Abstract:

Polyethersulfone ultrafiltration（UF）membrane with an average pore size of 25 nm was used for preparing W/O diesel emulsion. With the help of UF membrane，emulsification was accomplished by dispersing  deionized water into 0^#diesel oil using Tween-20 and Span-80 as surfactant in each phase. Nanoparticles formed at the permeate side of the membrane are swept away by the recirculating organic phase inside the membrane module when the aqueous phase is forced to pass through the membrane. The prepared diesel emulsion demonstrated 200%—250% longer stability and 50%—65% less emulsifier consumption compared with those prepared with traditional methods，such as high speed homogenization.  In addition，the impact of operating parameters，such as emulsifier dosage，flow rate and organic phase pressure，on emulsion properties was also discussed. Results illustrated that emulsified diesel with nanoparticle sizes of as small as 30—65 nm and a distribution coefficient a of 0.12—0.3 could be obtained at a transmembrane pressure of 0.02 MPa and a cross flow rate of 2.0—5.0 m/s with the mass content of emulsifier higher than 0.5%.