Presence Of Peroxymonosulfate Research Articles

Construction of CoFe2O4/Fe2O3 S-type heterojunctions on biochar for activating peroxymonosulfate towards simultaneous removal of TC and Cr(VI)

The construction of S-type heterojunctions for restraining the rapid recombination of photogenerated charges is considered an efficient approach to boost redox capacity. Herein, the growth of CoFe2O4/Fe2O3 S-type heterojunctions on biochar (BC) was accomplished by thermal polymerization-hydrothermal. BC/CoFe2O4/Fe2O3 displayed a wide range of light absorption from 200 to 800 nm and enhanced photocurrent (0.41 μA cm−2). Furthermore, BC/CoFe2O4/Fe2O3 can remove tetracycline (TC) (98.84 %) and Cr(VI) (88.43 %) more efficiently compared to the CoFe2O4 (40.32 % of TC, 68.52 % of Cr(VI)) and Fe2O3 (29.81 % of TC, 53.67 % of Cr(VI)) single counterparts upon 45 min visible light irradiation in the presence of peroxymonosulfate (PMS). Free radical capture experiments revealed that •OH, •O2−, and SO4−• are the primary activated species for the removal of TC and e− is the major activated species for the removal of Cr(VI). Meanwhile, the degradation pathway of TC was monitored via LC-MS and Fukui index calculations. Combining density functional calculations (DFT) with UPS and radical capture tests, the possible mechanism of photocatalytic degradation was proposed. The findings demonstrated the remarkable photocatalytic activity and stability of the photocatalyst, evidencing the potential of BC/CoFe2O4/Fe2O3 for practical wastewater treatment.

Enhanced Photodegradation of Acetaminophen Using Efficient ZnO-NiO Nanofibers

The increasing presence of pharmaceutical pollutants, such as acetaminophen, in water bodies poses a significant environmental challenge due to their persistence and potential toxicity. This study investigated the enhanced photodegradation of acetaminophen using ZnO-NiO nanofibers as superior photocatalysts. The nanofibers synthesized with varying NiO contents (designated as ZN0.5, ZN1, ZN1.5, and ZN2), were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, FTIR, Brunauer–Emmett–Teller (BET) analysis, and diffuse reflectance spectroscopy (DRS) to elucidate their structural, morphological, and optical properties. Thermogravimetric analysis (TGA) indicated that the nanofibers exhibit high thermal stability, with major weight loss attributed to the decomposition of the polymer matrix and residual organics. The BET analysis revealed that the specific surface area remains stable after increasing the NiO content up to a certain ratio. This stability correlates with the enhanced photocatalytic performance due to increased light absorption and improved charge separation. The diffuse reflectance spectra and Kubelka–Munk plots demonstrated a reduction in bandgap energy with higher NiO content, facilitating greater visible light absorption. Photocatalytic experiments under visible light irradiation, in the presence of peroxymonosulfate (PMS), showed that the ZN1.5 nanofibers achieved the highest acetaminophen degradation rate, i.e., 92%, within 3 h. Mechanistic studies, supported by radical trapping experiments, revealed that the improved photocatalytic efficiency is due to the synergistic effects of ZnO and NiO heterojunctions, which enhance charge separation and reactive oxygen species (ROS) generation. This research highlights the potential of ZnO-NiO nanofibers as effective photocatalysts for the degradation of pharmaceutical pollutants. The findings demonstrate that optimizing the composition and structure of nanofibers can significantly improve their environmental remediation capabilities, providing a promising solution for sustainable water treatment.

In situ-growth of Fe2S3 ultrathin layer on CdS nanorod through cation-exchange for efficient photocatalytic degradation of organic pollutants under visible light coupled oxidant activation

A new core-shell structure CdS@Fe2S3 material was synthesized by in situ cation exchange method to enhance the degradation of organic pollutants in water under visible light. It is proved that Fe2S3 nanolayer is successfully loaded on CdS nanorods by TEM and UV-Vis spectra and other means. The representative Rhodamine B was selected as the target pollutant and the results of degradation experiment showed that after 60 min of exposure to LED visible light with a low energy (25 W), the removal efficiency for this dye could reach 98 % in the presence of peroxymonosulfate (PMS) forming free radicals, which displayed a observed kinetic rate constant exceeding 0.62 min−1 that is approximately 5 times higher than the system without PMS addition and 10 times than the system with original CdS as catalyst. The result of inhibition experiments shows that sulfate radical (SO4·-) and singlet oxygen (1O2) play as important roles during the photocatalytic process. In addition, this core-shell material can be recycled at least four times. Generally, this study can make full use of visible light which can be easily obtained and effectually resolve the organic pollution problems.

