Peroxymonosulfate Dosage Research Articles

Catalytic degradation of Rhodamine B through peroxymonosulfate activation by the Co-doped hydroxyapatite.

Supported Co-based catalysts have shown attractive prospects for peroxymonosulfate (PMS) activation. In this work, Co-doped hydroxyapatite (H-Co/HAP) composites were prepared by a simple hydrothermal method. The Co content in H-Co/HAP could reach 71.2mg/g, while the Co leaching rate remained relatively low. By right of the excellent catalytic performance, the as-prepared H-Co/HAP could achieve 99.02% degradation of Rhodamine B (RhB) within 10min in the presence of 0.5mM PMS and a first-order kinetic rate constant of 0.876min-1. Even after 8 cycles, the RhB degradation efficiency remained at 81.96%. In addition, the effects of vital reaction parameters, including catalyst dosage, PMS dosage, initial pH, humic acid, and coexisting anions, on the catalytic performance in the H-Co/HAP10/PMS system were systematically investigated and discussed. The degradation mechanism of a non-radical (1O2) as the dominant active specie and a radical (•O2- and SO4•-) as the minor active specie was identified through quenching experiments and electron paramagnetic resonance testing. Moreover, possible degradation pathways of RhB were proposed in the H-Co/HAP10/PMS system. Overall, this study offers a meaningful strategy for designing high-content Co-based catalysts to degrade dye molecules in wastewater.

Bacteria-supported manganese oxide for enhanced fluoroquinolone antibiotics removal in peroxymonosulfate oxidation system.

The biosynthesis of bacteria-supported manganese nanoparticles is an inexpensive and environmentally friendly method for producing metal nanocatalysts, which exhibit excellent performance in peroxymonosulfate (PMS) activation and the degradation of fluoroquinolone antibiotics while alleviating ion leakage issues. Manganese oxide is synthesized in situ by bacteria. This study presents a novel approach for synthesizing bacteria-supported manganese oxide (BMOx) using the heavy metal-resistant bacterium Ralstonia pickettii. The biogenic BMOx effectively activates PMS to achieve 97.6% degradation efficiency of ciprofloxacin within 15 min under optimal conditions (pH 7.0, BMOx dosage of 0.40 g/L, and PMS dosage of 0.55 g/L). The degradation mechanism was elucidated, revealing that singlet oxygen (1O2) is the primary reactive species responsible for ciprofloxacin degradation, facilitated by mediated electron transfer from BMOx. The study identified three degradation pathways, primarily involving oxidation reactions by 1O2. Toxicity assessments indicated a significant reduction in toxicity of the degradation intermediates compared to ciprofloxacin, highlighting the environmental benefits of the BMOx/PMS system. This research underscores the potential of biogenic metal oxide catalysts in advanced oxidation processes, offering a promising solution for the remediation of antibiotic-contaminated water.

Performance and Mechanism of In Situ Prepared NF@CoMnNi-LDH Composites to Activate PMS for Degradation of Enrofloxacin in Water

To overcome the disadvantage of difficult recovery of powder catalysts and improve catalyst utilization, the selection of foam metal substrates as supports can reduce the difficulty of material recovery and effectively inhibit the leaching of metal ions. Herein, CoMnNi-layered double hydroxide (LDH) derived from Co-Mn ZIF was immobilized onto nickel foam (NF) through in situ synthesis. The results of XRD and SEM analyses of the samples indicated that the LDH was successfully grown on the nickel foam matrix, and the material could maintain its original morphology to the maximum extent after loading. By comparing the XPS of the material before and after the reaction, it was confirmed that the surface hydroxyl group and C=O of the material were involved in the activation of peroxymonosulfate (PMS). The results of the quenching reaction showed that SO4•− and 1O2 are the main active substances in the oxidation of enrofloxacin (ENR). When the dosage of NF@CoMnNi-LDH was 0.4 g/L, the pH of the solution was 6.82, and when the dosage of PMS was 2.0 mM, the degradation rate of ENR reached 82.6% within 30 min. This research offers novel insights into the degradation of antibiotics from water using a monolithic catalyst supported by metal foam.

