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Temixco, Mexico

Vergara-Sanchez J.,Autonomous University of the State of Morelos | Vergara-Sanchez J.,Research Center en Energia | Silva-Martinez S.,Autonomous University of the State of Morelos
Water Science and Technology

The degradation of used cooking safflower oil aqueous solutions by photolysis, Fenton, and photo Fenton under solar light is reported. The processes were carried out in a photochemical reactor with recirculation. Operating variables such as, pH, oil concentration and molar ratio of [H 2O2]:[oil] were investigated to test their effects on the treatment efficiency of Fenton process. Also the iron catalyzed decomposition of hydrogen peroxide in the solar photo Fenton reaction was studied under different experimental conditions. The degree of oil oxidation was monitored by the measurements of chemical oxygen demand (COD) analyses. It was found that at pH 2.6 and a molar ratio of [H2O2]:[oil] of 489:1 were more efficient for COD abatement. The experimental results showed that the sole effect of the solar irradiation (photolysis) aided to decrease ∼65% of COD at neutral pH in a reaction time period of 15 h; whereas a decrease of 47% and ∼90% of COD was obtained by Fenton and photo Fenton treatment, respectively, after a reaction time of 50 min. It was observed a decrease in the decomposition of H2O2 in the solar photo Fenton process, in subsequent additions of H2O2, and H2O 2 +Fe2+. © IWA Publishing 2010. Source

Silva Martinez S.,Autonomous University of the State of Morelos | Vergara Sanchez J.,Research Center en Energia | Moreno Estrada J.R.,Autonomous University of the State of Morelos | Flores Velasquez R.,Electric Research Institute of Mexico
Solar Energy Materials and Solar Cells

FeIII supported on ceria as an effective catalyst for oxidation was prepared and used for the degradation of basic orange 2 azo textile dye (BO2). BO2 was chosen as a model pollutant and the catalytic oxidation was carried out in a batch reactor using hydrogen peroxide as the oxidant at pH 3. The influent factors on BO2 oxidation, such as catalyst dosage, H 2O2 concentration, and BO2 concentration were studied by considering the BO2 conversion and chemical oxygen demand (COD) removal. The FeIIIceria catalyst showed a high catalytic activity for the oxidation of BO2 in aqueous solution. It was observed that the solution became colorless after 5 h of oxidation and over 90% COD removal was achieved with all the FeIIIceria catalysts used under dark conditions in the catalytic oxidation system. The catalytic removal of BO2 during BO2 oxidation was improved under solar radiation, which notably increased the BO2 degradation rate. Consecutive BO2 oxidation cycles carried out with the same FeIIIceria catalyst and untreated fresh dyestuff solution showed that the catalyst had good stability and good degradation performance, thus evidencing the possibility of being used in continuous processes. This study showed that the Fe IIIceria catalytic oxidation process is an efficient method for the treatment of BO2 aqueous solutions. © 2010 Elsevier B.V. Source

Cruz J.C.,CIDETEQ | Rivas S.,Research Center en Energia | Beltran D.,CIDETEQ | Meas Y.,CIDETEQ | And 5 more authors.
International Journal of Hydrogen Energy

An IrO2 catalyst was prepared using a colloidal method followed by a thermal treatment. The catalyst was later mixed with Pt-Black and supported on the Sb-doped SnO2 (ATO), synthesized through the same colloidal method. ATO was investigated as a possible catalyst support in an electrode of a regenerative fuel cell (URFC), where Pt-IrO2 was used as the catalyst for the oxygen evolution and reduction reactions. The morphology and composition of the ATO support was investigated through transmission electron microscopy, X-ray diffraction (including Rietveld Refinement), BET analysis, and X-ray fluorescence. An ATO support was obtained with a highly homogeneous distribution and crystal sizes, measuring approximately 4-6 nm. The Pt-IrO 2/ATO material was deposited on a Nafion 115 membrane with 0.5 mg cm-2 of catalyst loading. Pt/Vulcan XC-72 (30 wt. %, E-TEK) was used as the catalyst in the H2 compartment with a Pt loading of 0.4 mg cm-2. The electrochemical activity of the Pt-IrO2/ATO for oxygen evolution/reduction in the URFC system was investigated by AC-impedance spectroscopy, linear voltammetry, and chronoamperometry techniques. The maximum mass current activity was 1118 A g-1 at 1.8 V in proton-exchange membrane water electrolyser mode (PEMWE) and 565 A g-1 at 0.3 V in proton-exchange membrane fuel cell mode (PEMFC), both at 80 °C. The value of the round-trip energy efficiency was approximately 48% at 50 A g-1. Highlights: Pt-IrO2 catalyst was prepared using a colloidal method and supported on Sb-doped SnO2 ATO. ATO was investigated as possible catalyst support in electrodes of regenerative fuel cells. The electrochemical activity of Pt-IrO2/ATO for O2 evolution/reduction was investigated. The maximum mass current activity was 1118 Ag-1 at 1.8 V in WE mode and 565 Ag-1 at 0.3 V in FC mode. The value for round-trip energy efficiency was approximately 48% at 50 A g-1. © 2012 Hydrogen Energy Publications, LLC. Source

Rivas S.,Research Center en Energia | Fernandez A.M.,Research Center en Energia
International Journal of Electrochemical Science

The Unitized Regenerative Fuel Cell (URFC) is a device that works as a Fuel Cell (FC) to produce electric energy and as a Water Electrolyzer (WE) to produce the oxygen and hydrogen for the FC operation mode. One of the challenges for URFĆs is the development of bifunctional electrocatalysts capable of carrying out efficiently the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), since those electrocatalysts that performs well the oxygen reduction have also poor oxygen evolution performance. The objective of this paper is to evaluate the efficiency of four different atomic composition electrocatalytic materials, based on Pt-Ru-Ir, to carry out the oxygen reduction and evolution reactions. The studies of the performance for this material were made in a Proton Exchange Membrane Fuel Cell (PEMFC), using the linear voltammetry technique at 30, 60 and 80°C in FC and WE mode. The Membrane Electrode Assembly (MEA) was prepared by the Hot-Spray technique for the oxygen electrode without using an electrocatalysts support; meanwhile the hydrogen electrode was prepared using the paste technique over the gas diffusion layer. The electrocatalyst loading was 3-5 mg·cm -2 on the oxygen electrode and 0.5-1 mg Pt·cm -2 on the hydrogen side. © 2012 by ESG. Source

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