Elucidating the mechanism on carbon nanotube-coated cobalt phosphide catalyst activating PMS to degrade norfloxacin contaminants

Transition metal phosphides have shown great potentials in persulfate activation for eliminating organic contaminants, while the understanding of the activation mechanism still remains fragmentary. Herein, a series of nitrogen-phosphorus-doped carbon nanotube-coated cobalt phosphide catalysts (Co/P-CNTs) were synthesized for activating peroxymonosulfate (PMS) to degrade norfloxacin (NOR). The optimal Co/P-CNTs-0.3 could eliminate NOR up to 97 % within 60 min in the presence of PMS. Results confirm that the synergistic interaction between multi-valent Co species in the Co/P-CNTs significantly contributes to the excellent PMS activation performance. The contribution of reactive oxygen species (ROS) to pollutant removal and the steady-state concentration of free radicals were quantitatively analyzed by means of chemical probe and reaction kinetics. A free radical mechanism dominated by SO4•– and NOR degradation pathway were identified, and the effect of coexisting inorganic anions was systematically evaluated. This study offers profound insights into the activation mechanism of metal phosphides towards environmental remediation.

Constructing S-scheme Au/g-C3N4/BiVO4 heterojunction with peroxymonosulfate-enhanced photocatalytic activity and mechanism insight

Dissolved organic matter (DOM) in black-odorous water can cause excessive growth of plants and algae, leading to deterioration of water quality. Herein, an S-scheme Au/g-C3N4/BiVO4 heterojunction was constructed using a three-step method for DOM degradation in real black-odorous water in the presence of peroxymonosulfate (PMS). 4Au/g-C3N4/BiVO4/PMS exhibited highly efficient photocatalytic performance, and the DOM removal rate could reach 92.9 %, which was 19.1 and 9.9 times higher than that of g-C3N4/PMS and BiVO4/PMS, respectively. The changes of fluorescence components in DOM were detected using synchronous fluorescence spectra and two-dimensional correlated spectroscopy analysis, and the toxicity of catalytically treated black-odorous water was evaluated by growth inhibition of Escherichia coli. A reasonable S-scheme mechanism was suggested by theoretical calculations and photoelectrochemical tests. The S-scheme mechanism and the synergistic effect of photocatalysis and hybrid advanced oxidation process (HAOP) increased the catalytic activity of Au/g-C3N4/BiVO4/PMS.

Heterogeneous sulfate radical-mediated benzotriazole oxidation by ferrospinel nanoparticles catalyzed peroxymonosulfate: A catalyst for environmental remediation

The sulfate radical-based advanced oxidation process has been widely investigated via peroxymonosulfate (PMS) activation in recent years, in which the development of catalysts with high efficiency and stability is crucial. The current work prepared a series of magnetic nanoparticles, including CuFe2O4 (CuF) and CoFe2O4 (CoF), for benzotriazole (BTA) degradation via PMS activation. Various techniques (XRD, VSM, BET, FESEM, and TEM) employed to examine the physicochemical, textural, magnetic, and structural characteristics of the as-prepared catalysts. Moreover, a response surface methodology (RSM) based on central composite design (CCD) used to identify the optimum levels of operational variables and explore the interactions between them. The results showed that 99.7 and 100% of BTA can be removed under optimal conditions when CuF and CoF catalysts were applied in the system in the presence of PMS, respectively. Both catalysts exhibited high degradation efficiencies, even after eight consecutive cycles, highlighting their high stability and reusability in decontamination applications. According to the trapping tests, HO• and SO4•– species were responsible for the BTA degradation in both systems. These results suggested that CuF and CoF could be applied as effective recoverable catalysts for activating PMS and degrading persistent pollutants in wastewater treatment.

