photo-Fenton Catalyst Research Articles

Highly dispersed of Ag/AgCl nanoparticles on exfoliated FeOCl nanosheets as photo-Fenton catalysts for pollutants degradation via accelerating Fe(II)/Fe(III) cycle

In this work, Ag/AgCl/FeOCl (Ag–Fe) catalysts were successfully prepared via multistep routes in which Ag was uniformly anchored to the enriched Cl sites provided by exfoliated FeOCl nanosheets. Among these Ag–Fe catalysts, 5% Ag–Fe exhibited the highest pseudo first-order kinetic constant 0.1056 min−1 for photo-Fenton degradation of Rhodamine B (RhB), which was 11 times higher than that of FeOCl (0.0096 min−1). Ag–Fe catalysts exposed more coordinatively unsaturated Fe active sites to coordinate with H2O2 due to the cleavage of Fe–Cl bond. The exposed coordinatively unsaturated Fe(III) active sites could capture the photoinduced electrons and reduce them to Fe(II), which boosted the separation efficiency of photogenerated charge carriers. Meanwhile, the photogenerated electrons of Ag0 transferred to the FeOCl, promoting the reduction of Fe(III) to Fe(II). In addition, the intensified visible light adsorption (SPR effect) was achieved after introducing Ag/AgCl nanoparticles on exfoliated FeOCl. Hydroxyl radicals (·OH) and holes (h+) were determined as the main reactive oxidative species (ROS) in the photo-Fenton degradation process.

Binding Fe-doped g-C3N4 on the porous diatomite for efficient degradation of tetracycline via photo-Fenton process

We fabricated iron-doped carbon nitride on a diatomite surface through a single-step polymerization (FGD-x, where x represents Fe loading content). The FGD-x efficiently degrades tetracycline hydrochloride by a collaborative photo-Fenton process. The FGD-3 (FeCl3 loading 75 mg) showed the best catalytic performance in TC degradation with minimal H2O2 (viz. 1 mmol/L) at a wide pH range (2.0–7.0). Under optimized conditions, the FGD-3 can degrade 98.3% of 20.0 mg/L TC at pH 4.0 within 100 min under visible light irradiation. The scanning electron microscopic and X-ray photon spectroscopic data show that iron is successfully doped on g-C3N4. Electrochemical impedance spectroscopy and transient photocurrent performance analyses confirmed that photogenerated electrons rapidly transfer at FGD-3 and solution interface. Free radical quenching experiments and electron spin resonance analysis show that h+, ∙O2-, and ∙OH can degrade TC efficiently. Besides, FGD-3 has an ultra-high catalytic activity and extremely low iron leaching after repeated use. The FGD-3 provides a feasible way to design a new photo-Fenton catalyst for the destruction of organic pollutants from water.

Green synthesis of graphite-based photo-Fenton nanocatalyst from waste tar via a self-reduction and solvent-free strategy

Thermochemical conversion of biomass yields large quantities of tar as a by-product, which is a potential precursor for the synthesis of renewable carbon-based functional materials. In this study, high-performance photo-Fenton catalyst of graphite‑carbon-supported iron nanoparticles was synthesized using a self-reduction and solvent-free approach. The results showed that the tar-derived catalyst had unique properties including a defect-rich graphitic structure, high surface area, and an abundant porous structure resulting from the inherent properties of biomass tar. The iron nanoparticles were highly dispersed within the prepared catalysts and were stably anchored on the carbonaceous surface by the FeC bond. The prepared nanocatalyst showed the highest decomposition constant (91.87 × 10−3 min−1) for 20 mM H2O2, and 40 mg/L RhB can be completely degraded within 2 h under catalyst dosage of 1 g/L and H2O2 addition of 20 mM. The degradation mechanism under the photo-Fenton catalyst/H2O2/light system included the heterogeneous Fenton reaction of iron nanoparticles and photo-Fenton reaction of iron oxide, and the efficient RhB degradation was mainly ascribed to the heterogeneous Fenton reaction. In addition, recycling and leaching tests demonstrated that the photo-Fenton catalyst had excellent reusability and stability, where only 7.3% catalytic reactivity was reduced after five cycles. This work provided a green, sustainable, and facile approach for synthesizing photo-Fenton catalysts by value-added utilization of tar wastes.

