Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est, EA 4508, UPEMLV, 77454, Marne-la-Vallée, France,
Environ Sci Pollut Res Int. 2014;21(14):8387-97. doi: 10.1007/s11356-014-2788-9. Epub 2014 Mar 27.
The oxidative degradation of imidacloprid (ICP) has been carried out by electrochemical advanced oxidation processes (EAOPs), anodic oxidation, and electro-Fenton, in which hydroxyl radicals are generated electrocatalytically. Carbon-felt cathode and platinum or boron-doped diamond (BDD) anodes were used in electrolysis cell. To determine optimum operating conditions, the effects of applied current and catalyst concentration were investigated. The decay of ICP during the oxidative degradation was well fitted to pseudo-first-order reaction kinetics and absolute rate constant of the oxidation of ICP by hydroxyl radicals was found to be k abs(ICP) = 1.23 × 10(9) L mol(-1) s(-1). The results showed that both anodic oxidation and electro-Fenton process with BDD anode exhibited high mineralization efficiency reaching 91 and 94% total organic carbon (TOC) removal at 2 h, respectively. For Pt-EF process, mineralization efficiency was also obtained as 71%. The degradation products of ICP were identified and a plausible general oxidation mechanism was proposed. Some of the main reaction intermediates such as 6-chloronicotinic acid, 6-chloronicotinaldehyde, and 6-hydroxynicotinic acid were determined by GC-MS analysis. Before complete mineralization, formic, acetic, oxalic, and glyoxylic acids were identified as end-products. The initial chlorine and organic nitrogen present in ICP were found to be converted to inorganic anions Cl(-), NO₃(-), and NH₄(+).
已通过电化学高级氧化工艺（EAOPs）、阳极氧化和电芬顿法对吡虫啉（ICP）进行氧化降解，其中羟基自由基是通过电催化产生的。在电解槽中使用了碳纤维毡阴极和铂或掺硼金刚石（BDD）阳极。为了确定最佳操作条件，研究了施加电流和催化剂浓度的影响。ICP 在氧化降解过程中的衰减很好地符合假一级反应动力学，并且发现 ICP 被羟基自由基氧化的绝对速率常数为 kabs(ICP) = 1.23 × 10(9) L mol(-1) s(-1)。结果表明，BDD 阳极的阳极氧化和电芬顿法均表现出高矿化效率，分别在 2 小时内达到 91%和 94%的总有机碳（TOC）去除率。对于 Pt-EF 工艺，矿化效率也达到了 71%。鉴定了 ICP 的降解产物，并提出了一种合理的一般氧化机制。通过 GC-MS 分析确定了一些主要的反应中间体，如 6-氯烟酸、6-氯烟醛和 6-羟基烟酸。在完全矿化之前，确定了甲酸、乙酸、草酸和乙醛酸作为终产物。发现 ICP 中最初存在的氯和有机氮被转化为无机阴离子 Cl(-)、NO₃(-)和 NH₄(+)。
