photo-Fenton Activity Research Articles

Highly efficient photocatalysis-Fenton degradation of antibiotics and phenol over sulfidated FeOCl under natural sunlight illumination

Sulfidated FeOCl is prepared as a heterogeneous photo-Fenton catalyst. And the surface sulfidation of FeOCl can remarkably accelerate the photoinduced charge separation and transfer, while also increase Fe2+/Fe3+ atomic ratio, leading to the boosted photo-Fenton activity in the presence of H2O2. Under irradiation of natural sunlight (light intensity: ∼80 mW·cm−2), over 10 mg sulfidated FeOCl catalyst with using 20 μL 15 % H2O2, 91.2 % of ofloxacin solution (50 mg·L−1) and 97.5 % of sulfisoxazole solution (60 mg·L−1) can be degraded in 80 min, and 99.6 % of phenol solution (625 mg·L−1) is decomposed in 4 h. Under irradiation of a white Light-Emitting Diode (LED) lamp (light intensity: 5 mW·cm−2), 99.8 % of ofloxacin solution is decomposed after treatment for 4 h. Moreover, this photo-Fenton degradation system displays a stable activity in a wide range of pH (1−10), diverse water bodies, and various coexisting ions with concertation from 1 mM to 500 mM. Moreover, sulfidated FeOCl catalyst coated on a frosted glass sheet exhibits excellent stability for degrading ofloxacin even in seven continuous cycles. Particularly, the non-toxicity of the treated ofloxacin, sulfisoxazole, and phenol solution, have been proven by testing their toxic effects on cabbage seed, bacteria, and human embryonic kidney cell, respectively.

Iron mediated n → π* electron transitions and mid-gap states formation in CN under low-temperature secondary calcination enhances photodegradation of organic pollutants

Iron modified carbon nitride (CN) materials have attracted widespread attention from researchers in different application fields. In this paper, single atom iron anchored CN (FeCN) with mid-gap states and n → π* electron transition was synthesized through low temperature secondary calcination. The mid-gap states introduce surface states capable of trapping photogenerated electrons, enabling FeCN to absorb photons with energies lower than its intrinsic optical bandgap. 10%FeCN also exhibits distinct optical absorption above 490 nm derived from the n → π* electron transition, which expand the visible light response range of photocatalysts and enhance electron transport ability. Additionally, the Fe-Nx site enhances the separation and transmission efficiency of photoexcited charges. The prepared 10%FeCN exhibits extremely high photocatalysis and photo-Fenton activity. Mercaptobenzothiazole (MBT) degradation rate of 10%FeCN is 3.47 times higher than CN, achieving a mineralization rate of 86.7% in 100 min. Additionally, the oxytetracycline hydrochloride (OTC) degradation rate of 10%FeCN in photo-Fenton reaction is 11.9 times higher than CN. After five cycles, this catalyst still has good reactivity, indicating its good stability.

Development of hydrothermal carbonaceous carbon/NH2-MIL-101(Fe) composite photocatalyst with in-situ production and activation of H2O2 capabilities for effective sterilization

