics to Fe/Mo-doped sponge-carbon: Mo5+ enhanced electron transfer for boosting Fenton-like performance

The rate-limiting steps of promoting the conversion of Fe3+ to Fe2+ in Fenton-like systems are crucial for achieving efficient degradation of organic contaminants in aquatic environments. Herein, a novel magnetic Fe/Mo bimetallic doped sponge carbon (Fe/Mo-N-C) derived from polystyrene microplastics was successfully synthesized and the presence of metastable Mo5+ remarkably synergized the electron transfer of Fe2+ in internal microenvironment. In the Fe/Mo-N-C activating peroxymonosulfate (PMS) system, Mo5+ boosted the oxidation of Fe2+, and the conversion of Mo4+/Mo6+ accelerated the restoration of Fe2+ from Fe3+, resulting in nearly 100 % of 17α-ethinylestradiol (EE2) degradation with the kinetic rate constant of 0.343 min−1, which was 8.1 times faster than that of Fe-N-C. Moreover, Fe/Mo-N-C possessed excellent resistance to interference from various coexisting anions (especially chloride, sulfate, and nitrate ions up to 500 mM), natural organic matter, nano-plastics, and different water matrices. Density functional theory analysis demonstrated that Mo centers regulated the electron rearrangement of the Fe 3d orbital, enhancing the activation performance of Fe/Mo-N-C towards PMS. This study lays the groundwork for understanding the mechanism of metastable Mo, which holds significant importance for the up-recycling of polyethylene plastics and environmental remediation.

Preparation of Fe-doped coffee ground biochar and activation of PMS for chloroquine phosphate removal

Iron-doped biochar catalyst (Fe-CGB) was synthesized by embedding rust into coffee grounds using a high-temperature water bath. Fe-CGB was then used with activated peroxymonosulfate (PMS) to treat chloroquine phosphate (CQP) contaminated wastewater. The presence of biochar facilitates the cycling between Fe(III) and Fe(II) species, thereby augmenting the activation efficacy of PMS. The Fe-CGB/PMS system demonstrated exceptional catalytic degradation efficacy, achieving complete removal of CQP within a mere 30 min, with a reaction rate constant of 0.1501 min−1, surpassing the unmodified coffee grounds biochar by a factor of 47. Notably, under extreme pH conditions and in the presence of complex inorganic ions, CQP was entirely eliminated within 60 min. Mechanistic investigations revealed that biochar-mediated promotion of the Fe(III)/Fe(II) cycle amplifies the activation efficiency of PMS, leading to the generation of abundant sulfate radicals (SO4·−) and hydroxyl radicals (·OH), which facilitate pollutant decomposition. Furthermore, Fe-CGB exhibited notable stability across multiple cycles, with minimal iron ion leaching and facile separation from the solution. Subsequently, the degradation effects of 18 organic pollutants were evaluated, and their potential as effective treatment methods for multiple pollution scenarios were explored in combination with theoretical calculations. Overall,this study provides insights into PMS activation as well as waste management.

Oxyanion-Sensitive Catalytic Activity of Ni(II)/Oxyanion Systems for Heterogeneous Organic Degradation: Differential Oxidizing Capacity of Ni(III) and Ni(IV) as High-Valent Intermediates.

