Catalytic activity of copper (II) oxide prepared via ultrasound assisted Fenton-like reaction

Abstract

Copper (II) oxide nanoparticles were synthesized in an ultrasound assisted Fenton-like aqueous reaction between copper (II) cations and hydrogen peroxide. The reactions were initiated with the degradation of hydrogen peroxide by ultrasound induced cavitations at 0 °C or 5 °C and subsequent generation of the OH radical. The radical was converted into hydroxide anion in Fenton-like reactions and copper hydroxides were readily converted to oxides without the need of post annealing or aging of the samples. The products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) surface area analysis. Catalytic activity of the nanoparticles for the hydrogen peroxide assisted degradation of polycyclic aromatic hydrocarbons in the dark was tested by UV-visible spectroscopy with methylene blue as the model compound. The rate of the reaction was first order, however the rate constants changed after the initial hour. Initial rate constants as high as 0.030 min(-1) were associated with the high values of surface area, i.e. 70 m(2)/g. Annealing of the products at 150 °C under vacuum resulted in the decrease of the catalytic activity, underlying the significance of the cavitation induced surface defects in the catalytic process.

Solid‐Liquid Interface Based Biphasic Reaction for Nanomaterial Preparation: Bundled CuO Nanorods as an Example and Their Outstanding Photocatalytic Efficiencies

“…First, the lattice cupric ion of the CuO nanorods, ≡Cu 2+ , can oxidize adsorbed H 2 O 2 molecules to produce hydroperoxyl free radicals, HO 2 • . In this process, the lattice cupric ion was reduced to cuprous ion, ≡Cu + , which in turn can be oxidized by the adsorbed H 2 O 2 molecules to regenerate the lattice cupric ion and also create hydroxyl radicals, HO • . The end result of this redox cycle is the creation of the two reactive free radicals, HO 2 • and HO • , both able to degrade RhB.…”

CuO nanorods from carrier solvent assisted interfacial reaction processes: An unexpected extraordinary Fe-free photocatalyst in sunlight assisted Fenton-like processes

“…First, it has been proposed that CuO can generate oxidative free radicals in the presence of H 2 O 2 through a mechanism similar to the redox procedures commonly accepted for Fe containing oxides in Fenton-like processes [14][15][16][17][18][19][20][21][22][23][24] . The H 2 O 2 molecules adsorbed on the surface of the CuO nanorods are oxidized by the lattice cupric ion, ≡Cu 2 + , to produce hydroperoxyl free radicals, HO 2 [15] .…”

“…The H 2 O 2 molecules adsorbed on the surface of the CuO nanorods are oxidized by the lattice cupric ion, ≡Cu 2 + , to produce hydroperoxyl free radicals, HO 2 [15] . The lattice cuprous ion, ≡Cu + , produced from the above reaction can reduce the adsorbed H 2 O 2 molecules to create hydroxyl radicals, HO, and regenerates the lattice cupric ion [15,22] . The end result of this redox cycle is the conversion of H 2 O 2 to the two oxidative free radicals, HO 2 and HO.…”

“…CuO has thus been applied as a Fenton-like catalyst [14][15][16] . Most of the work done were with CuO nanoparticles and the degradation efficiencies achieved were not impressive [17][18][19][20][21][22][23][24] . One-dimensional (1D) CuO nanostructures have also been applied as photo-degradation catalysts and showed promising performances [25,26] .…”

Ultrasound agitated phytofabrication of palladium nanoparticles using Andean blackberry leaf and its photocatalytic activity

“…In general, ultrasonication is a physical treatment employing ultrasound with frequency higher than the threshold of human hearing (>16 kHz) and locally creates a strong shear force, high temperature, and free radicals which change the structure and properties of organic materials [1]. Many researchers have studied ultrasonication for the synthesis of various metal nanoparticles (MNPs) including silver [2], gold [3], iron [4], cobalt [5], zinc [6], tin [7], copper [8] and palladium [9] nanoparticles. Although gold, silver, platinum and palladium are precious MNPs, and it acts as a catalyst via electron-transfer reactions due to their better stability and well understood physicochemical properties.…”