Electrodeposición de vanadio y níquel de los asfaltenos de crudos pesados

(Eng) Heavy metals are present in porphyrins in oil asphaltenes. High content of V and Ni could be attractive to produce high value metal oxides. These metals are undesirable due to corrosion issues and catalyst contamination in cracking processes. The purpose of this project was to prepare an electrochemical cell, with graphite work electrode, wire Ag counterelectrode and a Ag/AgNO3 reference electrode, in order to evaluate and make the electrochemical characterization and deposition of V and Ni content in resin asphaltene concentrate and pure asphaltenes obtained from Colombian heavy oils. High resolution analytics before and after the deposition was done: elemental analysis, FT-IR, and atomic absorption. The variables as work potential, reaction time and electrode materials during the electro-reduction was evaluated by cyclic voltammetry and chronoamperommeter in two solutions: (I) Tetrahydrofuran and LiClO4 at 0.02 M, and (II) 20% CH3OH, 0.5 % H3PO4, 0.1 M LiClO4 in acetonitrile. Results are discussed compared with traditional method of demetallization by acid digestion.(Spa) La presencia de metales en los asfaltenos, especialmente del vanadio y níquel, puede ser una fuente de productos de valor agregado, pero representan una desventaja en las refinerías ya que no solo contaminan los productos sino que envenenan los catalizadores durante el proceso de craqueo catalítico. El objetivo de este proyecto fue el montaje de una celda electroquímica (donde se utilizó una barra de grafito como electrodo de trabajo, un alambre de Pt como contraelectrodo y un electrodo de Ag/AgNO3 como electrodo de referencia) para la caracterización y electrodeposición de V y Ni contenidos en los extractos resino-asfaltenicos y asfaltenos purificados de los crudos pesados. Los análisis de alta resolución antes y después de la deposición fueron: análisis elemental, FT-IR y absorción atómica. El efecto de las variables electroquímicas como potencial de trabajo, tiempo de reacción y material del electrodo en el proceso de electroreducción se evaluó por voltametría cíclica (VC) y cronoamperometría en dos medios: (I) Tetrahidrofurano y LiClO4 al 0.02 M, (II) 20% de CH3OH, 0.5 % de H3PO4, 0.1 M de LiClO4 en acetonitrilo. Los resultados obtenidos se discuten comparándolos con los obtenidos por el método tradicional de desmetalización en ambientes de digestión ácida

Electrochemical Monitoring and Microbial Characterization of a Domestic Wastewater-Fed Microbial Fuel Cell Inoculated with Anaerobic Sludge

A dual-chambered microbial fuel cell with aqueous cathode was operated with domestic wastewater to investigate the electrogenic ability of anaerobic bacteria from a municipal wastewater treatment plant. Curves of cell potential vs. current density, power density vs. current density and current at a fixed load of 100 Ω, were obtained daily to monitor the electrochemical evolution of the system as a function of substrate use in several batch cycles. A maximum power density of 1.11 µWcm-2 was obtained after 65 days of continuous operation and a coulombic efficiency of 7% and a chemical oxygen demand removal of 76% were found in the last batch cycle. Anaerobic culture of the bacteria from the anode biofilm resulted in the isolation of two Gram-positive and two Gram-negative bacteria with divergent sugar fermentation capabilities, while analysis of 16S rRNA gene fragments showed three clones from the phyla Firmicutes, δ-Proteobacteria and α-Proteobacteria. Scanning electron imaging analysis revealed an increase in cell diversity and proliferation of methanogenic archaea when changing from synthetic to real wastewater. These results reveal the influence of substrate concentration and presence of methanogenic microorganisms on the production of power in microbial fuel cells, suggesting that future developments could be a contribution for the use of this technology to decontaminate domestic wastewater in small communities.A dual-chambered microbial fuel cell with aqueous cathode was operated with domestic wastewater to investigate the electrogenic ability of anaerobic bacteria from a municipal wastewater treatment plant. Curves of cell potential vs. current density, power density vs. current density and current at a fixed load of 100 Ω, were obtained daily to monitor the electrochemical evolution of the system as a function of substrate use in several batch cycles. A maximum power density of 1.11 µWcm-2 was obtained after 65 days of continuous operation and a coulombic efficiency of 7% and a chemical oxygen demand removal of 76% were found in the last batch cycle. Anaerobic culture of the bacteria from the anode biofilm resulted in the isolation of two Gram-positive and two Gram-negative bacteria with divergent sugar fermentation capabilities, while analysis of 16S rRNA gene fragments showed three clones from the phyla Firmicutes, δ-Proteobacteria and α-Proteobacteria. Scanning electron imaging analysis revealed an increase in cell diversity and proliferation of methanogenic archaea when changing from synthetic to real wastewater. These results reveal the influence of substrate concentration and presence of methanogenic microorganisms on the production of power in microbial fuel cells, suggesting that future developments could be a contribution for the use of this technology to decontaminate domestic wastewater in small communities