Construction of a C-decorated and Cu-doped (Fe,Cu)S/CuFe2O4 solid solution for photo-Fenton degradation of hydrophobic organic contaminant: Enhanced electron transfer and adsorption capacity

To effectively treat the hydrophobic organic contaminant and utilize an industrial solid waste manganese residue (MR), a novel starch-derived carbon (SC)-decorated and Cu-doped (Fe,Cu)S/CuFe2O4 solid solution (CFS/CFO@SC) was prepared from MR via mechanical activation treatment of precursor materials followed by one-step pyrolysis and applied as a photo-Fenton catalyst to treat a hydrophobic organic compound, 17α-ethinylestradiol (EE2). Characterization results showed that the CFS/CFO@SC solid solution with unique crystal and electronic structures exhibited high adsorption capacity and catalytic activity, ascribed to that Cu doping and C decorating enhanced its hydrophobicity and BET surface area. The CFS/CFO@SC showed excellent degradation efficiency with nearly 100% of EE2 removal rate in 40 min (degradation rate constant of 0.112 min−1), and a high mineralization degree with 95.2% of TOC removal in 180 min. This could be ascribed to that C decorating and the formation of CFS/CFO solid solution promoted the charge transfer in a continuous band, resulting in effective separation of photogenerated holes–electrons (h+–e–). The strong interaction of Fe–Cu collaborating with the photoelectron could effectively accelerate the recycle of Fe3+/Fe2+ and Cu2+/Cu+, thus generating more active radicals. Moreover, CFS/CFO@SC showed promising stability and recyclability with the EE2 removal rates all >95% after five cycles. This work brings a valuable approach for the rational design of high-performance Fe-based photo-Fenton catalysts for environmental remediation and the valorization of MR.

Graphitic-C3N4 quantum dots modified FeOOH for photo-Fenton degradation of organic pollutants

Developing an efficient heterogeneous Fenton-like synergistic photocatalyst is paramount for degrading organic pollutants. Here, based on two types of g-C3N4 quantum dots (CNQDs) with different fluorescence properties, two kinds of composites (CNQDs/ FeOOH) were fabricated by using a facile method. These composites were used as efficient photo-Fenton catalysts for the treatment of organic pollutants. The composites showed enhanced photocatalysis, Fenton, and photo-Fenton in the degradation of tetracycline (TC), p-nitrophenol (PNP), and 2,4-dinitrophenol (2,4-DNP) compared with pure FeOOH. The degradation efficiencies of composites for TC was up to 89% in 2 min, that for PNP was up to 90% in 10 min, and that for 2,4-DNP was up to 90% in 5 min. Finally, the photo-Fenton catalytic mechanism was discussed on the basis of the reactive radical experiments. The results reported herein provide a strategy for degrading organic pollutants efficiently.

Immobilization of Fe2O3 on perlite for photo-Fenton degradation of methylene blue

Photo-Fenton catalysts with floating features based on the immobilization of Fe2O3 particles on the surface of perlite granules were synthesized by a simple precipitation-annealing method. The effects of annealing temperature on the crystal structure, phase composition, morphology, surface area, surface functional groups, and surface atomic composition of the prepared catalysts were investigated by powder X-ray diffraction, field emission scanning electron microscope, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, and low voltage energy-dispersive X-ray spectroscopy. The catalytic activity was evaluated via the degradation of methylene blue in the presence of oxalic acid under UVA light and visible light. Immobilization of Fe2O3 on the perlite surface resulted in photo-Fenton catalytic activity for all samples, attributable to the formation of the hematite phase and the presence of surface Fe species. Owing to the low density of perlite, all catalysts float on the surface of the solution, which allows them to be easily separated.

Photo-fenton degradation of RhB via transition metal oxides composite catalyst Fe3O4/CuO under visible light optimized using response surface methodology

ABSTRACT This paper reports on the facile synthesis and degradation of a heterogeneous photo-Fenton catalyst Fe3O4/CuO to improve the conventional photo-Fenton catalyst. The results using Fe3O4/CuO as a heterogeneous photo-Fenton catalyst showed that the degradation of 98.9% was achieved through visible light irradiation of 10 mg·L−1 RhB solution at pH 2 in the presence of 30 mmol·L−1 H2O2 for 1 h. In addition, the process parameters were optimised using the Response Surface Methodology (RSM). After optimisation, optimum conditions of process factors such as catalyst dosage, initial concentration of H2O2, pH and initial concentration of RhB were determined as 17 mg·L−1, 28.14 mmol·L−1,2.32 and 5.31 mg·L−1, respectively. The quenching experiments of active species demonstrated that hydroxyl radical (·OH) was the main active group. Cycling experiments proved that the catalyst has good reusability. Finally, the possible reaction pathways of the photo-Fenton catalyst under the conditions of visible light and hydrogen peroxide were proposed.

