Loading...

Oxidative Degradation of Methylene Blue by Nano-Sized Particles of Metal Oxides and Synthesis, Characterization and Catalytic Activity of Novel Mo and Fe Complexes in Oxidation Reactions

Khaksar, Mostafa | 2015

1622 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47007 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Mohammadi Boghaei, Davar; Amini, Mojtaba
  7. Abstract:
  8. In the first part of this thesis, the application of metal oxide nanoparticles in oxidative degradation of methylene blue is discussed. Nanoparticles of manganese tungstate (MnWO4) were prepared via an impregnation method using Mn(NO3)2.4H2O and WO3 as a source of Mn and W, respectively. The morphology of the manganese tungstate nanoparticles was studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MnWO4 nanoparticles showed severe catalytic performance for the degradation of organic dye (methylene blue) in the presence of tertiary-butyl hydrogen peroxide, TBHP, as the oxidant at room temperature in water. Mn doped ZnO nanoparticles, Zn1-xMnxO, were synthesized by a polyethylene glycol (PEG) solgel method and the physicochemical properties of compounds were characterized by atomic absorption spectroscopy (AAS), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), SEM and TEM. The catalytic degradation of an organic dye, methylene blue, in the presence of Zn1-xMnxO as the catalyst and hydrogen peroxide, H2O2, as a green oxidant has been studied at room temperature in water. Effects of oxidant, catalyst amount, catalyst composition, pH value of the solution as well as the presence of an OH-radical scavenger on the degree of the decomposition of MB dye were also studied. Cubic phase nanoparticles of ZrO2 and Manganese-doped ZrO2 were synthesized and the physicochemical properties of compounds were characterized by atomic absorption spectroscopy (AAS), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic degradation of an organic dye, methylene blue, in the presence of Mn-doped ZrO2 nanoparticles, as well as ZrO2 nanoparticles as catalyst with aqueous hydrogen peroxide, H2O2, as an oxidizing agent has been studied in aqueous solution at room temperature. Effects of solution pH, catalyst composition and radical scavenging agents on the degree of degradation of MB were also studied. Finally, the reusability of the Mn-doped ZrO2 catalyst was evaluated. In the second part, the catalytic oxidation of sulfides n the presence of Mo(VI) and Fe(III) complexes was investigated. The reaction of a solution of MoO2(acac)2 in CH3OH and salicylidene 2-picoloyl hydrazone ligand as a tridentate ONO donor Schiff base ligand (ONO) afford a six-coordinated Mo(VI) complex [MoO2(ONO)(CH3OH)] with the distorted octahedral configuration. Complex [MoO2(ONO)(CH3OH)] was isolated as air-stable crystalline solid and fully characterized by single-crystal X-ray structure analysis. Complex [MoO2(ONO)(CH3OH)] showed very efficient reactivity in the oxidation of sulfides to their corresponding sulfoxides using urea hydrogen peroxide (UHP) as the oxidant at room temperature under air. The reaction of Fe(acac)3 and 2-(2'-hydroxyphenyl)oxazoline (Hphox) as a bidentate O, N donor ligand afford a six-coordinated Fe(III) complex [Fe(phox)2(acac)] having distorted octahedral configuration. Complex [Fe(phox)2(acac)] was isolated as air-stable crystalline solid and fully characterized by elemental analysis, FT-IR, electrical conductivity in solution, and by single-crystal X-ray structure analysis. Oxidation of sulfides to their corresponding sulfoxides was conducted by this catalyst using urea hydrogen peroxide (UHP) as the oxidant at room temperature under air. The catalyst showed very efficient reactivity in the oxidation reactions giving high yields and selectivities. A series of various types of structurally diverse sulfides were subjected to the oxidation reaction using [Fe(phox)2(acac)] complex as a catalyst and UHP as an oxidant. Arylalkyl, arylbenzyl, dibenzyl, diaryl and dialkyl sulfides underwent clean and selective oxidation to the corresponding sulfoxide under air, in impressive selectivity (91-100%). Significantly, the very good conversions of substrates depending on the nature of the sulfide, in the range of 33-81% (TON=6.6-16.2), were obtained for all cases
  9. Keywords:
  10. Metal Oxides ; Oxidation Reactions ; Nanoparticles ; Methylene Blue ; Molybdenum Schiffbase Complex ; Iron Complexes ; Methylene Blue Degradation

 Digital Object List

 Bookmark