Recyclable and dual-functional Ag3PO4/3D graphene aerogel photocatalysts for simultaneous water oxidation and pollutant degradation

Exploiting recyclable and reusable photocatalysts in pollutants elimination and water splitting has drawn extensive research attention for solving the increasing energy and environmental issues. Herein, we designed a high-performance dual functional Ag3PO4/three-dimensional (3D) graphene aerogel (APGA) photocatalyst, in which the 3D GA with extremely lightweight and high mechanical stability served as the support for Ag3PO4 particles, preventing the serious weight loss during the recovery process. Moreover, different from the traditional powder photocatalysts, the application of 3D GA support avoided the secondary contamination caused by the catalyst residue during the reaction. The abundant hydroxyl groups on the surface of porous 3D GA prevented the aggregation of Ag3PO4 particles, forming a close interfacial contact. Profiting from the large number of active sites and high conductivity of 3D GA, the optimized APGA-12 sample showed excellent O2 generation (814.1 μmol·g−1) and synchronous Cr (VI) reduction (87.5 %) efficiency. In addition, the APGA-12 sample also exhibited excellent carbamazepine (CBZ) degradation activity (99 % within 30 min) in the presence of peroxymonosulfate (PMS). Cycling experiments combined with the scaled-up reactions verified the good mechanical and chemical stability of APGA samples. This work provided a promising strategy for solving the problems of catalyst recycling in the field of pollutant degradation and water oxidation.

Preparation of Cobalt-Nitrogen Co-Doped Carbon Nanotubes for Activated Peroxymonosulfate Degradation of Carbamazepine.

Cobalt-nitrogen co-doped carbon nanotubes (Co3@NCNT-800) were synthesized via a facile and economical approach to investigate the efficient degradation of organic pollutants in aqueous environments. This material demonstrated high catalytic efficiency in the degradation of carbamazepine (CBZ) in the presence of peroxymonosulfate (PMS). The experimental data revealed that at a neutral pH of 7 and an initial CBZ concentration of 20 mg/L, the application of Co3@NCNT-800 at 0.2 g/L facilitated a degradation rate of 64.7% within 60 min. Mechanistic investigations indicated that the presence of pyridinic nitrogen and cobalt species enhanced the generation of reactive oxygen species. Radical scavenging assays and electron spin resonance spectroscopy confirmed that radical and nonradical pathways contributed to CBZ degradation, with the nonradical mechanism being predominant. This research presents the development of a novel PMS catalyst, synthesized through an efficient and stable method, which provides a cost-effective solution for the remediation of organic contaminants in water.

Advanced sustainable processes via functionalized Fe–N co-doped fishbone biochar for the remediation of plasticizer di-(2-ethylhexyl) phthalate-contaminated marine sediment

Sediments are important sinks for di-(2-ethylhexyl) phthalate (DEHP), a plasticizer, and thus, maintaining the sediment quality is essential for eliminating plasticizers in aqueous environments and recovering the sediment ecological functions. To mitigate the potential risks of endocrine-disrupting compounds, identifying an effective and eco-friendly degradation process of organic pollutants from sediments is important. However, sustainable and efficient utilization of slow pyrolysis for converting shark fishbone to generate shark fishbone biochar (SFBC) has rarely been explored. Herein, SFBC biomass was firstly produced by externally incorporating heteroatoms or iron oxide onto its surface in conjunction with peroxymonosulfate (PMS) to promote DEHP degradation and explore the associated benthic bacterial community composition from the sediment in the water column using the Fe-N-SFBC/PMS system. SFBC was pyrolyzed at 300–900 °C in aqueous sediment using a carbon-advanced oxidation process (CAOP) system based on PMS. SFBC was rationally modified via N or Fe–N doping as a radical precursor in the presence of PMS (1 × 10−5 M) for DEHP removal. The innovative SFBC/PMS, N-SFBC/PMS, and Fe-N-SFBC/PMS systems could remove 82%, 65%, and 90% of the DEHP at pH 3 in 60 min, respectively. The functionalized Fe3O4 and heteroatom (N) co-doped SFBC composite catalysts within a hydroxyapatite-based structure demonstrated the efficient action of PMS compared to pristine SFBC, which was attributed to its synergistic behavior, generating reactive radicals (SO4•–, HO•, and O2•–) and non-radicals (1O2) involved in DEHP decontamination. DEHP was significantly removed using the combined Fe-N-SFBC/PMS system, revealing that indigenous benthic microorganisms enhance their performance in DEHP-containing sediments. Further, DEHP-induced perturbation was particularly related to the Proteobacteria phylum, whereas Sulfurovum genus and Sulfurovum lithotrophicum species were observed. This study presents a sustainable method for practical, green marine sediment remediation via PMS-CAOP-induced processes using a novel Fe-N-SFBC composite material and biodegradation synergy.

