The paper presents the dispersion of the concentration y(t, s) on the length (s) with respect to time (t), corresponding to the adsorption process of a phenothiazine derivative on graphite electrodes. The numerical simulation by equations with partial derivatives of the second order with two independent variables (t and s) (PDE II.2), based on (M pdx ) which associates with Taylor series was performed. Also, the adsorption process defined by PDE II.2 was included in a regulation scheme of concentration y(t, s) with multiple freedom levels. It insures good performances and a remarkable flexibility for extending the method in similar categories of applications.

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For the study of Cu2+ - S2O32- reaction kinetics was used an experimental stopped flow apparatus with two types of observation cells. The first has a toroidal mixing chamber, and the other, with a separate mixing chamber has the entrance of the reactants on two perpendicular directions. The reaction rate and the residence time have been calculated during the flow in the mixing chambers and the observation cells. The calculated values have been compared with the real formation and decomposition time of the reaction intermediate. The deviations due to the residence-time in the toroidal chamber and in the observation cell respectively are smaller than those for the cell with separate mixing chamber due to its different geometry. The shape of the experimental curves I = f(t) with the toroidal cell lead to kinetic parameters which are different than the ones obtained with the other cell.