Green Decomposition of Organic Dyes Using Octahedral Molecular Sieve Manganese Oxide Catalysts

Abstract

The catalytic degradation of organic dye (methylene blue, MB) has been studied using green oxidation methods (tertiary-butyl hydrogen peroxide, TBHP, as the oxidant with several doped mixed-valent and regular manganese oxide catalysts in water) at room and higher temperatures. These catalysts belong to a class of porous manganese oxides known as octahedral molecular sieves (OMS). The most active catalysts were those of Mo(6+)- and V(5+)-doped OMS. Rates of reaction were found to be first-order with respect to the dye. TBHP has been found to enhance the MB decomposition, whereas H(2)O(2) does not. Reactions were studied at pH 3-11. The optimum pH for these reactions was pH 3. Dye-decomposing activity was proportional to the amount of catalyst used, and a significant increase in catalytic activity was observed with increasing temperature. X-ray diffraction (XRD), energy dispersive spectroscopy (EDX), and thermogravimetric analysis (TGA) studies showed that no changes in the catalyst structure occurred after the dye-degradation reaction. The products as analyzed by electrospray ionization mass spectrometry (ESI-MS) showed that MB was successively decomposed through different intermediate species.

Management on the location and concentration of Ti3+ in anatase TiO2 for defects-induced visible-light photocatalysis

“…After 15 min of reaction in the presence of TiO 2-x -500 catalyst, the intensity of the peak at m/z=283 is decreased to 41 % compared to reactant at 0 min. A new peaks appearing at m/z=300, suggesting that hydroxyl group is incorporated into the aromatic ring of MB [45].…”

Yerba Mate Tea Extract: a Green Approach for the Synthesis of Silica Supported Iron Nanoparticles for Dye Degradation

“…Tests with the catalysts synthesized using NaBH 4 The Fe/SiO 2 catalysts were tested in the reductive degradation of the dye MO. Figure 6a illustrates the UV-Vis spectra during the reaction of MO and 50% Fe/SiO 2 .…”

“…Organic dyes are stable, resistant to bioremediation and highly toxic to human and aquatic life. To minimize their negative effect, chemical methods of remediation have been developed; [1][2][3][4] for instance, the treatment with iron nanoparticles. [5][6][7][8][9][10] The main advantages of iron are the low toxicity, biodegradability, low cost, and abundance, besides high chemical reactivity and affinity for the substrate, [11][12][13] and magnetic properties.…”

“…The effect of synthesis conditions in the organic and iron content of the catalysts was investigated. For the sake of comparison, iron nanoparticles prepared by NaBH 4 were also obtained with different iron contents. Both materials were applied in the degradation of the dye methyl orange.…”

Manganese Oxide Octahedral Molecular Sieves (OMS-2) Multiple Framework Substitutions: A New Route to OMS-2 Particle Size and Morphology Control

“…For example, partial exchange of K + ions in the K-OMS-2 tunnels with H + ions (protons) has yielded excellent acid catalysts for selective oxidation reactions, [ 18 ] whereas doping of single-type, low-, or high-valent metal cations, such as Co 2 + , Zr 2 + , Cu 2 + , Cr 3 + , Fe 3 + , In + 3 , V 5 + , W 6 + , and Mo 6 + into the framework, [19][20][21][22][23][24][25] via a subtle balance of the redox properties and depending on the extent of substitution, has produced cryptomelane with novel morphologies [ 26 ] and catalytic properties. [ 27 ] In terms of morphology, doping Cr 3 + into the K-OMS-2 structure produced well-ordered dendritic structures, which are unusual compared to the regular K-OMS-2 morphology. [ 26 ] found to dramatically infl uence the crystallinity of multidoped OMS-2.…”