This study demonstrated that NiO and Ni(OH)2 as Ni(II) catalysts exhibited significant activity for organic oxidation in the presence of various oxyanions, such as hypochlorous acid (HOCl), peroxymonosulfate (PMS), and peroxydisulfate (PDS), which markedly contrasted with Co-based counterparts exclusively activating PMS to yield sulfate radicals. The oxidizing capacity of the Ni catalyst/oxyanion varied depending on the oxyanion type. Ni catalyst/PMS (or HOCl) degraded a broad spectrum of organics, whereas PDS enabled selective phenol oxidation. This stemmed from the differential reactivity of two high-valent Ni intermediates, Ni(III) and Ni(IV). A high similarity with Ni(III)OOH in a substrate-specific reactivity indicated the role of Ni(III) as the primary oxidant of Ni-activated PDS. With the minor progress of redox reactions with radical probes and multiple spectroscopic evidence on moderate Ni(III) accumulation, the significant elimination of non-phenolic contaminants by NiOOH/PMS (or HOCl) suggested the involvement of Ni(IV) in the substrate-insensitive treatment capability of Ni catalyst/PMS (or HOCl). Since the electron-transfer oxidation of organics by high-valent Ni species involved Ni(II) regeneration, the loss of the treatment efficiency of Ni/oxyanion was marginal over multiple catalytic cycles.

Iron and nitrogen co-doped carbon catalysts derived from ZIF-8 towards enhanced peroxymonosulfate activation and contaminants removal: The synergistic effects of FeNx and α/γ-Fe species

The performance upgrading of iron and nitrogen co-doped carbon (Fe-N-C) for peroxymonosulfate (PMS) activation towards contaminants removal and elucidation of the activation mechanism still remains a challenge. In this study, novel iron and nitrogen co-doped carbon (Fe-N-C) catalysts are fabricated through pyrolysis of Fe-modified zeolitic imidazolate framework-8 (ZIF-8) nanocrystals. Catalytic experiments prove that synergistic effects of FeNx and α/γ-Fe species can boost peroxymonosulfate activation and pollutants degradation. Density functional theory simulations disclose that α/γ-Fe species can optimize the d-band center of FeNx and adsorption energy for PMS activation, and thus achieve the enhanced catalytic activities for degradation process. Mechanism studies testify that Fe-N-C-PMS* complex and 1O2 are main contributors for the catalytic process. This work paves a new way for elaborate design of high-performance Fe-N-C materials and understanding about the non-radical mechanism during environmental applications.

Synergistic Coordination in Cu Single-Atom Catalysts Enhances High-Valent Copper-Oxo Species for Efficient PMS Activation.

In the domain of heterogeneous catalytic activation of peroxymonosulfate (PMS), high-valent metal-oxo (HVMO) species are widely recognized as potent oxidants for the abatement of organic pollutants. However, the generation selectivity and efficiency of HVMO are often constrained by stringent requirements for catalyst adsorption sites and electron transfer efficiency. In this study, a single-atom catalyst, CuSA/CNP&S, is synthesized featuring multiple types (planar/axial) of heteroatom coordination via an H-bond-assisted self-assembly strategy. It isconfirmed that CuN3 active centers with axial S coordination are uniformly distributed in a carbon matrix modified by planar P atoms. CuSA/CNP&S activated PMS to selectively generate Cu(III)═OH species as the primary reactive oxygen species (ROS). The pseudo-first-order kinetic rate for bisphenol A degradation reached 1.51min-1, a 17.57-fold increase compared to the unmodified CuSA/CN catalyst. Additionally, the CuSA/CNP&S catalyst demonstrates high efficiency and durability in removing contaminants from various aqueous matrices. Theoretical calculations and experimental results indicate that the intrinsic electric field generated by distal planar P atoms enhances electron transfer efficiency within the carbon matrix. Meanwhile, axial S coordination elevates the d-band center and tunes the eg * band broadening of Cu, thereby enhancing the adsorption selectivity for the terminal oxygen of PMS. This multitype coordination synergistically mitigates the issues of low selectivity and yield of HVMO species.

