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道南渗析(Donnan dialysis)是电化学势差驱动的选择性膜过程,可用于饮用水中砷酸根离子[As(Ⅴ)]的去除。通过对膜相As(Ⅴ)传质模型中参数的系统分析讨论了As(Ⅴ)膜相自扩散系数、膜对As(Ⅴ)的选择性、膜面积和膜厚度等对道南渗析除砷过程的影响。结果表明,当转速高于200 r·min-1时膜相传质为道南渗析除砷的速率限制步骤。提高膜相自扩散系数、增大膜有效面积、减小膜厚度能同等程度地改善As(Ⅴ)渗析传质效果,但这些参数并不影响道南平衡达到时料液中As(Ⅴ)的残余浓度。改变料液和解吸液的溶液条件直接影响膜相As(Ⅴ)浓度梯度,不仅影响As(Ⅴ)渗析通量,也会改变道南平衡。选择高填充密度的膜组件、及时去除解吸液中富集的As(Ⅴ)是提高道南渗析除砷装置运行效率的有效手段。
Donnan dialysis is a selective membrane process driven by electrochemical potential difference and can be used for the removal of arsenate ion [As (Ⅴ)] in drinking water. The effects of As (Ⅴ) membrane phase diffusion coefficient, membrane selectivity on As (Ⅴ), membrane area and membrane thickness on the dialysis and arsenic removal The impact of the process. The results showed that when the rotating speed was higher than 200 r · min-1, membrane phase mass transfer was the rate limiting step for the de-arsenic removal in South Dawn. Increasing the self-diffusion coefficient of the membrane phase, increasing the effective area of the membrane and decreasing the membrane thickness can improve the dialysis mass transfer efficiency of As (Ⅴ) to the same extent, but these parameters do not affect the As (Ⅴ) Residual concentration. Changing the solution conditions of feed solution and desorption solution directly affects the concentration gradient of As (Ⅴ) in the membrane phase, which not only affects the dialysis flux of As (Ⅴ), but also changes the southbound equilibrium. It is an effective way to improve the operating efficiency of the Dandan dialysis and arsenic removal unit by selecting membrane modules with high packing density and timely removing As (Ⅴ) enriched in desorption solution.