NiFe(C2O4)x as a heterogeneous Fenton catalyst for removal of methyl orange

Enhancing catalyst stability: Immobilization of Cu-Fe catalyst in sodium alginate matrix for methyl orange removal via Fenton-like reaction

This study aims to enhance the stability and effectiveness of heterogeneous catalysts in Fenton-like reactions, explicitly addressing the acidity limitations inherent in traditional Fenton processes. Copper-iron was synthesized through co-precipitation, and a catalyst bead was produced from hydrogel formation. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirm phases in the bimetallic Copper-iron, aligning with the intended composition. Modification with alginate led to reduced metal leaching compared to the bare bimetallic counterpart, as confirmed by atomic absorption spectroscopy (AAS). Additionally, Fourier-transform infrared spectroscopy (FTIR) revealed the deactivation of alginate through the disappearance of carboxyl groups, indicating the depolymerization of the catalyst bead. Under the suggested conditions (Methyl Orange concentration of 25 mg/L, initial solution pH of 7, 2 g/L catalyst loading, concentration of hydrogen peroxide 100 mM in a 120-min reaction time), the catalyst demonstrated remarkable decolorization efficiency of Methyl Orange, achieving 97.67 %. Further highlighting its practicality, the catalyst exhibited outstanding reusability over four cycles under identical conditions, showcasing robust immobilization capabilities and sustained performance. Notably, the catalyst's magnetic properties facilitated easy separation using an external magnet. In conclusion, the developed catalyst beads offer a solution with high reusability, magnetic separability, and reduced iron leaching. The advantageous characteristics underscore its potential as a heterogeneous catalyst for wastewater treatment applications, warranting further exploration under practical conditions.

Fenton-Like Reaction: Recent Advances and New Trends

The Fenton reaction refers to the reaction in which ferrous ions (Fe2+) produce hydroxyl radicals and other reactive oxidizing substances by decomposing hydrogen peroxide (H2O2). This paper reviews the mechanism, application system, and materials employed in the Fenton reaction including conventional homogeneous and non-homogeneous Fenton reactions as well as photo-, electrically-, ultrasonically-, and piezoelectrically-triggered Fenton reactions, and summarizes the applications in the degradation of soil oil pollutions, landfill leachate, textile wastewater, and antibiotics from a practical point of view. The mineralization paths of typical pollutant are elucidated with relevant case studies. The paper concludes with a summary and outlook of the further development of Fenton-like reactions.

Catalytic Degradation of Anionic Organic Dye on Greenly Synthesized CuO/ZnO Nanocomposites

CuO/ZnO nanocomposites were greenly prepared and tested for the catalytic degradation of methyl orange. The XRD analysis confirmed the existence of CuO and ZnO with crystallite sizes within the range of 15–30 nm. TEM and SEM images showed different morphological properties. The TGA analysis revealed a good thermal stability of the nanocomposite, with a total loss of less than 18% at a temperature of 700 °C. The nanocomposites were tested for the catalytic degradation of methyl orange under mild conditions with a catalyst mass/wastewater volume of 10 g/3 L, an initial dye concentration of 40 ppm, a pH of 4.5, and a degradation time of 3 h. The best efficiency of 49.1% was achieved by CuO nanoparticles (C), followed by 47.6%, which was obtained by 1C1Z. The degradation efficiency of ZnO (Z) was 16.4%, and it was increased by increasing the CuO precursor in the synthesis mixture, while adding ZnO to the CuO, resulting in a decrease in its catalytic performance.

A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton: high activity, wide pH range and catalytic mechanism

A charcoal-shaped catalyst NiFe₂O₄/Fe₂O₃ in electro-Fenton (EF) was synthesized by a facile precipitation approach via sintering products of oxalate co-precipitation. This obtained NiFe₂O₄/Fe₂O₃ catalyst was easily separated via an external magnetic field and was used as a heterogeneous electro-Fenton catalyst for rhodamine B (RhB, a target pollutant) degradation. Characteristics of NiFe₂O₄/Fe₂O₃ catalyst were assessed using scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Barrett-Emmett-Teller (BET), respectively. SEM results revealed that the proposed NiFe₂O₄/Fe₂O₃ was charcoal-shaped with the size in the range of 0.5-5 μm. Experiment results show that the EF process with the proposed catalyst could work in a wide pH range from 3 to 9. Under optimized conditions, estimated 90% RhB degradation was achieved in 60 min under the following conditions: 0.6 g/L NiFe₂O₄/Fe₂O₃, pH 3. Radical scavengers and electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was ⋅OH, accounting for RhB degradation in EF. Moreover, according to our research on interfacial reaction, ⋅OH was mainly generated from the homogenous Fenton reaction rather than the surface Fenton reaction, stimulating by the dissolved Fe²⁺, Fe³⁺ and Ni²⁺ from catalyst. The reusability of NiFe₂O₄/Fe₂O₃ catalyst was evaluated for recycling the same catalyst for 5 runs. In conclusion, the facile fabrication NiFe₂O₄/Fe₂O₃ catalyst shows great potential in wastewater treatment with promising activity.

Preparation of new adsorbent-supported Fe/Ni particles for the removal of crystal violet and methylene blue by a heterogeneous Fenton-like reaction

Prepared material-supported Fe/Ni particles (PM-Fe/Ni) were produced and applied as an adsorbent, reductant and Fenton-like catalyst for removing methylene blue (MB) and crystal violet (CV) from aqueous solutions. Fe/Ni particles were prepared by reducing ferric chloride with sodium borohydride and supported on the produced porous material. Various techniques including X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy analysis (SEM) were employed to characterize the crystal phase, surface area, surface morphology and functional groups. Removal experiments were conducted to study the effects of different factors such as PM-Fe/Ni dosage, initial pH, H₂O₂ concentration, initial concentrations and temperature on MB and CV removal. The removal efficiency of CV and MB by PM-Fe/Ni/H₂O₂ were 91.86% and 61.41% under the conditions of dye concentration of 1000 mg L⁻¹, H₂O₂ concentration of 50 mM, PM-Fe/Ni dosage of 0.20 g and temperature of 293 K. The analysis of the degradation kinetics showed that the degradation of MB and CV followed well pseudo-first-order kinetics. A possible mechanism of removal of MB and CV was proposed, including the adsorption, reduction and dominating Fenton oxidation. The regeneration experiments of PM-Fe/Ni demonstrated that PM-Fe/Ni with H₂O₂ still showed a high removal efficiency after six reaction cycles.

Possible reaction mechanism for CV and MB removal by the PM-Fe/Ni with H₂O₂ system.