화학공학소재연구정보센터
Journal of Membrane Science, Vol.138, No.1, 135-140, 1998
Characterisation of zirconium/poly(acrylic acid) low pressure dynamically formed membranes by use of the extended Nernst-Planck equation
The rejection of a single electrolyte solution, try a hydrous zirconium oxide/poly(acrylic acid) (Zr/PAA) dual layer dynamically formed membrane (DFM), has been investigated. A flat sheet titania-coated sintered stainless steel (IMAS UK) was used as a substrate for DFM formation. Flux and rejection were recorded for a series of experiments at different transmembrane pressures, feed solution cross-flow rates and salt concentration. Experimental data was interpreted using a model based on the extended Nernst-Planck equation. This interpretation allows characterisation of the membrane in terms of two parameters, the effective membrane charge density and a structural parameter which combines porosity and membrane thickness. Good correlation between experimental data and theory has been obtained. Calculation of the effective membrane charge density and the structural parameter at pH 6.7 and 9.0 for a range of salt concentrations provides conclusive evidence that membrane pore size decreases with increasing salt concentration and that the degree of ionisation of the PAA contained within the membrane increases with increasing pH and salt concentration.