Facile hydrothermal synthesis and continuously improved sonophotocatalytic performance of PO4-doped Bi2WO6 nanoplates

The doping of ionic group composed of various atoms can play a great role in regulating electronic structure, optimizing light absorption capacity, and enhancing the catalytic performance of semiconductor catalysts. Herein, we took a urea-precipitate assisting hydrothermal route for preparing PO4-doped Bi2WO6 nanoplates and discussed the effect of the ionic group doping on the sonophotocatalytic performance toward the degradation of pollutant. The result of the X-ray photoelectron spectrometer (XPS) measurements revealed that abundant oxygen vacancies were formed in PO4-doped Bi2WO6 owing to the incorporation of the ionic group, which would contribute to the regulation of electronic structure and activated carriers’ migration rate. The sonophotocatalytic activity toward the removal of tetracycline hydrochloride (TCH) was investigated under visible-light coupling with ultrasonic irradiation. The results showed that PO4-doped Bi2WO6 nanoplates possessed higher sonophotocatalytic degradation rate than pure Bi2WO6. More interestingly, the TCH removal efficiency was continuously improved over PO4-doped Bi2WO6 nanoplates with the assistance of the sulfate radical-mediated technique. Based on the comprehensive discussion and analysis, a possible enhancement mechanism of the sonophotocatalytic behavior was proposed for PO4-doped Bi2WO6 nanoplates catalyst in the presence of peroxymonosulfate.

Enhanced visible-light-driven peroxymonosulfate activation for antibiotic mineralization using electrosynthesized nanostructured bismuth oxyiodides thin films

The search for non-specific catalysts capable of removing a wide range of organic contaminants remains a key challenge given their increasing presence in aquatic environments. In this ongoing exploration, this work proposes the use of bismuth oxyiodides as activators of ecological oxidative radicals, wherein raw substances like peroxymonosulfate (PMS) gain prominence due to the valuable efficiency of the radicals they can generate. For BiOI, serving as a precursor to the photocatalysts, the effect of the electroactive solution components on its electrochemical preparation was analyzed using the voltamperometric technique. The compositional and structural characterization confirmed successful formation. Deposit annealing treatments result in new species such as Bi7O9I3 at 250ºC and, primarily, Bi5O7I at 420 or 520ºC—species that also exhibit visible light absorption, paving the way for their use under sunlight. Initially, a single tetracycline (TC) solution was employed to test the degradation and mineralization capability of the prepared films, assessing the impact of the solution's pH, the presence of PMS, light irradiation, and annealing temperature. The annealing temperature increases the catalytic effect. It is noteworthy that for all bismuth iodide films, the highest catalytic activity was observed when combining PMS and visible light irradiation, showcasing a synergistic improvement. This trend holds for multipollutant solutions as well. In a crucial role for the material's application, the results demonstrate that annealing temperatures below 450ºC promote films that reasonably maintain their activity and chemical stability after continuous reuse.

Photocatalytic persulfate activation by highly dispersed nano-TiO2 supported by silica for efficient carbamazepine degradation

A silica-loaded nano-TiO2 composite (A-SiO2/TiO2) was prepared by wet-grinding method, using industrial silica (A-SiO2) as the carrier. A-SiO2/TiO2 was used for photocatalytic activation of peroxymonosulfate (PMS) to degrade carbamazepine (CBZ). The A-SiO2/TiO2 containing 20 wt% nano-TiO2 resulted in the CBZ degradation efficiency of 94.83 % after 90 min simulated sunlight irradiation with the presence of PMS. The main reactive species during CBZ degradation in the system of photocatalytic PMS activation by A-SiO2/TiO2 were O2•−, •OH and SO4•−. Compared to nano-TiO2, A-SiO2/TiO2 exhibits enhanced dispersion, increased surface active sites and improved photo-generated carrier separation efficiency, which contributed to enhanced degradation performance.