Decomposition of tetracycline with peroxymonosulfate activated by an ordered hierarchical pores Fe-N/C catalyst rich in FeNx sites: Insights into singlet oxygen mechanism

FeNx sites show significant superiority in the degradation of antibiotic contaminants, but there are difficulties in successfully constructing highly dispersed FeNx sites. In this work, Fe-N/C catalysts doped with hierarchical ordered pores structure and FeNx active sites were prepared by metal node exchange strategy. Among them, Fe-N/C-2 had more excite species for peroxymonosulfate (PMS) owing to the synergy between Fe and N coordination, which achieved 89.36 % tetracycline (TC) removal rate within 20 min, and its reaction kinetic (k = 0.245 min−1) is 7.66 times more than original PMS system. Moreover, the material exhibited excellent activation performance in a variety of complex water environments, such as the coexistence of multiple anions, strong acids and alkalis (pH = 2.90 ∼ 10.73), and natural organic matter interference. Chemical bond detection confirmed the successful formation of FeNx sites, free radical trapping experiments showed that FeNx was the main catalytic site, and 1O2 was the main active component. Furthermore, the reaction principle of the FeNx site catalyzing the production of 1O2 from PMS was revealed in detail through mechanism exploration. Next, the probable pathways of TC decomposition were elaborated in terms of the intermediates identified by Liquid Chromatograph Mass Spectrometer (LC-MS). This study emphasized the significant potential of synthesizing Fe-N/C catalysts with activated FeNx sites, elucidated mechanism of FeNx in PMS activation, and confirmed its feasibility in TC degradation.

In-situ manganese-aluminum-iron biochar derived from waste flocs for enhanced peroxymonosulfate oxidation: Role of Fe/Mn drives active species based on aluminum adsorption and synergistic promoted electron transfer

Conventional coagulation or enhanced coagulation water treatment produced mass floc sludge, which contained plenty of metals and organic matter. Floc sludge disposal and resource recycling was vital relevance and urgently needed. Here, we reported on the waste flocs recycling through in-situ manganese-aluminum-iron biochar (MAFBC) synthesized via one-step pyrolysis using potassium permanganate (KMnO4) oxidation- aluminum-iron composite flocculant coagulation for humic acid removal floc sludge as raw material. Compared with ex-situ loaded or similar types of biochar, MAFBC showed faster and efficient activation effect of peroxymonosulfate (PMS) to degrade tetracycline (TC). TC was rapidly removed within 1 min in MAFBC/PMS system with degradation rate constant Kobs was 1.825 min−1, which mainly attributed to the multiple promoting effects of manganese-aluminum-iron. Aluminum oxides facilitated TC adsorption and synergistic Fe/Mn further significantly promoted electron transfer on the surface of the MAFBC. Additionally, bimetallic structure of Fe/Mn and the CO functional group on MAFBC accelerated the formation of reactive species. The redox cycles of Fe2+/Fe3+ and Mn2+/Mn3+/Mn4+ promoted the formation of free radicals OH and SO4−. Moreover, O2– and 1O2 also assumed an important role for TC removal during active species evolution drived by Fe/Mn. This research provides a new perspective for in-situ design of economical and stable metal carbon-based water treatment activator, and make contributions to the utilization of waste flocs in water treatment.

Sonoelectrochemical degradation of aspirin in aquatic medium using ozone and peroxymonosulfate activated with FeS2 nanoparticles

The catalytic performance of nano-FeS2 in the sonoelectrochemical activation of peroxymonosulfate (PMS) and ozone to remove aspirin (ASP) was studied for the first time. The crystal structure and Fe bonds in the catalyst were confirmed through XRD and FTIR analysis. Within 30 min, ASP (TOC) was removed by 99.2 % (81.6 %) and 98.6 % (77.4 %) in nano-FeS2/PMS and nano-FeS2/O3 sonoelectrochemical systems, respectively. Water anions, especiallyHCO3− (almost 50 %), had an inhibitory effect on ASP removal. The probes confirmed that SO4•−and HO• were the key to ASP degradation in nano-FeS2/PMS and nano-FeS2/O3 systems, respectively. The effective activation of oxidants due to the ideal distribution of Fe2+ by catalyst was the main mechanism of ASP removal, in which electric current (EC) and ultrasound (US) played a crucial role through the recycling of Fe ions, dissolution and cleaning of the catalyst. LC-MS analysis identified thirteen byproducts in the ASP degradation pathways. The energy consumption of the proposed sonoelectrochemical systems was lower than previous similar systems. This study presented economic and sustainable hybrid systems for pharmaceutical wastewater remediation.

