Separation of stable oil-water emulsion by the hydrophilic nano-sized ZrO2 modified Al2O3 microfiltration membrane

Membrane fouling weakens seriously the membrane's separating performance, which can be reduced by the membrane surface modification. Commercial Al2O3 microfiltration membranes were modified by the nano-sized ZrO2 coating to reduce the membrane fouling by oil droplets and to keep the unique character of the inorganic membrane. The nano-sized ZrO2 coating is prepared by in situ hydrolysis of ZrCl4. The results show that the nano-coating does not form a separating layer, and just makes the ceramic membrane more hydrophilic. Using the stable 1 g/L 20(#) engine oil-water emulsion as feed, the steady flux of the modified membrane is obtained in a very short time. The steady flux keeps 88% of the initial flux and the oil rejection is above 97.8%. The hydrophilic nano-sized coating, the backflushing and the appropriate cross-flow velocity contribute to reducing the membrane fouling by oil droplets. The modified membrane has the good performance in the oil-water separation of stable emulsions. (C) 2010 Elsevier B.V. All rights reserved.