Microfiltration of oil in water (O/W) emulsions: Effect of membrane microstructure and surface properties

In this work, oil in water (O/W) emulsions prepared with a natural emulsifier and different oil phase concentrations were processed by using Anodisc, cellulose acetate (CA), polyester/nylon, silicon nitride microsieves and polycarbonate track etched (PCTE) membranes of different pore sizes (0.22-0.8 μm). The effect of membrane characteristics on properties of the emulsions was assessed by droplet size distribution, ζ-potential and pH. Results suggest that membrane hydrophilicity is critical to avoid breaking during microfiltration of O/W emulsions. Partial or total retention of oil droplets from concentrated emulsions (10-30% oil) occurred with all 0.22 μm membranes, except with the 0.26 μm microsieves. PCTE membrane (uniform straight pores) performance was function of the d¯droplet/dpore ratio, i.e. (a) if d¯droplet/dpore<1, emulsions fully filtered, (b) if 1.0