我们使用尺寸稳定的阳极研究了电化学氯化(EC)过程中尿液中亚硝胺的形成。在25mAcm-2下短期电解(<1小时)尿液产生了7种亚硝胺(0.1-7.4µgL-1),其中N-亚硝基二甲胺,N-亚硝基甲基乙胺,和N-亚硝基二乙胺占主导地位,浓度范围为1.2至7.4µgL-1。机理研究表明,亚硝胺的形成动力学受尿液老化和成分的影响,与老年人相比,新鲜尿液产生的水平最高(0.9-5.8µgL-1),离心,或过滤的尿液(0.2-4.1µgL-1)。同时,通过过滤和离心进行尿液预处理的研究强调了含氮代谢物(例如蛋白质样产物和尿中氨基酸)和颗粒相关的腐殖质组分在尿液EC形成亚硝胺中的重要性。通过使用LCOCD的色谱和光谱研究证实了这一发现,拉曼光谱,和3DEEM荧光光谱。参数研究表明,最终的[亚硝胺]在4.5-6.2的pH范围内增加,并且随着[溴化物]的增加,[铵],和电流密度。相反,硫酸根和碳酸根离子抑制亚硝胺的形成。此外,评估了含尿源水中EC的影响.结果表明,无论尿液来源如何(个体志愿者,化粪池,游泳池,未经处理的市政废水),产生了高水平的亚硝胺(0.1-17.6µgL-1),超过10ngL-1的可饮用再利用准则。总的来说,这项研究为阐明亚硝胺形成的潜在机制和优化操作条件提供了见解。这样的见解有助于在含尿液废水的电化学处理期间抑制亚硝胺副产物的产生。
We investigated the formation of nitrosamines from urine during electrochemical chlorination (EC) using dimensionally stable anodes. Short-term electrolysis (< 1 h) of urine at 25 mA cm-2 generated seven nitrosamines (0.1-7.4 µg L-1), where N-nitrosodimethylamine, N-nitrosomethylethylamine, and N-nitrosodiethylamine were predominant with concentrations ranging from 1.2 to 7.4 µg L-1. Mechanistic studies showed that the formation kinetics of nitrosamines was influenced by urine aging and composition, with fresh urine generating the highest levels (0.9-5.8 µg L-1) compared with aged, centrifuged, or filtered urine (0.2-4.1 µg L-1). Concurrently, studies on urine pretreatment through filtration and centrifugation underscored the significance of nitrogenous metabolites (such as protein-like products and urinary amino acids) and particle-associated humic fractions in nitrosamine formation during EC of urine. This finding was confirmed through chromatographic and spectroscopic studies utilizing LCOCD, Raman spectra, and 3DEEM fluorescence spectra. Parametric studies demonstrated that the ultimate [nitrosamines] increased at a pH range of 4.5-6.2, and with increasing [bromide], [ammonium], and current density. Conversely, sulfate and carbonate ions inhibited nitrosamine formation. Moreover, the implications of EC in urine-containing source waters were evaluated. The results indicate that regardless of the urine source (individual volunteers, septic tank, swimming pool, untreated municipal wastewater), high levels of nitrosamines (0.1-17.6 µg L-1) were generated, surpassing the potable reuse guideline of 10 ng L-1. Overall, this study provides insights to elucidate the mechanisms underlying nitrosamine formation and optimize the operating conditions. Such insights facilitate suppressing the generation of nitrosamine byproducts during electrochemical treatment of urine-containing wastewater.