Examinando por Materia "Ultraviolet radiation"

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    Degradación de Colorante Amarillo 12 de Aguas Residuales Industriales utilizando Hierro Cero Valente, Peróxido de Hidrógeno y Radiación Ultravioleta
    (Centro de Informacion Tecnologica, 2016-01-01) Gilpavas, E.; Medina, J.; Dobrosz-Gómez, I.; Gómez, M.Á.; Gilpavas, E.; Medina, J.; Dobrosz-Gómez, I.; Gómez, M.Á.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    The Fenton heterogeneous process in a fluidized bed reactor using Zero Valent Iron (ZVI), in the metallic state, for the treatment of textile wastewater has been used an analyzed. The aim of this work was to optimize the following operating parameters: initial dye concentration, H2O2 concentration, pH, amount of ZVI, and UV radiation, for the removal of dye and organic matter. At first, a fractional factorial experimental design allows defining the most influential factors. After that, they were optimized using the Response Surface Methodology coupled to the Box-Behnken experimental design. The optimal conditions were found to be as follows: initial dye concentration, 881 mg/L; pH 5; ZVI concentration, 5,31 g/L; H2O2 concentration, 0,86 mL/L. At these conditions, the degradation kinetics was performed, reaching 100% and 80,83% of dye and chemical oxygen demand respectively, in 150 minutes of reaction.
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    Solar and artificial UV inactivation of bacterial microbes by Ca-alginate immobilized TiO2 assisted by H2O2 using fluidized bed photoreactors
    (SCIENCE & TECHNOLOGY NETWORK INC, 2014-07-01) GilPavas, Edison; Acevedo, Jose; Lopez, Luis F.; Dobrosz-Gomez, Izabela; Angel Gomez-Garcia, Miguel; GilPavas, Edison; Acevedo, Jose; Lopez, Luis F.; Dobrosz-Gomez, Izabela; Angel Gomez-Garcia, Miguel; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    In this work, TiO2 (Degussa, P-25) supported on calcium alginate pearls was evaluated as catalyst for the photocatalytic inhibition of pathogenic microorganisms. Considering that water samples were taken directly from a natural source, a primary treatment (coagulation, sedimentation and filtration) was executed to remove solids and impurities. Photocatalytic experiments were carried out in two types of laboratory scale equipments, one using an annular UV irradiated reactor and the other a solar UV parabolic collector, both operated in the fluidized bed mode. H2O2 was included to the reactive mixture in order to enhance the photodegradation rate. The Response Surface Methodology and the Box-Behnken experimental design techniques were applied as tools for the optimization of the operational conditions of the UV water purification system. Thus, the influence of UV radiation, TiO2 dose and H2O2 concentration on the faecal and total coliform percentage degradation were statistically analysed. The following optimal operational conditions were found: UV radiation = 310 nm, TiO2 dose = 0.2 g/L and H2O2 concentration = 30 mg/L. After water treatment at optimized conditions, total microorganism growing inhibition was observed. Additional experiments allowed proving the reusability of the immobilized catalyst. © 2014 Science & Technology Network, Inc.
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    Space-qualified liquid-crystal variable retarders for wide-field-of-view coronagraphs
    (SPIE-INT SOC OPTICAL ENGINEERING, 2011-01-01) Uribe-Patarroyo, N.; Alvarez-Herrero, A.; García Parejo, P.; Vargas, J.; Heredero, R.L.; Restrepo, R.; Martínez Pillet, V.; Del Toro Iniesta, J.C.; López, A.; Fineschi, S.; Capobianco, G.; Georges, M.; López, M.; Boer, G.; Manolis, I.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    Liquid-crystal variable retarders (LCVRs) are an emergent technology for space-based polarimeters, following its success as polarization modulators in ground-based polarimeters and ellipsometers. Wide-field double nematic LCVRs address the high angular sensitivity of nematic LCVRs at some voltage regimes. We present a work in which wide-field LCVRs were designed and built, which are suitable for wide-field-of-view instruments such as polarimetric coronagraphs. A detailed model of their angular acceptance was made, and we validated this technology for space environmental conditions, including a campaign studying the effects of gamma, proton irradiation, vibration and shock, thermo-vacuum and ultraviolet radiation. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).