Peroxymonosulfate System Research Articles

Catalytic micro-structured ceramic beads and efficacy evaluation through SMX degradation in PMS-activated systems

This study tackles the challenge of applying fine and nano-catalyst particles in Advanced Oxidation Processes (AOPs), primarily due to the complexities of nanoparticle removal from treated water to prevent secondary nano-hazards. We propose an innovative solution: micro-structured ceramic beads (MSCBs, approximately 3 mm in diameter) with a unique anisotropic pore structure. For the first time, we prepared MSCBs impregnated with cobalt oxide (Co/MSCBs) using a phase-inversion and sintering-assisted process. The Co/MSCBs were investigated for the degradation of sulfamethoxazole (SMX) in the peroxymonosulfate (PMS) induced AOPs system under mild reaction conditions. The effects of operating parameters (e.g., SMX concentration, reaction temperature, and catalyst dosage) in the Co/MSCBs|PMS system were studied on three different types of catalytic ceramic beads: 2Co/MSCB0 (beads with a common isotropic pore structure), 2Co/MSCB1 (beads with radial finger-like microstructures and a denser outer skin-layer), and 2Co/MSCB2 (beads with finger-like microstructures and no outer skin layer). At 20 °C, 2Co/MSCB2 (59.1 %) demonstrated a higher degradation efficiency for 40 mg/L SMX in comparison to 2Co/MSCB1 (54.9 %) and 2Co/MSCB0 (49.6 %). Additionally, it is noteworthy that the sample 2Co/MSCB2, after being used and regenerated, exhibited significantly a higher catalytic performance (70.83 % removal in 20 min during the 16th run) than the fresh one (70.47 % removal in 120 min). After reactions, Co/MSCBs can be readily separated from the bulk solution and used for the next run, making them ideal for practical applications. Furthermore, a radical quenching experiment was conducted, and a plausible catalytic mechanism was proposed. This research presents a new approach for the fabrication of micro-structured ceramic beads that are capable of effectively overcoming the diffusion limitations encountered in both heterogeneous reactions and adsorption processes.

Regulation of reactive oxygen species generation by graphitization and defect degree of Co-loaded carbon in peroxymonosulfate activation

The designing of functional groups and structured active sites is a vital strategy for efficient Peroxymonosulfate (PMS)-based advanced oxidation processes (PMS-AOPs). However, the regulation mechanism and correlation of graphitization/defect degree and reactive oxygen species (ROS) are still not fully understood for a composite catalyst. Herein, a family of metal–organic framework (MOF)-derived cobalt-nitrogen-carbon with different graphitization/defect degrees was designed and synthesized successfully to activate PMS for carbamazepine (CBZ) degradation. NC-0.6/PMS system exhibited efficient performance for several contaminants, but NC-10/PMS system preferred to remove contaminants with low electrophilicity. The correlation analysis and Fukui index calculation revealed that high graphitization and low defect degree of catalysts stimulated diverse ROS generation (•OH and 1O2) and the decreasing of graphitization was beneficial to form a single 1O2 oxidation system. The regulation of ROS was a potential approach for the selective removal of contaminants. This work provides a new insight into the mechanism transformation of ROS-oriented degradation of pollutants in PMS-AOPs.

Regulating cobalt-nitrogen function centers via Cu incorporation enhances ciprofloxacin destruction through peroxymonosulfate activation

