Microfiltration of water in oil emulsions and evaluation of fouling mechanism

An analysis of the crossflow microfiltration of water in oil emulsions is reported. The emulsion considered was water, containing copper sulphate with kerosene using Span 80 as surfactant. Three membrane materials were studied: PTFE, PVDF and regenerated cellulose. The effects of crossflow velocity, transmembrane pressure, and temperature are analysed using several cake filtration models. Increases in transmembrane pressure, temperature and flow rate of emulsion all result in an increase in membrane flux. Membrane flux declines initially with time under most conditions of operation, except at a temperature of 50 °C, where values of flux are stable. Analysis of the fall in flux with time for the PTFE and PVDF membranes indicates that cake formation gives the best prediction of behaviour. In the case of PVDF the model does not predict the performance over the complete range of filtration times but rather two stages of filtration appear to occur; possibly cake formation initially followed by some intermediate pore blocking. In the case of the regenerated cellulose membrane, two stages of filtration seem to occur: an initial phase of cake formation or some pore blocking followed by intermediate pore blocking.