Enhanced dewaterability and triclosan removal of waste activated sludge with iron-rich mineral-activated peroxymonosulfate.

High water and pharmaceutical and care products (PPCPs) bounded in sludge flocs limit its utilization and disposal. The advanced oxidation process of perxymonosulfate (PMS) catalyzed by iron salts has been widely used in sludge conditioning. In this study, two iron-rich minerals pyrite and siderite were proposed to enhance sludge dewatering performance and remove the target contaminant of triclosan (TCS). The permanent release of Fe2+ in the activation of PMS made siderite more effective in enhancing sludge dewater with capillary suction time (CST) diminishing by 60.5 %, specific resistance to filtration (SRF) decreasing by 79.2 %, and bound water content (BWC) dropping from 37.1 % to 2.6 % at siderite/PMS dosages of 0.36/0.20 mmol/g-TSS after 20 min of pretreatment. Pyrite/PMS performed slightly inferior under the same conditions and the corresponding CST and SRF decreased by 51.5 % and 71.8 % while the BWC only declined to 17.8 %. Rheological characterization was employed to elucidate the changes in sludge dewatering performance, with siderite/PMS treated sludge showing a 48.3 % reduction in thixotropy, higher than 28.4 % of pyrite/PMS. Oscillation and creep tests further demonstrated the significantly weakened viscoelastic behavior of the sludge by siderite/PMS pretreatment. For TCS mineralization removal, siderite/PMS achieved a high removal efficiency of 43.9 %, in comparison with 39.9 % for pyrite/PMS. The reduction in the sludge solids phase contributed the most to the TCS removal. Free radical quenching assays and EPR spectroscopy showed that both siderite/PMS and pyrite/PMS produced SO4-·  and ·OH, with the latter acting as the major radicals. Besides, the dosage of free radicals generated from siderite/PMS exhibited a lower time-dependence, which also allowed it to outperform in destroying EPS matrix, neutralizing the negative Zeta potential of sludge flocs, and mineralizing macromolecular organic matter.

Simultaneous elimination of antibiotic-resistant bacteria and antibiotic resistance genes by different Fe-N co-doped biochars activating peroxymonosulfate: The key role of pyridine-N and Fe-N sites.

The coexistence of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in the environment poses a potential threat to public health. In our study, we have developed a novel advanced oxidation process for simultaneously removing ARGs and ARB by two types of iron and nitrogen-doped biochar derived from rice straw (FeN-RBC) and sludge (FeN-SBC). All viable ARB (approximately 108 CFU mL-1) was inactivated in the FeN-RBC/ peroxymonosulfate (PMS) system within 40 min and did not regrow after 48 h even in real water samples. Flow cytometry identified 96.7 % of dead cells in the FeN-RBC/PMS system, which verified the complete inactivation of ARB. Thorough disinfection of ARB was associated with the disruption of cell membranes and intracellular enzymes related to the antioxidant system. Whereas live bacteria (approximately 200 CFU mL-1) remained after FeN-SBC/PMS treatment. Intracellular and extracellular ARGs (tetA and tetB) were efficiently degraded in the FeN-RBC/PMS system. The production of active species, primarily •OH, SO4•- and Fe (IV), as well as electron transfer, were essential to the effective disinfection of FeN-RBC/PMS. In comparison with FeN-SBC, the better catalytic performance of FeN-RBC was mainly ascribed to its higher amount of pyridine-N and Fe0, and more reactive active sites (such as CO group and Fe-N sites). Density functional theory calculations indicated the greater adsorption energy and Bader charge, more stable Fe-O bond, more easily broken OO bond in FeN-RBC/PMS, which demonstrated the stronger electron transfer capacity between FeN-RBC and PMS. To encapsulate, our study provided an efficient and dependable method for the simultaneous elimination of ARGs and ARB in water.

Zinc peroxide-based nanotheranostic platform with endogenous hydrogen peroxide/oxygen generation for enhanced photodynamic-chemo therapy of tumors.