Photocatalytic production of H2O2 has garnered significant attention, but the use of sacrificial reagents in H2O2 photosynthesis and the subsequent limited H2O2 activation efficiency would impede its practical application in water decontamination. In this work, hydrothermal carbonaceous carbon/NH2-MIL-101(Fe) (abbreviated as HTC-cf/NMIL-101(Fe)) heterojunction was fabricated through a solvothermal strategy, and serving as a self-sufficient photo-Fenton-like catalyst to in-situ generate and activate H2O2. Hydrothermal carbonaceous carbon derived from cost-effective waste coffee grounds, serving as a green and sustainable photocatalyst, demonstrated high H2O2 production rate of 612 μmol/g/h without the need for sacrificial reagents or aeration assistance. Moreover, the excellent self-sufficient photo-Fenton activity for HTC-cf/NMIL-101(Fe) can be obtained, which ascribed to the synergistic effect of self-generated H2O2 production as well as the in-situ catalytic H2O2 decomposition of •OH by Fe species in NMIL-101(Fe) and photogenerated electrons. The optimized HTC-cf/NMIL-101(Fe) photocatalyst showed simultaneous improvements in both H2O2 production and activation capabilities. Impressively, the effective circulation of Fe3+/Fe2+ in NMIL-101(Fe), aided by photogenerated electrons, results in a 5-fold increase toward H2O2 decomposition rate constant (Kd) compared to HTC-cf alone under light irradiation in open-air conditions. The enhanced charge separation and appropriate band structure of HTC-cf/NMIL-101(Fe) photocatalyst assured the high selectivity of two-electron O2-reduction to H2O2. HTC-cf/NMIL-101(Fe) displayed excellent photocatalytic sterilization efficiency against E. coli and S. aureus under visible light, and its sterilization application in actual water was also demonstrated. Notably, the adaptability of this system to ambient conditions, including open-air atmosphere, non-sacrificial reagents, and low leaching of Fe ions, highlights the promising practical utility of the HTC-cf/NMIL-101(Fe) photocatalyst.

Construction of Bi2S3/FeWO4 Z-Scheme heterojunction for efficient photo-Fenton degradation of antibiotics: Performance and degradation mechanism

Herein, the Bi2S3/FeWO4 (BS/FWO) nanocomposite with excellent photo-Fenton activity was successfully prepared by dispersing FeWO4 nanoparticles onto the Bi2S3 nanorods using the hydrothermal method. Upon optimizing the ratio of Bi2S3 to FeWO4 in the BS/FWO photocatalyst, the degradation rate constants for tetracycline hydrochloride (TCH) and oxytetracycline (OTC) reach as high as 1.597 and 1.289 L·mg−1·min−1, respectively. These values were 5.4 and 6.1 times higher than those of pure FeWO4. The enhanced degradation performance of the BS/FWO composite could be attributed to the formed Z-scheme heterojunction, which facilitated the directional carrier transfer and inhibited the electron-hole recombination, thereby increasing the production of more reactive species. Active species capture experiments and electron paramagnetic resonance (EPR) analysis indicated that the BS/FWO heterojunction could generate superoxide radicals (·O2-) and hydroxyl radicals (·OH), which play a crucial role in the degradation of organics. Furthermore, the BS/FWO composite exhibited excellent stability across multiple reuse cycles. These findings propose a novel approach for wastewater treatment.

Construction of 2D porous g-C3N4 by steam reforming with the introduction of Fe clusters forming Fe-Nx to enhance photo-Fenton catalytic activity

In this study, the Fe clusters were anchored onto 2D porous g-C3N4 nanosheets to synthesize Photo-Fenton catalysts Fe-CNS with highly and uniformly dispersed Fe-Nx active sites via a supramolecular thermal polymerization and subsequent impregnation strategy. The obtained Fe-CNS composites exhibited excellent Photo-Fenton catalytic activity and stability even under high pH and anion conditions, suggesting Fe clusters doping into 2D porous g-C3N4 nanosheets host through Fe-Nx coordination structures enhanced the separation efficiency of light-generated charge carriers, promoted Fe3+/Fe2+ redox cycle, accelerated the activation of H2O2 and improved the stability of Fe species and leading to a remarkable Photo-Fenton synergistic effect. Among these Fe-CNS composites, Fe-CNS with doping amount of 7 % Fe species shows superior Photo-Fenton activity for the elimination of Tetracycline (TC), and the corresponding k value is 0.04729 min−1, which is 25.4 times superior to that of photocatalytic oxidation TC of bulk g-C3N4, indicating that the strategy on changing Fe doping amount yielded opportunity to optimize Photo-Fenton combined action between Fe clusters and g-C3N4 nanosheets host. The degradation mechanism of TC using Fe-CNS composites in the Photo-Fenton system has been further elucidated by considering that the embedded Fe clusters in the N-rich 2D g-C3N4 nanosheets form abundant Fe-Nx active sites.

