Abstract:

The decomposition kinetics of FeO^-2₄ in the aqueous NaOH solutions of 7.0 mol·L^-1, 10.0 mol·L^-1 and 14.0 mol·L^-1 were determined by spectrophotometry with and without ultrasonic action at 500 W and 25 kHz.The results showed that the decomposition followed first-order kinetics and the rate was faster with ultrasonic action than without ultrasonic action.The decomposition activation energies were 52.4 kJ·mol^-1, 70.5 kJ·mol^-1 and 91.5 kJ·mol^-1 without ultrasonic action, and 49.6 kJ·mol^-1, 66.6 kJ·mol^-1 and 85.9 kJ·mol^-1 with ultrasonic action, in the aqueous NaOH solutions of 7.0 mol·L^-1, 10.0 mol·L^-1 and 14.0 mol·L^-1respectively.The fact that the activation energies increased with increasing concentrations of NaOH indicated that FeO-4 was much stable in a higher concentration NaOH solution.The effect of ultrasound on the decomposition kinetics of FeO^-2₄ decreased with operating temperature.

Key words: 高铁酸盐, 超声, 分解反应, 反应动力学

摘要： 采用分光光度法研究了静止条件和超声作用（500W, 25kHz）下FeO42-在7.0 mol•L-1、10.0 mol•L-1和14.0 mol•L-1 NaOH溶液中的均相分解反应，分别测定了不同浓度NaOH溶液中FeO42-的浓度随反应时间的变化。实验结果表明，在不同浓度的NaOH溶液中，无论是否有超声作用，FeO42-的分解均满足一级反应动力学规律。无超声作用时，在7.0 mol•L-1、10.0 mol•L-1、14.0 mol•L-1 NaOH溶液中，FeO42-的分解反应活化能分别为52.4 kJ•mol-1、70.5 kJ•mol-1和91.5 kJ•mol-1；在有超声作用下，活化能则分别为49.6 kJ•mol-1、66.6 kJ•mol-1和85.9 kJ•mol-1。有超声作用时FeO42-的分解反应速率高于静止条件的分解反应速率。随着NaOH溶液浓度的增加，FeO42-分解反应的活化能增大，即在较高浓度的NaOH溶液中FeO42 -分解反应较慢。

关键词: 高铁酸盐, 超声, 分解反应, 反应动力学