Magnetic cobalt nanoparticles embedded in a carbonaceous hydrogel for the activation of peroxymonosulfate to degrade azo dyes and organic pollutants.

Heterogeneous cobalt-based catalysts have recently gained attention as persulfate activators to degrade dyes and organic pollutants in sulfate radical-based advanced oxidation processes (SR-AOPs). This study fabricated magnetic cobalt nanoparticles embedded in a carbonaceous hydrogel (Co@C) using high-temperature pyrolysis of the Co2+-embedded chitosan-graft-poly(acrylic acid) (Co2+-embedded CTS-g-PAA) hydrogel. Subsequently, the prepared Co@C was evaluated as a peroxymonosulfate (PMS) activator for degrading azo dyes. The catalyst showed the highest performance toward reactive red 141 (RR141) than Congo red, methyl orange, direct yellow 50, and reactive black 5. RR141 was completely degraded within 10min, with a 3.20min-1 pseudo-first-order rate constant. The degradation rate increased with higher catalyst dosage, PMS dosage, and temperature. The pH of the solution had a minimal effect on the degradation of RR141, indicating that the catalyst could be effective across a wide pH range. Moreover, the quenching experiment and the electron paramagnetic resonance analysis indicated that the catalytic system generated SO4•-, HO•, O2•-, and 1O2. The RR141 degradation was slightly affected by Cl-, NO3-, and SO42-. The catalyst demonstrated high efficiencies in real water samples. The catalyst could be easily recovered using a magnet and reused for ten cycles with only a 10% degradation efficiency loss. Furthermore, the catalyst could effectively degrade other organic pollutants, including tetracycline and 4-nitrophenol. This study demonstrates that the Co@C catalyst can effectively purify wastewater via SR-AOPs.

Yolk-shell structured Co3O4 catalyst modified ceramic membrane synergistically improved wastewater purification and membrane fouling mitigation

Wastewater increases and water shortage crises have forced the rapid innovation of water reuse technologies. Ceramic membrane process (CM), as one of the key technologies for wastewater reclamation, can effectively light the current difficulties. However, membrane fouling and low retention rate are critical bottles that hinder its further application. Herein, we proposed yolk-shell Co3O4 spheres modified CM (CoHM-CM) activating peroxymonosulfate (PMS) to improve membrane filtration performance. The results showed that the synergistic effect of size exclusion of CM and spatial confinement of CoHM enhanced the collision between organic pollutants and active sites. CoHM-CM/PMS (30 mg CoHM loading combined with 0.5 mM PMS dosage) degraded 100 % of 10 mg/L phenol, bisphenol F and sulfamethoxazole, and 91.29 % of 5 mg/L carbamazepine at an instant of membrane filtration. This process efficiently removed secondary effluent organic matter and reduced membrane fouling resistance by more than 70 % in actual wastewater environments. Besides, the yolk-shell catalytic membrane had strong Co2+ regeneration capacity and chemical stability. It coupled PMS-generated sulfate radicals and singlet oxygen play a core role in increasing the membrane interface energy barrier and releasing the developing tendency of membrane pore blocking to severe cake layer filtration fouling. The results provided a new opportunity for wastewater remediation based on the yolk-shell modified membrane technology.

In-situ immobilization of Fe PBA in the zeolite structure for efficient degradation of benzalkonium chloride: Towards compressed reaction site loss and promoted PMS utilization