Photo-Fenton-Active MIL-88A/CNT-Based PVA Hydrogel for Solar-Driven Water Evaporation and Simultaneous Volatile Organic Compound Removal.

Solar-driven interfacial water evaporation (SIWE) has emerged as a promising avenue for cost-effective freshwater production from seawater or wastewater. However, the simultaneous evaporation of volatile organic compounds (VOCs) presents a limitation for the widespread implementation of this technique. Thus, developing dual-functional evaporators capable of both desalining seawater and degrading VOCs is challenging. Herein, we fabricated an iron-based metal-organic framework MIL-88A/carbon nanotubes (CNTs) poly(vinyl alcohol) hydrogel (MCH) evaporator via the conventional freezing method for solar-driven seawater desalination and simultaneous photo-Fenton VOC degradation. Because of the superior photothermal conversion capability of CNTs, reduced thermal conductivity and water evaporation enthalpy within the hydrogel, and the photo-Fenton activity of rod-shaped MIL-88A, the MCH evaporator exhibits a higher evaporation rate of 2.26 kg m-2 h-1 under 1 sun illumination with simultaneous VOC degradation. The higher hydrophilicity and vertical channels in the MCH evaporator enable its self-salt cleaning ability, facilitating consistent seawater desalination, even in high salt concentrations up to 10 wt %. The synergistic effects of localized heating from CNTs and hydrogen peroxide activation through reactive sites of MIL-88A allow the MCH evaporator to degrade more than 93% of the added phenol during evaporation. This work presents a sustainable and efficient approach for solar-driven seawater desalination, offering simultaneous VOC degradation.

Ginkgo biloba-derived biochar loaded with FeOCl for photo-Fenton degradation of tetracycline

A series of FeOCl/biochar composite catalysts were synthesized from Ginkgo biloba using a calcination method for the purpose of degrading tetracycline (TC). Photo-Fenton tests revealed that the activities of FOC/GBC-0.2, FOC/GBC-0.5, FOC/GBC-0.8, and FOC/GBC-1 catalysts surpassed that of pure FeOCl. Notably, FOC/GBC-0.5 exhibited the highest photo-Fenton activity, achieving a TC degradation rate of 97.8 % within 60 min. This was attributed to the biochar's ability to inhibit electron-hole recombination. Furthermore, the TC removal rate remained at 89 % after four cycles, demonstrating the composite catalyst's robust structural stability. Lastly, a potential mechanism for TC degradation via the FOC/GBC-0.5 catalyst was proposed, based on free radical trapping experiments. This study offers novel insights for the modification of FeOCl and the treatment of antibiotic organic wastewater.

Photo-Fenton Degradation of Tetracycline and Photoelectrochemical Properties of ZnFe2O4@ZnWO4 Heterostructure Composite Coupling.

Problems such as bacterial resistance caused by tetracycline antibiotics pose a serious threat to human production and life and ecosystems. We prepared ZnFe2O4@ZnWO4 heterojunction nanocomposites using hydrothermal and coprecipitation methods. The micromorphology, structure, and photoelectrochemical properties were analyzed. In combination with the presence of H2O2, the photo-Fenton activity of the antibiotic tetracycline at high concentration was tested under visible light irradiation, and its catalytic mechanism was investigated. The results showed that the composition of the composite heterojunction improved the catalytic activity of the catalyst. At a pollutant concentration of 50 mg L-1 and pH 5, 30% ZnWO4/ZnFe2O4 degraded 92.1% of tetracycline in 60 min with a degradation rate of 0.0295 min-1, which was 6.7 times higher than that of pure ZnFe2O4. The results of free radical trapping experiments and electron spin resonance techniques indicated that hydroxyl radical (•OH) and superoxide radical (O2-) played important roles in the photo-Fenton degradation of tetracycline. Notably, the catalyst maintained a high degradation rate (80%) after five cycles. ZnFe2O4 introduced in this article may provide a promising strategy for achieving strong light absorption and is authoritative in meeting future environmental requirements.