Nanotheranostic platforms, which can respond to tumor microenvironments (TME, such as low pH and hypoxia), are immensely appealing for photodynamic therapy (PDT). However, hypoxia in solid tumors harms the treatment outcome of PDT which depends on oxygen molecules to generate cytotoxic singlet oxygen (1O2). Herein, we report the design of TME-responsive smart nanotheranostic platform (DOX/ZnO2@Zr-Ce6/Pt/PEG) which can generate endogenously hydrogen peroxide (H2O2) and oxygen (O2) to alleviate hypoxia for improving photodynamic-chemo combination therapy of tumors. DOX/ZnO2@Zr-Ce6/Pt/PEG nanocomposite was prepared by the synthesis of ZnO2 nanoparticles, in-situ assembly of Zr-Ce6 as typical metal-organic framework (MOF) on ZnO2 surface, in-situ reduction of Pt nanozymes, amphiphilic lipids surface coating and then doxorubicin (DOX) loading. DOX/ZnO2@Zr-Ce6/Pt/PEG nanocomposite exhibits average sizes of ∼78 nm and possesses a good loading capacity (48.8 %) for DOX. When DOX/ZnO2@Zr-Ce6/Pt/PEG dispersions are intratumorally injected into mice, the weak acidic TEM induces the decomposition of ZnO2 core to generate endogenously H2O2, then Pt nanozymes catalyze H2O2 to produce O2 for alleviating tumor hypoxia. Upon laser (630 nm) irradiation, the Zr-Ce6 component in DOX/ZnO2@Zr-Ce6/Pt/PEG can produce cytotoxic 1O2, and 1O2 generation rate can be enhanced by 2.94 times due to the cascaded generation of endogenous H2O2/O2. Furthermore, the generated O2 can suppress the expression of hypoxia-inducible factor α, and further enable tumor cells to become more sensitive to chemotherapy, thereby leading to an increased effectiveness of chemotherapy treatment. The photodynamic-chemo combination therapy from DOX/ZnO2@Zr-Ce6/Pt/PEG nanoplatform exhibits remarkable tumor growth inhibition compared to chemotherapy or PDT. Thus, the present study is a good demonstration of a TME-responsive nanoplatform in a multimodal approach for cancer therapy.

Elucidating the enhanced role of carbonate radical in propranolol degradation by UV/peroxymonosulfate system.

Carbonate radical (CO3•-) has been proved to be an important secondary radical in advanced oxidation processes due to various radical reactions involved HCO3-/CO32-. However, the roles and contributions of CO3•- in organic micropollutant degradation have not been explored systematically. Here, we quantified the impact of CO3•- on the degradation kinetics of propranolol, a representative pollutant in the UV/peroxymonosulfate (PMS) system, by constructing a steady-state radical model. Substantially, the measured values were coincident with the predictive values, and the contributions of CO3•- on propranolol degradation were the water matrix-dependent. Propranolol degradation increased by 130% in UV/PMS system containing 10 mM HCO3-, and the contribution of CO3•- was as high as 58%. Relatively high pH values are beneficial for propranolol degradation in pure water containing HCO3-, and the contributions of CO3•- also enhanced, while an inverse phenomenon was shown for the effects of propranolol concentrations. Dissolved organic matter exhibited significant scavenging effects on HO•, SO4•-, and CO3•-, substantially retarding the elimination process. The developed model successfully predicted oxidation degradation kinetics of propranolol in actual sewage, and CO3•- contribution was up to 93%, which in indicative of the important role of CO3•- in organic micropollutant removal via AOPs treatment.

Highly Reactive Peroxide Species Promoted Soot Oxidation over an Ordered Macroporous Ce0.8Zr0.2O2 Integrated Catalyzed Diesel Particulate Filter.

Particulate matter, represented by soot particles, poses a significant global environmental threat, necessitating efficient control technology. Here, we innovatively designed and elaborately fabricated ordered hierarchical macroporous catalysts of Ce0.8Zr0.2O2 (OM CZO) integrated on a catalyzed diesel particulate filter (CDPF) using the self-assembly method. An oxygen-vacancy-enriched ordered macroporous Ce0.8Zr0.2O2 catalyst (VO-OM CZO) integrated CDPF was synthesized by subsequent NaBH4 reduction. The VO-OM CZO integrated CDPF exhibited a markedly enhanced soot oxidation activity compared to OM CZO and powder CZO coated CDPFs (T50: 430 vs 490 and 545 °C, respectively). The well-defined OM structure of the VO-OM CZO catalysts effectively improves the contact efficiency between soot and the catalysts. Meanwhile, oxygen vacancies trigger the formation of a large amount of highly reactive peroxide species (O22-) from molecular oxygen (O2) through electron abstraction from the three adjacent Ce3+ (3Ce3+ + Vö + O2 → 3Ce4+ + O22-), contributing to the efficient soot oxidation. This work demonstrates the fabrication of the ordered macroporous CZO integrated CDPF and reveals the importance of structure and surface engineering in soot oxidation, which sheds light on the design of highly efficient PM capture and removal devices.