Advanced oxidation processes based on peroxymonosulfate (PMS) for the removal of quaternary ammonium compounds have challenges, including high metal leaching and excessive oxidant consumption, which limit their practical application. In this work, Fe atoms were firstly intercalated into the structure of the zeolite through ion exchange and then transformed into Fe prussian blue analog (Fe PBA) in-situ through coprecipitation followed by a calcination process. Through immobilizing the reactive catalytic center to a specific site, the leaching rate of Fe was compressed to about 0.25 mg·L-1, accounting for only 6 % of the Fe PBA without zeolite immobilization. The incorporation of zeolite has triggered increased hydrophilicity while retaining the negatively charged property of Fe PBA, implying enhanced dispersity of the catalyst in the aqueous environment and attraction towards benzalkonium chloride (BAC) and PMS molecules. Intuitively, the reactive oxidative species (ROS) generated through PMS activation require less diffusion distance to encounter BAC molecules, as they are confined within the microenvironment around the surface due to this weak electrostatic attraction. Therefore, an increase in ROS utilization efficiency was observed with a significant reduction in PMS dosage. Remarkably, 99.83 % of BAC (10 mg·L-1) was eliminated within 60 min with only 0.5 mM PMS, which is much lower than the reported 5–100 mM PMS. More importantly, the post-annealing brought an increased amount of graphitic carbon, which enhanced singlet oxygen production and further improved the degradation efficiency of BAC molecules due to its unique selectivity. This study presents a feasible strategy for simultaneously enhancing PMS utilization and reducing metal ion leaching.

Facile synthesis of ultrafine Co3O4/Al2O3 catalysts for superior peroxymonosulfate activation in rhodamine B degradation

Advanced oxidation processes based on persulfate (PS-AOPs) have emerged as effective strategies for environmental remediation, with cobalt-based oxides serving as prominent catalysts for peroxymonosulfate (PMS) activation. In this study, we developed a highly active Co3O4/Al2O3 catalyst (Co/AA) featuring ultrafine nanoparticles, synthesized via a facile approach using tannic acid (TA) as a coordinating agent and activated alumina as a robust support. Co/AA-0.1, as the representative catalyst, was characterized and exhibited outstanding performance in degrading rhodamine B (RB) via PMS activation. Our findings highlight TA's critical role in reducing Co3O4 nanoparticle size, thereby increasing the availability of active sites. The degradation mechanism was elucidated through reactive oxygen species (ROS) quenching experiments and electron paramagnetic resonance (EPR) analysis, revealing that sulfate radicals (SO4•−) are the dominant ROS. The high activity of Co/AA-0.1 is confirmed by analyzing X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area and O2-temperature programmed desorption data of the samples. We also investigate the effects of various factors, such as anions, reaction temperatures, and PMS dosage, on RB degradation. Higher temperatures for treating the catalyst are found to reduce activity but improve stability. Notably, the catalyst synthesized through EDTA-assisted synthesis showed balanced activity and stability. Furthermore, the versatility of our synthesis method was demonstrated by successfully applying it to other supports, such as SiO2 and TiO2, offering the development of more efficient and stable catalysts for environmental applications.

Oxidative degradation of anionic dyes in wastewater by magnetic lignin micro-nano spheres catalyzed peroxymonosulfate

Lignin has gained significant attention in wastewater treatment due to its abundant resources and good adsorbability. In this work, magnetic lignin micro-nano spheres (Fe3O4@SiO2-LNS) was prepared using alkali lignin as the raw material, and was used as the adsorbent and catalyst to activate peroxymonosulfate (PMS) to build an inhomogeneous catalytic oxidation system (Fe3O4@SiO2-LNS/PMS). The system was then used to remove the stubborn acid blue 9 (AB9) dye in wastewater, and the effects of pH, catalyst dosage, PMS dosage of the system on the removal percentage of AB9 dye and the corresponding degradation mechanism were explored. The results showed that Fe3O4@SiO2-LNS/PMS system had good removal efficiency for AB9 in wastewater, and AB9 dye was completely oxidized and finally degraded into CO2 and H2O. The maximum removal percentage of AB9 was observed when the pH and temperature of the system were 6.0 and 313 K, and the removal percentage of AB9 achieved 100 % when the optimal dosage of Fe3O4@SiO2-LNS and PMS were 3.44 g/L and 53.15 mM, respectively. In addition, Fe3O4@SiO2-LNS had good stability and reusability. This work provides a promising approach for abatement of dyeing wastewater pollution and a new direction for high-value utilization of alkali lignin.

