Heterogeneous photo-Fenton Catalyst Research Articles

Photo-Fenton process for degradation of methylene blue using copper ferrite@sepiolite clay

In this research, CuFe2O4 decorated on sepiolite clay (SC@CuFe2O4) catalyst was fabricated using a simple solvothermal process. To study the structure, morphology, and photoelectric characters of the preapred catalyst, a series of methods including SEM, TEM, VSM, DRS, XRD, and EDX were employed in the present study. The investigation demonstrated that the CuFe2O4 particles had a spherical shape and were successfully incorporated onto the fibrous structure of the sepiolite clay (SC). The SC@CuFe2O4 catalyst was utilized in a heterogeneous photo-Fenton reaction to degrade methylene blue (MB) dye. The use of SC effectively inhibited the agglomeration of CuFe2O4 and significantly improved the performance of the heterogeneous catalyst in degrading MB under visible light irradiation. The results of the suggested photo-Fenton-like reaction demonstrated that the complete degradation of MB (C = 20 ppm) could be achieved in 200 min reaction time under mild pH conditions. The results of the reuse experiments indicated that the proposed catalyst exhibited a high degree of reusability, maintaining its effectiveness even after six successive cycles. The SC@CuFe2O4 catalyst exhibits a high degree of catalytic capability, low price, and remarkable chemical stability, making it a promising candidate for use as a heterogeneous photo-Fenton catalyst in the degradation of organic pollutants.

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.

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.

Enhanced photo-Fenton degradation of dyes under visible light with recyclable γ-Fe2O3/CQDs: Catalyst preparation, performance and mechanism insight

A low band gap and visible light-responsive heterogeneous Photo-Fenton catalyst of γ-Fe2O3/CQDs micron composite was prepared under the one-pot hydrothermal method. The Photo-Fenton degradation of γ-Fe2O3/CQDs towards dye solution of rhodamine B(RhB), methyl blue (MB), and methyl orange (MO) was studied comparatively with α-Fe2O3. The γ-Fe2O3/CQDs exhibited remarkable catalytic performance for various dyes and with a first-order rate (k) of 14 times higher than that of initial α-Fe2O3 with a low concentration of H2O2 of 0.049 mmol. L−1 and a wider pH range of 3.1–7.1. The microstructure of the compounds was observed by XRD, SEM, TEM, FT-IR, and XPS characterization results suggested that the γ-Fe2O3/CQDs nanocomposite was formed through the stable Fe–O–C bonds, thus, the band gap decreased, and it is more favorable for the distance of holes and electrons. The free radical trapping experiment and EPR analysis indicated that •OH and 1O2 were the major active species during the typical photo-Fenton reaction. What's more, the γ-Fe2O3/CQDs also exhibited good stability and magnetic properties. DFT conclusion shows that the mechanism of the potential determination step (PDS) on α-Fe2O3(220) is the cleavage of H2O2 with an energy barrier of only 0.08 eV, which is 0.54 eV lower than that of OH* on γ-Fe2O3(220). Thus it can be deemed that γ-Fe2O3/CQDs perform much higher catalytic activity for the dissociation of H2O2 than α-Fe2O3. This work gives a feasible and economical countermeasure of visible light Photo-Fenton dispose of dye wastewater with a recyclable magnetic γ-Fe2O3/CQDs micron catalyst.

Synergistic photogeneration of reactive oxygen species by Fe species self-deposited on resorcinol-formaldehyde towards the degradation of phenols under visible light

In this study, a heterogeneous photo-Fenton catalyst of Fe species/resorcinol-formaldehyde (Fe/RF) was synthesized in the degradation process of phenols under visible light in a homogeneous photo-Fenton system. The in situ generated H2O2 by bare RF in the medium and the follow-added Fe2+ can construct homogeneous photo-Fenton system, and Fe/RF heterogeneous photo-Fenton catalyst was formed after the reaction through Fe species self-deposition. Due to the addition of Fe2+, more hydroxyl radical (·OH) generated in the homogeneous Fenton system, which lead to the higher degradation efficiency of phenols that achieved 90.5 % with 150 min. Fe/RF was subsequently formed and more C=O functional group in the structure appeared, which was beneficial to the production of H2O2. The above-mentioned results can be proved by the involved calculation and experimental results. Fe species, including Fe2+ and Fe3+, were beneficial to the conversion of reactive oxygen species (ROSs), and further improved the degradation efficiency of Phenols. Since the existence of photo-generated electrons, Fe2+ concentration in the solution can maintain a stable level. Interestingly, the degradation efficiency of Phenols was higher when Fe3+ was used instead of Fe2+ as the additive, which may be caused by the promotive effect of Fe3+ on singlet oxygen (1O2) generation. In addition, the degradation efficiency of Phenols under alkaline conditions was higher than that under acid conditions, which broke the limit of traditional Fenton process that works mostly in acidic medium. This study shows promising results in terms of synergistic photocatalytic/photo-Fenton processes for the degradation of organic pollutants in water.

