Araceli Elisabet Lavat

Heterogeneous Photocatalytic Discoloration/Degradation of Rhodamine B with H2O2 and Spinel Copper Ferrite Magnetic Nanoparticles

The discoloration/degradation of the artificial dye Rhodamine B (RhB) was investigated using advanced oxidation technologies. Aqueous solutions of RhB containing spinel copper ferrites (CuFe2O4) as a heterogeneous catalyst were exposed to UV irradiation/hydrogen peroxide. Under these experimental conditions the discoloration/degradation of RhB is strongly promoted by copper ferrites, reaching 95 % discoloration of the dye in 10 min and 97 % degradation in 200 min. The influence of the catalyst amount, H2O2 concentration, light source, and UV light intensity were studied. Optimum concentrations of H2O2 and catalyst dosage were found for the RhB degradation reaction. The catalyst had high magnetic sensitivity under an external magnetic field, which allowed its magnetic separation from water avoiding secondary pollution processes, and its recycling. A markedly synergetic effect of spinel copper ferrite and UV light irradiation was observed for the RhB discoloration/degradation with H2O2 as a green oxidant.

Characterization of the Firing Steps and Phases Formed in Mg-Zr-Containing Refractory Dolomitic Materials

The production of cement clinker is one of the most important industrial processes at world scale. Many technological innovations have been developed in order to increase the production at a lower cost, having in mind that the materials are exposed to severe operational conditions. The fabrication process of modern Portland clinker basically involves the firing at around 1500°C of limestone-CaCO3 accompanied by silica-SiO2 sources such as clays, sand, iron ore, shale, fly ashes and slags. The final product is a synthetic mineral called clinker which is basically formed by four crystalline phases: alite (Ca3SiO5), belite (β-Ca2SiO4), tricalcium aluminate (Ca3Al2O6) and ferrite (Ca2(AlxFe2-x)2O5); and other minor common components. Therefore the process involves aggressive basic environments and atmospheres, with high alkali and sulphur contents, that can strongly modify the microstructure and phase composition of the refractories of the kilns work zone (Kingery et al., 1976). On the other hand, over the last decades the substitution of fossil fuels for alternative or industrial wastes; such as rubber, used tires, fly ashes, among others; has affected drastically the useful life and performance of the refractory bricks which coat the rotary kilns. Nowadays the burning zone of the kilns is exposed to alkali salts, chlorine, sulphur oxides, proceeding from industrial by products or hazardous products of animal origin, that enhance the corrosion process of the kilns refractory. This technological problem is the reason for focussing in the development of new suitable refractories. Improvements have been made by using higher purity raw materials; however there are economic limits and therefore other more sustainable alternatives are necessarily searched. According to the modern tendencies in refractories the improvements in the thermal, chemical and mechanical properties of refractories are related to the optimization of the matrix, through the careful design of the mixture of the phases and the microstructural characteristics. As it is well known the performance of these structural parts is a function of the grain material, the nature of the bonding phase, and the distribution and shape of grains and pores. The increase in the proportion of “direct” bonding between refractory aggregate grains is very important. Furthermore the microstructural bonding is the main attribute for an adequate refractory matrix because it contributes to the resistance by the combination of rigidity and sufficient structural flexibility in order to prevent the formation of cracks and disintegration of the hot phase.

Zr-supported CuFe 2 O 4 Nanoparticles as Catalysts for the Combustion of Propane

Fil: Lavat, Araceli. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingenieria Olavarria; Argentina

Preparation and Characterization of Supported Vanadia Catalyst for the Selective Catalytic Reduction of NO with NH3

The structure characteristics and the catalytic behavior are analyzed on catalysts obtained by oxidative degradation of a planar VO complex on alumosilicate support (cordierite). By means of different techniques (FTIR, DRX, TGA), vanadium oxide formation was determined during the thermal decomposition of the organometallic precursor and the formation of NH4 species during the reaction. Besides, the catalytic activity was also determined for the selective reduction of NO with ammonia.

Double perovskites La2MMnO6 as catalyst for propane combustion

Abstract The synthesis, structural, spectroscopic and morphological characterization; as well as the evaluation of the catalytic properties, of a family of oxides La2MMnO6, with M = Co, Ni and Cu are presented in this work. The materials were obtained by solid state reaction and through citrate route. The structure was determined by X-ray diffraction and a correlation was found between the crystal cell parameters and the M(II) cation sizes, as a consequence of MO6 and MnO6 octahedral ordering. According to infrared spectroscospic characterization of the materials prepared by citrate route, a diminution of the M4+-O bond strength was observed, according with M(II) sizes, in the sequence: Cu > Ni > Co. More labile O species should be present in La2CoMnO6-CIT. The electron microscopy morphology of this oxide confirmed the presence of agglomerated tiny particles. The presence of nanometic crystallites was confirmed by transmission electron microscopy. The catalytic tests, using propane as reaction test, were carried out in a fixed bed micro reactor, coupled with an “on line” chromatograph. The materials obtained by citrate route, despite M(II) cations, are better suited for propane combustion and the catalyst La2CoMnO6 is the most active of the investigated series with T90 ∼ 500 °C.

Comparative Structural and Spectroscopic Characterization of MI LnIIITiO4 Ion-exchanged Phases, with MI : Na, H, K

Fil: Lavat, Araceli Elisabet. Universidad Nacional del Centro de la Pcia.de Bs.as.. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tandil. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires. Provincia de Buenos Aires. Gobernacion. Comision de Invest.cientificas. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia D; Argentina