Impact of Metal Ions, Peroxymonosulfate (PMS), and pH on Sulfolane Degradation by Pressurized Ozonation

This study investigated the degradation of sulfolane using pressurized ozonation under varying initial concentrations and the influence of different catalysts and peroxymonosulfate activation methods on the degradation efficiency. Initial sulfolane concentrations of 1 mg L−1, 20 mg L−1, and 100 mg L−1 were tested over 120 min, revealing a degradation efficiency of 73%, 41%, and 18%, respectively. The addition of various metal ions (Zn2+, Mg2+, Cu2+, Ni2+, and Co2+) demonstrated that only zinc and magnesium enhanced degradation, with zinc achieving a 92% removal efficiency and magnesium achieving 86%. Different doses of magnesium and zinc were further tested, showing optimal degradation at specific concentrations. The combination of PMS with ozonation was explored, revealing that zinc activation did not significantly enhance degradation, while NaOH activation achieved near-total degradation, with a 100 mg L−1 NaOH concentration. Varying PMS concentrations indicated that altering pH was more effective than changing PMS dosage. Finally, the impact of pH changes in both reverse osmosis water and tap water matrices confirmed that higher pH levels significantly improved degradation efficacy, achieving up to 98% removal with NaOH concentrations of 50 mg L−1 in reverse osmosis water. These results suggest that optimizing pH and catalyst type are critical for enhancing sulfolane degradation in pressurized ozonation systems.

Cobalt/iron bimetallic oxide coated with graphitized nitrogen-doped carbon (Fe2O3-CoO@NC) derived from cobalt/iron solid complex as peroxymonosulfate (PMS) activator for efficient bensulfuron-methyl degradation

Cobalt/iron bimetallic oxide coated with graphitized nitrogen-doped carbon (Fe2O3-CoO@NC) was synthesized by convenient solid phase coordination combined with calcination method to activate PMS for the degradation of BSM. A series of Co/Fe bimetallic oxides with different metal ratios were designed and prepared to select the most efficient catalyst and Fe2O3-CoO@NC(Co:Fe = 1:1) demonstrated the highest catalytic activity and the lowest ions leaching. The reasons for high catalytic activity of Fe2O3-CoO@NC(Co:Fe = 1:1) were evaluated by a range of characterization techniques and the results showed it stemmed from higher mental content and larger current density. Complete (100%) degradation of 10 g L−1 BSM was achieved within 10 min under the conditions of 0.05 g L−1 catalyst and 0.3 mmol/L PMS dosage at 25 °C. Moreover, Fe2O3-CoO@NC(Co:Fe = 1:1) showed more excellent catalytic activity and lower ions leaching than Fe2O3, CoO and Fe2O3-CoO, indicating superior bimetallic synergy and carbon encapsulation effect. Furtherly, radical experiments and XPS analysis revealed the main active species and catalytic mechanism of the Fe2O3-CoO@NC/PMS system, respectively. Finally, the degradation pathway of BSM by Fe2O3-CoO@NC/PMS system was deduced by LC-TOF-MS. This paper is aimed to provide a new insight into the convenient preparation method for the construction of catalysts which could reach efficient removal of complex organic pollutants.

Efficient Adsorption and Degradation of Tetracycline Hydrochloride Using Metal-Organic Framework-Derived Cobalt-Based Catalysts and Mechanism Insight.

High-performance Co-based catalysts were derived by pyrolysis using synthesized MOFs as self-sacrificial templates. Various catalytic systems were constructed by peroxymonosulfate (PMS) to degrade tetracycline hydrochloride (TC). Adsorption-degradation efficiencies, cycle performance, dynamics, and the adsorption catalytic mechanism of various catalytic systems for TC were studied. The effects of different synthetic solvents, pyrolysis temperatures, and single/bimetallic element compositions on degradation efficiency were innovatively compared. The optimal catalyst and PMS dosage for the experiment were determined to be 10 mg and 0.1 mL, respectively. The results indicated that all catalytic systems could efficiently degrade TC and have a high acid-base resistance. The catalyst activity was significantly influenced by the pyrolysis temperature. The optimum pyrolysis temperatures for Zn@Co-N-C-T, CH3OH@Co-N-C-T, and H2O@Co-N-C-T were 1000, 900 and 900 °C, respectively. More abundant pore structures and active sites were generated in Zn@Co-N-C-1000, exhibiting an excellent TC degradation efficiency and adsorption capacity, achieving 94.73% and 167.564 mg/g, respectively. Meanwhile, the total organic carbon (TOC) of TC (50 mL, 50 mg/L) achieved a removal rate (TOC/TOC0) of 50.28%. Zn@Co-N-C-1000/PMS maintained over 83.27% TC degradation after five cycles. The adsorption mechanism of the catalyst for TC was investigated through the analysis of adsorption kinetics and isotherm models. The quenching test and EPR results indicated that TC was primarily degraded through the nonradical pathway. The efficient degradation of TC is attributed to the rapid electron transfer processes occurring at the two-phase interface and the redox cycling of Co0/Co2+/Co3+. Finally, LC-MS was used to analyze the intermediate products of TC degradation in the Zn@Co-N-C-1000/PMS system, and two degradation pathways were proposed.