Single-step solvothermal synthesis of sepiolite-CoFe2O4 nanocomposite as a highly efficient heterogeneous catalyst for photo Fenton-like reaction

In present research, a novel sepiolite-CoFe2O4 (Sep-CoFe2O4) catalyst was prepared using a facile solvothermal strategy. The structure, morphology, and photoelectric properties of the synthesized catalyst were explored by the SEM, TEM, VSM, DRS, XRD, XPS and EDX methods. The results showed that CoFe2O4 particles had a spherical shape and was successfully deposited on the fibrous structure of Sep clay. The prepared Sep-CoFe2O4 catalyst was employed in heterogeneous photo-Fenton reaction for methylene blue (MB) degradation. Sep effectively prevented the aggregation of CoFe2O4 and clearly enhanced the efficiency of the heterogeneous catalyst for degradation of MB under visible light irradiation. In photo Fenton-like reaction, complete degradation of MB (C = 10 ppm) was achieved in 150 min at mild pH value. The reusability experiments showed that the suggested catalyst can be reused after five successive cycles. Besides, a possible degradation mechanism using the photo Fenton-like system was presumed. Accounting for the high catalytic capability, low cost, as well as good chemical stability, the Sep-CoFe2O4 has great potential working as a heterogeneous photo-Fenton catalyst for degradation of organic contaminants.

UV photocatalytic remediation of Methyl Red in aqueous medium by sulfate (SO4•-) and hydroxyl (•OH) radicals in the presence of Fe2+and Co@TiO2 NPs photocatalysts

Metal doping is an efficient approach to improve the performance of photocatalysts, and few attempts have been made to apply mixed metals as dopants. In this work, the decomposition of methyl red (MR) was investigated using UV/peroxymonosulfate (PMS)/Fe2+ (homogeneous) and UV/PMS/Co@TiO2 NPs (heterogeneous) advanced oxidation process (AOP) systems. The Co@TiO2 NPs for UV/PMS/Co@TiO2 nanoparticle (NPs) system was prepared by a simple reduction method. The prepared samples were characterized by transmission electron microscopy (TEM), Fourier transformer infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and energy dispersive X-ray (EDX). The small peak at 38° (004) angle indicates the presence of cobalt. The peak increased with the increase in cobalt concentration. The doped Co-TiO2 showed larger particle size due to the greater ionic radius of Co (0.74 Å) than TiO2 (0.60 Å). The photocatalytic efficiency of the catalysts was evaluated by degradation of methyl red (MR) at a wavelength of 503 nm under UV irradiation. The results showed that Co/TiO2 photocatalyst containing (0.015 g) exhibited the highest removal efficiency of 20% for adsorption of MR after 1 h in the dark. Subsequently, superior photocatalytic activity for the degradation of MR, with 99% removed after 18 min was demonstrated. The Kapp (rate constant) was found to be approximately 5.554 min−1. It was determined that the synthesized Co@TiO2 NPs remained stable during the photocatalytic reaction which could be used repeatedly with excellent degradation efficiency, hence, exposing their promising application in the treatment of wastewater. The mineralization of methyl red was confirmed by total organic carbon (TOC) analysis. The results will be useful for future enhancement of active heterogeneous photo-Fenton catalysts for developing organic dye-containing wastewater handling procedures.

