Department of Chemistry
Permanent URI for this collection
Browse
Recent Submissions
Item Comparison of degradation of methylene blue dye by zno, n doped zno and iron ore rejects(European Chemical Bulletin, 2014) Borker, Vrinda; Mordekar, Rajashri Karmali; Rane, KoyarTextile effluent containing unused dye when released in surroundings pollutes water bodies. It requires processing before disposal. Iron ore reject created during mining creates environmental pollution but contains minerals of technological importance. It has ~30-50 % iron in the form of γ-Fe2O3, α-Fe2O3 and Fe3O4 is wasted if thrown in fields, so can be used to degrade organic dyes. Mineralization of methylene blue, MB a model dye is carried out using photocatalyst either iron ore reject, synthesized ZnO or ZnO1-xNx and the results are compared. ZnO is synthesised from oxalate and nitrogen doped ZnO from hydrazinated oxalate precursors. FTIR study of zinc complexes indicates formation of precursors and XRD of decomposed complexes reveal formation of zinc oxide with wurtzite structure. The presence of nitrogen in ZnO1- xNx is confirmed by chemical estimation and XPS studies. SEM reveals the particle size of ZnO1-xNx ~69 nm and ZnO ~0.5-1μm. ZnO1-xNx absorbs in the visible region and ZnO in UV region. Band gap energy calculated using Diffuse reflectance Spectrum is 2.48 eV for the former, 3.19eV for the later and 2.38 eV for ore reject. Mineralizing property of ore reject, ZnO and ZnO1-xNx are compared by electrons spray ionisation mass spectrometry study (ESI-MS) of degradation products, COD measurement and CO2, NO3- and SO4-2 estimation. Reusability study, kinetic study of degradation of MB dye using photocatalysts and ESI-MS study of degraded products of MB reveal better efficacy of iron ore rejects amongst three. Thus efficiency of iron ore reject > ZnO1-xNx. > ZnO as photocatalyst.Item Silver substituted cobalt zinc ferrites as magnetic antimicrobials(Elsevier, 2023) Mordekar, Rajashri Karmali; Samant, Pranita; Mishra, Puja; Joseph, JaisonSilver-substituted cobalt zinc ferrite series, CoxAg0.5-xZn0.5Fe2O4 (x = 0.4, 0.3, 0.2, 0.1), is synthesized using the citrate gel method, wherein ferrite formation is achieved at 600 °C. The low-temperature crystallization results in agglomerated and porous ferrites. In this sample preparation methodology, as the silver content in the series increases, metallic silver deposits at the grain boundaries, and vacancies are created at the octahedral sites. With a further increase in silver content, the magnitude of magnetic properties decreases. Antimicrobial activity increases and further decreases with an increase in silver content. The composition Co0.4Ag0.1Zn0.5Fe2O4 exhibits both magnetic and antimicrobial behaviour. These materials can potentially be beneficial in the manufacture of removable antimicrobial agents for water purification and drug delivery systems.Item Thiourea modulated supercapacitive behavior of reduced graphene oxide(Diamond & Related Materials, 2024) Naik, Arti K.; Samant, Purnakala V.In this report, we investigated the role of the concentration of nitrogen and sulfur containing thiourea in modulating the electrochemical properties of reduced Graphene Oxide (rGO) by controlling the percentage of heteroatoms on the rGO surface. The synthesis route involved the preparation of Graphene Oxide (GO) using an improved method of synthesis in an economical way by reducing the volume of concentrated acids used. Furthermore, GO is reduced by using different mass proportions of thiourea via a simple reflux method. Characterization of the rGO samples by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDAX) and elemental analysis through CHNS analyzer exhibited successful doping and impact of nitrogen and sulfur atoms on the graphene framework. The comparative electrochemical performance from Cyclic Voltammograms (CV), Galvanostatic Charge Discharge (GCD) profiles and Electrochemical Impedance Spectroscopy (EIS) measurements on the various rGO samples revealed the superiority of 1:8rGO having 15.190 wt% of nitrogen and 26.849 wt% of sulfur and S/N ratio of 1.768, in delivering highest specific capacitance of 465.21 F·g−1 at 1 mV·s−1 scan rate with a remarkable cyclic stability exhibiting a capacitive retention of 119 % and offering lowest charge transfer resistance and diffusion resistance. The study also demonstrated detrimental effect of excess thiourea on electrochemical properties of rGO. This work suggests an effective and simple approach for optimizing the nitrogen and sulfur content in rGO to enhance its electronic properties using thiourea.Item Insitu FTIR studies for the enhanced activity of Pt(HY) and Pt-Ru(HY) zeolite catalysts for electrooxidation of methanol in fuel cells(Chemical Physics Letters, 2020) Samant, Purnakala V.; Fernandes, Julio B.Insitu FTIR (Fourier transform infrared spectroscopy) technique has been employed to study the oxidation of methanol on Platinum and Platinum - Ruthenium catalysts supported on HY zeolites [Pt-Ru (HY)/C]. The reaction has been studied by recording the spectra at different temperature ranges from room temperature till 170 °C. The catalytic activity has been studies in presence and absence of oxygen supply. The mechanism for oxidation of methanol has also been interpreted from the data obtained. The decomposition of methanol on Platinum (HY)/C catalyst occurs via carbonate/formate pathway in presence of oxygen and carbonate/carboxylate in absence of oxygen. The optimum efficiency of the Pt (HY) catalyst occurs at 120 °C. But on the surface of Pt- Ru (HY)/C catalyst, methanol oxidation occurs at room temperatures, thus emphasizing higher catalytic efficiency. The enhanced activity of the Platinum–Ruthenium/HY has been explained on the basis of intermediates formed during the reaction.