异丙醇的O3/H2O2复合氧化动力学研究

采用停流光谱仪研究了异丙醇在T=298K和pH=3～11范围内O3 / H2O2复合氧化的反应动力学.结果表明异丙醇的O3 / H2O2复合氧化反应动力学随反应体系的pH值不同而不同.在酸性和中性条件下,反应相对于O3浓度、异丙醇浓度都为1级;在碱性条件下,异丙醇较容易被O3/H2O2复合氧化降解,总反应级数为2级,相对于O3浓度、异丙醇浓度和H2O2浓度分别为1级、0级和1级,可见异丙醇的降解速率与它的浓度无关.在T=298K,当pH值从9增大到11, 反应速率常数从3486.1(mol·L-1)-1·s-1增大到38239.2(mol·L-1)-1·s-1. 表明在酸性条件下,异丙醇的O3/H2O2复合氧化是O3分子直接攻击异丙醇的反应占主导;在碱性条件下,自由基型反应占主导.

Kinetics of Oxidation of 2-Propanol by Ozone with Hydrogen Peroxide

A stopped-flow spectrophotometer system was applied to study the kinetics of oxidation of 2-propanol in aqueous solution containing ozone and hydrogen peroxide at pH values of 3 to 11 and 298K. It is found that the reaction kinetics of peroxone oxidation changes with pH values. In acidic and neutral conditions, the kinetics of the peroxone oxidation of 2-propanol is first order with respect to the concentration of ozone and 2-propanol. On the other hand, in alkaline conditions, 2-propanol is easily degradable by O3/H2O2, the overall oxidation reaction is second order and is first order, zero order and first order with respect to the concentration of ozone, 2-propanol and hydrogen peroxide, respectively. This means that the depletion rate of 2-propanol is nearly independent of its concentration. As the pH value increases from 9 to 11, the overall rate constant increases from 3486.1 (molL-1)-1s-1 to 38239.2 (molL-1)-1s-1 at 298K. The results show that the reaction mechanism of the peroxone oxidation is mainly direct oxidation of 2-propanol with ozone molecules in acidic conditions and is mainly radical reactions in alkaline conditions.