Facile single-step synthesis of ZnFe2O4@biochar for synergistic adsorption and photo-Fenton degradation of RB and RBR binary dyes

BackgroundBiochar ferrite composites have attracted widespread interest in adsorption and photocatalysis. MethodsZnFe2O4@biochar (ZnFe2O4@C) photo-Fenton catalyst was synthesized by single-step pyrolysis strategy and characterized by SEM-EDS, FT-IR, XRD, BET, XPS, VSM, UV–vis DRS. The activity of ZnFe2O4@C was investigated via rhodamine B (RB) and reactive brilliant red X-3B (RBR) binary dyes photo-Fenton degradation. Significant FindingsZnFe2O4 was uniformly anchored on biochar and formed magnet-separable ZnFe2O4@C. ZnFe2O4@C exhibited synergistic adsorption and photo-Fenton activity. Combination ZnFe2O4 with biochar reduced the recombination rate of photo-generated carriers, and effectively accelerated the degradation of RB and RBR binary dyes. Under the optimal conditions, the removal efficiency of RB and RBR were both more than 99.00%, and the reaction rate constants were 0.1276 min–1 and 0.0928 min–1, respectively. The photo-generated holes and •OH were the main active species. The possible degradation pathways were involved in cleavage of C–N, N-de-ethylation, chromophore cleavage and benzene ring opening for RB, and deionization, cleavage of N = N and C–N, oxidization and benzene ring opening for RBR. This work provided a facile single-step synthesis strategy for ZnFe2O4@biochar photo-Fenton catalyst, which was magnet-separable, environment-friendly, pH adaptability-widely, and there was the potentiality for organic dyes wastewater treatment.

Regulating Fe(III) spin state by anchoring iron on titanium dioxide for enhancing photo-Fenton treatment of tetracycline wastewater

Tetracycline (TC) wastewater can hardly be treated effectively by conventional processes due to its stable chemical structure and its refractoriness to biodegradation. Photo-Fenton technology based on iron-based catalyst exhibits excellent capacity on organic wastewater treatment, but current iron-based catalyst materials exist crucial problems such as slow regeneration of Fe(II) and low utilization of H2O2. In this study, Fe atom was anchored on TiO2 to regulate the spin state of Fe to prepare a new efficient photo-Fenton material. The results showed that the removal of TC by Fe2O3-TiO2(high spin, HS) can reach 94.7%, while the removal of TC by Fe-TiO2(low spin, LS) was only 83.0%. The Fe2O3-TiO2(HS) maintained high photo-Fenton activity after five cycles, and the TC removal rate still reached 91.8%. Fe2O3-TiO2(HS) had a narrow bandgap and excellent photogenerated charge separation properties, which facilitates the generation of photogenerated charges, improves the electron transfer, and accelerates the redox cycle of Fe(III)/Fe(II). The electrons in the 3d orbital of Fe2O3-TiO2(HS) are more easily to cross the antibonding orbital of the H2O2, which is conducive to the adsorption of H2O2 and generation of ·OH to accelerate TC degradation. This study provides a new photo-Fenton material for the treatment of TC wastewater and offers a new strategy for the development of photo-Fenton.

