Charge Characteristics of Nanofiltration Membrane by Streaming Potential Method

Surface charge properties of DL nanofiltration membrane were studied using streaming potential method. The results indicate that in the experimental concentration range, the relationship between NF membrane surface charge density and electrolyte solution concentration is in good agreement with Freundlich-isotherm adsorption, which indicates that the membrane surface charge comes from the adsorption of ions of the solution. In addition, the analysis of anion and cation adsorption on nanofiltration membrane surface showed that adsorption of common ions to the Inner Helmholtz Plane through specific adsorption increases the charge density, while adsorption of counter ions to the Outer Helmholtz Plane through electrostatic interactions leads to electric double-layer contracting inward, decreasing the membrane surface charge density.