Activation of persulfate by MOF-derived MnFeOx to efficiently degrade sulfadiazine: Synergistic effects from free radicals and singlet oxygen

In this study, a facile hydrothermal approach was used to synthesize the MOFs materials [Mn-doped MIL-101(Fe)]. These materials were subsequently subjected to high temperature annealing process via calcination to generate the MOFs derivatives (MnFeOx). The synthesized materials were utilized for the removal of sulfadiazine (SDZ) removal through activated peroxymonosulfate (PMS). At the optimum Mn doping, the removal ratio of SDZ could reach 98.9 % (at natural pH) within 20 min. In addition, the study investigated the influence of PMS dosage, catalyst dosage, initial pH, various inorganic anions, and humic acid (HA) on the degradation of SDZ. The activation processes of both free and non-free radicals in the MnFeOx/PMS system were examined by free radical quenching experiments and electron paramagnetic resonance (EPR) techniques. The analysis of the degradation products of SDZ was conducted by using high performance liquid chromatography-mass spectrometry (HPLC-MS), and the breakdown pathways of SDZ in the MnFeOx/PMS system were proposed.

Catalytic performance of FeCo2O4 spinel cobaltite for degradation of ethylparaben in a peroxymonosulfate activation process: Response surface optimization, reaction kinetics and cost estimation

The presence of cosmetics and personal care products in water resources has become an increasing concern for environment due to their toxicity and persistence in aquatic medium. Peroxymonosulfate mediated advanced oxidation methods have a great potential for the efficient removal of complex organic compounds due to the generation of highly reactive radicals with high oxidation ability. Iron cobaltite, FeCo2O4 catalyst was used as a peroxymonosulfate (PMS) activator for the degradation of ethylparaben which was selected as a model personal care product ingredient. Paraben degradation was modelled and the optimum operating parameters were determined by using Box-Behnken design. The ethylparaben degradation efficiency was calculated as 94.6 % under the optimized conditions which were determined as 0.9 g/L FeCo2O4 loading, pH 6.15, and 0.26 g/L PMS dosage. The ethylparaben degradation reaction followed second-order reaction kinetics. The activation energy was evaluated as 40.1 kJ/mol. Quenching radical tests showed that the dominant reactive species were hydroxyl radicals. Toxicity of the treated samples in terms of L. sativum growth inhibition was evaluated as 1.5 %. The total cost of the treatment including the operating and the amortization costs was calculated as 0.91 €/L.

Construction of multi-transition metal sulphides and its superiority for degradation of carbamazepine by activation of peroxymonosulfate

The extensive utilization of pharmaceuticals and personal care products poses a potential crisis to human health and the environment. In this study, a series of multi-transition metal sulphides were synthesized by a combined approach of co-precipitation and hydrothermal to activate peroxymonosulfate (PMS) for the effective degradation of carbamazepine (CBZ). Notably, the prepared (MoFeCoZnCu)Sx had the best PMS activation performance and exhibited the highest CBZ elimination efficiency. Subsequently, the structure and composition of the (MoFeCoZnCu)Sx catalyst were characterized systematically. Key parameters including catalyst dosage, PMS dosage, and initial pH were optimized to enhance the performance of (MoFeCoZnCu)Sx/PMS catalytic system. To investigate the potential application of (MoFeCoZnCu)Sx/PMS, its cyclic stability and universality were evaluated. Furthermore, the mechanism for CBZ elimination using (MoFeCoZnCu)Sx/PMS was verified and attributed to the involvement of sulfate radicals (SO4-·), hydroxyl radicals (·OH), and superoxide anion radicals (·O2-). Consequently, the (MoFeCoZnCu)Sx/PMS catalytic system holds promising prospects for wastewater treatment and environmental remediation.