Improvement of the photo-Fenton performance at near neutral pH by the addition of tannic acid from tea leaves waste as a complexing agent in the Pb(II) photo-oxidation

<p>IIntroducing tannic acid from tea leaves waste as a complexing agent of Fe(III) into photo-Fenton process to prevent Fe(OH)3 precipitation at pH 7, and further to increase photo-Fenton activity in the near neutral pH for Pb(II) photo-oxidation is systematically addressed. The photo-Fenton process for Pb(II) photo-oxidation involving Fe2+ and H2O2 solutions as well as UV light was conducted by batch technique, both in the absence and present of tannic acid. Furthermore, the optimization of tannic acid concentration, solution pH, and reaction time were also conducted. The research results assign that the addition of tannic acid in the photo-Fenton process for photo-oxidation of Pb(II) is able to considerably enhance the effectiveness at pH 6-8 (near neutral pH). The activity of the tannic acid from tea leaves waste is comparable to the that of the commercial tannic acid. The best condition of Pb(II) photo-oxidation having 10 mg.L-1 in 50 mL of the solution can be reached by using Fe2+ as high 10 mmol.L-1, H2O2 100 mmol.L-1, with the addition of tannic acid as much as 30 mg.L-1 at pH 7 and 60 min of the time that gave about 85% of the photo-oxidation effectiveness. It is also indicated that the Pb(II) photo-oxidation has resulted in the harmless PbO2 solid . Hence, it is obviously assigned that the priceless tea waste could significantly contribute in the improvement of the photo-Fenton performance to prevent environmental pollution.</p>

Synthesis of 3D Sb2O3-based heterojunction reinforced by SPR effect and photo-Fenton mechanism for upgraded oxidation of metronidazole in water environments

The traditional homogenous and heterogenous Fenton reactions have frequently been restrained by the lower production of Fe2+ ions, which significantly obstructs the generation of hydroxyl radicals from the decomposition of H2O2. Thus, we introduce novel photo-Fenton-assisted plasmonic heterojunctions by immobilizing Fe3O4 and Bi nanoparticles onto 3D Sb2O3 via co-precipitation and solvothermal approaches. The ternary Sb2O3/Fe3O4/Bi composites offered boosted photo-Fenton behavior with a metronidazole (MNZ) oxidation efficiency of 92% within 60 min. Among all composites, the Sb2O3/Fe3O4/Bi-5% hybrid exhibited an optimum photo-Fenton MNZ reaction constant of 0.03682 min− 1, which is 5.03 and 2.39 times higher than pure Sb2O3 and Sb2O3/Fe3O4, respectively. The upgraded oxidation activity was connected to the complementary outcomes between the photo-Fenton behavior of Sb2O3/Fe3O4 and the plasmonic effect of Bi NPs. The regular assembly of Fe3O4 and Bi NPs enhances the surface area and stability of Sb2O3/Fe3O4/Bi. Moreover, the limited absorption spectra of Sb2O3 were extended into solar radiation by the Fe3+ defect of Fe3O4 NPs and the surface plasmon resonance (SPR) effect of Bi NPs. The photo-Fenton mechanism suggests that the co-existence of Fe3O4/Bi NPs acts as electron acceptor/donor, respectively, which reduces recombination losses, prolongs the lifetime of photocarriers, and produces more reactive species, stimulating the overall photo-Fenton reactions. On the other hand, the photo-Fenton activity of MNZ antibiotics was optimized under different experimental conditions, including catalyst loading, solution pH, initial MNZ concentrations, anions, and real water environments. Besides, the trapping outcomes verified the vital participation of •OH, h+, and •O2− in the MNZ destruction over Sb2O3/Fe3O4/Bi-5%. In summary, this work excites novel perspectives in developing boosted photosystems through integrating the photocatalysis power with both Fenton reactions and the SPR effects of plasmonic materials.

MOF-on-MOF-derived Fe[sbnd]Zr bimetal oxides supported on hierarchically porous carbonized wood to promote photo-Fenton degradation of ciprofloxacin