Multiple interface coupling on natural tourmaline enables high-efficiency removal of antibiotic: Superior property and mechanism

Reasonably designing highly active, environmentally friendly, and cost-effective catalysts for efficient elimination of pollutants from water is desirable but challenging. Herein, an efficient heterogeneous photo-Fenton catalyst tourmaline (TM)/tungsten oxide (WO3-x) (named TW10) containing tungsten/boron/iron (W/B/Fe) synergistic active centers and 90% of cheap natural tourmaline (TM) mineral rich in Fe and B elements. The TW10 catalyst can quickly activate peroxymonosulfate (PMS) to generate massive active free radicals, which may induce the rapid and efficient degradation of tetracycline (TC). The TW10/PMS/Visible light system can effectively degrade up to 98.7% of tetracycline (TC) in actual waters (i.e. seawater, Yellow River, and Yangtze River water), and the catalytic degradation rates reach 1.65, 5.569, and 2.38 times higher than those of TM, WO3-x, and commercial P25 (Degussa, Germany), respectively. In addition, the catalyst can be recycled and reused multiple times. Electron spin resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS), and liquid chromatograph-mass spectrometer (LC-MS) analyses confirm that the synergistic catalytic effect of W/B/Fe sites on the TW10 catalyst accelerates the electron transfer between Fe(II) and Fe(III), as well as between W(V) and W(VI), and thus promotes the rapid degradation of TC. The catalytic reaction mechanism and degradation pathway of TC were explored. This work provides a feasible route for the design and development of new eco-friendly and efficient catalyst.

Nitrogen–doped titanium dioxide/schwertmannite nanocomposites as heterogeneous photo–Fenton catalysts with enhanced efficiency for the degradation of bisphenol A

Potential health risks related to environmental endocrine disruptors (EEDs) have aroused research hotspots at the forefront of water treatment technologies. Herein, nitrogen–doped titanium dioxide/schwertmannite nanocomposites (N–TiO2/SCH) have been successfully developed as heterogeneous catalysts for the degradation of typical EEDs via photo–Fenton processes. Due to the sustainable Fe(III)/Fe(II) conversion induced by photoelectrons, as–prepared N–TiO2/SCH nanocomposites exhibit much enhanced efficiency for the degradation of bisphenol A (BPA; ca. 100% within 60 min under visible irradiation) in a wide pH range of 3.0-7.8, which is significantly higher than that of the pristine schwertmannite (ca. 74.5%) or N–TiO2 (ca. 10.8%). In this photo–Fenton system, the efficient degradation of BPA is mainly attributed to the oxidation by hydroxyl radical (•OH) and singlet oxygen (1O2). Moreover, the possible catalytic mechanisms and reaction pathway of BPA degradation are systematically investigated based on analytical and photoelectrochemical analyses. This work not only provides a feasible means for the development of novel heterogeneous photo–Fenton catalysts, but also lays a theoretical foundation for the potential application of mineral–based materials in wastewater treatment.

Fe2O3/BiVO4 heterogeneous photo-Fenton catalyst with excellent dye degradation performance prepared by ultrasonic-assisted calcination

Fe2O3/BiVO4 heterogeneous photo-Fenton catalyst with excellent dye degradation performance prepared by ultrasonic-assisted calcination

Utilizing three-dimensional ordered macroporous NiFe2O4 Loaded With g-C3N4 as a heterogeneous photo-Fenton catalyst for tetracycline degradation

Heterogeneous photo-Fenton technology, efficiently utilizing the solar energy and hydrogen peroxide, which combines photocatalysis and Fenton reaction, is one of the most efficient methods for eliminating organic contaminants. Here, graphitic carbon nitride (CN) and three-dimensionally ordered macroporous (3DOM) nickel ferrite (NFO) were combined to create highly catalytically active CN/3DOM-NFO composites. The composites were characterized with XRD, SEM, TEM, HRTEM, XPS, BET, DRS, and PL. And tetracycline (TC) photo-Fenton degradation catalytic activity of the composites was evaluated. The results showed that under visible light irradiation, the maximum rate constants of TC degradation of 10CN/3DOM-NFO were 7.3 times and 5.4 times that of pure g-C3N4 and bulk NFO, respectively. The optimum apparent reaction rate constant can reach as high as 0.0618 min−1 due to the synergistic interaction between the increased specific area and excellent charge carrier separation and transfer capabilities, resulting from the CN/3DOM-NFO heterojunction and the 3DOM structure, respectively. Finally, the mechanism of photo-Fenton-catalyzed degradation is briefly discussed. And this research reveals a new strategy to improve the efficiency of photo-Fenton-catalyzed degradation.

