Quantitative determination of the electrical properties of RO membranes during fouling and cleaning processes using electrical impedance spectroscopy
Quantitative determination of the electrical properties of RO membranes during fouling and cleaning processes using electrical impedance spectroscopy
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DOI：
10.1016/j.desal.2015.11.006
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发表时间：
2016-02
期刊：
影响因子：
9.9
通讯作者：
L. N. Sim;Jun Gu;H. Coster;A. Fane
中科院分区：
文献类型：
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作者：
L. N. Sim;Jun Gu;H. Coster;A. Fane
阻抗谱(EIS)已被用作表征反渗透(RO)膜在污染和清洗过程中的电性能的一种非侵入性手段。本研究中使用的横流反渗透装置配备了合适的电极，并与高分辨率阻抗谱一起使用，可以监测膜和污染层的电学性质的变化。膜的内部结构可以用并联电导和电容元件的串联组合来表示。所推导的支撑层厚度与光学测量结果相吻合，有效聚酰胺皮层厚度与最近报道的高分辨率透射电子显微镜数据相吻合。在以二氧化硅和海藻酸盐为模型污垢的过滤过程中，所有电子元件的电导都随着时间的推移而减小，然后随着污垢的进展而增大。这种增加与局部盐度的增加有关，因为滤饼的发展增强了浓差极化。膜表面的电容随着污染过程的进行而减小，这可能是膜表面污秽层堆积的证据。用氯化钠溶液冲洗污染膜约17h，膜恢复到原来的状态，其电容值和电导值与未污染膜接近。
Electrical impedance spectroscopy (EIS) has been used as a non-invasive means of characterising the electrical properties of a reverse osmosis (RO) membrane during fouling and cleaning processes. The crossflow RO unit used in this study was equipped with suitable electrodes and used in conjunction with a high resolution impedance spectroscope that allowed changes in the electrical properties of the membrane and foulant layer to be monitored. The internal structure of the membrane could be represented by a series combination of parallel conductance and capacitance elements. The deduced support layer thickness matched optical measurements and the effective polyamide skin layer thickness matched recently reported data using high resolution TEM. During the filtration process using silica and alginate as model foulants, the conductance of all the electrical elements initially decreased with time and then increased as fouling progressed. The increase was associated with a local increase in salinity due to the development of cake enhanced concentration polarization. The capacitance of the skin layer decreased as the fouling process progressed and this could be evidence of the built up of foulant layers on membrane surface. By flushing the fouled membrane with NaCl solution for about 17 h, the membrane returned back to its original state, with its capacitance and conductance values similar to the unfouled membrane.