Metal-nitrogen (M-N) coupling has shown promise as a catalytic active component for various reactions. However, the regulation of heterogeneous catalytic materials with M-N coupling for peroxymonosulfate (PMS) activation to enhance the degradation efficiency and reusability of antibiotics remains a challenge. In this study, an efficient modulation of M-N coupling was achieved through the incorporation of Cu into Co4N to form a Cu-Co4N composite with sea urchin-like morphology assembled by numerous nano-needles using hydrothermal and nitriding processes. This modulation led to enhanced PMS activation for ciprofloxacin (CIP) degradation. The Cu-Co4N/PMS system demonstrated exceptional removal efficiency with a degradation rate of 95.85% within 30 min and can be reused for five time without obvious loss of its initial activity. Additionally, the catalyst displayed a high capacity for degrading various challenging organic pollutants, as well as remarkable stability, resistance to interferences, and adaptability to pH changes. The synergistic effect between Co and Cu facilitated multiple redox cycles, resulting in the generation of reactive oxidized species. The primary active species involved in the catalytic degradation process included 1O2, SO4•-, O2•-, •OH, and e−, with 1O2 and SO4•- playing the most significant roles. The degradation pathways and toxicity of the intermediates for CIP were unveiled. This study offers valuable insights into the regulation of M-N centers for degrading antibiotics through PMS activation.

Chitosan-derived N-doped carbon supported Cu/Fe co-doped MoS2 nanoparticles as peroxymonosulfate activator for efficient dyes degradation

Peroxymonosulfate (PMS), which is dominated by free radical (SO4•-) pathway, has a good removal effect on organic pollutants in complex water matrices. In this article, a new catalyst (CFM@NC) was synthesized by hydrothermal carbonization method with chitosan (CS) as N and C precursors, and used to activate PMS to degrade dye wastewater. CFM@NC/PMS system can degrade 50 mg·L−1 rhodamine B by 99.59 % within 30 min, and the degradation rate remains as high as 97.32 % after 5 cycles. It has good complex background matrices, acid-base anti-interference ability (pH 2.6–10.1), universality and reusability. It can degrade methyl orange and methylene blue by >98 % within 30 min. The high efficiency of the composite is due to the fact that CS-modified MoS2 as a carrier exposes a large number of active sites, which not only disperses CuFe2O4 nanoparticles and improves the stability of the catalyst, but also provides abundant electron rich groups, which promotes the activation of PMS and the production of reactive oxygen species (ROS). PMS is effectively activated by catalytic sites (Cu+/Cu2+, Fe2+/Fe3+, Mo4+/Mo6+, pyridine N, pyrrole N, edge sulfur and hydroxyl group) to produce a large number of radicals to attack RhB molecules, causing chromophore cleavage, ring opening, and mineralization. Among them, free radical SO4•- is the main ROS for RhB degradation. This work is expected to provide a new idea for the design and synthesis of environmentally friendly and efficient heterogeneous catalysts.

Comparative study of Fe(III)/peroxymonosulfate, Fe(III)/hydrogen peroxide and Fe(III)/peroxydisulfate systems modified by sinapic acid for micropollutants degradation

Sinapic acid (SA) as an environmentally friendly natural phenolic acid, has the properties of antioxidant because of containing –OH and –OCH3 on the benzene ring and it is safe. The Fe(III)/peroxymonosulfate (PMS) system modified by SA for enhancing micropollutant degradation had been studied, while weather SA could improve micropollutant degradation in other Fe(III)/oxidants systems was still unclear. The Fe(III)/hydrogen peroxide (H2O2) and Fe(III)/peroxydisulfate (PDS) systems modified by SA for micropollutants degradation were studied, the results indicated that SA could enhancing micropollutants degradation by accelerating the Fe(III)/Fe(II) cycle in both systems. In addition, the PMS, the H2O2 and the PDS systems were compared, and ten micropollutants commonly present in natural water were selected to evaluate the oxidation capacity of different systems. The PMS and PDS systems have higher oxidation degradation capacity for ten micropollutants than that of H2O2 system, attributed to the SO4•−, HO• and Fe(IV) all contributing to micropollutants degradation. However, in the H2O2 system, ten micropollutants degradation almost entirely relied on HO•. In the PMS and PDS systems, the SO4•− played a dominated role for micropollutants removal, attributed to its higher steady-state concentration than HO• and its higher second-order reaction rate with micropollutants than Fe(IV). Economic evaluation indicted that the H2O2 system was more cost-effective than the PMS and PDS systems for micropollutants removal. This was because the cost of H2O2 was lower than PMS and PDS, and concentration of Fe(III), oxidants and SA requirements in the H2O2 system were lower than that in the PMS and PDS systems. Overall, this study provided an economical and environmental-friendly method for the efficient treatment of harmful micropollutants in wastewater.