Fe-doped g-C3N4 synthesized by supramolecular preorganization for enhanced photo-Fenton activity

The photo-Fenton process, with a synergistic effect of Fenton oxidation and photocatalysis, is a promising technique for the removal of refractory organic pollutants. However, the rapid recombination of photogenerated charge carriers results in less electrons for Fe(III)/Fe(II) cycle and later generation of hydroxyl radicals. In this work, Fe-doped graphite carbon nitride with a thin nanosheet structure (∼5 nm thickness) was prepared using the supramolecular preorganization method (Fe/CNSP), which effectively suppresses the recombination of photogenerated charges compared with that of Fe-doped bulk carbon nitride (Fe/BCN), resulting in an obviously improved photo-Fenton performance by increasing the electron gain at the Fe sites and the speed of the reduction of Fe(III) to Fe(II). The heterogeneous photo-Fenton activity of Fe/CNSP displays a 6.5 times higher kinetic constant for carbamazepine degradation than that of Fe/BCN, and universal effectiveness toward other organic pollutants, namely phenol, sulfamethoxazole, bisphenol A, and 2,4-dichlorophenol, with TOC removals between 37.4% and 91.3% in 150 min. OH, O2−, e−, h+, and 1O2 contribute to the degradation of organic pollutants. Fe/CNSP was proven to be stable and reusable in cyclic experiments. The analysis of the intermediate toxicity demonstrated that the Fe/CNSP photo-Fenton system effectively reduced the toxicity of carbamazepine. This study offers a simple, highly reproducible method for developing efficient heterogeneous photo-Fenton catalysts.

Bimodal mesoporous α-Fe2O3/SiO2 composite: A highly efficient heterogeneous solar-driven photo-Fenton catalyst

In recent years, an extensive research interest has been focused on photo-Fenton catalysis for oxidative degradation of wide range of organic pollutants including non-biodegradable organic dyes in industrial effluents. The present article demonstrates formerly unexplored, an easy wet chemical, soft template assisted sol-gel approach for the synthesis of bimodal mesoporous α-Fe2O3/SiO2 composite for its application as a photo-Fenton catalyst. In this synthesis, a combination of non-surfactant template tartaric acid and an anionic surfactant sodium dodecyl sulphate (SDS) have been employed which produce two different pore dimensions of 3.1 nm and 5.1 nm in the mesoporous composite. The synthesized mesoporous α-Fe2O3/SiO2 composite has surface area as high as 127 m2/g. It exhibits an excellent photo-Fenton dye degradation under natural daylight in an optimized strategy in presence of minimal concentration of H2O2. Thus, the developed mesoporous α-Fe2O3/SiO2 composite is likely to be an inexpensive alternative heterogeneous photo-Fenton catalyst for dye degradation under natural daylight and for wastewater treatment.

Double-Shelled Porous g-C3 N4 Nanotubes Modified with Amorphous Cu-Doped FeOOH Nanoclusters as 0D/3D Non-Homogeneous Photo-Fenton Catalysts for Effective Removal of Organic Dyes.

Graphite phased carbon nitride (g-C3 N4 ) has attracted extensive attention attributed to its non-toxic nature, remarkable physical-chemical stability, and visible light response properties. Nevertheless, the pristine g-C3 N4 suffers from the rapid photogenerated carrier recombination and unfavorable specific surface area, which greatly limit its catalytic performance. Herein, 0D/3D Cu-FeOOH/TCN composites are constructed as photo-Fenton catalysts by assembling amorphous Cu-FeOOH clusters on 3D double-shelled porous tubular g-C3 N4 (TCN) fabricated through one-step calcination. Combined density functional theory (DFT) calculations, the synergistic effect between Cu and Fe species could facilitate the adsorption and activation of H2 O2 , and the separation and transfer of photogenerated charges effectively. Thus, Cu-FeOOH/TCN composites acquire a high removal efficiency of 97.8%, the mineralization rate of 85.5% and a first-order rate constant k= 0.0507 min-1 for methyl orange (MO) (40mg L-1 ) in photo-Fenton reaction system, which is nearly 10 times and 21 times higher than those of FeOOH/TCN (k= 0.0047 min-1 ) and TCN (k= 0.0024 min-1 ), respectively, indicating its universal applicability and desirable cyclic stability. Overall, this work furnishes a novel strategy for developing heterogeneous photo-Fenton catalysts based on g-C3 N4 nanotubes for practical wastewater treatment.