MOF-on-MOF derivatives have served as promising heterogeneous Photo-Fenton (hetero-PF) catalysts, but its self-aggregation instability and limited photocatalytic activity inhibit the effective ciprofloxacin (CIP) removal. In this study, a novel hetero-PF catalyst, dual MOF-derived FeZr bimetal oxide embedded in a wood-converted porous carbon skeleton (ZrO2@Fe3O4/WPC), was successfully synthesized via a straightforward in-situ growth strategy combined with co-pyrolysis. The as-prepared hybrid photocatalysts, featuring a large surface area, effective porous structures, efficient light absorption and a narrow band gap demonstrated superior photo-Fenton activity, accomplishing approximately 99.1 % degradation of CIP within 120 min under neutral conditions. Furthermore, the ZrO2@Fe3O4/WPC hetero-PF system showed satisfactory performance in treating real water matrices. It can be inferred that the abundant heterojunctions, resulting from the synergistic effect of FeZr mixed oxide and the porous carbonized wood substrate, contributed to the rapid separation and migration of photogenerated electron-hole pairs. Meanwhile, the FeZr site in the graphitized carbon framework activates H2O2 to accelerate the generation of the OH and O2− radicals, leading to a heightened degradation efficiency of CIP. Besides, the photodegradation pathway of CIP is obtained by liquid chromatography-mass spectrometry (LC-MS). This study indicates that combining porous carbonized wood and heterometallic MOF derived materials provides a promising method for realizing high-efficiency photo-Fenton degradation of antibiotic water pollutions.

Phytic acid metal complex as precursor for fabrication of superhydrophilic membrane with photo-Fenton self-cleaning property for microalgae dewatering and oil/water emulsion separation

Membrane technology is regarded as one of the most effective approaches for microalgae dewatering in the biofuel production industrial and oil/water emulsion separation. However, it inherently suffers from the issue of membrane fouling, particularly irreversible membrane fouling, which is hard to remove by physical methods. Herein, a robust superhydrophilic membrane combined with photo-Fenton self-cleaning property was developed for microalgae dewatering and oil/water emulsion separation. Phytic acid (PA) and FeIII formed a hydrophilic PA-FeIII complex on the polyethersulfone (PES) membrane as the precursor for the in situ growth of β-FeOOH nanorods. When used for microalgae filtration, the irreversible fouling that blocked membrane pores could be degraded by the photo-Fenton reaction. Hence, the obtained PES/PA@β-FeOOH membrane possessed a flux recovery rate (FRR) of 90.2 % (within 30 min), which was significantly higher than that of the PES membrane (32.9 %). The proteins and polysaccharides (extracellular organic matter) attached on the PES/PA@β-FeOOH membrane with photo-Fenton cleaning were 11.2 and 9.1 mg/m2, which was considerably lower than that of PES after hydraulic cleaning (184.1 and 334.9 mg/m2). Moreover, due to the superhydrophilic, the prepared PES/PA@β-FeOOH membrane also exhibited excellent oil/water emulsion separation ability. This work presents a facile and mild strategy to design an anti-fouling coating with superhydrophilic and photo-Fenton activity, which can be used in membrane technology for microorganism filtration and wastewater treatment.

Synthesis, characterization, and photo-Fenton activity of Bi[Fe(CN)6]·4H2O

The Fenton reaction has been widely used in wastewater treatment processes, and the reaction rate is improved by irradiation with light. In this work, Bi[Fe(CN)6]·4H2O was synthesized as a photo-Fenton catalyst by precipitation at room temperature without any stabilizer or capping agent. Two synthesis routes were used and compared; one using K3[FeIII(CN)6] solution and the other using K4[FeII(CN)6]. When Bi(NO3)3 solution was mixed with K3[FeIII(CN)6] solution, the Bi[Fe(CN)6]·4H2O was obtained. However, the KBi(H2O)2[Fe(CN)6]·H2O was first precipitated by the reaction of Bi3+ with [FeII(CN)6]4-, and this intermediate was transformed into Bi[Fe(CN)6]·4H2O. Compared with Bi[Fe(CN)6]·4H2O prepared with K3[FeIII(CN)6], the photo-Fenton degradation of Rhodamine B (RhB) with Bi[Fe(CN)6]·4H2O prepared with K4[FeII(CN)6] exhibited a higher activity. It attributed to a smaller particles size of Bi[Fe(CN)6]·4H2O prepared with K4[FeII(CN)6]. Although Bi[Fe(CN)6]·4H2O could degrade RhB in darkness, its activity increased under visible light irradiation. The prepared catalyst also degraded reactive orange 16 (RO) and tetracycline hydrochloride (TC) under visible light irradiation. The degradations of RhB, RO, and TC were confirmed by mass spectrometry. From experimental results, the Bi[Fe(CN)6]·4H2O prepared with K4[FeII(CN)6] showed high activity and promise as a catalyst for wastewater treatment.