Carbon monoxide oxidation on Pt-Ru electrocatalysts supported on high surface area carbon

This find is registered at Portable Antiquities of the Netherlands with number PAN-0000787

Development of a Passive Mini-Direct Ethanol Fuel Cell: Effect of Mea Assembly Parameters by Hot Pressure

This paper presents preliminary results on the design, construction and evaluation of a passive mini direct ethanol fuel cell (DEFC), capillary fed with 2 mol l-1 aqueous ethanol, at a rate of 2.03 μL min-1, and air oxygen in the cathode through an air vent. Parameters such as pressure, temperature and time of manufacturing a membrane-electrode assembly (MEA) by hot-pressure were evaluated. As the electrode holder used a 0.25 cm2 carbon tissue which was deposited on the catalytic layer (C. L.) for both the anode (0.8 mg cm-2of PtRu/C) and the cathode (0.8 mg cm -2of Pt/C), Nafi on® 115 membranes were used as the electrolyte. The results show, an average power density of 302 μWcm2 under the best conditions used, a catalytic layer with a Nafi on percentage of 50% at 25 °C. A temperature of 125 °C, a pressure of 49.2 Kg/cm2, and 90 seconds duration were used to obtain the MEA

Development of a passive mini-direct ethanol fuel cell : effect of mea assembly parameters by hot pressure.

This paper presents preliminary results on the design, construction and evaluation of a passive mini direct ethanol fuel cell (DEFC), capillary fed with 2 mol l-1 aqueous ethanol, at a rate of 2.03 μL min-1, and air oxygen in the cathode through an air vent. Parameters such as pressure, temperature and time of manufacturing a membrane-electrode assembly (MEA) by hot-pressure were evaluated. As the electrode holder used a 0.25 cm2 carbon tissue which was deposited on the catalytic layer (C. L.) for both the anode (0.8 mg cm-2 of PtRu/C) and the cathode (0.8 mg cm-2 of Pt/C), Nafi on® 115 membranes were used as the electrolyte. The results show, an average power density of 302 μWcm2 under the best conditions used, a catalytic layer with a Nafi on percentage of 50% at 25 °C. A temperature of 125 °C, a pressure of 49.2 Kg/cm2, and 90 seconds duration were used to obtain the MEA

Evaluation of gas diffusion electrodes as detectors in amperometric hydrogen sensors

Abstract: This work is directed to the study and evaluation of gas diffusion electrodes as detectors in hydrogen sensors. Electrochemical experiments were carried out with rotating disk electrodes with a thin porous coating of the catalyst as a previous step to select useful parameters for the sensor. An experimental arrangement made in the laboratory that simulates the sensor was found appropriate to detect volumetric hydrogen percentages above 0.25% in mixtures H 2 :N 2 . The system shows a linear response for volumetric percentages of hydrogen between 0.25 and 2 %

Lectura crítica en los cursos básicos de la universidad. De la realidad observada, a una propuesta pedagógica de mejoramiento

Tesis (Maestria en Docencia).-- Universidad de La Salle. Facultad de Ciencia de la Educación. Maestría en Docencia, 201