Membrane oscillation and slot (pore) blocking in oil–water separation

•The influence of membrane oscillation on pore (slot) blocking has been investigate.•Membrane pore blocking was found to be a linear function of the applied shear rate.•Higher deformation of oil drops were noticed at a lower interfacial tension.•Lower number of drops in the permeate was found at a higher interfacial tension.•The divergence between experimental data and the model was due the slots, deforming drops and applied shear. Deformable oil drops of two interfacial tensions (namely, 4 and 30mNm−1) were filtered through a slotted-pore membrane (with pore dimensions of 4×400μm) at four vibrational shear rates (namely, 0, 1200, 3200 and 8000s−1) and two permeate fluxes (namely, 200 and 1000lm−2h−1). The membrane material was made of nickel. The membrane surface was modified with Poly tetra fluoroethylene (PTFE)F for better performance in-terms of higher flux rate rejection. The oil with the lower interfacial tension was more deformable, because the increase in TMP was less due to the passage of even larger drops to the slot opening, also the permeate quality was lower as a result of the higher concentration of the oil in the permeate. The impact of interfacial tension was more significant under the following conditions; first at lower shear rates, the particle back-transport effects become more dominant than the deformability effects at higher shear rates, and secondly at the higher permeate flux, the higher permeate drag enhances the deformability effects. Discrepancies were observed between experimental results and model predictions based on circular membrane pores and non-deformable foulants. In the future, it is expected that a better agreement of the experimental results and the analytical model could be obtained if the model is modified for the slotted pore membrane.