Preparation of immobilized coating Fenton-like catalyst for high efficient degradation of phenol

Honeycomb-like biochar framework coupled with Fe3O4/FeS nanoparticles as efficient heterogeneous Fenton catalyst for phenol degradation

Achieving an efficient and stable heterogeneous Fenton reaction over a wide pH range is of great significance for wastewater treatment. Here, a pollen-derived biochar catalyst with a unique honeycomb-like structure, coupled with the dispersion of magnetic Fe3O4/FeS (Fe/S) nanoparticles, was synthesized by simple impregnation precursor, followed by pyrolysis. The prepared Fe/S-biochar catalyst demonstrated outstanding phenol degradation efficiency across a wide pH range, with 98% of which eliminated even under neutral conditions (pH 7.0). The high catalytic activity was due to the multilevel porous structure of pollen-derived biochar provided enough active sites and allowed for better electron transfer, then increases oxidation ability to promote the reaction. Moreover, the acid microenvironment formed by SO42- group from Fe/S composite extended the pH range for Fenton reaction, and S2- facilitated the conversion of Fe3+ to Fe2+, resulting in remarkable degradation efficiency. Further, biochar can effectively promote cycling stability by limiting Fe leaching. This work may provide a general strategy for designing 3D framework biochar-based Fe/S catalysts with excellent performance for heterogeneous Fenton reactions.

Synthesis of the SO42−–Fe3O4/FeS coating catalyst on a TC4 titanium alloy for the enhanced Fenton-like degradation of phenol

SO₄²⁻–Fe₃O₄/FeS coatings prepared by PEO as Fenton-like catalysts exhibit remarkable catalytic performance.

Fenton-Like Oxidation of Antibiotic Ornidazole Using Biochar-Supported Nanoscale Zero-Valent Iron as Heterogeneous Hydrogen Peroxide Activator

Biochar (BC)-supported nanoscale zero-valent iron (nZVI-BC) was investigated as a heterogeneous Fenton-like activator to degrade the antibiotic ornidazole (ONZ). The characterization of nZVI-BC indicated that BC could enhance the adsorption of ONZ and reduce the aggregation of nZVI. Thus, nZVI-BC had a higher removal efficiency (80.1%) than nZVI and BC. The effects of parameters such as the nZVI/BC mass ratio, pH, H2O2 concentration, nZVI-BC dose, and temperature were systematically investigated, and the removal of ONZ followed a pseudo-second-order kinetic model. Finally, possible pathways of ONZ in the oxidation process were proposed. The removal mechanism included the adsorption of ONZ onto the surface of nZVI-BC, the generation of •OH by the reaction of nZVI with H2O2, and the oxidation of ONZ. Recycling experiments indicated that the nZVI-BC/H2O2 system is a promising alternative for the treatment of wastewater containing ONZ.

Effect of peroxydisulfate on the degradation of phenol under dielectric barrier discharge plasma treatment

The activation of peroxydisulfate (PDS) by gas/liquid dielectric barrier discharge (DBD) plasma in a flat plate configuration was assessed through phenol removal. The results indicated that PDS addition exhibited a significantly promoting effect on phenol removal and mineralization. In the reaction lacking PDS, phenol in aqueous solution was removed from the initial 10 mg L^-1 to 4.75 mg L^-1 (by 52.5%), whereas the addition of 1770 mg L^-1 PDS increased the overall removal to 78.7%, as indicated by a one-fold increase in the pseudo-first-order kinetic constant. In addition, the corresponding total organic carbon (TOC) removal was increased from 27.5% to 48.4%. Furthermore, an increased input voltage was favourable for increases in phenol removal, the kinetic constant and PDS utilization, which were also influenced by the PDS dose, initial solution pH and water matrix. In addition, through the analysis of radical quenching experiments, the enhancement could be mainly attributed to the production of SO₄^•- and •OH by PDS activation by discharge plasma. The DBD system coupled with PDS exhibited a high removal efficiency for phenol, and thus, the overall findings could provide new insight into wastewater treatment.

