PERFORMANCE EVALUATION OF SURFACE HYDROPHILIZED NOVEL ULTRAFILTRATION MEMBRANES USING AQUEOUS PROTEINS

The performance of four commercial ultrafiltration membranes with the same nominal molecular weight cut-off (MWCO) but with different surface hydrophilicity was compared with attention to flux, water flux recovery after cleaning, protein deposition as a function of pH, pressure, and ionic strength using 0.1 wt% aqueous bovine albumine solution. The membranes modified for greater hydrophilicity (Biomax, OMEGA) resulted in enhanced UF flux with slower flux loss and lower solute resistance in comparison with unmodified membranes (PFGC, NOVA) at all experimental conditions tested (salt, pH, pressure) with similar protein retention. The results also indicate that this hydrophilic character is related to the flux decline. However, these hydrophilic membranes were not necessarily easier to clean. The intrinsic properties of the membrane surface such as surface charge, hydrophobicity appear to determine the first layer of protein deposition which is difficult to remove. Proteins deposited at low pressure were more difficult to remove by chemical cleaning than those at higher pressure, presumably due to differences in adsorption configuration (i.e. multi-point adsorption at low pressure) at the membrane surface. Differences in initial membrane flux ranging 222-620 l/m2h had little effect on final flux during protein UF under hydrodynamic conditions used in this work.