KINETIC PECULIARITIES OF REDOX REACTIONS SENSITIZED BY COLLOIDAL CDS UNDER STEADY-STATE IRRADIATION - THE EFFECT OF ADSORPTION-DESORPTION PROCESSES ON THE REACTION
In. Martyanov et al., KINETIC PECULIARITIES OF REDOX REACTIONS SENSITIZED BY COLLOIDAL CDS UNDER STEADY-STATE IRRADIATION - THE EFFECT OF ADSORPTION-DESORPTION PROCESSES ON THE REACTION, Russian chemical bulletin, 44(2), 1995, pp. 236-246
Photoreduction of Methyl Orange dye (MOr) by sodium sulfide was studie
d under steady-state photolysis (lambda = 365 nm). The reaction was se
nsitized by the CdS colloid with the characteristic similar to 5-nm pa
rticle size. The quantum yield of the reaction is independent of the l
ight intensity when the latter is less than 5 mW cm(-2). The form of t
he dependence of the initial quantum yield of the reaction on [MOr] co
incides qualitatively with the adsorption isotherm of the dye on the C
dS surface. The reaction kinetics under steady-state irradiation were
analyzed. The kinetics in solution as a whole are shown to be adequate
to those on a single colloidal particle. On the basis of the experime
ntal data, two types of surfaces of the colloidal particles are sugges
ted (''open'' and ''covered'' with macromolecules of a colloid stabili
zer), which significantly differ in the rate at which they establish a
n adsorption-desorption equilibrium with the solution.