Inorganic microfiltration membranes incorporated with hydrophilic silica nanoparticles for oil-in-water emulsion separation

Hydrophilic modification of alumina microfiltration membranes was achieved by incorporating silica nanoparticles into the alumina matrix. The alumina tubular membrane, incorporated with silica nanoparticles, was tested for cyclohexane-in-water emulsion separation. The incorporated silica nanoparticles increased the hydrophilicity of the membrane surface with the oil contact angles changing from 155° to 165°. The alumina membrane treated with a 0.5 wt.% silica-nanoparticle solution yielded a water flux greater than 350 L m−2 h-1 and oil rejection greater than 93%, which represented a 20.5% and 6.0% enhancement in water flux and oil rejection compared with the pristine alumina membrane. Due to the hydrophilic silica nanoparticle incorporation, the cyclohexane concentration of the permeate was less than 40 ppm when the cyclohexane concentration of the feed was 500 ppm at 40 °C and feed pressure was 43.7 psia. This work represents a key advancement toward the use of inorganic membranes to treat marginal water that contains hydrocarbon contaminants.