Examinando por Autor "Torres Hernández, Walter"

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    An Electrochemical Desalination Cell Based on Conducting Polymers.
    (2018-07-24) Torres Hernández, Walter
    Insufficient access to potable water is becoming one of the major threats to sustainable development around the globe. The implementation of water conservation policies and the use of mature and novel desalination technologies are key to address the water demand for an increasing population. Desalination systems based on electrochemical cells are of current interest. This paper discusses an electrochemical cell based on carbon electrodes modified with polypyrrole and a polypyrrole/polystyrene sulfonate composite which have anion and cation exchange properties, respectively. The cell was used to substantially decrease the concentration of sodium chloride solution in the 10-1 and the 10-2 M concentration range. The long term stability of this cell is also discussed.
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    Electrochemical Characterization of Mass Transport at Microelectrode Arrays.
    (2015-09-21) Torres Hernández, Walter
    Electrodes with dimensions in the micro- and nano-meter scale can be used as analytical probes in confi ned places such as cells and organelles. Arrays of microelectrodes, particularly disk-shaped electrodes, are now a platform to fabricate electrochemical sensors and multisensors. A useful characteristic of such arrays is that enhancement of the current signal is due to the fact that radial diffusion becomes important as the disk radius gets smaller and steady state currents are attainable in a relatively short time. Because there is no general analytical solution for the current response at MEAs, previous characterization of any micro electrode array at hand is still required. This paper discusses the electrochemical characterization of the mass transport of a reversible electrochemical probe at a commercially available micro-disk electrode array by two commonly used tools for electro analysis, namely: cyclic voltammetry and chronoamperometry. The questions to be addressed are whether clear radial diffusion control can be effectively achieved and the time required for the electrode system to reach steady state. For chronoamperometric experiments, the current response almost achieves steady state in the time range between 0.49 s and 1 s. This is precisely the time bracket in which analytical measurements should be made in order to achieve high sensitivity.
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    Synthesis and Spectroscopic Characterization of the Products Derived from the Reaction of [Ru3(CO)12] with the Chloroaryliderhodanine Ligand.
    (2015-09-21) Cerón Hernández, Maira Raquel; de la Vega Quintero, Gala Paulina; Torres Hernández, Walter; Micolta Salazar, Germania; Galarza de Becerra, Esperanza
    Abstract In this article, we report on the synthesis and spectroscopic characterization of two polymeric complexes from [Ru3(CO)12] and 5-(4-chlorobenzylidene)-2-thioxo-1,3-thiazolidin-4-one, Cl-BRd. Spectroscopic evidence shows that the Cl-BRd ligand promotes the breaking of the cluster generating a dimer, and binds to the metal center in different confi gurations. Thus, in product 1, the ligand binds through the nitrogen and oxygen atoms and, in product 2, through the nitrogen atom and the exo-cyclic sulfur. Resumen Este artículo presenta la síntesis y caracterización de los productos de la reacción del agregado (o cluster) [Ru3(CO)12] con el ligando heterocíclico 5-(4-clorobenciliden)-2-tioxo-1, 3-tiazolidin- 4-ona, Cl-BRd. La reacción rindió dos productos, ambos de naturaleza polimérica. Los resultados espectroscópicos muestran que el ligando Cl-BRd promueve el rompimiento del agregado, generando un dímero y se enlaza al centro metálico en diferentes confi guraciones; así, en el producto 1, el ligando utiliza los átomos de nitrógeno y oxígeno y, en el producto 2, usa el átomo de nitrógeno y el azufre exocíclico.