Oscillatory reaction as novel method in distinguishing bentonites

Abstract

In the chemical oscillatory reaction the concentrations of the reactants decrease and products increase in stepwise form, while the concentrations of intermediates oscillate with time. In this paper, the influence of different bentonites on Briggs-Rauscher (BR) oscillatory reaction was investigated. In BR the oxidation of malonic acid in the presence of hydrogen peroxide and iodate in acidic medium, catalyzed by manganese ions occurs. The same mass (0.25 g) of bentonite from different deposits: Wyoming (SWy-2), Texas (STx-1b), Bogovina (B) and Mečji Do (MD) were added to the reaction solution consisting of 7 ml [CH2(COOH)2]=0.28 M, 5 ml [MnSO4]=0.04 M, 5 ml [HClO4]=0.15 M, 5 ml [KIO3] =0.38 M, and 3 ml [H2O2]=9.80 M. The obtained results were compared with basic BR oscillogram without bentonite. According to the obtained results the effects of bentonite on an oscillatory dynamics can be divided into three groups. The first group consisted of SWy-2 that negligibly affected the duration of the BR oscillogram. In the second group were B and MD which quenched oscillatory behavior, while STx-1b in third group extended oscillatory period. The results revealed that BR oscillatory reaction could be used as novel method for distinguishing of bentonites.