N, S co-doped porous carbon derived from waste medical masks to support LaFexCo1-xO3 as highly effective peroxymonosulfate catalysts for degradation of tetracycline

N and S co-doped porous carbon was prepared by decorating the waste disposable medical masks (WDMM) with thioacetamide (TAA) as the N/S source and then carbonizing at high temperature, which was subsequently incorporated Co-doped LaFeO3 to obtain NSC@LaFexCo1-xO3 catalysts. The resulting catalysts were used to construct an advanced oxidation process (AOP) based on activation of peroxymonosulfate (PMS) to degrade tetracycline (TC) in water. The physicochemical properties of the as-obtained catalysts were characterized and environmental factors affecting the catalytic performances of NSC@LaFexCo1-xO3/PMS were systematically investigated. The results showed that N and S co-doped porous carbon derived from thioacetamide (TAA)-functionalized WDMM at high temperature could be used as good support for LaFexCo1-xO3. The synergistic effects between N/S co-doped carbon and polyvalent metals (Co2+/Co3+ and Fe3+/Fe2+) endowed NSC@LaFexCo1-xO3 with enhanced catalytic performances, in which nearly 100% of TC could be removed by NSC@LaFe0.95Co0.05O3/PMS system within 10 min under the conditions of 0.2 g/L of catalyst dose, 2.5 mmol/L of PMS concentration and 10 mg/L of initial TC concentration. Furthermore, the constructed NSC@LaFe0.95Co0.05O3/PMS system exhibited a wider pH adaptability (3.0 ∼ 10.0), good salt resistance and reusability as well as high mineralization. The mechanisms and possible pathways of TC degradation by NSC@LaFe0.95Co0.05O3/PMS system were proposed and the ecotoxicity of TC and its intermediates was also evaluated. This study demonstrated the feasible transformation of waste masks into porous carbon with high added value for water pollution control and remediation, accomplishing the dual purposes of recycling and resource utilization of waste masks and protecting the environment.

Efficient removal of plasticiser dibutyl phthalate on CoP cluster anchored MXene via boosting peroxymonosulfate activation: Catalytic performance and decomposition mechanism

A novel Ti3C2 synthesis method via strong alkaline etching (MXeneba) was developed to degrade dibutyl phthalate (DBP) using a CoP/MXeneba + peroxymonosulfate (PMS) system. The MXeneba's modified surface properties enabled stable Co2+ adsorption and homogeneous loading of ultrasmall CoP clusters post-phosphatisation. Complete DBP degradation was achieved within 30 min, facilitated by reactive oxygen species (ROS: SO4·-, ·OH, O2·-, and 1O2) and the highly reduced titanium atoms promoting Co3+ to Co2+ conversion. Density functional theory (DFT) calculations elucidated PMS adsorption sites and active species for DBP degradation. This study clarifies the activation mechanism, linking catalyst structure to performance, and provides insights for future advanced oxidation processes in environmental remediation. The findings emphasize the practical application and significance of the CoP/MXeneba catalyst in treating harmful plasticisers in water, contributing to efficient and sustainable water purification methods. The research also highlights this novel catalyst system's robustness and versatility in tackling diverse pollutants.

Ranitidine degradation in layered double hydroxide activated peroxymonosulfate system: impact of transition metal composition and reaction mechanisms.

