Magnetically separable and reusable rGO/Fe3O4 nanocomposites for the selective liquid phase oxidation of cyclohexene to 1,2-cyclohexane diol

Characteristics and catalytic behavior of Ru-Sn bimetallic catalysts for TMCB hydrogenation to CBDO

A series of Ru-Sn/γ-Al2O3 catalysts were prepared by the immersion method for tetramethylcyclobutane-1,3-dione (TMCB) hydrogenation to prepare 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO). The effect of the preparation method and reaction technology on TMCB hydrogenation activity was discussed. The catalysts were analyzed by means of XRD, BET, H2-TPR, XPS, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and it was found that the synthesized Ru was distributed on the surface of the carrier in the form of nanoparticles, showing a good catalytic effect. The results showed that when Ru loading was fixed at 5%, Sn was used as an auxiliary agent, and Ru/Sn = 1 : 1 as the catalyst, the reaction conditions were 120 °C, 4 MPa, and 1 h, and the catalytic hydrogenation effect of TMCB on CBDO was the best. The selectivity was as high as 73.5%, and the cis-trans ratio was 1.11. It may be the strong interaction between Ru and Sn under this ratio condition, which leads to the largest number of nano-active centers of elemental Ru. Finally, the reaction mechanism of TMCB hydrogenation to CBDO is discussed.

V2O5-Fe3O4/rGO Ternary Nanocomposite with Dual Applications as a Dye Degradation Photocatalyst and OER Electrocatalyst

The design and synthesis of structured nanomaterials with dual properties have always been highly attractive in various fields, especially in the reduction of environmental pollution as well as the generation of renewable energy. In this study, the synthesized ternary V2O5-Fe3O4/rGO nanocomposite was investigated to evaluate both the photocatalytic and electrocatalytic activities for the removal of methylene blue (MB) dye under UV/visible light radiation and oxygen evolution reaction (OER), respectively. The magnetized V2O5-Fe3O4/rGO nanocomposite is characterized by TEM, FE-SEM (with coupling by elemental mapping), EDS, XRD, FTIR, Raman, PL, DRS, and UV-vis analyses. The obtained results show that the graphene oxide substrate is decorated very well using Fe3O4 and V2O5 nanoparticles and converted to reduced graphene oxide (rGO). Furthermore, the V2O5-Fe3O4/rGO nanocomposite is considered as an active catalyst material to modify the commercial glassy carbon electrode for OER using linear sweep voltammetry (LSV). The photocatalytic activity of this novel nanocomposite revealed 89.2% (kobs = 1.7 × 10-2 min-1) and 76% (kobs = 8.3 × 10-3 min-1) degradation efficiencies of MB dye under UV and visible light irradiation at room temperature, respectively, and the surface area of the V2O5-Fe3O4/rGO nanocomposite was examined to be 705.8 cm2/g by N2 adsorption-desorption isotherms. In addition, electrochemical measurements determined the best OER performance of the ternary nanocomposite with the lowest overpotential (458 mV) and Tafel slope (132 mV dec-1) compared to the rGO substrate, Fe3O4, V2O5 nanoparticles, and binary nanocomposites. This work shows much enhancements in both photocatalytic and electrocatalytic activities due to the synergistic effect of the decorated GO support with V2O5 and Fe3O4 nanoparticles.

Synthesis and characterization of rGO/Fe0/Fe3O4/TiO2 nanocomposite and application of photocatalytic process in the decomposition of penicillin G from aqueous

