Kinetic identification of three metal ions by using a Briggs-Rauscher oscillating system

Abstract

In this paper, a kinetic method for identification of metal ions (Fe3+, Cu2+ and Ag+) was reported by using their perturbation effects on a Briggs-Rauscher (BR) oscillating system involving a tetraazamacrocyclic complex [NiL](ClO4)2 as a catalyst. The ligand (L) in the catalyst is 5,7,7,12,14, 14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene. When an equal amount of analytes (metal ions) were separately added to the active BR-system under the same concentration, quite different perturbation results were obtained in their concentration ranges from 1.0 × 10−4 to 2.0 × 10−3 mol/L. Furthermore, based on the FCA and NF models, the perturbation mechanisms of three metal ions on BR system were explained in details. It is shown that the different perturbation manners are attributed to kinetic-controlled mechanisms. Such mechanisms suggested that both Fe3+ and Cu2+ may face a competitive reaction with IO3− to form iodate precipitate when they react with I− (an intermediate in BR system) vs redox reaction, whereas Ag+ directly binds to I− to generate AgI without a competitive reaction which yields iodate precipitate. Also, the method could be used for quantitative determination of Ag+.