Mechanisms on the removal of gram-negative/positive antibiotic resistant bacteria and inhibition of horizontal gene transfer by ferrate coupled with peroxydisulfate or peroxymonosulfate.

The existence of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has been a global public environment and health issue. Due to the different cell structures, gram-positive/negative ARB exhibit various inactivation mechanisms in water disinfection. In this study, a gram-negative ARB Escherichia coli DH5α (E. coli DH5α) was used as a horizontal gene transfer (HGT) donor, while a gram-positive ARB Bacillus as a recipient. To develop an efficient and engineering applicable method in water disinfection, ARB and ARGs removal efficiency of Fe(VI) coupled peroxydisulfate (PDS) or peroxymonosulfate (PMS) was compared, wherein hydroxylamine (HA) was added as a reducing agent. The results indicated that Fe(VI)/PMS/HA showed higher disinfection efficiency than Fe(VI)/PDS/HA. When the concentration of each Fe(VI), PMS, HA was 0.48 mM, 5.15 log E. coli DH5α and 3.57 log Bacillus lost cultivability, while the proportion of recovered cells was 0.0017 % and 0.0566 %, respectively, and HGT was blocked. Intracellular tetA was reduced by 2.49 log. Fe(IV) and/or Fe(V) were proved to be the decisive reactive species. Due to the superiority of low cost as well as high efficiency and practicality, Fe(VI)/PMS/HA has significant application potential in ARB, ARGs removal and HGT inhibition, offering a new insight for wastewater treatment.

Ascorbic acid enhanced the circulation between Fe(II) and Fe(III) in peroxymonosulfate system for fluoranthene degradation.

In this research, ascorbic acid (AA) was used to enhance Fe(II)/Fe(III)-activated permonosulfate (PMS) systems for the degradation of fluoranthene (FLT). AA enhanced the production of ROS in both PMS/Fe(II) and PMS/Fe(III) systems through chelation and reduction and thus improved the degradation performance of FLT. The optimal molar ratio in PMS/Fe(II)/AA/FLT and PMS/Fe(III)/AA/FLT processes were 2/2/4/1 and 5/10/5/1, respectively. In addition, the experimental results on the effect of FLT degradation under different groundwater matrixes indicated that PMS/Fe(III)/AA system was more adaptable to different water quality conditions than the PMS/Fe(II)/AA system. SO4·- was the major reactive oxygen species (ROS) responsible for FLT removal through the probe and scavenging tests in both systems. Furthermore, the degradation intermediates of FLT were analyzed using gas chromatograph-mass spectrometry (GC-MS), and the probable degradation pathways of FLT degradation were proposed. In addition, the removal of FLT was also tested in actual groundwater and the results showed that by increasing the dose and pre-adjusting the solution pH, 88.8 and 100% of the FLT was removed for PMS/Fe(II)/AA and PMS/Fe(III)/AA systems. The above experimental results demonstrated that PMS/Fe(II)/AA and PMS/Fe(III)/AA processes have a great perspective in practice for the rehabilitation of FLT-polluted groundwater.

Role of biochar in superoxide-dominated dye degradation in catalyst-activated peroxymonosulphate process.

In recent times, the application of biochar (BC) as an upcoming catalyst for the elimination of recalcitrant pollutants has been widely explored. Here, an iron loaded bamboo biochar activated peroxymonosulphate (PMS) process was tested for removing Congo red (CR) dye from water medium. The catalyst was synthesized using a green synthesis method using neem extracts and characterized using SEM, FTIR, and XRD. The effects of various operating parameters, including solution pH, catalyst dosage, and pollutant dosage, on dye degradation efficiency were examined. The results showed that at the optimized conditions of 300 mg L-1 PMS concentration, 200 mg L-1 catalyst dosage, and pH 6, about 89.7% of CR dye (initial concentration 10 ppm) was removed at 60 min of operation. Scavenging experiments revealed the significant contribution of O2•-, •OH, and 1O2 for dye degradation, with a major contribution of O2•-. The activation of PMS was mainly done by biochar rather than iron (loaded on biochar). The catalyst was highly active even after four cycles.