Heterogeneous Fenton degradation of bisphenol A using Fe3O4@β-CD/rGO composite: Synergistic effect, principle and way of degradation

In this study, a multi-component catalyst, β-cyclodextrin (β-CD) and reduced graphene oxide (rGO) co-modified Fe₃O₄, was fabricated via one-pot solvothermal method and used as a synergistic catalyzer for Bisphenol A (BPA) removal. The study found that catalytic reactions of BPA followed the pseudo-first-order kinetics model, and the correlation rate constants (k_obs) were calculated. Compared with Fe₃O₄@β-CD (0.02173 min^-1), Fe₃O₄/rGO (0.09735 min^-1) and Fe₃O₄ (0.01666 min^-1), the composite (0.15733 min^-1) exhibited stronger catalytic ability to remove BPA from aqueous solution under the same conditions, which were attributed to the synergistic enhancement effect among the components. The introduction of rGO in the composites was beneficial to the generation of •OH, and the role of β-CD might enhance the utilization of •OH. A possible three-element catalytic schematic diagram was described. The effects of pH, dosage of the catalyst, initial H₂O₂ and NH₂OH concentrations on the removal efficiency were further investigated. The removal of BPA and TOC retained 78.2 ± 2.4% and 52.9 ± 2.5% after five cycles, indicating its excellent stability and reusability. Furthermore, a probable reaction pathway of BPA removal was suggested by analyzing the intermediate products. All results indicated that the composite had high and stable catalytic performance, which made it have potential application on the industrial treatment of wastewater.

Enhancement of H2O2 Decomposition by the Co-catalytic Effect of WS2 on the Fenton Reaction for the Synchronous Reduction of Cr(VI) and Remediation of Phenol

The greatest problem in the Fe(II)/H₂O₂ Fenton reaction is the low production of ·OH owing to the inefficient Fe(III)/Fe(II) cycle and the low decomposition efficiency of H₂O₂ (<30%). Herein, we report a new discovery regarding the significant co-catalytic effect of WS₂ on the decomposition of H₂O₂ in a photoassisted Fe(II)/H₂O₂ Fenton system. With the help of WS₂ co-catalytic effect, the H₂O₂ decomposition efficiency can be increased from 22.9% to 60.1%, such that minimal concentrations of H₂O₂ (0.4 mmol/L) and Fe²⁺ (0.14 mmol/L) are necessary for the standard Fenton reaction. Interestingly, the co-catalytic Fenton strategy can be applied to the simultaneous oxidation of phenol (10 mg/L) and reduction of Cr(VI) (40 mg/L), and the corresponding degradation and reduction rates can reach up to 80.9% and 90.9%, respectively, which are much higher than the conventional Fenton reaction (52.0% and 31.0%). We found that the expose reductive W⁴⁺ active sites on the surface of WS₂ can greatly accelerate the rate-limiting step of Fe³⁺/Fe²⁺ conversion, which plays the key role in the decomposition of H₂O₂ and the reduction of Cr(VI). Our discovery represents a breakthrough in the field of inorganic catalyzing AOPs and greatly advances the practical utility of this method for environmental applications.

Continuous generation of hydroxyl radicals for highly efficient elimination of chlorophenols and phenols catalyzed by heterogeneous Fenton-like catalysts yolk/shell Pd@Fe3O4@metal organic frameworks

Core/shell Fe₃O₄-decorated Pd nanoparticles (NPs) hybrids (Pd@Fe₃O₄) are prepared through a "green", and one-pot chemical process. The Pd@Fe₃O₄ hybrids consisted of faceted quasi-spherical Pd nanoparticles (NPs) cores (∼20 nm) surrounded by close-packed Fe₃O₄ NPs (∼7 nm). To improve the stability and avoid aggregation of Pd@Fe₃O₄ hybrids in water, hollow Fe-metal organic frameworks (Fe-MOFs) were applied to enwrap Pd@Fe₃O₄ to obtain yolk/shell structured composites. Sub-10 nm Fe₃O₄ and Pd NPs close to each other were distributed evenly in the MOFs shell of Pd@Fe₃O₄@MOFs. The yolk/shell Pd@Fe₃O₄@MOFs can catalyze the oxidative degradation of chlorophenols and phenols by hydroxyl radicals (OH) decomposed from H₂O₂. With low molar ratio of H₂O₂/pollutants, the pollutants are degraded and mineralized efficiently and rapidly. The outstanding catalytic efficiency of Pd@Fe₃O₄@MOFs is contributed by the fast and continuous generation of OH radicals in Pd@Fe₃O₄@MOFs suspension which is detected with the electron spin resonance spin-trap technique and a continuous-flow chemiluminescence system. Lack of consumption of hydroperoxyl radicals/superoxide radicals (HO₂/O₂^-) in the Pd@Fe₃O₄@MOFs-H₂O₂ system might suggest that the production of OH radicals results from the electron transferring from Pd to Fe₃O₄ component both in the inner Pd@Fe₃O₄ and MOF shell, which facilitates fast Fe(III)/Fe(II) redox cycle.

A magnetic CoFe2O4–CNS nanocomposite as an efficient, recyclable catalyst for peroxymonosulfate activation and pollutant degradation

An efficient, stable, easily recoverable hybrid nanomaterial for heterogeneous activation of PMS and sulfonamide degradation.