化工学报 ›› 2018, Vol. 69 ›› Issue (7): 3286-3292.DOI: 10.11949/j.issn.0438-1157.20171471

• 材料化学工程与纳米技术 • 上一篇    下一篇

临阈浓度时纳滤膜软化过程中膜面动电现象研究

宋跃飞, 秦文博, 张姗, 户启华, 任睿宜, 薛守聪   

  1. 河南师范大学环境学院, 黄淮水环境与污染防治教育部重点实验室, 河南 新乡 453007
  • 收稿日期:2017-11-05 修回日期:2018-05-15 出版日期:2018-07-05 发布日期:2018-07-05
  • 通讯作者: 宋跃飞
  • 基金资助:

    国家自然科学基金项目(21606074);中国博士后科学基金项目(2016M592297,2017T100533);河南师范大学优秀青年基金项目(YQJJ201603)。

Surface electrokinetic phenomenon of DK nanofiltration membrane under threshold concentration condition

SONG Yuefei, QIN Wenbo, ZHANG Shan, HU Qihua, REN Ruiyi, XUE Shoucong   

  1. Key Laboratory of Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, School of Environment, Henan Normal University, Xinxiang 453007, Henan, China
  • Received:2017-11-05 Revised:2018-05-15 Online:2018-07-05 Published:2018-07-05
  • Supported by:

    supported by the National Natural Science Foundation of China (21606074), the China Postdoctoral Science Foundation (2016M592297, 2017T100533) and the Henan Normal University Fund for Excellent Young Scholars (YQJJ201603).

摘要:

荷电纳滤(NF)膜在相似浓度范围的进水端主体溶液软化过程中,浓水端的膜面处易出现结垢污染,因此开展临阈浓度条件下膜表面动电现象研究是十分必要的。本文选定DK型NF膜和cK2SO4cCaCl2=1:1的双组分溶液为载体,以CaSO4·0.5H2O为典型代表的非碱性难溶垢为研究对象,通过自制的切向流动电位测试系统,分别考察临阈浓度条件下,进水端主体溶液中不同构晶离子浓度(0.5~18 mol·m-3)、操作压力(25~200 kPa)和不同pH(3.0~10.0)对该NF膜流动电位、Zeta电位和膜表面电荷密度的影响效应。当操作压力恒定为180 kPa且逐渐增加构晶离子浓度(0.5~18 mol·m-3)时,DK膜面流动电位和Zeta电位绝对值分别从87.37和59.13 mV下降至3.41和36.34 mV,均呈先急剧后缓慢下降的变化趋势。这可能是由于静电屏蔽和扩散层压缩共同作用的结果。而同时膜面电荷密度从13.94 mC·m-2逐渐增加至34.86 mC·m-2。研究表明,当NF浓水端膜面处开始出现结垢时,膜表面仍有中低强度的动电现象。

关键词: DK纳滤膜, 边界层, 临阈浓度, 动电现象, Zeta电位

Abstract:

In the process when inlet bulk solution with low or medium concentration was involved, the scaling was apt to appeared on the nanofiltration (NF) membrane surface in the retentate side. Therefore, the study of surface electrokinetic phenomena of NF membrane termed as DK membrane under threshold concentration condition is very important. In this paper, the surface charge properties of DK nanofiltration membrane were studied using streaming potential method, and a series of two-component ternary electrolyte solutions (K2SO4+CaCl2) with the molar ratio of 1:1 were involved as the study objects. Using the home-made tangential streaming potential test device, DK membrane was characterized with streaming potential (Es), Zeta (ζ) potential and other measurements encountering with a wider scale-prone ionic concentration (0.5-18 mol·m-3), operating pressure (25-200 kPa) and feed pH (3.0-10.0). The results showed that at operating pressure of 180 kPa, with the scale-prone ionic concentration of feed solution ranged from 0.5 to 18 mol·m-3, it turned out Es and ζ -potential values increased from -87.37 and -59.13 mV to -3.41 and -36.34 mV, respectively. It becomes less negative and tends to be neutral due to electrostatic charge shielding and compression of the diffuse layer. But the calculated surface charge density (σ) value always increased from 13.94 to 34.86 mC·m-2 under the same operating conditions. It could be inferred that under the condition of non-alkaline sparingly soluble salt CaSO4 occurring in brine side, there are still some surface electrokinetic phenomena with low or medium level on NF membrane surface.

Key words: DK nanofiltration membrane, boundary layer, threshold concentration, electrokinetic phenomenon, Zeta potential

中图分类号: