Diuron degradation in irradiated, heterogeneous iron/oxalate systems: the rate-determining step.
Diuron degradation in irradiated, heterogeneous iron/oxalate systems: the rate-determining step.
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DOI：
10.1021/es001324q
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发表时间：
2001-07
影响因子：
11.4
通讯作者：
P. Mazellier;B. Sulzberger
中科院分区：
文献类型：
--
作者：
P. Mazellier;B. Sulzberger
本研究的目的是检查控制含针铁矿 (α-FeOOH) 和草酸盐的辐照充气悬浮液中敌草隆降解动力学的各种因素，在下文中表示为异质光芬顿系统。在这些系统中，羟基自由基（HO.）的攻击是敌草隆降解的唯一途径。研究在最初含有 80 或 200 mg L(-1) 针铁矿（相当于 0.9 或 2.25 mM 总铁）和 20、50、75、100、200 和 400 microM 草酸盐（3 < 或 = pH < 或 = 6）的系统中进行。草酸盐浓度和 pH 值都极大地影响光诱导敌草隆转化的速率。在初始 200 µM 草酸盐存在的情况下，敌草隆降解速率在 pH 4 时达到最大，与针铁矿表面草酸盐吸附的最大程度一致。在pH 4时，光诱导敌草隆降解速率随着草酸盐浓度的增加而增加，在初始草酸盐浓度为200μM时达到平台，即针铁矿表面草酸盐吸附程度达到最大的草酸盐溶液浓度。这些实验结果表明，以草酸盐作为电子供体，通过光化学还原溶解针铁矿形成 Fe(II)(aq) 的速率，决定了这些异质光芬顿系统中敌草隆降解的动力学。
The purpose of this study was to examine the various factors that control the kinetics of diuron degradation in irradiated, aerated suspensions containing goethite (alpha-FeOOH) and oxalate, in the following denoted as heterogeneous photo-Fenton systems. In these systems, attack by hydroxyl radicals (HO.) was the only pathway of diuron degradation. Studies were conducted in systems containing initially 80 or 200 mg L(-1) goethite (corresponding to 0.9 or 2.25 mM total iron) and 20, 50, 75, 100, 200, and 400 microM oxalate at 3 < or = pH < or = 6. Both oxalate concentration and pH greatly affected the rate of light-induced diuron transformation. In the presence of initial 200 microM oxalate, the rate of diuron degradation was maximal at pH 4, coinciding with the maximal extent of oxalate adsorption on the surface of goethite. At pH 4,the rate of light-induced diuron degradation increased with increasing oxalate concentration, reaching a plateau at initial 200 microM oxalate, i.e., at the oxalate solution concentration at which the extent of oxalate adsorption on the surface of goethite reached a maximum. These experimental results suggest that the rate of Fe(II)(aq) formation through photochemical reductive dissolution of goethite, with oxalate acting as electron donor, determines the kinetics of diuron degradation in these heterogeneous photo-Fenton systems.