MXene-supported Co3Ti and single-atom Co catalyst activated PMS for efficient removal of Pb-EDTA: The involvement of Co (Ⅳ)

Activation of peroxymonosulfate (PMS) by MXene-supported Co3Ti and single-atom Co catalyst (Co@MXene) achieved the efficient decomplexation of lead-ethylenediaminetetraacetic acid (Pb-EDTA) and the recovery of lead (Pb) over the pH range of 3.0–9.0. The removal efficiency of Pb-EDTA reached up to 93.6 % within 30 min and total Pb was completely removed within 15 min. The coordination structure differences between Co3Ti and single-atom Co induced their various electron transfer pathways with PMS, in which Co3Ti brought key effect to the generation of Co (Ⅳ), while single-atom Co and regenerative Co (II) were responsible for the generation of HO and SO4−and 1O2, More importantly, the oxygen transfer reaction from O-Co3Ti to Co3Ti-O and the reducibility of MXene triggered the regeneration of low-valent Co. This study proposed a novel mechanism of Co (Ⅳ) generation and low-valent Co regeneration, which improved the understanding of the electron transfer pathways of Co@MXene/PMS oxidation process.

Support work-function dependent Fenton-like catalytic activity of Co single atoms for selective cobalt(IV)=O generation

In Fenton-like reactions, high-valent cobalt-oxo (CoIV=O) has attracted increasing interests due to high redox potential, long lifetime, and anti-interference properties, but its generation is hindered by the electron repulsion between the electron rich oxo- and cobalt centers. Here, we demonstrate CoIV=O generation from peroxymonosulfate (PMS) activation over cobalt single-atom catalysts (Co-SACs) using in-situ Co K-edge X-ray absorption spectra, and discern that CoIV=O generation is dependent on the support work-function (WF) due to the strong electronic metal-support interaction (EMSI). Supports with a high WF value like anatase-TiO2 facilitate the binding of PMS-terminal oxo-ligand to Co sites by extracting Co-d electrons, thus decreasing the generation barrier for the critical intermediate (Co-OOSO32−). The Co atoms anchored on anatase-TiO2 (Co-TiO2) exhibited enhanced CoIV=O generation and superior activity for sulfamethoxazole (SMX) degradation during PMS activation. The normalized steady-state concentration of CoIV=O in Co-TiO2/PMS system was three orders of magnitude higher than that of free radicals, and 1.3- to 11-fold higher than that generated in other Co-SACs/PMS systems. Co-TiO2/PMS sustained efficient removal of SMX with minimal Co2+ leaching under continuous flow operation, suggesting its attractive water purification potential. Overall, these results underscore the significance of support selection for enhanced generation of high-valent metal-oxo species and efficient PMS activation in supported metal SACs.

Accelerated Fe3+/Fe2+ cycle in Mo2C-based Fe catalyst to promote peroxymonosulfate activation

The harmful impact of organic pollutants on aquatic ecosystems underscores the pressing need for effective remediation. While activating peroxymonosulfate (PMS) with Fe catalyst offers a promising approach for eliminating these pollutants, its widespread use is hindered by the sluggish regeneration of Fe2+ from Fe3+. Here, this study demonstrates for the first time that combining an Fe catalyst with Mo2C (Fe-Mo2C) enhances the Fe³⁺/Fe2⁺ cycle, thereby improving PMS activation. The Fe-Mo2C/PMS system achieved near-complete degradation of carbamazepine (CBZ) within only 8 minutes, with an impressive observed rate constant (kobs) of up to 0.624 min-1, about 15 times greater than that of Fe-C catalyst. It also exhibits the capability to degrade a broad range of common antibiotics, phenols, and dye-like organic compounds. Through electron paramagnetic resonance (EPR) analysis and quenching experiments, it was verified that hydroxyl radicals (·OH), sulfate radicals (SO4·-), singlet oxygen (1O2), and superoxide radicals (·O2-) species during the reaction, with the former three serving as the primary active species. These findings offer a hopeful avenue for the systematic development and enhancement of catalysts specifically designed to efficiently remediate organic pollutants in wastewater.