Construction of Fe3S4/g-C3N4 composites as photo-Fenton-like catalysts to realize high-efficiency degradation of pollutants

To perfect the photocatalytic performance of Fe3S4 under visible light irradiation using tetracycline hydrochloride (TCH) as a target contaminant, magnetic Fe3S4/g-C3N4 composites with a visible light response were synthesized by a one-step hydrothermal method. The effects of varying quality ratios, temperatures, pH value, and H2O2 concentrations on photocatalysis was investigated, and the composites were characterized by XRD, FTIR, XPS, SEM, etc. The results show that the highest photo-Fenton catalytic efficiency is obtained for a composite with a Fe3S4 to g-C3N4 quality ratio of is 1:0.75 (Fe1C0.75). More than 97.5% of TCH is removed by Fe3S4/g-C3N4/H2O2 within 60 min under visible light irradiation and near-neutral conditions (pH 6.2), and its first-order kinetic constant is determined to be 0.06802 min−1. The removal efficiency for Fe3S4/g-C3N4 is 1.61 and 13.34 times higher than that of the parent Fe3S4 and g-C3N4, respectively. At this time, g-C3N4 can effectively increase the leaching of S0. The effects of different active species in the TCH degradation experiment with the Fe1C0.75 composite were studied, and it is found that h+, ·O2−, and ·OH radicals are the main substances involved in the degradation of TCH. The synthesized Fe3S4/g-C3N4 catalyst is a promising heterogeneous photo-Fenton catalyst for the removal of organic pollutants.

Fe-polyoxometalate nanodots decorated Bi2MoO6 nanosheets with dominant {0 1 0} facets for photo-Fenton degradation of antibiotics over a wide pH range: Mechanism insight and toxicity assessment

It remains challenging to rationally design ultra-efficient and reusable heterogeneous photo-Fenton catalysts with a wide pH working range for environmental remediation. Here, Fe-polyoxometalate (Fe-POM)-modified Bi2MoO6 with dominant {010} facets, denoted as Fe-POM/BMO, was elaborately designed and synthesized for the degradation of typical antibiotics. Benefiting from the synergistic effect of oxygen vacancies and the Fe3+/Fe2+ redox couple, the Fe-POM/BMO heterojunctions exhibited remarkable photo-Fenton degradation performance at a wide pH range of 3.0–11.0. Based on the density functional theory calculations and intermediates analysis, the probable degradation pathways of TC were unraveled. In addition, the QSAR prediction and the Microtox test (Photobacterium phoshoreum T3 spp. as the luminescent bacteria) proved that the degradation process of tetracycline could effectively alleviate the ecotoxicity. According to the findings, the application of Fe-POM/BMO in the photo-Fenton degradation process of antibiotics is eco-friendly and exhibits high application potential in environmental remediation.

Visible Fenton Degradation of Bisphenol A by Boron-Doped, Graphene-Oxide-Coated Nano-Fe3O4

Phenolic pollutants in industrial wastewater are considered to be harmful aromatic compounds. With the development of industry and pharmaceuticals, phenolic pollutants and their derivatives have gradually started to affect people’s daily lives. Therefore, it is necessary to strictly control the content of phenolic pollutants in industrial wastewater, not only for the natural environment but also for human life. The research optimized the existing treatment methods for classified pollutants, and successfully prepared a heterogeneous photo-Fenton catalyst Fe3O4@B-rGO (9.3%). The characterization results of the catalyst showed that the synthesis of the catalyst was successful, and its specific surface area was 11.28 (m2/g), and the pore volume area was 0.137 (m3/g), respectively, which were larger than those of the other two comparative catalysts. In addition, the research conclusion also showed that the catalyst prepared during the research had good catalytic activity, the treatment efficiency of Fe3O4@B-rGO (9.3%) to bisphenol A could reach 100%, and the mineralization rate could reach 67.4%. In the reaction, the main active radicals are generated, and catalyst Fe3O4@B-rGO (9.3%) can produce more active free radicals compared with Fe3O4 and Fe3O4@rGO.

