Analytical solution catalytic mechanism

The theoretical study of other electrode processes as a reduction followed by a dimerization of the reduced form or a second-order catalytic mechanism (when the concentration of species Z in scheme (3.IXa, 3.IXb) is not too high) requires the direct use of numerical procedures to obtain their voltammetric responses, although approximate solutions for a second-order catalytic mechanism have been given [83-85]. An approximate analytical expression for the normalized limiting current of this last mechanism with an irreversible chemical reaction is obtained in reference [86] for spherical microelectrodes, and is given by... 

For a second-order catalytic mechanism with an irreversible chemical reaction, an approximate analytical solution has been reported [86] ... 

A. Molina, C. Serna, and J. Gonzalez. General analytical solution for a catalytic mechanism in potential step techniques at hemispherical microelectrodes Apphcations to chronoamperometry, cyclic staircase voltammetry and cyclic linear sweep voltammetry, J. Electroanal. Chem. 454, 15-31 (1998). 

A number of simple and inexpensive materials catalytically promote the cobalt-carbonylation (Reaction 2) in aqueous solution. These include ion-exchange resins, zeolites, or special types of activated carbon. Formation of the active catalyst in a separate reactor is thus economically feasible. The mechanism of this catalysis has not yet been elucidated and seems to differ for each promoter mentioned. After an induction period during which the cobalt fed to the reactor is partially retained by the promoter, fully active materials have absorbed cobalt carbonyl anion Co(CO)4 (ion exchange resins), Co2+ cation (zeolites), or a mixture of Co2+, cobalt carbonyl hydride, and cluster-type cobalt carbonyls (activated carbon). This can be shown by analytical studies (extraction, titration, and IR studies) of active material withdrawn from the reactor. 

Reactive or catalytic systems are based on pH-responsive hydrogels where the chosen reaction generates a pH shift, which in mm leads to a swelling change in the hydrogel. This response can either be used to increase the internal mesh size to increase solute diffusivity in the gel phase for a diffusive membrane [44] or alternatively the gel can be used as a mechanical valve within the pores of a microporous membrane such that a convective flux may be mmed on or off in response to analyte... 

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