A highly efficient Co-based catalyst for peroxymonosulfate activation for rapid degradation of RhB over a wide pH range

Cobalt-based materials have been demonstrated to be effective heterogeneous catalysts for peroxymonosulfate activation in degrading many refractory organic pollutants. In this study, a new cobalt-based catalyst was prepared using cobalt chloride hexahydrate (CoCl2·6H2O) as the Co2+ source, 2,3-pyrazine dicarboxylic acid and 3,6-DI-4-pyridyl-1,2,4,5-tetrazine (4-PYTZ) as ligands. This catalyst was employed as a peroxymonosulfate activator for the degradation of Rhodamine B(RhB). The results indicated that the prepared Co-based catalyst can effectively degrade RhB dye in aqueous solution by activating peroxymonosulfate (PMS). Specifically, when the initial concentration of RhB was 20 mg/L, its degradation rate exceeded 98 % within merely 9 min. The factors influencing the activation of PMS by the Co-based catalyst were examined, including PMS concentration, reaction temperature, solution pH, and the concentration of organic pollutants. Stability and reusability tests demonstrated that the prepared catalyst exhibited good stability, with the degradation rate of RhB remaining above 97 % after four repetitive experiments. Free radical quenching experiments and electron paramagnetic resonance (EPR) analyses revealed that sulfate radicals (SO4−) and hydroxyl radicals (OH) are the primary reactive radicals accountable for the degradation process. Additionally, it displayed excellent adaptability over a wide pH range, particularly within the pH levels ranging from 5 to 9. This study demonstrates that the prepared Co-based catalyst can serve as a stable and effective option for degrading organic dyes in wastewater treatment applications.

Utilizing MXene-mediated electron transfer pathway to boost peroxymonosulfate activation for water purification

Regulating the performance of manganese oxide catalysts to enhance peroxymonosulfate (PMS) activation for degrading emerging organic pollutants remains a significant challenge. To address this issue, Mn3O4/MXene composites with precisely controlled MXene contents are synthesized by combining hydrothermal and calcining methods, resulting in a significant regulate the pathway of Mn3O4 activation of PMS and a notable enhancement bisphenol A (BPA) degradation efficiency. The normalized first-order rate constant for optimized Mn3O4/MXene composites is 0.0218 g/(m2⋅min), which is 8.4 and 2.0 times higher than those of MXene and Mn3O4, respectively. Moreover, this catalyst exhibits excellent mineralization capacities, achieving up to 88.2 % total organic carbon removal efficiency. Combining with electrochemical and electron paramagnetic resonance analysis, the mechanism of electron transfer processes in this composite is elucidated comprehensively. Moreover, Mn3O4/MXene displays remarkable efficiency in degrading refractory pollutants, including antibiotics, phenols, and dyes. Furthermore, Mn3O4/MXene composites exhibit superior stability, reusability, and resistance to interference, highlighting their versatility in diverse environmental contexts. Notably, the catalyst maintains stable catalytic activity for long-term pollutant removal in a continuous-flow system. This study presents a novel approach for developing composite catalysts, providing new avenues for the treatment of emerging pollutants in wastewater.