Construction of core-shell Fe3O4@GO-CoPc photo-Fenton catalyst for superior removal of tetracycline: The role of GO in promotion of H2O2 to •OH conversion

A novel core-shell structured Fe3O4@GO-CoPc magnetic catalyst, which is with magnetite (Fe3O4) as the core, graphene oxide (GO) as the interlayer and cobalt-phthalocyanine (CoPc) as the shell, was successfully prepared and used as a heterogeneous photo-Fenton catalyst for tetracycline (TC) degradation in this work. The core-shell structure of the catalyst was confirmed by XRD, FTIR, SEM and TEM. BET and magnetic hysteresis loops measurements indicated that Fe3O4@GO-CoPc catalyst owned large specific surface area and could be easily recovered under an external magnetic field. Meanwhile, the experimental results of TC degradation demonstrated that the photo-Fenton efficiency of Fe3O4@GO-CoPc was excellent. When the reaction time was 120 min, TC could be degraded almost completely in the photo-Fenton system with Fe3O4@GO-CoPc. The high photo-Fenton catalytic activity of Fe3O4@GO-CoPc could be resulted from the effective transfer of photo-generated electrons between CoPc and Fe3O4 by GO. Moreover, the main reaction species, •OH, O2•-, 1O2 and h+, were verified by the analysis of active species in this system. Finally, the mechanism analyses and quantitative analysis results of active species indicated that the introduction of GO accelerated the cycle between Fe(II) and Fe(III) as well as improved the effective utilization of H2O2 (the efficiency of conversion of H2O2 to •OH).

Red mud supported on reduced graphene oxide as photo-Fenton catalysts for organic contaminant degradation

In this study, the reduced graphene oxide (rGO) modified red mud (RM) composite was successfully prepared and used as the highly effective heterogeneous photo-Fenton catalyst for Rhodamine B (RhB) contaminant degradation. The acid leaching and calcination treatment reduced the impurities in RM, making α-Fe2O3 active for H2O2 decomposing. The rGO modification can not only inhibit the recombination of charge carriers but also accelerate the Fe3+/Fe2+ cycle during heterogenous Fenton process. Attributed to such advantages, 99.8% degradation of RhB within 20 min was achieved by the optimal RM-H/rGO composite. More importantly, the prepared RM-H/rGO showed excellent performance and high stability for various organic contaminants degradation at a wide pH range. This study not only demonstrates that rGO-modified RM can be used as an efficient, low-cost photo-Fenton catalyst for organic pollutants treatment, but also provides an effective approach for RM disposal.

Sunlight mediated photo-Fenton degradation of tetracycline antibiotic and methylene blue dye in aqueous medium using FeWO4/Bi2MoO6 nanocomposite

An optimized batch of 0.25FeWO4/Bi2MoO6 nanocomposites has been developed as an efficient solar photo-Fenton catalyst for degradation of tetracycline antibiotic and methylene blue in an aqueous medium. The catalyst is synthesized by hydrothermal route. Its structure, composition, and morphology are thoroughly characterized. The catalyst dose of 30 mg/50 mL spiked with 20 µL of H2O2 (30% v/v) resulted in 97% degradation of tetracycline and 99% degradation of methylene blue within 90 min. The corresponding degradation rate constants are 0.026 min−1 and 0.043 min−1, respectively. The total organic carbon estimation indicated mineralization of ~80% tetracycline and ~90% methylene blue. The photo-Fenton degradation of tetracycline and methylene blue by FeWO4/Bi2MoO6 nanocomposites is significantly enhanced as compared to Bi2MoO6 photocatalyst, attributed to photo-Fenton heterojunction catalyst, charge carrier separation and mobility, and sustained reactive oxygen species (ROS) generation. The role of ROS, e.g., hydroxyl radicals and superoxide radicals, towards the degradation process is confirmed from ROS scavenging studies. The degradation mechanism has been discussed by identifying the degradation products by ultra-performance liquid chromatography (UPLC)-Q-Tof-MS technique.

