The oscillatory Bray-Liebhafsky reaction as a matrix for analyzing enzyme and polymeric catalysts for hydrogen peroxide

Abstract

The Bray-Liebhafsky (BL) oscillatory reaction, as a reaction where hydrogen peroxide decomposes into the water and oxygen in the presence of iodate and hydrogen ions through a complex mechanism involving a number of intermediates, such as I-, I2, HIO and HIO2, was used as the matrix for analysis of kinetic properties of the catalysts for hydrogen peroxide decomposition. The examined catalysts were enzyme peroxidase (isolated from the horseradish root) and polymeric catalyst (acid form of poly-4-vynil-pyridine functionalized by fericsulfate). The change of kinetic state of the system caused by the presence of added catalyst is reflected in the form of oscillograms, in the time elapsed from the beginning of the reaction to the first oscillation, in the time elapsed from the beginning of the reaction to the end of oscillatory evolution, the number of oscillations, the average period between oscillations and its frequency. Since all these kinetic properties depend on the added amounts of both mentioned catalysts in a complex but analogous manner, a similar reaction mechanism could be expected in both cases.Braj-Liebhafski (BL) oscilatorna reakcija, kao reakcija u kojoj se vodonik-peroksid, u prisustvu jodata i vodoničnih jona, razlaže na vodu i kiseonik, po kompleksnom mehanizmu koji uključuje nastanak brojnih intermedijera kao što su I-, I2, HIO i HIO2 je korišćena kao matrica za analizu kinetičkih osobina katalizatora za razlaganje vodonik-peroksida. Ispitivani katalizatori su peroksidaza izolovana iz korena rena i sintetički polimer (kiseli oblik poli-4-vinil-piridina funkcionalizovanog sa ferisulfatom). Promene kinetičkog stanja sistema izazvane prisustvom dodatih količina katalizatora se reflektuju na formu oscilograma, na vreme proteklo od početka reakcije do pojave prve oscilacije, na vreme proteklo od početka reakcije do kraja oscilatorne evolucije, broj oscilacija, srednjeg perioda oscilovanja i njihovu frekvenciju. Kako sva ova kinetička svojstva zavise od dodatih količina katalizatora na kompleksan ali analogan način, sličan reakcioni mehanizam se može očekivati u oba slučaja