Huang Dan, Liu Xiangxuan, Wang Xuanjun, Huang Zhiyong, Xie Zheng, Wang Huanchun
High-Tech Institute of Xi'an, Shaanxi 710025, People's Republic of China.
R Soc Open Sci. 2019 May 8;6(5):190263. doi: 10.1098/rsos.190263. eCollection 2019 May.
The majority of unsymmetrical dimethylhydrazine (UDMH) treatments produce lots of toxic by-products, among which -Nitrosodimethylamine (NDMA) is a strong carcinogen. The compositions of the by-products are important for evaluating the treatment efficiency and understanding the UDMH degradation mechanism to achieve UDMH mineralization. The intermediate and end products of UDMH treatment with different oxidants were investigated by using a simple and fast method, solid-phase micro-extraction (SPME) in combination with gas chromatography-mass spectrometry (GC-MS). The effects of several parameters (coating fibre, salt addition, pH, sampling time and desorption time) were studied to optimize analyte recovery. The best response can be attained by the 65 µm PDMS/DVB fibre at pH 7 during 10 min after desorption of 1 min in the GC inlet. The intermediate and final oxidative products of UDMH wastewater treatment with different oxidants (O, Mn/O, Fe/HO) were investigated. The results showed that the UDMH treatment with O could lead to high yields of NDMA. Metal catalytic ozonation could largely minimize the formation of NDMA. No NDMA was observed in the final decontaminated samples after treatment with Fe/HO. The NDMA formation and degradation mechanism were discussed based on the intermediates. This study is expected to provide useful information for controlling NDMA formation during UDMH wastewater treatment.
大多数不对称二甲基肼（UDMH）处理过程会产生大量有毒副产物，其中 - 亚硝基二甲胺（NDMA）是一种强致癌物。副产物的组成对于评估处理效率以及理解UDMH降解机制以实现UDMH矿化至关重要。采用一种简单快速的方法，即固相微萃取（SPME）结合气相色谱 - 质谱联用（GC - MS），研究了不同氧化剂处理UDMH的中间产物和最终产物。研究了几个参数（涂层纤维、加盐量、pH值、采样时间和解吸时间）对分析物回收率的影响以优化回收率。在气相色谱进样口解吸1分钟后10分钟内，pH值为7时使用65 µm PDMS/DVB纤维可获得最佳响应。研究了不同氧化剂（O、Mn/O、Fe/H₂O₂）处理UDMH废水的中间氧化产物和最终氧化产物。结果表明，用O处理UDMH会导致大量NDMA生成。金属催化臭氧化可大幅减少NDMA的形成。用Fe/H₂O₂处理后的最终净化样品中未观察到NDMA。基于中间产物讨论了NDMA的形成和降解机制。本研究有望为控制UDMH废水处理过程中NDMA的形成提供有用信息。
