Peroxymonosulfate Dosage Research Articles

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.

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.

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.

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.

Peroxymonosulfate activated by CoMn@CNT nanocomposite for moxifloxacin degradation

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

The role of chitosan in promoting the catalytic activity of bismuth ferrite as peroxymonosulfate activator for antibiotics removal

Chitosan possesses electron-rich amino (−NH2) and hydroxyl (-OH) moieties which can anchor with transition metal ions during synthesis. Herein, chitosan was employed as an additive to prepare bismuth ferrite (BFO) via hydrothermal approach. The characterization studies revealed that adding chitosan during BFO synthesis leads to the creation of more oxygen vacancies. The performance of chitosan modified BFO (CMB) was evaluated as peroxymonosulfate (PMS) activator for ciprofloxacin (CIP) removal. Apparently, the addition of 10 wt% chitosan during BFO synthesis (CMB-10) resulted in 1.7 times increase of performance compared to the pristine BFO. Increasing the catalyst loading and PMS dosage resulted in positive effect with 5.7 and 1.9 times rate enhancement, respectively. The CMB-10 exhibited tolerance against pH variation, water matrix, and interfering species. The scavenging experiments indicated that singlet oxygen (1O2), superoxide radicals (O2•-) and sulfate radicals (SO4•-) played a major role in CIP degradation. These reactive oxygen species were generated from PMS activation via Fe3+/Fe2+ and Bi5+/Bi3+ coupling, and oxygen vacancies on the catalyst surface. The CIP degradation pathways were also elucidated based on the detected CIP intermediates. Overall, this study provides insights into the use of chitosan to prepare sustainable materials for pollutants removal via PMS activation.

Effective peroxymonosulfate activation by lithium cobaltite recovered from spent lithium-ion batteries for enhanced carbamazepine degradation in a wide pH range.

Considering the high cost and complicated recycling process of spent lithium-ion batteries (SLIBs), transforming SLIBs into environment functional materials may be a wise approach. Herein, lithium cobaltite (LCO) cathode powders recovered from SLIBs were used to activate peroxymonosulfate (PMS) for removing carbamazepine (CBZ). The recovered LCO enables a 98.2% removal efficiency of CBZ (2.5mg/L) within 10min, which was effective at a broader pH range (pH = 5.0-11.0). The influence of key factors (initial pH, PMS, and catalyst dosage) and coexisting substances (SO42-, H2PO4-, NO3-, Cl-, HCO3-, and HA) on CBZ degradation were examined in detail. The primary radical species during the degradation of CBZ were proved to be 1O2, SO4-, and.OH that generated from PMS activation initiated by the valence change of Co in recovered LCO. The recovered LCO displayed excellent reusability with about 80.0% removal of CBZ after six cycles. Homogeneous activation of PMS mainly contributed to CBZ degradation in the first run, but the recovered LCO catalyst dominated the heterogeneous activation of PMS for the degradation of CBZ in the second to sixth run. Finally, the CBZ degradation pathways were presented based on the identified intermediates. This research has offered a new strategy of "treating wastes with wastes" to maximize the recycling of electronic wastes to remove emerging pollutants.

Urban wastewater disinfection by FeCl3-activated biochar/peroxymonosulfate system: Escherichia coli inactivation and microplastics interference

Biochar coupled with peroxymonosulfate (PMS) to produce sulfate radicals and its application to urban wastewater disinfection has been rarely investigated and no information is available about microplastics (MPs) interference on the disinfection process. In this study, FeCl3-activated biochar (Fe-BC) was coupled to PMS to evaluate the inactivation of Escherichia coli (E. coli) in real secondary treated urban wastewater. Surface morphology of Fe-BC sample, characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), showed a rough texture with uniform distribution of iron particles over the entire surface area. E. coli inactivation improved (∼3.8 log units, detection limit = 1 CFU/100 mL) as Fe-BC concentration was decreased (from 1.0 g/L to 0.5 g/L), at a constant PMS dose (300 mg/L). Besides, removal efficiency of E. coli was negatively affected by the presence of small (30–50 μm) polyethylene MPs (PE MPs) (200 mg/L), which could be attributed to the adsorption of MPs on Fe-BC surface, according to SEM images of post-treated Fe-BC. The low disinfection efficiency of Fe-BC/PMS system in presence MPs could be due to blocking of Fe-BC sites for PMS activation and/or radicals scavenging during treatment. These results allowed to unveil the mechanisms of MPs interference on E. coli inactivation by Fe-BC/PMS, as well as the potential of this process to make the effluent in compliance with the stringent limit for agricultural reuse.

Acetaminophen removal by peroxymonosulfate catalyzed by C and O co-doped graphitic carbon nitride in synthetic secondary treatment effluent matrix

Catalytic oxidation using carbonaceous materials and peroxymonosulfate (PMS) has attracted attention because of high potential in pharmaceuticals removal. For successful field applications, it is essential to identify the components and characteristics in real water matrices affecting the performance, though it has hardly been elaborated. Therefore, acetaminophen (ACT) removal by C and O co-doped graphitic carbon nitride (COCN) and PMS was investigated in synthetic secondary treatment effluent (SSTE) and compared to that in deionized water (DIW). ACT removal was significantly suppressed in SSTE (20.33 %) compared to that in DIW (94.20 %) under 10 mg/L ACT, 100 mg/L COCN, and 0.5 mM PMS. However, it was enhanced greatly with increasing COCN and/or PMS dose. The reactive species were the same in SSTE and DIW, of which 1O2 from O2− dominantly contributed. However, the amount of them was considerably lower in SSTE than in DIW. ACT removal was slightly affected by the anions in SSTE, such as Cl−, SO42−, and NO3−, at 1.41 × 10−3–0.71 mM. But it was suppressed greatly by 0.71 mM phosphates and by 10 mg/L humic acid and natural organic matter, via consuming hydrophobic and aromatic fractions. It is strongly suggested that the reactivity of COCN/PMS in SSTE was dominantly affected by raised pH and scavenging O2− reducing DOM, which decreased 1O2 generation. The results would significantly contribute to successful practical applications of catalytic 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-.

ZIF-67-derived monolithic bimetallic sulfides as efficient persulfate activators for the degradation of ofloxacin

In this study, we successfully synthesized ZIF-67 material on three-dimensional (3D) nickel foam (NF) substrate by co-precipitation method, and then fixed CoSx on NF by hydrothermal vulcanization method to form CoSx/NF. The optimized CoSx/NF can effectively activate peroxymonosulfate (PMS) and improve the degradation efficiency of ofloxacin (OFL). The effects of PMS dosage, reaction temperature, initial pH and co-existing ions on the degradation effect of OFL were investigated in detail. CoSx/NF (1 piece 2 × 2 cm) and PMS (1 mM) in an aqueous solution (pH = 7) degraded 85 % of OFL (20.0 mg/L) within 45 min. This favorable degradation performance is mainly attributed to the enhanced electron transfer capability introduced by the bimetallic material. In addition, CoSx/NF still maintained high degradation effect and stable structure after 5 cycles. Quenching experiments further revealed that radicals •OH and 1O2 play a major role in degrading OFL. In addition, the degradation pathway, ecotoxicity evaluation and degradation mechanism of OFL were comprehensively investigated. In summary, the CoSx/NF catalyst proved to be a highly efficient, stable and recyclable heterogeneous composite, and opened up the possibility of using Metal-organic framework (MOF) derivatives in fields such as wastewater treatment.