Simplified Mechanistic Study And Application Of B-Z Chemical Oscillating Systems In Determined Of Rare Earth Ions

In recent year, many researchers focused their interests on the nonlinear chemistry. And oscillating chemical reaction has become the most important field because of its various nonlinear dynamic behaviors. A simplified model of the Fe(II) catalyzed B-Z oscillating chemical reaction and the mechanism of multistability phenomena for the oxalic acid - acetone - KBrO₃- Ce(IV) - H₂SO₄ oscillating system were investigated in this paper. In addition, europium was determined by using this chemical oscillating system.Chapter I: IntroductionThe research history, types of oscillating chemical reaction and mechanism of oscillating system were introduced brifely in this part. On the other hand, the application of oscillating chemical system in analytical chemistry was reviewed and the perspective of oscillating chemical reactions was also discussed.Chapter II: A simplified model of the Fe(II) catalyzed B-Z oscillating chemical reactionA mathematical simulation of B-Z oscillating chemical reaction catalyzed by ferroin was performed in this paper. A 10-step skeleton scheme was abtracted from the well-known Oregonator model by using a 4×4 nonlinear ordinary differential equation groups to describe the changes of the concentrations of HBrO₂, bromide ion, Fe³⁺ and HBrO. Results showed that the simulated behaviors were consistent with experimental observations very well.Chapter III: Multistability phenomena and simplified mechanistic study of the oxalic acid-acetone-KBrO₃-Ce(â…£)-H2_SO₄ oscillating systemA simplified mechanism of B-Z oscillating chemical reaction catalyzed by Ce(â…£) with double organic substrates (oxalic acid and acetone) was performed in this paper. A 11-step skeleton scheme was extracted from the well-known FKN mechanism. The five key reactions which play an important role in the positive and negative feedbacks of overall cycle were obtained. The roles of double organic substrates were investigated through a series of experiments. Results indicated that the multistability phenomena were observed by adjusting the concentrations of the double organic substrates.Chapter IV: The role of bromination reaction in the oxalic acid-acetone-KBrO₃- Ce(â…£) - H₂SO₄ oscillating systemThe dynamic behaviors of oxalic acid - acetone - KBrO3 - Ce(IV) - H2SO4 oscillating system were investigated repeatedly and the concentrations of Br– ion were calculated in different concentration of acetone. Results showed that the bromination reaction between enol form of acetone and bromine is very important for the regeneration of Br^– ion in the B-Z oscillating system.Chapter V: Determined europium by using the chemical oscillating system of Ce(IV)-KBrO₃-acetone-oxalic acid-H₂SO₄A new sensitive and convenient analytical method for the trace determination of europium ions (Eu3+) by using the double organic substrates chemical oscillating reaction of Ce(IV) - KBrO₃ - acetone - oxalic acid - H₂SO₄ was proposed. Results indicate that the change of the period (ΔT) is linearly proportional to the negative logarithm concentration of Eu³⁺ ions (-logC) in the range of 1.41×10⁽–8_-1.41×10^–4 mol L?1 (r=0.9982) with a detection limit of 1.04×10^–9 mol L^-1. The recoveries were limited in the range from 99.5% to 100.8%. In addition, the mechanism of perturbation of europium ions in the double organic substrates chemical oscillating reaction was investigated.