氨三乙酸强化零价铁/过一硫酸盐降解橙黄G

采用氨三乙酸（NTA）强化和改善零价铁/过一硫酸盐（Fe⁰/PMS）体系降解水中偶氮染料的氧化效能，以橙黄G （OG）为目标污染物，研究了NTA强化Fe⁰/PMS （NTA/Fe⁰/PMS）体系中OG的降解效果和NTA的强化作用机制，并考察了NTA、Fe⁰、PMS等主要反应物浓度和水中常见的共存物质对OG降解效能的影响.结果表明，NTA能够强化Fe⁰/PMS体系降解OG的氧化效能，且初始pH值对其强化作用有显著影响.中性（pH=7）和酸性（pH=3）条件下，NTA/Fe⁰/PMS体系去除OG的表观速率常数分别较Fe⁰/PMS体系提高了31.3倍和5.5倍；增加NTA、Fe⁰和PMS浓度有助于OG的降解，但NTA超过8mmol/L或PMS超过1.0mmol/L时出现抑制现象；水质背景中，Cl^-的存在促进了OG的降解，HCO₃^-、H₂PO₄^-和腐殖酸则表现为不同程度的抑制作用；NTA/Fe⁰/PMS体系中，主导的活性物种为Fe⁰界面产生的SO₄^·-和·OH，界面作用和均相作用对OG的降解分别贡献了约83.2%和16.8%；加入NTA后，体系中生成的Fe³⁺/Fe²⁺能与其迅速形成络合物，既缓解了Fe⁰表面钝化层的形成，促进Fe⁰界面对PMS的直接活化，又提高了溶液中溶解性铁的浓度，促进均相作用对PMS的活化分解，使NTA/Fe⁰/PMS体系降解OG的氧化效能得到强化和改善.

Degradation of Orange G by Fe0/peroxymonosulfate with nitrilotriacetic acid enhancement

Nitrilotriacetic acid (NTA) was applied to enhance and improve the oxidation efficiency of azo dyes in Fe⁰/PMS system. Taking Orange G (OG) as the target pollutant, the degradation efficiency of OG, the strengthening role of NTA, the effects of NTA, Fe⁰, PMS and general coexistence substances in water on the degradation of OG were studied in Fe⁰/PMS system enhanced with NTA(NTA/Fe⁰/PMS).The results demonstrated that the introduction of NTA could enhance the degradation of OG by Fe⁰/PMS system, and the initial pH had a significant effect on the enhancement. Under neutral (pH=7) and acidic (pH=3) conditions, the apparent rate constants of OG removal by NTA/Fe⁰/PMS system were 31.3 times and 5.5 times higher than those of Fe⁰/PMS system, respectively. Increasing the concentration of NTA, Fe⁰ and PMS facilitated the degradation of OG, but negative effects were observed when NTA or PMS concentration were over 8mmol/L and 1.0mmol/L, respectively. In the context of water quality, the presence of Cl^- promoted the degradation of OG, while HCO₃^-, H₂PO₄^- and Humic Acid showed different degrees of inhibition. In NTA/Fe⁰/PMS system, SO₄^·- and·OH produced at Fe⁰ interface was confirmed to be the dominant active species responsible for OG degradation, and heterogeneous and homogeneous activation of PMS contributed about 83.2% and 16.8% to the degradation of OG, respectively. When adding NTA to Fe⁰/PMS system, Fe³⁺/Fe²⁺ generated could be complexed rapidly with NTA, which not only alleviated the formation of passive layer and promoting the direct activation of PMS on Fe⁰ interface, but also increased the concentration of soluble iron in system, promoting the activation of PMS by homogeneous interaction. Thus, the degradation effect of OG in Fe⁰/PMS system was enhanced by NTA.