Singlet oxygen dominant-activation by hollow structural cobalt-based MOF/peroxymonosulfate system for micropollutant removal

Despite the keen interest in potentially using the metal-organic framework (MOF) in advanced oxidation processes (AOPs), their application for environmental abatement and the corresponding degradation mechanisms have remained largely elusive. This study explores the use of cobalt-based MOF (CoMOF) for peroxymonosulfate (PMS) activation to remove tetracycline (TC) from water resources. Under optimal conditions, the given catalytic system could achieve a TC removal of 83.3%. Radical quenching tests and EPR analysis revealed that SO4•–, HO•, •O2−, and 1O2 could participate in the catalytic degradation, but the discernible removal mechanism was mainly ascribed to the nonradical pathway induced by 1O2. At only 5 mg/L of CoMOF, the performance of the catalytic system was superior to that of PMS alone for different types of micropollutants. The CoMOF/PMS system could also reliably deal with typical anions in water, such as Cl−, SO42−, HCO3−, and PO43−. The MOF catalyst could last for four cycles with a minor decrease in reactivity of ∼30%. However, the removal performance decreased markedly when aromatic natural organic matter (NOM) were present in the water bodies, and the effectiveness was lower in alkaline or acidic environments. Our work offers insights into the catalytic degradation of CoMOF/PMS applied in contaminated water remediation and serves as a baseline for fabricating an efficient MOF with enhanced catalytic performance and stability.

Activation of Peroxymonosulfate using a novel heterogeneous catalyst SO-gCN@ZIF-67 for excellent degradation of Brilliant Green dye

This work presents a design of a novel heterogeneous catalyst, SO-gCN@ZIF-67, comprising Co-based MOF, ZIF-67, over a two-dimensional S and O co-doped graphitic carbon nitride nanosheet is reported. This novel heterogeneous SO-gCN@ZIF-67 catalyst is used to degrade organic polluting dyes by activating Peroxymonosulfate (PMS) at room temperature. Various analytical and spectroscopic techniques, such as PXRD, FT-IR, FE-SEM, EDS, HR-TEM, XPS, and UV-DRS, were employed to characterize the as-synthesized nano-catalyst. The as-prepared catalyst can activate PMS effectively to rapidly decolorize the Brilliant Green dye (BG dye) solution at room temperature. The catalyst SO-gCN@ZIF-67 showed high efficiency for PMS activation and decolorization of approximately 96.7 % BG dye with a catalyst concentration of 80.0 mg/L, which was achieved in 15 min. The degradation of the dye obeyed pseudo-first-order kinetics with a reaction rate constant of 0.2262 min−1. Further, the parameters that could influence the activation of PMS, such as the role of different catalysts, catalyst dosage, PMS dosage, and initial dye concentration, were also investigated. Radical trapping experiments revealed that O2− radicals and non-radical singlet oxygen, 1O2, were involved in the degradation of BG dye. A plausible mechanism for the degradation has been proposed using SO-gCN@ZIF-67 and the PMS system.

Interfacial photothermal-enhanced FeCo@BC nanocomposites activating peroxymonosulfate for efficient tetracycline degradation

This study explores leveraging the exceptional photothermal properties of carbon-based catalysts for enhanced tetracycline degradation via PMS activation. To minimize the impact of the high heat capacity of bulk water, we engineered a siphon-driven interfacial reactor that utilizes the photothermal effect to significantly enhance the efficiency of PMS activation. The increased temperature accelerates catalytic reactions, enabling the effective activation of peroxymonosulfate (PMS) to degrade pollutants through this thermal advantage. The photothermal-enhanced FeCo@BC demonstrates nearly 100% degradation efficiency of tetracycline within 15 min in differential batch mode. Further investigations, including quenching experiments and electron paramagnetic resonance tests, confirm that singlet oxygen (1O2) is the principal active species in the FeCo@BC/PMS system. This system also benefits from oxygen vacancies (Ov) that improve the adsorption and binding of PMS on FeCo@BC surfaces, aiding in the conversion of PMS into 1O2 and other radicals. In continuous operation mode, the interface photothermal reactor (IPR) achieved continuous tetracycline degradation, maintaining over 94% activity for 60 min.