EFFECT OF SALT CONCENTRATION ON THE STRUCTURE OF LOW-PRESSURE DYNAMICALLY-FORMED MEMBRANES

Data are presented from an experimental investigation of dynamically-f ormed membranes (DFMs) operated under conditions of low pressure. Hydr ous zirconium oxide-polyacrylic acid (Zr-PAA) DFMs have been formed on a composite, ceramic/metal mesh microfiltration (MF) membrane at pres sures and cross-flow velocities of 1.1 MPa and 2.67 m/s, respectively. Similar conditions were employed during operation. After correcting f or the effects of concentration polarisation the salt concentration wa s shown to have a significant effect on the intrinsic rejection and pe rmeability of the DFMs. Permeation trials against non-ionic solutes re vealed that the decrease in permeability could be attributed to physic al changes in the membrane material. Further processing of the correct ed data showed the Brian correlation to give a reasonable representati on of mass transfer under the turbulent flow conditions employed durin g the study.