Enhanced oxalate-induced degradation of organic dyes using magnetic photo-Fenton catalysts based on CuFe2O4-Fe2O3 composites

ABSTRACT The aim of this study was to synthesise magnetic CuFe2O4-Fe2O3 composite materials with enhanced photo-Fenton catalytic activity for the degradation of organic dyes in the presence of oxalic acid as radical-producing source. The composite catalysts were prepared by a simple hydroxide precipitation process followed by an annealing at 300°C with different annealing times. Their phase composition, morphology, surface atomic composition, surface functional groups and magnetic properties were characterised by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The catalytic tests were carried out using methylene blue as a cationic dye and methyl orange as an anionic dye. According to the results, all CuFe2O4-Fe2O3 composite catalysts exhibited significantly higher photo-Fenton activities than CuFe2O4 sample under UVA light and visible light, which can be attributed to the enhanced content of Fe species and the high roughness observed on composite surface. These composite catalysts were found effective in degrading both cationic and anionic dyes although the decomposition of methyl orange was more difficult than that of methylene blue. Moreover, oxalic acid was also experimentally proved to be an excellent radical-producing source, which is superior to H2O2, in our photo-Fenton catalytic system. When the annealing time used in the synthetic procedure was extended, the catalytic performance of composite samples tended to increase but their magnetic properties were reduced, revealing that the annealing time is an important factor to be considered for the preparation of magnetic photo-Fenton composite catalysts.

Surface Oxygen Vacancies and Carbon Dopant Co-Decorated Magnetic Znfe2o4 as Photo-Fenton Catalyst Towards Efficient Degradation of Tetracycline Hydrochloride

Surface Oxygen Vacancies and Carbon Dopant Co-Decorated Magnetic Znfe2o4 as Photo-Fenton Catalyst Towards Efficient Degradation of Tetracycline Hydrochloride

Construction of high-performance g-C3N4-based photo-Fenton catalysts by ferrate-induced defect engineering

A highly-efficient Fe–g-C3N4 photo-Fenton catalyst was prepared using ferrate as a critical iron source and defect control additive. The complementary synergistic effects of Fe species and defect sites promote photoelectron transfer.

Nitrogen–Doped Titanium Dioxide/Schwertmannite Nanocomposites as Heterogeneous Photo–Fenton Catalysts with Enhanced Efficiency for the Degradation of Bisphenol a

Nitrogen–Doped Titanium Dioxide/Schwertmannite Nanocomposites as Heterogeneous Photo–Fenton Catalysts with Enhanced Efficiency for the Degradation of Bisphenol a

Photo-Fenton and oxygen vacancies' synergy for enhancing catalytic activity with S-scheme FeS2/Bi2WO6 heterostructure

A series of FeS2/Bi2WO6 S-scheme photo-Fenton catalysts with efficient catalytic performances were successfully prepared by coupling FeS2 into the surface oxygen vacancy enriched Bi2WO6 using calcination and solvothermal methods.

Iron-doped g-C3N4 catalysts fabricated by forming Fe–N moieties with outstanding photo-Fenton activity toward tetracycline degradation

Porous Fe-doped g-C3N4 photo-Fenton catalysts are successfully prepared by a convenient one-step pyrolysis strategy and applied in the degradation of tetracycline hydrochloride.

Mil-101(Fe)@Zn/Co-Zifs Metal–Organic Frameworks are Effective Photo-Fenton Catalysts for Rhb Removal

Mil-101(Fe)@Zn/Co-Zifs Metal–Organic Frameworks are Effective Photo-Fenton Catalysts for Rhb Removal

New and highly efficient Ultra-thin g-C3N4/FeOCl nanocomposites as photo-Fenton catalysts for pollutants degradation and antibacterial effect under visible light