Cu single atoms anchored on hydrangea-like carbon nitride for facilitating photo-Fenton: Role of Cu2+/Cu+ cycle

Single-atom photo-Fenton (PF) reaction is widely employed for the degradation of antibiotics and water disinfection. However, the key fundamental issues of the valence state cycling of single-atom metals and the activation of hydrogen peroxide (H2O2) in the PF process remain indistinct. Herein, we developed a catalyst donated as Cu single atoms anchored hydrangea-like carbon nitride (Cu-SA/CNH) with Cu−N4 coordination for PF reaction. Compared to pristine CNH, the Cu-SA/CNH exhibited a 2.42-fold increase in PF kinetics. The Cu-SA/CNH/PF system achieved 98.1% degradation efficiency of tetracycline and effectively inactivated Escherichia coli within 30 min. Density functional theory calculations demonstrated that the formation of Cu−N4 effectively improved the energy of the Cu d orbitals, leading to the generation of intermediate states that facilitated the Cu2+/Cu+ cycle. The adsorption capacity of Cu dxz orbitals on H2O2 increased nearly 10 times. This work provides valuable insights for enhancing single-atom PF activity to address environmental pollution.

Prussian blue analogue nanospheres immobilized on self-floating biochar for micropollutant degradation via photo-Fenton process

Fe-Co Prussian blue analogue (PBA) nanospheres were immobilized on biochar (PBA-on-biochar) to remove contaminants via photo-Fenton process. The loading weight of FeCo PBA on biochar increased with increasing PBA aging temperature and time. The PBA exhibited efficient chloroquine phosphate (CQ) degradation under both LED light and sunlight, where OH and 1O2 dominated the oxidation. The CQ degradation was slightly affected by pH value (3.5–9.5) and co-existing anions like SO42−, Cl− and NO3–. The application potential of the PBA-on-biochar was evaluated in a continuous reaction device. Theoretical calculation revealed the dominant role of Fe sites in PBA for H2O2 activation. The degradation pathway was proposed based on nine intermediate products. Also, the excellent photo-Fenton activity and good floatability enable PBA-on-biochar to be efficient in inhibiting the activity of Microcystis aeruginosa under sunlight. The results implied that PBA-on-biochar is applicable for fast micropollutant oxidation from water.

Wood-converted porous carbon decorated with MIL-101(Fe) derivatives for promoting photo-Fenton degradation of ciprofloxacin.

In response to the escalating concerns over antibiotics in aquatic environments, the photo-Fenton reaction has been spotlighted as a promising approach to address this issue. Herein, a novel heterogeneous photo-Fenton catalyst (Fe3O4/WPC) with magnetic recyclability was synthesized through a facile two-step process that included in situ growth and subsequent carbonization treatment. This catalyst was utilized to expedite the photocatalytic decomposition of ciprofloxacin (CIP) assisted by H2O2. Characterization results indicated the successful anchoring of MIL-101(Fe)-derived spindle-like Fe3O4 particles in the multi-channeled wood-converted porous carbon (WPC) scaffold. The as-synthesized hybrid photocatalysts, boasting a substantial specific surface area of 414.90 m2·g-1 and an excellent photocurrent density of 0.79 μA·cm-2, demonstrated superior photo-Fenton activity, accomplishing approximately 100% degradation of CIP within 120 min of ultraviolet-light exposure. This can be attributed to the existence of a heterojunction between Fe3O4 and WPC substrate that promotes the migration and enhances the efficient separation of photogenerated electron-hole pairs. Meanwhile, the Fe(III)/Fe(II) redox circulation and mesoporous wood carbon in the catalyst synergistically enhance the utilization of H2O and accelerate the formation of •OH radicals, leading to heightened degradation efficiency of CIP. Experiments utilizing chemical trapping techniques have demonstrated that •OH radicals are instrumental in the CIP degradation process. Furthermore, the study on reusability indicated that the efficiency in removing CIP remained at 89.5% even through five successive cycles, indicating the structural stability and excellent recyclability of Fe3O4/WPC. This research presented a novel pathway for designing magnetically reusable MOFs/wood-derived composites as photo-Fenton catalysts for actual wastewater treatment.

