RSM optimization of stirred-cell membrane separation for O/W emulsions

To mitigate membrane fouling effectively during the treatment of oil-in-water (O/W) emulsions, this study optimized a stirred-cell membrane filtration system using Response Surface Methodology (RSM) based on a Box-Behnken Design (BBD). The combined effects of the water-to-oil ratio, stirring rate, and transmembrane pressure (TMP) on permeate flux were systematically investigated. Analysis of Variance (ANOVA) results yielded a highly predictive quadratic model (R2=0.9817). Critical interaction analyses revealed that increased stirring significantly reduces concentration polarization, whereas excessive TMP at low water-to-oil ratios induces pore blocking via oil droplet deformation. Numerical optimization identified the ideal operating conditions as a water-to-oil ratio of 8.5, a stirring rate of 213 rpm, and a TMP of 0.059 MPa. Validation experiments under these conditions achieved a permeate flux of 4.37 L.m-2.h-1 with an effluent oil content of <50 ppm. These findings provide essential hydrodynamic strategies for enhancing separation efficiency and controlling fouling in industrial applications.