Synthesis and characterization of copper-nickel ferrite catalysts for ethyl acetate oxidation

An Efficient Nanocatalyst Cobalt Copper Zinc Ferrite for the Thermolysis of Ammonium Nitrate

This work reports synthesis and catalytic effect of cobalt copper zinc ferrite (CoCuZnFe₂O₄) on the thermal decomposition of ammonium nitrate (AN). AN is a crystalline hygroscopic powder widely applicable as an oxidizer in the propellant formulations for high energetic materials but requires improvement in its thermal decomposition characteristics. Nanocatalyst spinel ferrite CoCuZnFe₂O₄ was prepared using the coprecipitation method and characterized by various physicochemical instrumental techniques like XRD, FE-SEM, UV-vis, Raman, and TG-DSC. Catalytic study of AN in the presence of nano-CoCuZnFe₂O₄ was investigated using DSC analysis. The Raman and XRD study confirm the formation of ferrite with a crystalline size 9-22 nm. TG suggests that the catalyst was thermally stable up to 400 °C with ∼10% mass loss. The UV-vis study shows that the optical band gap energy of CoCuZnFe₂O₄ was 2.6 eV, which may help in fast acceleration of electrons during thermolysis of AN, making the thermal decomposition of AN more favorable in the presence of CoCuZnFe₂O₄. The thermal decomposition investigation suggests that the activation energy of AN thermolysis in the presence of 2 wt % CoCuZnFe₂O₄ was decreased by ∼37%. It is concluded that CoCuZnFe₂O₄ can be used as an efficient catalyst for improving AN's thermal characteristics.

Solution combustion synthesis: the relevant metrics for producing advanced and nanostructured photocatalysts

The current developments and progress in energy and environment-related areas pay special attention to the fabrication of advanced nanomaterials via green and sustainable paths to accomplish chemical circularity. The design and preparation methods of photocatalysts play a prime role in determining the structural, surface characteristics and optoelectronic properties of the final products. The solution combustion synthesis (SCS) technique is a relatively novel, cost-effective, and efficient method for the bulk production of nanostructured materials. SCS-fabricated metal oxides are of great technological importance in photocatalytic, environmental and energy applications. To date, the SCS route has been employed to produce a large variety of solid materials such as metals, sulfides, carbides, nitrides and single or complex metal oxides. This review intends to provide a holistic perspective of the different steps involved in the chemistry of SCS of advanced photocatalysts, and pursues several SCS metrics that influence their photocatalytic performances to establish a feasible approach to design advanced photocatalysts. The study highlights the fundamentals of SCS and the importance of various combustion parameters in the characteristics of the fabricated photocatalysts. Consequently, this work deals with the design of a concise framework to link the fine adjustment of SCS parameters for the development of efficient metal oxide photocatalysts for energy and environmental applications.

A facile green synthesis of MgCoFe2O4 nanomaterials with robust catalytic performance in the synthesis of pyrano[2,3-d]pyrimidinedione and their bis-derivatives

In this study, an efficient, rapid and simple plant-mediated green sol-gel auto-combustion procedure was presented to synthesis magnesium-cobalt ferrite (MgCoFe2O4) nanocatalyst using an aqueous extract of apple skins as a chelating/combustion agent. The catalyst was assessed by multiple techniques, including FT-IR, XRD, FE-SEM, EDS, elemental mapping, TGA-DTA and VSM. Then, the catalytic potential of the as-prepared MgCoFe2O4 nanocatalyst was examined in the three-component condensation reaction of 1,3-dimethyl barbituric acid, aldehydes and malononitrile for the one-pot synthesis of pyrano[2,3-d]pyrimidinedione and their bis-derivatives. The obtained results indicated the excellent catalytic activity of the MgCoFe2O4 in the three-component reaction. The high catalytic activity of these nanomaterials could be attributed to the synergistic electronic effect between nanoparticles, which showcased the enormous potential of multi-metallic nanomaterials in the catalysis field. More importantly, MgCoFe2O4 showed excellent magnetic properties, and it could be successfully separated and recovered by applying an external magnetic for further reuses. To the best of our knowledge, green synthesis of MgCoFe2O4 mediated by aqueous plant extract was reported here for the first time, and this work, therefore, can open up a new insight in the course of design, green synthesis and application of excellent green nanocatalyst for the sustainable processes. MgCoFe2O4 as a magnetically recyclable heterogeneous catalyst, has been synthesized through plant-mediated procedure using an aqueous extract of apple skins.

Magnetic CuNiFe2O4 nanoparticles loaded on multi-walled carbon nanotubes as a novel catalyst for peroxymonosulfate activation and degradation of reactive black 5

Novel copper-nickel ferrite nanocatalyst loaded on multi-walled carbon nanotube (MWCNTs-CuNiFe₂O₄) was synthesized and applied to activate peroxymonosulfate (PMS) in the degradation of the reactive black 5 (RB5). The structure of the catalyst was well characterized by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The MWCNTs-CuNiFe₂O₄/PMS system showed a high performance in the degradation of RB5 with a kinetic rate of 1.5-2.5 times higher than homogeneous and heterogeneous systems. Maximum degradation efficiency (99.60%) was obtained at an initial pH of 7, catalyst dosage of 250 mg/L, PMS dosage of 4 mM, the temperature of 25 °C, and reaction time of 15 min. Anion experiments emphasized that the presence of nitrate, carbonate, and phosphate in the solution reduced the degradation efficiency by producing reactive species with low oxidation potential. The RB5 degradation rate evolved with temperature, and the activation energy was obtained to be 44.48 kJ/mol. The mechanism of PMS activation and production of free radicals was proposed based on tert-butyl alcohol (TBA), ethanol (EtOH), and potassium iodide (KI) scavengers. Trapping experiments showed that both sulfate (SO₄^•-) and hydroxyl (^•OH) radicals are involved in the catalytic degradation of RB5. The effective treatment of real wastewater and tap water by the MWCNTs-CuNiFe₂O₄/PMS system requires a long reaction time. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that RB5 can be degraded via methylation, decarboxylation, hydroxylation, and ring/chain cleavage pathways. The stable catalytic activity after three consecutive cycles suggested that MWCNTs-CuFe₂O₄ is a novel reusability catalyst in PMS activation.