State Key Laboratory of Urban Water Resources and Environment, School of Municipal & Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, China.
Water Sci Technol. 2011;63(1):45-50. doi: 10.2166/wst.2011.007.
Removal of precursors of N-nitrosodimethylamine (NDMA), such as the most direct precursor dimethylamine (DMA), might be an effective method to control NDMA formation during practical water treatment process. Adsorption of DMA onto manganese dioxide (MnO₂) from aqueous solution has been investigated using batch experiments in this study. Results indicate that DMA adsorption is initially rapid (in the first 5 h) and the adsorption process reaches a steady state after 15 h. The adsorption isotherms are well described by the Freundlich models. The desorption shows an irreversibility of DMA adsorption onto MnO₂. The effects of temperature, pH, ionic strength, humic acid, and the presence of other secondary aliphatic amines on adsorption processes are also examined. According to the experimental results, the amount of DMA adsorbed increases with an increase of temperature from 288 to 308 K, and with a decrease of ionic strength from 1 to 10 mM. The maximum adsorption appeared at pH 7.0. However, the amount of DMA adsorbed onto MnO₂ does not show obvious difference in the presence of humic acid. According to the results, it suggests that the adsorption is primarily brought about by electrostatic interaction between DMA and MnO₂ surface.
去除 N-亚硝基二甲胺 (NDMA) 的前体物，如最直接的前体二甲胺 (DMA)，可能是控制实际水处理过程中 NDMA 形成的有效方法。本研究采用批量实验研究了从水溶液中吸附 MnO₂ 上的 DMA。结果表明，DMA 的吸附最初很快（在前 5 小时内），15 小时后吸附过程达到稳定状态。吸附等温线很好地用 Freundlich 模型描述。解吸表明 DMA 吸附到 MnO₂ 上是不可逆的。还考察了温度、pH 值、离子强度、腐殖酸和其他仲脂肪胺的存在对吸附过程的影响。根据实验结果，DMA 的吸附量随温度从 288 K 增加到 308 K 而增加，随离子强度从 1 mM 降低到 10 mM 而增加。在 pH 值为 7.0 时，最大吸附量出现。然而，在腐殖酸存在的情况下，MnO₂ 上吸附的 DMA 量没有明显差异。根据结果表明，DMA 与 MnO₂ 表面之间的静电相互作用是主要的吸附机制。
