Charged Nanofiltration Membrane Electrical Properties And Test Conditions

The purpose of this subject is to further study the charged performance of charged nanofiltration membranes through a charged membrane potential switch testing device which is our own research and development, and studied the effect of various test conditions and operating conditions on the charged performance of charged nanofiltration membranes.This paper mainly had a study in five aspects:1. Based on the theory of the double-layer formation mechanism, we have gotten the basic formulas which is used to calculate potential switch, Zeta potential, and the surface charge density of the nanofiltration through the study of surface potential and the formula derivation, to provide the most basic and the most important theory for the research of the charged performance of nanofiltration membranes.2. Using different concentrations and compositions of the salt solution as measurement media of charged nanofiltration membranes surface potential switch, we found that the types and valences of the cations and anions had an impact on the measurement results. Using KC1 solution as a potential switch measurement media, measurement results will be well received, and measurement concentration is generally 0.001mol/l for measuring the charged nanofiltration membranes.3. We examined the influence of a few of external test conditions on the membrane potential switch, and mainly compared and analyzed some test conditions such as temperature, pH value of the solution, membrane soak time and the effective filtration area. This is provided effective reference data for further improving the testing device.4. Carried out a research for the Zeta potential of nanofiltration membranes and the surface charge density, some definite laws were received: with increasing the concentration of salt solution, Zeta potential is reduced, yet surface charge density is increased; With increasing operating pressure, the potential switch is increased, but the Zeta potential and surface charge density are decreased. Furthermore, using Zeta potential and surface charge density the charged performance of membranes can be estimated indirectly, to provide a more simple and practical method for comparison of the charged performance of various nanofiltration membranes.5. Using nanofiltration membranes flowing devices to analyze the charged performance of. Mainly through the evaluation of the charged performance of self-made nanofiltration membranes which have different crosslinking time and different polymer coating layer, we can offer certain reference for further development of charged nanofiltration membranes.