Abstract:

Using methylene blue (MB) as the target pollutant, the active substances of MB degradation in Fe²⁺/H₂O₂ system were studied experimentally. The influence characteristics of main reaction conditions on MB degradation were clarified. The results showed that HO₂· had no ability to directly degrade MB and the capacity of the Fe²⁺/H₂O₂ system for MB degradation mainly came from ·OH radicals. The degradation of MB by Fe²⁺/H₂O₂ system can be divided into a rapid reaction stage and a uniform reaction stage. The MB degradation ratio in the rapid reaction phase decreased with the increase in temperature. The degradation ability of MB in the system increased first and then decreased with the increase of the initial concentration of H₂O₂. Under this experimental conditions, the optimal initial concentration of H₂O₂ was 5 mmol·L^-1. The degradation capacity of MB in the system increased monotonously with the inerease of Fe²⁺ initial concentration. The degradation rate of MB increased with the increase of initial concentration of MB, but the degradation ratio of MB increased first and then decreased with it. Ensuring the rate of ·OH production and its effective utilization are key to improving the oxidizing ability of the system and the utilization of H₂O₂.

Key words: Fe²⁺/H₂O₂ system, methylene blue, degradation, active substances, ·OH

摘要：

以亚甲基蓝（MB）作为目标污染物，实验研究了Fe²⁺/H₂O₂体系降解MB的活性物质，明确了主要反应条件对MB降解的影响特性。结果表明：HO₂?没有直接降解MB的能力；Fe²⁺/H₂O₂体系对MB的降解能力主要来自于?OH；Fe²⁺/H₂O₂体系降解MB可分为快速反应阶段和匀速反应阶段。快速反应阶段的MB降解率随温度升高而下降。体系对MB降解能力随H₂O₂初始浓度增加呈现先升高后减弱的趋势，本实验条件下，最佳H₂O₂初始浓度为5 mmol·L^-1。体系对MB降解能力随Fe²⁺初始浓度的增加而单调增加。MB降解速率随MB初始浓度的增加而增加，但MB降解率随其初始浓度呈现先增大后减小的趋势。保证?OH生成速率及其有效利用是提高体系氧化能力及H₂O₂利用率的关键。

关键词: Fe²⁺/H₂O₂体系, 亚甲基蓝, 降解, 活性物质, ?OH