Silver zirconate: A versatile visible light harvesting photocatalyst for oxygen evolution, PMS activation, and bactericidal activity

Herein, we have synthesized silver zirconate using a co-precipitation method at room temperature. The synthesized Ag2ZrO3 (SZ) was then subjected to calcination at different temperatures (300 °C, 500 °C, and 700 °C). The synthesized Ag2ZrO3 materials were evaluated for their photocatalytic oxygen evolution, activation of peroxymonosulfate (PMS) ions, and antibacterial activity under visible light irradiation. Among the different samples, the SZ sample (Ag2ZrO3 synthesized at room temperature) exhibited the highest photocatalytic oxygen evolution rate (2175.02 μmolg-1h−1). This enhanced performance can be attributed to the higher surface area of SZ compared to the other samples. Furthermore, all four samples were tested for the photoactivation of peroxymonosulfate (PMS) ions to assess their ability for the decontamination of organic pollutant. The SZ photocatalyst demonstrated complete degradation (100 %) of RhB dye (2.1 × 10-5 M) within 120 min of visible light irradiation in the presence of PMS. In contrast, without PMS, only 54.33 % degradation of RhB was recorded in 300 min. This result indicates that SZ effectively activates PMS ions for the degradation of organic pollutants. Additionally, SZ exhibited excellent bactericidal activity against E. coli and S. aureus bacteria, both in the dark and in the presence of visible light. The findings demonstrate the multifunctional properties of Ag2ZrO3, making it suitable for a wide range of environmental remediation applications.

Unravelling the activation mechanism of oxidants using copper ferrite nanopowder and its application in the treatment of real waters contaminated by phenolic compounds

Copper ferrites (CuFe2O4) nanopowder was prepared via hydrothermal method followed by annealing at 500 °C, and XRD, SEM, XPS and UPS were employed for its characterization. CuFe2O4 was tested for the catalytic degradation of bisphenol A (BPA) in the dark and under UVA light, both in the presence of peroxymonosulfate (PMS) or peroxydisulfate (PDS) as radical precursor under natural pH of 6.2. While the individual photo-induced processes i.e., photocatalysis (using CuFe2O4 alone) and photolysis of either PMS or PDS, exhibited limited efficiencies in BPA degradation, a significant increase of performance was observed by combining CuFe2O4 and UVA light with either PMS or PDS with a synergy effect of 3.8 and 34.1, respectively. Under the optimal conditions, employing 0.5 g/L of nanopowder, the degradation constant of 25 µM BPA was 0.211 min−1 with 2 mM of PMS and 0.018 min−1 with 2 mM of PDS, and resulted in the complete degradation of BPA within less than 20 min. The activation mechanism of PMS and PDS using CuFe2O4 was elucidated, revealing sulfate radicals as the primary reactive species in PMS-containing systems, whereas a predominantly non-radical pathway was observed in the presence of PDS. Indeed, advanced spectroscopic techniques indicated that surface copper played an important role in the non-radical pathway. Furthermore, the CuFe2O4/PMS/UVA system exhibited high performance in the degradation of different phenolic compounds including BPA, phenol and p-nitrophenol in real water matrices. These achievements were observed across different real water matrices with a particular emphasis on sewage treatment plant water.

A comparative investigation on the decomposition of triclosan via synthesized heterogeneous nano-catalysts in the presence of peroxymonosulfate

Advanced oxidation (AOPs) utilizing peroxymonosulfate (PMS) are efficient processes for the degradation of organic pollutants. This study aimed to synthesize and characterize cobalt ferrite (CoFe2O4), graphene oxide (GO), MIL-101(Fe), and their composite structures. The nanomaterials were applied as catalysts by PMS for triclosan (TCS) decomposition. The maximum removal rates of TCS were 49.29, 66.13, 84.04, 89.73, and 100% for PMS alone, CoFe2O4, GO, MIL-101(Fe), and CoFe2O4/MIL-101(Fe)/GO with PMS, respectively. Metal ions leaching declined in CoFe2O4/MIL-101(Fe)/GO/PMS compared with others. Hence, the composite nanomaterials appear to be effective catalysts for the degradation of organic pollutants by PMS activation.