Insight into the role of reactive species on catalyst surface underlying peroxymonosulfate activation by P-Fe2MnO4 loaded on bentonite for trichloroethylene degradation.

In this study, bentonite supporting phosphorus-doped Fe2MnO4 (BPF) was synthesized and applied for PMS activation to degrade TCE. Morphology and structure characterization results indicated the successfully synthesized of BPF, and the BPF/PMS system not only featured high TCE removal (97.4%) but also high reaction rate constant (kobs = 0.0554 min-1) and PMS utilization (70.4%, kobs = 0.0228 min-1). According to the results of various experiments, massive oxygen vacancies on P-Fe2MnO4 alter its charge balance and facilitate the electron transfer process named adjacent transfer (direct electron capture by adsorbed PMS from adjacent TCE). Mn(III) is the main adsorption site for PMS, and the hydroxyl groups on the catalyst (Fe sites of P-Fe2MnO4, Si and Al sites of bentonite) can also offer binding sites for PMS. The hydrogen-bonded PMS on Fe(III) and Mn(III) sites will subsequently accept the discharged electrons to generate free radicals and high-valent metal species. Meanwhile, electron loss of HSO5- that chemically bonded to hydroxyl groups on bentonite will generate SO5•-, which will further produce 1O2 through self-bonding. the active species on the catalyst surface contribute 65% of TCE degradation in the heterogeneous catalytic oxidation system.

Enhanced multi-metals stabilization: Synergistic insights from hydroxyapatite and peroxide dosing strategies.

Sediment contamination by heavy metals is a pressing environmental concern. While in situ metal stabilization techniques have shown promise, a great challenge remains in the simultaneous immobilization of multi-metals co-existing in contaminated sediments. This study aims to address this challenge by developing a practical method for stabilizing multi-metals by hydroxyapatite and calcium peroxide (HAP/CaO2) dosing strategies. Results showed that dosing 15.12 g of HAP/CaO2 at a ratio of 3:1 effectively transformed labile metals into stable fractions, reaching reaction kinetic equilibrium within one month with a pseudo-second-order kinetic (R2 > 0.98). The stable fractions of Nickel (Ni), Chromium (Cr), and lead (Pb) increased by approximately 16.9 %, 26.7 %, and 21.9 %, respectively, reducing heavy metal mobility and ensuring leachable concentrations complied with the stringent environmental Class I standard. Mechanistic analysis indicated that HAP played a crucial role in Pb stabilization, exhibiting a high rate of 0.0176 d-1, while Cr and Ni stabilization primarily occurred through the formation of hydroxide precipitates, as well as the slowly elevated pH (>8.5). Importantly, the proposed strategy poses a minimal environmental risk to benthic organisms exhibits almost negligible toxicity towards Vibrio fischeri and the Chironomus riparius, and saves about 71 % of costs compared to kaolinite. These advantages suggest the feasibility of HAP/CaO2 dosing strategies in multi-metal stabilization in contaminated sediments.

Facet-Dependent Fe2O3/BiVO4(110)/BiVO4(010)/Fe2O3 Dual S-Scheme Photocatalyst as an Efficient Visible-Light-Driven Peroxymonosulfate Activator for Norfloxacin Degradation.

A lack of eco-friendly, highly active photocatalyst for peroxymonosulfate (PMS) activation and unclear environmental risks are significant challenges. Herein, we developed a double S-scheme Fe2O3/BiVO4(110)/BiVO4(010)/Fe2O3 photocatalyst to activate PMS and investigated its impact on wheat seed germination. We observed an improvement in charge separation by depositing Fe2O3 on the (010) and (110) surfaces of BiVO4. This enhancement is attributed to the formation of a dual S-scheme charge transfer mechanism at the interfaces of Fe2O3/BiVO4(110) and BiVO4(010)/Fe2O3. By introducing PMS into the system, photogenerated electrons effectively activate PMS, generating reactive oxygen species (ROS) such as hydroxyl radicals (·OH) and sulfate radicals (SO4·-). Among the tested systems, the 20% Fe2O3/BiVO4/Vis/PMS system exhibits the highest catalytic efficiency for norfloxacin (NOR) removal, reaching 95% in 40 min. This is twice the catalytic efficiency of the Fe2O3/BiVO4/PMS system, 1.8 times that of the Fe2O3/BiVO4 system, and 5 times that of the BiVO4 system. Seed germination experiments revealed that Fe2O3/BiVO4 heterojunction was beneficial for wheat seed germination, while PMS had a significant negative effect. This study provides valuable insights into the development of efficient and sustainable photocatalytic systems for the removal of organic pollutants from wastewater.