Ranitidine, a competitive inhibitor of histamine H2 receptors, has been identified as an emerging micropollutant in water and wastewater, raising concerns about its potential impact on the environment and human health. This study aims to address this issue by developing an effective removal strategy using two types of layered double hydroxide (LDH) catalysts (i.e., CoFeLDH and CoCuLDH). Characterization results show that CoFeLDH catalyst has superior catalytic properties due to its stronger chemical bond compared to CoCuLDH. The degradation experiment shows that 100% degradation of ranitidine could be achieved within 20min using 25mg/L of CoFeLDH and 20mg/L of peroxymonosulfate (PMS). On the other hand, CoCuLDH was less effective, achieving only 70% degradation after 60min at a similar dosage. The degradation rate constant of CoFeLDH was 10 times higher than the rate constant of CoCuLDH at different pH range. Positive zeta potential of CoFeLDH made it superior over CoCuLDH regarding catalytic oxidation of PMS. The catalytic degradation mechanism shows that sulfate radicals played a more dominant role than hydroxyl radicals in the case of LDH catalysts. Also, CoFeLDH demonstrated a stronger radical pathway than CoCuLDH. XPS analysis of CoFeLDH revealed the cation percentages at different phases and proved the claim of being reusable even after 8 cycles. Overall, the findings suggest that CoFeLDH/PMS system proves to be a suitable choice for attaining high degradation efficiency and good stability in the remediation of ranitidine in wastewater.

Bridge-oxygen bonding modulates Ru single atoms for peroxymonosulfate activation: Importance of high-valent Ru species and 1O2

The application of single-atom catalysts (SACs) to advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) has attracted considerable attention. However, the catalytic pathways and mechanisms underlying these processes remain unclear. In this study, NiFe-LDH was synthesized and single Ru atoms were stably loaded onto it by forming Ru–O–M (M=Ni or Fe) bonds (Ru@NiFe-LDH). This was demonstrated using high-angle annular dark-field scanning TEM (HAADF-STEM) and X-ray absorption fine structure spectra (XANES). The Ru@NiFe-LDH/PMS system showed a high catalytic reactivity (100 % sulfamethoxazole degradation in only 30 min), high stability (97 % reactivity was maintained after continuous operation for 400 min), and wide pH suitability (working pH range 3–11) for AOPs. The crucial roles of the high-valent species (Ru(V) = O) and 1O2 in this reaction were verified. Density functional theory (DFT) calculations revealed that electron transfer produced a positively charged Ru. This enhances the adsorption of negatively charged PMS anions onto the Ru monoatomic sites, thereby, causing the formation of Ru-PMS* complexes. This study implies that the structure–function relationship between organic compounds and SACs plays a significant role in PMS-based AOPs, and provides a comprehensive mechanism for the role of high-valent species in heterogeneous Fenton-like systems.

Significant enhancement on ammonia removal by thermal/peroxymonosulfate system with bromide ion: Performance, influencing factors and mechanism

Although thermal-activated peroxymonosulfate (PMS) system possesses good performance on the removal of organic pollutants, thermal/PMS system exhibited poor capacity to remove ammonia nitrogen (NH4+-N). This study demonstrated the huge enhancement on the removal of NH4+-N by thermal/PMS system with the commonly coexistent bromide ion (Br-). The elimination of NH4+-N by thermal/PMS/Br- system fitted the pseudo-zero-order kinetics model well, while the corresponding kobs in the presence of 200 μM Br- was 5.76 times greater than that by thermal/PMS system. Bromine (HBrO) was confirmed as the dominant oxidant responsible for removing NH4+-N and TN, while the radicals of HO⋅, SO4⋅- and Br⋅ were also generated but made minor contribution to removing NH4+-N. HBrO was mostly produced by PMS reacting directly with Br-, while these radicals were produced from the cleavage of the O-O bond in PMS and the reaction between PMS and HBrO under high temperature. Thermal/PMS/Br- system exhibited superior performance on TN removal (up to 90 %) than that by thermal/PMS system (less than 5 %) and Cl--enhanced system (about 80 %). The main removal product of NH4+-N was identified as the environmentally friendly gas of N2, although nitrate was also detected. Neutral pH condition was the optical pH for NH4+-N removal. Increasing reaction temperature, PMS dosage and Br- concentration were beneficial to accelerating the removal of NH4+-N. Cations of Cu2+ and Fe3+, anions of SO42-, CO32- and NO3-, humic acid and the actual water matrix of landfill leachate negligibly influenced the removal of NH4+-N, while Cl- exhibited strong enhancement on NH4+-N removal. In summary, this study provided an effective method to improve the oxidizing capacity of thermal/PMS system, especially for NH4+-N removal in wastewater containing Br-.