In this study, we synthesized rGO/Fe⁰/Fe₃O₄/TiO₂ nanocomposite according to Hummer's, and straightforward sol-gel method. The FESEM, EDX, TEM, FT-IR, XRD, BET, UV spectra, and VSM analysis were applied to determine the catalyst properties. Optimization of influence parameters on photocatalytic process performance to penicillin G degradation in aqueous media. pH (4-8), nanocomposite dose (10-20 mg/L), reaction time (30-60 min), and penicillin G concentration (50-100 mg/L) were optimized via central composite design. In the optimum condition of PCP, supplementary studies were done. As a result of the analysis, the nanocomposite was well synthesized and displayed superior photocatalytic properties for degrading organic pollutants. In addition to being magnetically separable, the synthesized rGO/Fe⁰/Fe₃O₄/TiO₂ nanocomposite exhibits high recyclability up to 5 times. The quadratic model of optimization is based on the adjusted R²(0.99), and predicated R²(0.97) suggested. According to the analysis of variance test, the model was significant (F-Value = 162.95, P-Value = 0.0001). Photocatalytic process is most efficiently decomposed at pH = 6.5, catalyst dose = 18.5 mg/L, reaction time = 59.1 min, and penicillin G concentration = 52 mg/L (efficiency = 96%). The chemical oxygen demand and total organic carbon decrease were 78, and 65%. The photolysis and adsorption mechanism as a single mechanism had lower performance in penicillin G degradation. Benzocaine had the greatest effect on reducing the efficiency of the process as a radical scavenger. The °OH, h^+, and O₂^●- were the main reactive oxidant species in penicillin G removal. Phenoxyacetaldehyde, Acetanilide, Diacetamate, Phenylalanylglycine, N-Acetyl-l-phenylalanine, Diformyldapsone, and Succisulfone were the main intermediates in penicillin G degradation. The results indicated the photocatalytic process with rGO/Fe⁰/Fe₃O₄/TiO₂ nanocomposite on a laboratory scale has good efficiency in removing penicillin G antibiotic. The application of real media requires further studies.

Efficient activation of persulfate by C@Fe3O4 in visible-light for tetracycline degradation

A C@Fe₃O₄ material, Fe₃O₄ coated with carbon, was prepared by a simple one-pot hydrothermal method. The C@Fe₃O₄ material was investigated with persulfate (PS) and light to degrade tetracycline (TC) as a function of pH, aeration conditions and quenching. Experimental results suggest that TC was effectively degraded in the C@Fe₃O₄/PS/Vis system. In addition, due to the availability of different main active species in this catalytic system, TC degradation was possible under both strong acid and strong alkali pH conditions. The presence of dissolved oxygen can also generate oxygen-active species, such as superoxide radicals (O₂•^-) and singlet oxygen (¹O₂), to decompose TC organic matter in solution. Simply put, C@Fe₃O₄/PS/Vis catalytic system removed pollutants by the formation of O₂•^-, ¹O₂, hydroxyl radicals (•OH) and sulfate radicals (SO₄•^-) species for degrading TC. In addition, the stability of the C@Fe₃O₄ material was found to be outstanding.

Decorated reduced graphene oxide transfer sulfides into sulfur and sulfone in wastewater

Sulfides cannot be completely removed using oxidation due to the production of sulfate. In this work, a reduced graphene oxide (RGO)/Fe₃O₄ hybrid material was synthesized via a simple in situ chemical method for sulfide removal. The adsorption capacity of RGO/Fe₃O₄ was evaluated by sulfide removal from aqueous solution, and different experimental parameters including contact time, solution pH, adsorbent dosage, ion strength and temperature were investigated. The equilibrium data were in accordance with the Langmuir linear isotherm with a maximum uptake capacity of 173 mg g^-1. The adsorption of sulfide by the RGO/Fe₃O₄ hybrid material can be attributed to the synergistic effect of both chemical and physical adsorption according to kinetic, adsorption isotherm and thermodynamic studies. The RGO/Fe₃O₄ material with oxygenated functional groups could convert sulfides to stable elemental sulfur and sulfone organics. The external magnetic field could easily separate the magnetic RGO/Fe₃O₄ adsorbent from the liquid. This research provides a novel strategy for the green and low-cost treatment of sulfide-containing wastewater by the RGO/Fe₃O₄ hybrid material.

From methylarenes to Esters: Efficient oxidative Csp3-H activation promoted by CuO decorated magnetic reduced graphene oxide

Magnetic reduced graphene oxide supported CuO (rGO/Fe3O4-CuO) as the heterogeneous catalyst in cross dehydrogenative coupling (CDC) reactions has been demonstrated for the synthesis of esters using methyl aromatics, aldehydes/benzyl alcohols...