Carbon–silica composite nanofiber membrane for high flux separation of water-in-oil emulsion – Performance study and fouling mechanism

•Electrospun carbon-silica nanofiber membrane for purification of water-in-oil emulsion.•Operating pressure, cross-flow velocity and permeate flux affecting fouling.•Higher operating pressure resulted in higher permeate flux decline.•Lower permeate flux decline when lower cross-flow velocity applied.•Fouling can be external, internal or a combination of both.

A flexible, hydrophobic and oleophilic carbon nanofiber membrane was prepared from electrospinning for cross-flow filtration of water-in-oil emulsion under various operating conditions. Experimental results show that the membrane has a high throughput of clean oil at low pressure. Furthermore, the membrane performance in terms of permeate flux was governed by the operating pressure and cross-flow velocity. The membrane has a water breakthrough pressure of 0.206 bar under constant cross-flow velocity. The investigation of membrane fouling mechanisms using pore blocking models and resistance model reveals that the membrane experiences either of external or internal fouling or a combination of both under different operating conditions. Using the contour plot analysis, it was suggested that the optimum operating conditions for the membrane to perform efficiently shall be at high cross-flow velocity and at low pressure (between 0.07 and 0.206 bar).