The photo-Fenton reaction was widely used in the removal of pollutants in waste water, which makes it exhibit great potential in the field of environmental remediation. Hence, it is crucial to explore a new efficient and stable photo-Fenton catalyst driven by visible light.In this work, a simple two-step calcination method was used to synthesize sheet-like stacked Ultra-thin g-C3N4/FeOCl (CNF) materials. The morphology, composition, photo-Fenton performance, and antibacterial properties were systematically analyzed. Research results exhibited that the synthesized CNF catalysts showed enhanced visible light absorption capacity and excellent photo-Fenton performance. Compared with FeOCl alone, CNF displayed stronger degradation ability for rhodamine B (RhB) and could achieve 97% degradation within 9 min, which was about 10 times that of pure FeOCl. At the same time, the composite catalysts exhibited excellent antibacterial effects under photo-Fenton conditions. The antibacterial rate of CNF composite catalyst under photo-Fenton conditions can reach almost 99%, which was 3 times that of photocatalysis alone and 2 times that of Fenton alone. The heterojunction formed between Ultra-thin g-C3N4 and FeOCl promoted the separation of e− and h+. Simultaneously, the presence of e− promoted the cycle of Fe3+ and Fe2+ in FeOCl, thereby promoting the generation of hydroxyl radicals (OH) from H2O2 and improving the photo-Fenton activity to achieve the effect of degrading pollutants and antibacterial. The photo-Fenton catalysis and degradation mechanism were analyzed in detail. This work provided a theoretical basis for the application of CNF material in the removal of wastewater.

Superior photo–Fenton activity towards chlortetracycline degradation over novel g–C3N4 nanosheets/schwertmannite nanocomposites with accelerated Fe(III)/Fe(II) cycling

The low Fe(III)/Fe(II) conversion rate seriously hinders the progress of heterogeneous Fenton reactions. In this work, g–C3N4 nanosheets/schwertmannite (CNNS/SCH) nanocomposites were fabricated by means of an in situ growth strategy to enhance the interfacial synergistic effect of photo–Fenton systems for chlortetracycline (CTC) degradation. More specifically, the photogenerated electrons in g–C3N4 can quickly transfer to the SCH via Fe–N bonds formed at interfaces of g–C3N4 and SCH for viable Fe(III) reduction under visible irradiation, and thus to promote the production of active radicals. Compared with an individual CNNS or SCH, CNNS/SCH nanocomposites exhibit superior photo–Fenton catalytic activity. In optimized conditions, 98.7% degradation efficiency of 50 mg L–1 CTC and up to 96.6% of TOC removal have been achieved in 120 min at an optimized pH. CNNS/SCH nanocomposites also display excellent long–term stability without obvious deactivation in five consecutive runs of photo–Fenton reactions. Quenching experiments and EPR analyses identify that hydroxyl radicals (OH) and singlet oxygen (1O2) are the main active species contributing to the degradation of CTC. Mechanism of the photo–Fenton–like processes with CNNS/SCH nanocomposite catalysts has been tentatively explored based on various photoelectrochemical measurements. It is concluded that combinational use of CNNS and SCH could significantly promote the separation of photogenerated electron–hole pairs, the interfacial charge transfer and the Fe(III) reduction at surfaces. This study might offer a new insight for the construction of highly efficient photo–Fenton catalysts to achieve effective treatment of priority pollutants in wastewater.

Degradation of organophosphorus flame retardants in heterogeneous photo-Fenton system driven by Fe(III)-based metal organic framework: Intermediates and their potential interference on bacterial metabolism

Organophosphorus flame retardants (OPFRs) have been regarded as one of the most rebarbative classes of emerging contaminants due to their persistence and toxicity. In the current study, Fe-based metal organic framework (MIL-88A) was synthesized and employed as photo-Fenton catalyst for the degradation of tris-(2-chloroisopropyl) phosphate (TCPP), a typical representative of OPFRs. The observations indicated that visible light could boost the reduction of ≡FeIII to ≡FeII in Fe–O clusters of MIL-88A during the photo-Fenton system and consequently induce the transformation of H2O2 to OH, which realized efficient degradation of TCPP. Due to the excellent function of MIL-88A, the effective pH application range of photo-Fenton system was extended in comparison with traditional Fenton system. The degradation efficiency of TCPP was visibly influenced in presence of humic acid (HA). MIL-88A exhibited a commendable reusability and stability after 3 times cycle. As the photo-Fenton reaction proceeded, TCPP was disintegrated to several kinds of carboxylated, dechlorinated and hydroxylated products. The observations of metabolomics endorsed that the interference of intermediate products mixture on E. coli weakened to a certain extent. In conclusion, carboxylation, dechlorination, hydroxylation and oxidation of TCPP were likewise effective for its detoxification, revealing that heterogeneous photo-Fenton system driven by Fe-based metal organic framework will be an attractive and safe treatment technique for OPFRs control.