Accelerated peroxymonosulfate activation over defective perovskite with anchored cobalt nanoparticles for organic contaminant removal

In this study, a novel perovskite oxide (Co@D-PBSC) for activation peroxymonosulfate (PMS) to degrade organic pollutants in wastewater was developed. Cobalt nanoparticles (Co NPs) and oxygen vacancies (OVs) were introduced to the perovskite oxide lattice via a non-stoichiometric ratio and separate-out strategy. The OVs and Co NPs provided abundant active sites for the activation of PMS and the generation of reactive oxygen species. The Co metal-OVs bridge promote the adsorption of PMS, meanwhile, Co nanoparticles accelerate the Co2+/Co3+ redox cycle, resulting in the production of the main reactive substance, sulfate radicals (SO4•−). The results of catalytic experiments showed that 85 % of ofloxacin (OFX) degradation efficiency was obtained within 1 min at 0.1 g/L Co@D-PBSC, 0.3 g/L PMS, 20 mg/L OFX (150 mL), and solution pH 7.0, which indicated that Co@D-PBSC/PMS system exhibits excellent performance. This work demonstrated an efficient perovskite catalyst for PMS activation in wastewater treatment and provided a useful catalyst design strategy for the advanced oxidation processes (AOPs).

Efficient degradation of levofloxacin using peroxymonosulfate activated by a novel magnetic catalyst derived from waste walnut shell biomass

Developing an economical and efficient catalyst derived from biochar and metal-organic frameworks (MOFs) for the activation of peroxymonosulfate (PMS) to degrade pollutants holds promise for practical applications. Herein, a simple in-situ synthesis method was designed to generate zeolitic imidazole framework with Co-based (ZIF-67) on the surface of waste walnut shell biomass, and novel derived magnetic catalysts (BC@CobC, Biochar@Co base Carbon) were obtained by high-temperature carbonization. This structure could avoid the drawbacks of structural collapse and particle agglomeration of MOF derivatives, while the presence of biochar could accelerate electron transfer and improve the activation performance. For the degradation of levofloxacin, the removal rate in the 0.5-BC@CobC/PMS system reached 89.88 % in 15 min with a mineralization of 60.43 % when the dosage of catalyst was 0.01 g L−1. Capture experiments and EPR tests showed that SO4−•, •OH, •O2− and 1O2 were jointly participated in the levofloxacin degradation process. Meanwhile, the BC@CobC/PMS system was minimally affected by the pH, co-existing inorganic anions, and natural active substances. It is worth noting that the BC@CobC/PMS system also had excellent removal effect on other typical organic pollutants, and the removal rate could reach 100 %. Cycling experiments showed that BC@CobC maintained high catalytic activity after multiple recycling. The degradation pathway of levofloxacin was also analyzed. Compared to the existing reports, the catalyst is economically superior, with much improved pollutant removal, and boasts a lower catalyst usage. This work will provide a viable idea in terms of reusing biomass waste and activating PMS for wastewater treatment.