Regulating the peroxymonosulfate activation on N doped δ-MnO2 nanosheets for tetracycline degradation: N species as the degradation pathways switcher to convert radical to nonradical

Although the free radical pathway can obtain high organic degradation efficiency during advanced oxidation processes, it is difficult to cater the diverse degradation environment due to the coexistence of various interference. Here, the δ-MnO2 nanosheets are prepared to regulate the reactive oxidation species converting from radical-dominated to nonradical-dominated through the nitrogen doped operation in a gentle mechanical stirring method. The optimal 0.5 N-MnO2 materials present 91.2 % TC degradation efficiency in the presence of peroxymonosulfate (PMS) with the apparent rate constant is 0.63 min−1, which is 1.66 and 4.2 times higher than that of in δ-MnO2/PMS (0.38 min−1) and alone PMS (0.15 min−1) systems,respectively. Radicals quenching experiments, electron paramagnetic resonance spectra and competing kinetics experiments indicate that the δ-MnO2 nanosheets promote PMS decomposition with attaining a high radical (SO4·-, ·OH and ·O2–) oxidation path contribution (74.5 %) for TC degradation. Meanwhile, the doping of N species and electrons contribute to the generation of 1O2, allowing the whole reactive system dominated by a nonradical species (e- and 1O2) pathway (80.3 %). Importantly, electrochemical tests verify the participation of electrons and the electrons transfer from TC to the 0.5 N-MnO2 surface for PMS activation via 0.5 N-MnO2-PMS* surface complex. Overall, it is practical to cater the specific application of advanced oxidation processes through N as the degradation pathways switcher.

Efficient defluorination of perfluorooctanoic acid enabled by single-atom Cu/reduced graphene oxide electrocatalytic anode and peroxymonosulfate activation

In this study, an electrocatalytic system using reduced graphene oxide supported single-atom copper (SA-Cu/rGO) anode was constructed for perfluorooctanoic acid (PFOA) defluorination. The successful doping of SA-Cu elevated the oxygen evolution potential and electrochemical active surface area of the anode and provided high electrocatalytic properties. Under optimum initial conditions with a peroxymonosulfate (PMS) concentration of 10 mM, a current density of 15 mA·cm−2, and an unadjusted pH of 7.75, the SA-Cu/rGO system achieved 98.8% removal ratio, 92.5% defluorination, and 94.4% mineralization of 20 mg·L-1 PFOA in 120 min. Kinetic studies indicate PFOA degradation following a pseudo-first-order model, with a rate constant of 4.7 × 10−2 min−1. The presence of PMS in the electrocatalytic system significantly improved the degradation rate and defluorination ratio. Radical trapping and quenching experiments confirmed that both ·OH and ·SO4- radicals contributed to PFOA degradation, with ·SO4- playing a more important role in defluorination. The system show high flexibility in initial PFOA concentrations (0.2–20 mg·L−1) and environmental pH values (3.0–10.0), as well as good durability. The electrocatalytic degradation mechanism of PFOA was proposed through determination of intermediates and density functional theory (DFT) calculation. The total short-chain perfluorocarboxylic acids (PFCAs) intermediates generated throughout the degradation were far from sufficient recovery of the PFOA loss, indicating that apart from the ·OH mediated decarboxylation-hydroxylation-elimination-hydrolysis (DHEH) pathway, the ·SO4- mediated decarboxylation-hydroxylation-oxidation-decarbonyl fluoride (DHOD) pathway may play a significant role in the near-complete defluorination and mineralization of PFOA. Moreover, DFT calculations suggest that the DHOD pathway is energetically favorable over DHEH. This study provides a further understanding of the defluorination mechanism of PFOA in electrocatalytic systems and demonstrates that electrochemical degradation with single-atom copper catalyst is an promising method for PFOA remediation in aqueous environment.