CoFe2O4-catalytic ceramic membrane for efficient carbamazepine removal via peroxymonosulfate activation

Poor water removal of low-molecular-weight anthropogenic contaminants is always a key problem in low-pressure membrane filtration process. In this work, we successfully designed and fabricated a novel cobalt-based bimetallic catalytic ceramic membrane (CoFe2O4@CM-2) with peroxymonosulfate (PMS) activation and membrane filtration dual functionality, employing a facile impregnation-filtration-calcination method. The resulting CoFe2O4@CM-2/PMS filtration system was specifically tailored for the removal of carbamazepine (CBZ). Our results demonstrate that the CoFe2O4@CM-2/PMS system achieved efficient removal of CBZ from contaminated waters. Under optimal conditions (PMS dosage of 0.5 mM and an operating flux of 40 L·m−2·h−1), the CoFe2O4@CM-2/PMS system exhibited remarkable CBZ removal efficiency, reaching up to 96.5 %. This efficiency was 32.2 and 19.3 times higher than that achieved by ceramic membrane filtration alone and PMS treatment alone, respectively. Additionally, the CoFe2O4@CM-2/PMS system facilitated 37.0 % mineralization of CBZ and up to 87 % utilization of PMS in the permeate. Furthermore, the CoFe2O4@CM-2/PMS system demonstrated robust performance, removing over 91 % of CBZ across a pH range of 3–9 and maintaining stability stability in the presence of humic acid (HA) interference. Its exceptional anti-fouling ability effectively mitigates membrane flux loss compared to single membrane filtration process. Quenching test, electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) analyses revealed that 1O2, SO4-∙ and ·OH were the primary active substances in the system, while the redox cycle of Co2+/Co3+ played a crucial role in PMS activation. Moreover, the presence of iron (Fe) in the CoFe₂O₄@CM-2 expedited the Co2+/Co3+ cycle and enhanced PMS activation. This study introduces an innovative approach for fabricating ceramic membranes with catalytic degradation capabilities for organic pollutants and suggests promising avenues for integrating separation and advanced oxidation processes (AOPs) in future applications.

Monodispersed FeS nanoparticles decorated on kaolinite for synchronous removal of benzo [a]pyrene and Cr(VI) complex pollution

Novel FeS/kaolinite composite (K-FeS) were successfully prepared using an in-situ precipitation method. At 30 % FeS loading, 1 g/L of the composite material by activating peroxymonosulfate (PMS) was able to completely remove 20 mg/L benzo[a]pyrene (BaP) and 40 mg/L Cr(VI) within 20 min under optimized conditions. The simultaneous removal experiments of BaP and Cr(VI) for the influence factors of BaP concentration, Cr(VI) concentration, composites dosage and PMS dosage to be 20 mg/L, 40 mg/L, 1 g/L, and 0.75 mmol/L, respectively. Experiments on environmental factors show that low temperature and acidic conditions are more favorable for material activity, and the addition of Cl- could promote the removal of BaP and Cr(VI). Comparative experiments showed that the simultaneous presence of BaP and Cr(VI) did not affect the removal of each other. The pseudo second-order kinetic model and Langmuir adsorption isotherm model were better to fit the experimental data, and the thermodynamic analyses indicated that the removal processes of BaP and Cr(VI) were spontaneous and exothermic. Besides, the quenching experiments yielded that SO4− and OH played a dominant role in BaP removal, and Cr(VI) removal mainly depended on the reduction of composites. This study expands the application of clay minerals in water treatment and suggests new strategies for simultaneous treatment of multiple pollutants in the environment.

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.

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.

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.

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.