A novel cobalt-iron bimetallic hydrochar for the degradation of triclosan in the aqueous solution: performance, reusability, and synergistic degradation mechanism

Low activation performance is a critical issue limiting the practical application of low-cost biochar in the advanced oxidation. Given the high potential of transition metals in the persulfate activation process and abundant oxygen-containing groups of hydrochar, hydrochar derived from cobalt (Co)-modified iron (Fe)-enriched sludge was synthesized and its performance and activation mechanism for the degradation of triclosan were investigated. Co modification significantly altered the morphology of hydrochar, and the increased Co–Fe mass ratios transformed hydrochar from granular to rose-shaped lamellar and then to helical sheet structures. Specific surface area, defect degree, and oxygen-containing groups of hydrochar increased with increasing cobalt-iron mass ratios. The highest removal of triclosan was up to 98% in the hydrochar/peroxymonosulfate (PMS) system under a wide range of pHs (3–10) and still remained higher than 90% after four cycles. Both Radical (mainly hydroxyl radical) and nonradical pathways (singlet oxygen and electron transfer) were evidenced to play roles in the triclosan removal. Fe3+ promoted the regeneration of Co2+ and realized the efficient circulation of Co3+/Co2+. A ternary system consisting of electron donor (triclosan)-electron mediator (hydrochar)-electron acceptor (PMS) provided channels for electron transfer. No measurable Co and Fe were released during the reaction, and the toxicity of degradation intermediates was lower than that of triclosan. Beside triclosan, rhodamine B, bisphenol A, sulfamethoxazole, and phenol were also almost degraded completely in this oxidation system. This study provides a promising way for the enhancement of catalytic activity of carbonaceous material.

One-step rapid removal of Cu(II) complexes via dual-active-site MOF catalysis with Peroxymonosulfate: Cooperative oxidation and adsorption

The removal of heavy metal complexes (HMCs) from wastewater is challenging due to their structural stability. Traditional methods require advanced oxidation processes (AOPs) for decomplexation, followed by chemical precipitation or adsorption. This study proposes a one-step approach using Co-imidazolate zeolitic framework-67 (ZIF-67) for simultaneous oxidation-decomplexation and in-situ adsorption of HMCs. The ZIF-67/peroxymonosulfate (PMS) system achieves 97.8 % removal of Cu(II)-citric acid complex (Cu-CA) in 60 mins, even under alkaline conditions, and demonstrates strong selectivity against ions like Ca, Mg, Na, and humic acid (HA). It effectively treats various contaminated water sources, achieving over 90 % removal efficiency for Cu(II) complexes such as oxalic acid (OA) and ethylenediaminetetraacetic acid (EDTA). The mechanism involves sulfate radicals (SO4•−) and singlet oxygen (1O2) for decomplexation, followed by amine groups in MOFs capturing Cu(II) ions through coordination interactions. This work offers a straightforward one-step method for HMCs contamination mitigation.

A metal-free Z-scheme PPy/MCN heterojunction for antibiotic removal via synergism of photocatalysis and peroxymonosulfate activation

Developing an active and synergistic system based on photocatalysis and peroxymonosulfate (PMS) activation is considered an effective strategy for efficient removal of antibiotics. However, photocatalytic heterojunctions generally comprise metallic catalysts that can cause metal leaching and secondary pollution, and a clear understanding of the synergy between photocatalysis and PMS activation is still missing. Herein, a metal-free Z-scheme polypyrrole (PPy)/melamine-derived graphitic carbon nitride (MCN) heterojunction photocatalyst was synthesized via calcination and in-situ loading for catalyzing the degradation of ciprofloxacin (CIP) and other emerging pollutants in a visible light-emitting diode (LED)/PMS synergistic system, which showed a significantly higher activity than the single LED and PMS systems. The optimal 0.5 %PPy/MCN (0.5 % is the mass ratio of PPy in the mixture of PPy/MCN) performed well under a wide pH range (3–11), while exhibiting superior anti-interference for common water constituents and outstanding reusability and stability. The 0.5 %PPy/MCN/LED/PMS synergistic system showed the highest kinetic constant (0.0643 1/min), which increased 3.00, 6.77 and 2.91-fold over the 0.5 %PPy/MCN/PMS, 0.5 %PPy/MCN/LED, and MCN/LED/PMS system, respectively. Mechanistic investigation and theoretical calculations revealed that PPy, with its high conductivity and strong light absorption ability, facilitated the generation and separation of e−/h+ in the 0.5 %PPy/MCN/LED/PMS system and activated PMS for generating reactive species such as 1O2, which degraded cCIP together with h+. Furthermore, electron transfer pathway (ETP) was elucidated using electrochemical characterizations. CIP was degraded via ring opening, cleavage hydroxylation, ammonia oxidation and elimination reactions, which substantially reduced the toxicity of CIP. Overall, this study may help the rational design of metal-free catalysts and provide a deep insight for the LED/PMS synergistic mechanisms.

