Department of Chemistry, Universidade Federal de Santa Catarina, Brazil.
Department of Chemistry, Universidade Federal de Santa Catarina, Brazil.
J Hazard Mater. 2015 Dec 30;300:754-764. doi: 10.1016/j.jhazmat.2015.08.009. Epub 2015 Aug 6.
Methyl orange (MO) azo dye served as model organic pollutant to investigate the role of reactive nitrogen species (RNS) in non-thermal plasma (NTP) induced water treatments. The results of experiments in which MO aqueous solutions were directly exposed to N2-NTP are compared with those of control experiments in which MO was allowed to react with nitrite, nitrate and hydrogen peroxide, which are species formed in water exposed to N2-NTP. Treatment of MO was also performed in PAW, Plasma Activated Water, that is water previously exposed to N2-NTP. Both direct N2-NTP and N2-PAW treatments induced the rapid decay of MO. No appreciable reaction was instead observed when MO was treated with NO3(-) and H2O2 either under acidic or neutral pH. In contrast, in acidic solutions MO decayed rapidly when treated with NO2(-) and with a combination of NO2(-) and H2O2. Thorough product analysis was carried out by HPLC coupled with UV-vis and ESI-MS/MS detectors. In all experiments in which MO reaction was observed, the major primary product was a derivative nitro-substituted at the ortho position with respect to the N,N-dimethylamino group of MO. The reactions of RNS are discussed and a mechanism for the observed nitration products is proposed.
甲基橙（MO）偶氮染料被用作模型有机污染物，以研究反应性氮物种（RNS）在非热等离子体（NTP）诱导的水处理中的作用。将 MO 水溶液直接暴露于 N2-NTP 的实验结果与对照实验进行了比较，在对照实验中，MO 与亚硝酸根、硝酸根和过氧化氢反应，这些物质是在暴露于 N2-NTP 的水中形成的。MO 的处理也在 PAW（等离子体激活水）中进行，即先前暴露于 N2-NTP 的水。直接的 N2-NTP 和 N2-PAW 处理均导致 MO 的快速衰减。然而，当 MO 在酸性或中性 pH 下用 NO3(-)和 H2O2 处理时，没有观察到明显的反应。相比之下，在酸性溶液中，当用 NO2(-)和 NO2(-)和 H2O2 的混合物处理 MO 时，MO 迅速衰减。通过 HPLC 与 UV-vis 和 ESI-MS/MS 检测器进行了彻底的产物分析。在观察到 MO 反应的所有实验中，主要的初级产物是在 MO 的 N,N-二甲基氨基的邻位上取代硝基的衍生物。讨论了 RNS 的反应，并提出了观察到的硝化产物的机制。