Cu/N co-doped biochar activating PMS for selective degrading paracetamol via a non-radical pathway dominated by singlet oxygen and electron transfer.

The non-free radical oxidation pathway (PMS-NOPs) of peroxymonosulfate (PMS) holds significant promise for practical wastewater treatment applications, owing to its low oxidation potential, high PMS utilization rate, and robust anti-interference capability in the degradation of pollutants. A novel activator copper nitrogen co-doped porous biochar (Cu-N-BC) with rich defect edges and functional groups was obtained by adding Cu and N to the biochar matrix generated by sodium alginate through pyrolysis in this study. Under the condition of 1 mM PMS, 30 mg/L activator was used to activate PMS and achieve efficient degradation of 10 mg/L paracetamol (PCT) within 15 min, with a high reaction rate constants (kobs) of 0.391 min-1. The activation mechanism of the Cu-N-BC/PMS/PCT system was a non-radical activation pathway with the dominance of singlet oxygen (1O2) and the presence of catalyst-mediated electron transfer. The graphite nitrogen, pyridine nitrogen, and Cu-N coordination introduced by Cu/N co-doping, as well as the carbon skeleton and CO functional group of biochar, were considered active sites that promote the 1O2 generation. The Cu-N-BC/PMS system exhibits strong stability, eco-friendliness, effective mineralization, and interference resistance across diverse pH levels (3-11) and interfering ions, including Cl-, H2PO4-, NO3-, SO42-, and humic acid. Remarkably, it efficiently degrades PCT in tap and lake water, achieving a notable 63.73% TOC mineralization rate, with leached copper ions below 0.02 mg/L. This research introduces a novel method for obtaining metal nitrogen carbon activators and enhances understanding of PMS non-radical activation pathways and active sites.

Reactivity of unactivated peroxymonosulfate and peroxyacetic acid with thioether micropollutants: Mechanisms and rate prediction.

Thioether compounds, prevalent in pharmaceuticals, are of growing environmental concern due to their prevalence and potential toxicity. Peroxy chemicals, including peroxymonosulfate (PMS) and peroxyacetic acid (PAA), hold promise for selectively attacking specific thioether moieties. Still, it has been unclear how chemical structures affect the interactions between thioethers and peroxy chemicals. This study addresses this knowledge gap by quantitatively assessing the relationship between the structure of thioethers and intrinsic reaction rates. First, the results highlighted the adverse impact of electron-withdrawing groups on reactivity. Theoretical calculations were employed to locate reactive sites and investigate structural characteristics, indicating a close relationship between thioether charge and reaction rate. Additionally, we established a SMILES-based model for rapidly predicting PMS reactivity with thioether compounds. With this model, we identified 147 thioether chemicals within the high production volume (HPV) and Food and Drug Administration (FDA) approved drug lists that PMS could effectively eliminate with the toxicity (-lg LC50) decreasing. These findings underscore the environmental significance of thioether compounds and the potential for their selective removal by peroxides.

LaCoO3/SBA-15 as a high surface area catalyst to activate peroxymonosulfate for degrading atrazine in water.

An efficient perovskite-based heterogeneous catalyst is highly desired to activate peroxymonosulfate (PMS) for removing organic pollutants in water. A high surface area PMS-activator was fabricated by loading LaCoO3 on SBA-15 to degrade atrazine (ATR) in water. The LaCoO3/SBA-15 depicted better textural properties and higher catalytic activity than LaCoO3. In 6.0 min, atrazine (ATZ) degradation in the selected LaCoO3/SBA-15/PMS system, LaCoO3, adsorption by LaCoO3/SBA-15, sole PMS processes reached approximately 100%, 55.15%, 12.80%, and 16.65 % respectively. Furthermore, 0.04 mg L-1 Co was leached from LaCoO3/SBA-15 during PMS activation by LaCoO3/SBA-15. The LaCoO3/SBA-15 showed stable catalytic activity after reuse. The use of radical scavengers and electron paramagnetic resonance spectroscopy (EPR) demonstrated that ROS such as 1O2, O2•-, •OH, and SO4•- were generated by PMS activated by LaCoO3/SBA-15 owing to redox reactions [Co2+/Co3+, and O2-/O2]. EPR, XPS, ATR-FTIR, EIS, LSV, and chronoamperometric measurements were used to explain the catalytic mechanism for PMS activation. Excellent atrazine degradation was due to high surface area, porous nature, diffusion-friendly structure, and ROS. Our investigation proposes that perovskites with different A and B metals and modified perovskites can be loaded on high surface area materials to activate PMS into ROS.