Carboxymethyl chitosan modification of cobalt-zinc bimetallic MOF for tetracycline hydrochloride removal: Exploration of the enhancement mechanism of the process

This study synthesized a carboxymethyl chitosan-modified bimetallic Co/Zn-ZIF (CZ@CMC) with strong hydrophilicity and adsorption performance via the one-pot method. Tetracycline hydrochloride (TCH) was used as the model contaminant to evaluate the adsorption and peroxymonosulfate (PMS) activation properties of CZ@CMC. Mechanism showed that the adsorption behavior occurred through pore filling, electrostatic attraction, surface complexation, hydrogen bonding, and π-π stacking. In addition, a CZ@CMC/PMS system was constructed, which had excellent catalytic performance. The hydrophilicity and selective adsorption properties of CMC conferred a greatly accelerated CZ@CMC in catalyzing the PMS process with kobs of 0.095 min−1, in which OH, 1O2, SO4–, O2–, and Co(III) were the main ROS which quenching tests, EPR, and chemical probe experiments verified. In addition, the degradation pathways of TCH were obtained utilizing DFT and HPLC-MS and analyzed to show that the system possessed a good detoxification capacity. This work is expected to provide a green, efficient, and stable strategy to enhance the adsorption properties of catalytic materials and subsequently their co-catalytic properties.

Co@C Nanocatalyst: Enhanced Activation of Peroxymonosulfate for Paracetamol Degradation

A core–shell Co@C composite catalyst was prepared, characterized and used to activate peroxymonosulfate (PMS) for the degradation of paracetamol in water. Hybridized structures containing Co and graphitized carbon act as independent active sites for PMS activation initiating both radical and nonradical oxidation. A 91.57% paracetamol removal was reached in the Co@C/PMS system at 60 min. Radical quenching and electron paramagnetic resonance (EPR) tests show that nonradical 1O2 played predominant roles in the advanced oxidation process, while the other three radicals [Formula: see text], •OH and [Formula: see text]. also played a certain role in paracetamol degradation. After four cycles, the degradation could still reach 70%, which proves that the Co@C composite catalyst exhibits good stability.

Insight into the Discriminative Efficiencies and Mechanisms of Peroxy Activation via Fe/Cu Bimetallic Catalysts for Wastewater Purification.

Fe/Cu bimetallic catalysts have a synergistic effect that can effectively enhance catalytic activity, so Fe/Cu bimetallic catalysts have been extensively studied. However, the efficacy and mechanisms of Fe/Cu bimetallic catalysts' peroxidation activation have rarely been explored. In this study, Fe/Cu bimetallic materials were fabricated to catalyze different oxidizing agents, including peroxymonosulfate (PMS), peroxydisulfate (PDS), peroxyacetic acid (PAA), and hydrogen peroxide (H2O2), for the degradation of sulfamethoxazole (SMX). The Fe/Cu/oxidant systems exhibited an excellent degradation efficiency of sulfamethoxazole (SMX). In the Fe/Cu/PMS, Fe/Cu/PDS, and Fe/Cu/PAA systems, the main reactive oxygen species (ROS) responsible for SMX degradation were hydroxyl radical (•OH) and singlet oxygen (1O2), while the main ROS was only •OH in the H2O2 system. The differences in the surface structure of the materials before and after oxidation were examined, revealing the presence of a large amount of flocculent material on the surface of the oxidized PMS material. Anion experiments and actual body experiments also revealed that the PMS system had a strong anti-interference ability. Finally, a comprehensive comparison concluded that the PMS system was the optimal system among the four oxidation systems. Overall, this work revealed that the PMS oxidant has a better catalytic degradation of SMX compared to other oxidizers for Fe/Cu, that PMS generates more ROS, and that the PMS system has a stronger resistance to interference.

