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本文通过错流过滤方式下的流动电势测量对氧化铝微滤膜的电动性能进行表征,研究了过滤介质溶液pH、电解质种类和浓度等对膜的电动性能的影响。结果表明,膜流动电势大小取决于过滤溶液pH、电解质溶液种类和浓度。采用浓度为10-3M的NaCl溶液为过滤介质时,膜的等电点为6.1,而采用相同浓度的CaCl2和Na2SO4溶液时,由于对Ca2+和SO42-的特定吸附,膜等电点分别增大至6.8和减小至5.6。由于Ca2+和SO42-在膜孔表面存在特定吸附,溶液离子浓度提高导致膜的等电点和表面净电荷符号改变,而NaCl溶液浓度提高仅使膜流动电势逐渐减小,但等电点不变。
In this paper, the electrochemical performance of alumina microfiltration membrane was characterized by flow potential measurement under cross-flow filtration. The effects of pH, electrolyte type and concentration on the electrokinetic properties of the membrane were investigated. The results show that the membrane potential depends on the pH of the solution, the type and concentration of the electrolyte solution. When the concentration of 10-3M NaCl solution for the filter medium, the membrane isoelectric point of 6.1, and the same concentration of CaCl2 and Na2SO4 solution, due to Ca2 + and SO42- specific adsorption, the membrane isoelectric point increased To 6.8 and down to 5.6. Due to the specific adsorption of Ca2 + and SO42- on the pore surface of the membrane, the increase of solution ion concentration resulted in the change of the symbol of the isoelectric point and surface net charge of the membrane. However, the increase of the concentration of NaCl solution only decreased the flow potential of the membrane but the isoelectric point .