Influence of microplastics and environmentally persistent free radicals on the ability of biochar components to promote degradation of antibiotics by activated peroxymonosulfate.

Microplastics (MPs) in sludge can affect the ability of biochar-activated peroxymonosulfate (PMS) to degrade antibiotics. In this work, biochar was prepared by mixing sludge and polystyrene (PS) through hydrothermal carbonization (HTC) and high-temperature pyrolysis processes. The resulting biochar was used to activate PMS to degrade ofloxacin (OFX), levofloxacin (LEV), and pefloxacin (PFX). The addition of PS significantly enhanced the ability of biochar/PMS to degrade antibiotics and the levels of environmentally persistent free radicals (EPFRs, 4.59 × 1020 spin/g) due to the decomposition of PS. The addition of PS resulted in a slight decrease in the specific surface area of biochar (2-3 m2/g on average), but a significant increase in the concentration of EPFRs increased the removal efficiency. The activation of PMS by biochar is dominated by free radicals, accounting for about 70%, in which SO4•- and •OH contribute the most and O2•- the least. However, 1O2 contributes 15-20% to the degradation of antibiotics in non-free radical processes. Overall, the process of biochar/PMS degradation of antibiotics is mainly dominated by free radicals, and the effect of non-free radicals is not obvious. Both hydrochar and pyrocarbon samples showed good hydrophilicity, and this property should improve the ability of active sites on biochar to degrade antibiotics. In the HTC process, PS can decompose during hydrochar preparation, with a maximum reduction value of 40.09%. The three-dimension excitation emission matrix fluorescence spectroscopy (3D-EEM) and total organic carbon (TOC) results show that the protein content in sludge plays a major role in reducing PS, with little effect of polysaccharide and SiO2. There are six to seven degradation intermediates of quinolone antibiotics, which are eventually degraded into CO2, H2O, and inorganic substances. The regeneration experiment showed good reusability of hydrochar and pyrocarbon, further demonstrating the suitability of biochar for the degradation of antibiotics.

Ergosterols with rare peroxide, oxetane ring moiety, and a lactone ring from Aspergillus spectabilis and their immunosuppressive activities.

Ten ergostane-type steroids, including seven undescribed ones named spectasteroids A-G, were obtained from Aspergillus spectabilis. Their structures and absolute configurations were determined based on HRESIMS, NMR, ECD calculations, and single-crystal X-ray diffraction analyses. Structurally, spectasteroid A was a unique example of aromatic ergostane-type steroid that featured a rare peroxide ring moiety; spectasteroid B contained a rare oxetane ring system formed between C-9 and C-14; and spectasteroid C was an unusual 3,4-seco-ergostane steroid with an extra lactone ring between C-3 and C-9. Spectasteroids F and G specifically showed inhibitory effects against concanavalin A-induced T lymphocyte proliferation and lipopolysaccharide-induced B lymphocyte proliferation, with IC50 values ranging from 2.33 to 4.22 µM. Spectasteroid F also showed excellent antimultidrug resistance activity, which remarkable enhanced the inhibitory activity of PTX on the colony formation of SW620/Ad300 cells.

Insights into mechanism of peroxymonosufate activation by Mo single-atom catalysts: Singlet oxygen evolution and role of Mo-N coordination.

Recently, the Fenton-like reaction using peroxymonosulfate (PMS) has been acknowledged as a potential method for breaking down organic pollutants. In this study, we successfully synthesized a highly efficient and stable single atom molybdenum (Mo) catalyst dispersed on nitrogen-doped carbon (Mo-NC-0.1). This catalyst was then utilized for the first time to activate PMS and degrade bisphenol A (BPA). The Mo-NC-0.1/PMS system demonstrated the ability to completely degrade BPA within just 20 min. Scavenging tests and density functional theory (DFT) calculations have demonstrated that the primary reactive oxygen species was singlet oxygen (1O2) produced by Mo-N4 sites. The self-cycling of Mo facilitated PMS activation and the transition from a free radical activation pathway to a non-radical pathway mediated by 1O2. Simultaneously, the nearby pyridinic N served as adsorption sites to immobilize BPA and PMS molecules. The exceptionally high catalytic activity of Mo-NC-0.1 derived from its unique Mo-N coordination, which markedly reduced the distance for 1O2 to migrate to the BPA molecules. The Mo-NC-0.1/PMS system effectively reduced the acute toxicity of BPA and exhibited excellent cycling stability with minimal leaching. This study presented a new catalyst with high selectivity for 1O2 generation and provided valuable insights for the application of single atom catalysts in PMS-based AOPs.

The inherent nature of N/P heteroatoms in Sargassum fusiforme seaweed biochar enhanced the nonradical activation of peroxymonosulfate for acetaminophen degradation in aquatic environments.

This study investigated the catalytic activity of biochar materials derived from algal biomass Sargassum fusiforme (S. fusiforme) for groundwater remediation. A facile single-step pyrolysis process was used to prepare S. fusiforme biochar (SFBCX), where x denotes pyrolysis temperatures (600 °C-900 °C). The surface characterization revealed that SFBC800 possesses intrinsic N and P heteroatoms. The optimum experimental condition for acetaminophen (AAP) degradation (>98.70%) was achieved in 60 min using 1.0 mM peroxymonosulfate (PMS), 100 mg L-1 SFBC800, and pH 5.8 (unadjusted). Moreover, the degradation rate constant (k) was evaluated by the pseudo-first-order kinetic model. The maximum degradation (>98.70%) of AAP was achieved within 60 min of oxidation. Subsequently, the k value was calculated to be 6.7 × 10-2 min-1. The scavenger tests showed that radical and nonradical processes are involved in the SFBC800/PMS system. Moreover, the formation of reactive oxygen species (ROS) in the SFBC800/PMS system was confirmed using electron spin resonance (ESR) spectroscopy. Intriguingly, both radical (O2•-, •OH, and SO4•-) and nonradical (1O2) ROS were formed in the SFBC800/PMS system. In addition, electrochemical studies were conducted to verify the electron transfer process of the nonradical mechanism in the SFBC800/PMS system. The scavenger and electron spin resonance (ESR) spectroscopy showed that singlet oxygen (1O2) is the predominant component in AAP degradation. Under optimal condition, the SFBC800/PMS system reached ∼81% mineralization of AAP within 5 min and continued to ∼85% achieved over 60 min of oxidation. Coexisting ions and different aqueous matrices were investigated to examine the feasibility of the catalyst system, and the SFBC800/PMS system was found to be effective in the remediation of AAP-contaminated groundwater, river water, and effluent water obtained from wastewater treatment plants. Moreover, the SFBC800-activated PMS system demonstrated reusability. Our findings indicate that the SFBC800 catalyst has excellent catalytic activity for AAP degradation in aquatic environments.

Edge interface microenvironment regulation of CoOOH/commercial activated carbon nano-hybrids enabling PMS activation for degrading ciprofloxacin.

Peroxymonosulfate (PMS) is widely employed to generate oxygen-containing reactive species for ciprofloxacin (CIP) degradation. Herein, cobalt oxyhydroxide @activated carbon (CoOOH@AC) was synthesized via a wet chemical sedimentation method to activate PMS for degradation of CIP. The result suggested AC can support the vertical growth of CoOOH nanosheets to expose high-activity Co-contained edges, possessing efficient PMS activation and degradation activity and catalytic stability. In the presence of 3.0 mg of optimal CoOOH@AC and 2 mM PMS, 96.8 % of CIP was degraded within 10 min, approximately 11.6 and 9.97 times greater than those of CoOOH/PMS and AC/PMS systems. Notably, it was disclosed that the optimal CoOOH@AC/PMS system still exhibited efficient catalytic performance in a wide pH range, different organics and common co-existing ions. Quenching experiments and electron paramagnetic resonance indicated that both radical and non-radical processes contributed to the degradation of CIP, with 1O2 and direct electron transfer accounting for the non-radical pathway and SO4•- and •OH serving as the main radical active species. Finally, possible CIP degradation pathways were proposed based on high-performance liquid chromatography-mass spectrometry. This study provided an alternate method for wastewater treatment based on PMS catalyzed by cobalt-based hydroxide.