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环境化学

摘要：在2.0≤pH≤5.1、0.2mmol·L^-1≤[H₂O₂]₀≤100mmol·L^-1和0.05mmol·L^-1≤[Fe(Ⅲ)]₀≤0.5mmol·L^-1的试验条件下,考察了不含有机物的反应体系中[H₂O₂]₀/[Fe(Ⅲ)]₀、[Fe(Ⅲ)]₀、pH及Fe(Ⅲ)水解形态等因素对类-Fenton反应中Fe(Ⅲ)催化分解H₂O₂动力学的影响.结果表明,在[Fe(Ⅲ)]₀一定时,H₂O₂分解存在最佳[H₂O₂]₀/[Fe(Ⅲ)]₀摩尔比;当[H₂O₂]₀一定时,Fe(Ⅲ)催化H₂O₂分解可用二级动力学反应进行描述,其二级动力学常数kd为22.21L·mol^-1·min^-1;Fe(Ⅲ)催化H₂O₂分解的最佳pH为3.0;H₂O₂的分解速率随着Fe(Ⅲ)水解时间的增加而降低,Fe(Ⅲ)存在形态对H₂O₂催化分解起主导作用.

Abstract：In this paper, the effects of [H₂O₂]₀/[ Fe(Ⅲ)]₀, [ Fe(Ⅲ)]₀, pHand hydrolysis species of Fe(Ⅲ) on the kinetics of H₂O₂ decomposition in the Fenton-like system free of organic substrates had been investigated. Experiments were carried out over a wide range of experimental conditions (2.0 ≤ pH ≤ 5.1, 0.2 mmol·L^-1 ≤ [H₂O₂]₀ ≤100 mmol·L^-1, and 0.05 mmol·L^-1 ≤ [ Fe(Ⅲ)]₀ ≤ 0.5 mmol·L^-1). The experimental results showed that there was an optimum molar ratio of [H₂O₂]₀/[ Fe(Ⅲ)]₀ when the initial concentration of Fe(Ⅲ) kept constant. When the H₂O₂ concentration kept constant, the initial rate of catalytic decomposition of H₂O₂ by Fe(Ⅲ) abided by a second-order kinetic law with the second-order rate constant k d of 22.21 L·mol^-1·min^-1. The optimum solution pHfor the reaction was observed at around 3.0. The decomposition rate of H₂O₂ decreased with the increasing of hydrolysis time of Fe(Ⅲ) , and the hydrolysis species of Fe(Ⅲ) played an important role in the rates of catalytic decomposition of H₂O₂ by Fe(Ⅲ) in the Fenton-like system.