Mg-Fe-Al-O spinel: Preparation and application as a heterogeneous photo-Fenton catalyst for degrading Rhodamine B.

It is an urgent need to develop new environmentally friendly spinel ferrites with high catalytic efficiency. In this work, a series of Mg-Fe-Al-O spinels with different ratios of Mg/Al were successfully synthesized by the reaction sintering method and were used as a heterogeneous photo-Fenton catalyst for degradation of Rhodamine B (RhB). The effect of different ratios of Mg/Al on the properties of Mg-Fe-Al-O spinel was characterized and analyzed through a range of advanced characterization techniques and DFT calculations. The influence factors on the photo-Fenton reaction catalyzed by Mg-Fe-Al-O spinels were systematically investigated. The results showed that the prepared Mg-Fe-Al-O spinels had larger lattice parameters, wider bandgap, and stronger magnetism, with the Mg content increased. Among them, Mg-9 (Mg0.88Fe1.88Al0.23O4) had the best catalytic performance in the photo-Fenton reaction. The degradation efficiency of RhB reached 98.45%, and the TOC removal efficiency was 83.47%. The elemental valence and PDOS of Mg-9 (Mg0.88Fe1.88Al0.23O4) spinels were closer to MgFe2O4. The photo-generated holes could directly oxidize water and hydroxyl to generate reactive oxygen species ·OH, improving the catalytic activity.

Mn doping accelerates regeneration of Fe2+ in FeOOH and promotes efficient H2O2 activation for degradation of As(III)

In this study, a carbonized aerogel (CA) decorated with Mn-FeOOH hybrid nanoparticles was prepared and has been used as a better heterogeneous photo-Fenton catalyst. Mn doping accelerated the regeneration of Fe2+ and promoted the decomposition of H2O2 while producing many hydroxyl radicals (·OH), which solved the mass transfer problem in the traditional heterogeneous Fenton system. The amount of·OH in the Mn-FeOOH@CA/H2O2 system within 40 min was 2.4 times higher than that in the FeOOH@CA/H2O2 system, which further indicates that·OH was the main active species. High-porosity CA has been designed as an electron transport channel. During photocatalysis, electron transfer occurred between the Mn-FeOOH composite material and CA. The Fe2+ could be used as reaction sites to promote the activation of H2O2 on the surface of 1-Mn/FeOOH, and achieved 100 % As(III) degradation efficiency within 25 min. The catalyst maintained more than 80 % of its original oxidation capacity after five cycles of experiments, which indicates that it has good durability. This work is expected to provide rational design of heterometallic doped materials with oxygen vacancies to treat arsenic pollution.

Catalytic activity of magnetite fish-scales and tea-waste as heterogeneous photo-Fenton catalysts for removal of methyl orange through Cu(Ⅱ) adsorption

In this study, magnetite fish scales and tea waste (MFS and MTW) were first used to adsorb Cu(Ⅱ) cations (Cu-MFS and Cu-MTW) and were then applied as heterogeneous photo-Fenton catalysts to degrade methyl orange (MO) from an aqueous solution. The morphological and structural properties of the fabricated catalysts were characterized via SEM, XRD, EDX/MAP, VSM, BET and FTIR techniques. The effects of pH, catalyst dosage, initial concentration of MO, and the initial concentration of H2O2 on the degradation efficiency of MO were investigated. The degradation efficiency of MO through the use of MFS, Cu-MFS, MTW, and Cu-MTW in the photo-Fenton process was achieved 82.6%, 97.2%, 89.1%, and 96.9%, respectively, under optimum condition (pH of 3, 0.2 g/L of MFS and Cu-MFS and 0.4 g/L of MTW and Cu-MTW, an H2O2 concentration of 0.5 mM within 200 min). Additionally, the rate of degradation reactions followed the first-order kinetics. Catalytic action was assigned to the formation of hydroxyl radicals (OH•) via the reaction between H2O2 and Fe(II) and Cu(II) on the surface of Cu-MFS and Cu-MTW during the photo-Fenton process. Furthermore, not only did Cu-MFS and Cu-MTW exhibit negligible iron and copper leaching, but they also indicated long-term stability after three consecutive cycles.