二碘酞酸盐在高级氧化过程中的转化产物的鉴定：水基质和氧化过程的影响。
Identification of transformation products during advanced oxidation of diatrizoate: Effect of water matrix and oxidation process.
机构信息
Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
Federal Institute of Hydrology (BfG), Koblenz, Germany.
出版信息
Water Res. 2016 Oct 15;103:424-434. doi: 10.1016/j.watres.2016.07.066. Epub 2016 Jul 30.
Removal of micropollutants from reverse osmosis (RO) brines of wastewater desalination by oxidation processes is influenced by the scavenging capacity of brines components, resulting in the accumulation of transformation products (TPs) rather than complete mineralization. In this work the iodinated contrast media diatrizoate (DTZ) was used as model compound due to its relative resistance to oxidation. Identification of TPs was performed in ultrapure water (UPW) and RO brines applying nonthermal plasma (NTP) and UVA-TiO2 as oxidation techniques. The influence of main RO brines components in the formation and accumulation of TPs, such as chloride, bicarbonate alkalinity and humic acid, was also studied during UVA-TiO2. DTZ oxidation pattern in UPW resulted similar in both UVA-TiO2 and NTP achieving 66 and 61% transformation, respectively. However, DTZ transformation in RO brines was markedly lower in UVA-TiO2 (9%) than in NTP (27%). These differences can be attributed to the synergic effect of RO brines components during NTP. Moreover, reactive species other than hydroxyl radical contributed to DTZ transformation, i.e., direct photolysis in UVA-TiO2 and direct photolysis + O3 in NTP accounted for 16 and 23%, respectively. DTZ transformation led to iodide formation in both oxidation techniques but it further oxidized to iodate by ozone in NTP. In total 14 transformation products were identified in UPW of which 3 were present only in UVA-TiO2 and 2 were present exclusively in NTP; 5 of the 14 TPs were absent in RO brines. Five of them were new and were denoted as TP-474A/B, TP-522, TP-586, TP-602, TP-628. TP-522 (mono-chlorinated) was elucidated only in presence of high chloride titer-synthetic water matrix in NTP, most probably formed by active chlorine species generated in situ. TPs accumulation in RO brines was markedly different in comparison to UPW. This denotes the influence of RO brines components in the formation of reactive species that could further attack DTZ/TPs and/or scavenging performed by these brine components that could limit further TPs degradation. Five plausible degradation pathways are proposed for DTZ transformation in UPW.
反渗透（RO）海水淡化浓盐水（RO 浓盐水）中微污染物的去除受到浓盐水成分清除能力的影响，导致转化产物（TP）的积累而不是完全矿化。在这项工作中，由于其相对耐氧化，使用碘造影剂二碘酞酸盐（DTZ）作为模型化合物。在超纯水（UPW）和 RO 浓盐水中，应用非热等离子体（NTP）和 UVA-TiO2 作为氧化技术，对 TPs 进行了鉴定。还研究了 RO 浓盐水中的主要浓盐水成分，如氯化物、碳酸氢盐碱度和腐殖酸，对 UVA-TiO2 中 TPs 形成和积累的影响。在 UVA-TiO2 和 NTP 中，DTZ 在 UPW 中的氧化模式分别达到 66%和 61%的转化率。然而，在 RO 浓盐水中，DTZ 的转化在 UVA-TiO2 中明显低于 NTP（9%比 27%）。这些差异可以归因于 NTP 过程中 RO 浓盐水成分的协同作用。此外，除了羟基自由基之外，其他活性物质也有助于 DTZ 的转化，即在 UVA-TiO2 中为直接光解，在 NTP 中为直接光解+O3，分别占 16%和 23%。在两种氧化技术中，DTZ 转化都会导致碘化物的形成，但在 NTP 中，碘化物会进一步被臭氧氧化为碘酸盐。在 UPW 中共鉴定出 14 种转化产物，其中 3 种仅存在于 UVA-TiO2 中，2 种仅存在于 NTP 中；在 RO 浓盐水中，有 5 种 TPs 不存在。其中 5 种为新物质，分别命名为 TP-474A/B、TP-522、TP-586、TP-602、TP-628。只有在 NTP 中存在高氯化物浓度的合成水基质时，才能阐明 TP-522（单氯化），这很可能是由原位生成的活性氯物种形成的。与 UPW 相比，RO 浓盐水中 TPs 的积累明显不同。这表明 RO 浓盐水成分对活性物质形成的影响，这些活性物质可能进一步攻击 DTZ/TPs，或者这些浓盐水成分的清除作用可能限制进一步的 TPs 降解。提出了 DTZ 在 UPW 中转化的 5 种可能的降解途径。
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