Peroxymonosulfate activation by iron-cobalt bimetallic phosphide modified nickel foam for efficient dye degradation

Novel catalysts with multiple active sites and rapid separation are required to effectively activate peroxymonosulfate (PMS) for the removal of organic pollutants from water. Therefore, an integrated catalyst for PMS activation was developed by directly forming Co–Fe Prussian blue analogs on a three-dimensional porous nickel foam (NF), which were subsequently phosphorylated to obtain cobalt-iron bimetallic phosphide (FeCoP@NF). The FeCoP@NF/PMS system efficiently degraded dye wastewater within 20 min. The system exhibited excellent catalytic degradation over a broad pH range and at high dye concentrations due to the presence of unique asymmetrically charged Coa+ and Pb− dual active sites formed by cobalt phosphides within FeCoP@NF. These active sites significantly enhanced the catalytic activity of PMS. The activation mechanism of PMS involves phosphorylation that accelerates electron transfer from FeCoP@NF to PMS, to generate SO4·–, ·OH, O2·–, and 1O2 active species. Three-dimensional FeCoP@NF could be readily recycled and showed good stability for PMS activation. In this study, a highly efficient, stable, and readily recyclable integrated catalyst was developed. This catalyst system effectively resolves the separation and recovery issues associated with conventional powder catalysts and has a wide range of potential applications in wastewater treatment.

Enhanced Orange II Removal Using Fe/Mn/Mg2-LDH Activated Peroxymonosulfate: Synergistic Radical Oxidation and Adsorption

In this study, Fe/Mn/Mg2-LDH was utilized for the first time as a catalyst for peroxymonosulfate (PMS) activation to facilitate the removal of Orange II. This composite was characterized using various techniques, such as XRD, FTIR, SEM-EDS, BET, and XPS. The results revealed a well-defined lamellar structure of Fe/Mn/Mg2-LDH with a metal molar ratio of Fe/Mn/Mg at 1:1:2. Moreover, the structural stability of Fe/Mn/Mg2-LDH was confirmed through the XRD, FTIR, and SEM. Fe/Mn/Mg2-LDH exhibited a good adsorption capacity towards Orange II and highly efficient PMS activation. The optimal removal efficiency of Orange II (98%) was achieved under the conditions of pH 7.0, [PMS] = 1.0 mmol L−1, [Fe/Mn/Mg₂-LDH] = 1.6 g L−1, and [Orange II] = 50 μM. Additionally, this system demonstrated good adaptability across a wide pH range. The presence of Cl− and humic acids (HA) did not significantly inhibit Orange II removal, whereas inhibitory effects were observed in the presence of CO32− and PO43−. The removal mechanism of Orange II was attributed to a synergy of adsorption and oxidation processes, wherein the generated surface radicals (SO4•−ads and HO•ads) on the surface of the Fe/Mn/Mg2-LDH played a predominant role. Furthermore, the Fe/Mn/Mg2-LDH exhibited good reusability, maintaining a removal rate of 90% over five cycles of recycling. The Fe/Mn/Mg2-LDH/PMS system shows promising potential for the treatment of wastewater contaminated with refractory organic pollutants.