A direct Z-scheme 0D α-Fe2O3/TiO2 heterojunction for enhanced photo-Fenton activity with low H2O2 consumption

The insufficient F(III)/Fe(II) cycling rate resulted from high combination of photogenerated carriers severely hinders the photo-Fenton activity. In this work, 0 dimensional α-Fe2O3 nanoclusters decorated TiO2 heterojunction (FT-x) was prepared via in-situ phase transformation strategy. FT-200 exhibited the optimal photo-Fenton activity for 2,4-dichlorophenol degradation with the kinetic rate constant reaching 1.0806 min−1 under low H2O2 dosage (1 mmol/L), which was 126.1 and 202.8 times higher than that of TiO2 and α-Fe2O3. Radical quenching experiments and electron spin resonance spectra proved that ·OH was the leading reactive specie. The enhanced photo-Fenton activity was attributed to the accelerated F(III)/Fe(II) cycling rate induced by the direct Z-Scheme charge transfer mechanism. Benefiting from the abundant ·OH production, the dechlorinate ratios and mineralization ratios of multiple chlorophenol pollutants (2,4-dichlorophenol, 4-chlorophenol, 2,4,6-trichlorophenol) all exceeded 98 %. The biotoxicity of chlorophenol wastewater was greatly reduced after the treatment by Light/H2O2/FT-200 system. Overall, this work constructed a low-cost and highly efficient photo-Fenton system for refractory organic wastewater treatment.

Effect of different salt precursors on zinc ferrite synthesis and their photo-Fenton activity

Polycrystalline and mesocrystalline zinc ferrite were successfully fabricated via a solvo-thermal method using different salt precursors. This study found that when iron sulfate salt was used as a precursor, polycrystalline zinc ferrite was formed. Polycrystalline zinc ferrite is a well-dispersed 400-nm sphere solid particle. Primary nano-crystals have highly preferred orientations; however, defects exist among the particles. When iron chloride salt was used as a substitute as a prime material, mesocrystalline zinc ferrite was synthesised. The products are shaped as hollow-spheres with an average size of approximately 500 nm and are composed of nano-crystal sub-units aligned in a highly oriented crystallographic structure. Zinc ferrite mesocrystalline samples have many voids, and the inter-spaces of their structure indicate the high porosity hollow-sphere architecture of zinc ferrite. The experimental results show that specific adsorption of Cl− and SO42− ions on the surface plays a crucial role during the growth process of products with different morphologies and crystallographic structures. Cl− adsorption on the surface may promote the formation of mesocrystal hollow-sphere particles; whereas, SO42− gives rise to polycrystalline solid spheres. The use of the as-prepared products as catalysts for the photo-Fenton degradation of Rhodamine B (RhB) with an H2O2 oxidant under visible-light irradiation and the effects of reaction conditions, including pH, catalyst amount and H2O2 contratentation on the removal of RhB, were investigated. The reuse of the catalysts and a possible catalytic mechanism were also proposed. These results indicate that mesocrystalline hollow-sphere zinc ferrite is a favourable catalyst for dye degradation photo-Fenton processes.