Treatment of textile dye wastewater by peroxymonosulfate activation using facilely prepared Fe3O4@TiO2 heterogeneous photocatalyst

AbstractIn this study, Fe3O4@TiO2 was synthesized by a facile precipitation–impregnation method and applied as a magnetic photocatalyst for degrading synthetic and actual textile dyeing wastewater in the presence of peroxymonosulfate (PMS). In Rhodamine B (RhB) degradation, the removal efficiency reached 99.86% (for RhB) and 93.67% (for color) under optimal operating conditions of 80 mg L–1 RhB, 0.5 g L–1 PMS, 0.5 g L–1 Fe3O4@TiO2, at pH 6, and after 30 min of UVA irradiation. The influence levels of anions on the RhB removal and decolorization were in the order of Cl− < SO42− < CO32− < PO43−. In addition, the Fe3O4@TiO2 composite exhibited good applicability for treating other dyes (e.g., 99.6% of tartrazine and 60.3% of methylene blue after 30 min) in water and actual textile dyeing wastewater with high color (70.3% after 5 min) and COD removal (71.4% after 120 min). The radical scavenging tests indicated the role of reactive oxygen species in the order of O2•− ∼ 1O2 > h+ > SO4•− > HO• for RhB degradation but O2•− > h+ > 1O2 > SO4•− > HO• for decolorization. These results suggest the potential application of PMS activation using Fe3O4@TiO2 in the photocatalytic treatment of textile and dyeing wastewater with the dominant role of O2•−.

Iron-Cobalt magnetic porous carbon beads activated peroxymonosulfate for enhanced degradation and Microbial inactivation

Magnetic carbon-based catalysts are promising materials for advanced oxidation processes, offering both high catalytic activity and environmental friendliness, and hold great potential in environmental remediation. In this work, Fe and Co zeolite imidazole frameworks (ZIFs) derived micron-sized magnetic porous carbon beads (MPCBs) were prepared by phase inversion and following the carbonization procedure, and the morphological and structural characteristics of the MPCBs were confirmed. The presence of pores and channels in the MPCBs provides a specific microenvironment for the for the catalysis of the core. Bisphenol A (BPA) was selected for the targeted pollutant, and the catalytic experiments confirmed that the effective catalytic activity of MPCBs in the presence of peroxymonosulfate (PMS), which could almost completely degrade BPA in 20 min with a reaction rate of 0.368 min−1. Furthermore, the MPCBs were used to effectively bacterial inactivation. Intermediate products of the BPA degradation process were validated and the toxicological studies showed a gradual decrease in toxicity, indicating effective reduction of potential hazards. The macroscopic preparation methods we developed for MPCBs that is promising for industrial applications and has the potential to cope with complex environmental remediation.

Efficient and sustainable photocatalytic inactivation of E. coli by an innovative immobilized Ag/TiO2 photocatalyst with peroxymonosulfate (PMS) under visible light

A novel catalytic system for effective photocatalytic inactivation of Escherichia coli (E. coli) was constructed by anchoring Ag nanoparticles (AgNPs) on silane coupling agent (SCA) pretreated TiO2 nano-tube arrays (Ag/SCA/TiO2NTAs). Morphology and structural analyses revealed that SCA could disperse AgNPs evenly on TiO2NTAs, thus inducing a superior surface plasmon resonance (SPR) effect. Ag/SCA/TiO2NTAs catalyst exhibited excellent inactivation performance when in the presence of peroxymonosulfate (PMS) and visible light (VL), with 6-log E. coli was completely inactivated within 60 min, which was 5.3, 12.5 and 13.2 times higher than that of Ag/SCA/TiO2NTAs/VL, PMS/VL and Ag/SCA/TiO2NTAs/PMS/dark systems, respectively. Additionally, the photocatalyst exhibited a highly reusable property, with the inactivation performance almost unchanged after ten cycles of uses with minimal Ag leaching. The inactivation mechanism analysis demonstrated that both radical (SO4•-, OH) and non-radical (h+, 1O2) pathways involved in E. coli inactivation, and SCA played a pivotal role in the production of reactive species. Chloride ions (Cl−) greatly enhanced the inactivation efficiency, while bicarbonate (HCO3−) and phosphate (H2PO4−) showed an inhibitory effect. Humic acid (HA) displayed a dual effect on inactivation performance, where the low concentration of HA facilitated the bacteria inactivation, while the higher dose suppressed bacteria inactivation. Moreover, the system exhibited excellent inactivation performance in tap water. This work first used SCA as the binder to fix AgNPs on TiO2NTAs for VL photocatalytic inactivation of bacteria with the assistance of PMS, which was expected to provide some insights into the practical treatment of drinking water.