Ah. Gemeay et al., ACTIVITY OF SILICA-ALUMINA SURFACE-MODIFIED WITH SOME TRANSITION-METAL IONS, Colloids and surfaces. A, Physicochemical and engineering aspects, 117(3), 1996, pp. 245-252
Kinetics of H2O2 decomposition have been investigated in the presence
of a silica-alumina surface (25% Al2O3) modified with transition metal
ions including Cu(II), Co(II), and Fe(III). The decomposition reactio
n proceeded with first-order kinetics with respect to the peroxide con
centration. The rate of reaction depends upon the type of ions. The re
action rate and the energy of activation decrease in the order Cu(II)
> Co(II) > Fe(III). The initial concentration of H2O2 has a great infl
uence on the reaction rate and the coloration of the surface. The deco
mposition reaction involved the generation of free radical species as
confirmed by using the reference chromogen 2,2'-azino-bis(3-ethylbenzt
hiazoline)-6-sulphonate diammonium salt asa probe. An isokinetic relat
ionship indicates that the reaction is entropy-controlled. A probable
mechanism has been suggested for the decomposition process which agree
s with the results obtained.