Aerogel-glass fiber composite filter media for effective separation of emulsified water droplets from diesel fuel

This work evaluates several mechanisms of separation of surfactant-stabilized emulsified water droplets from diesel fuel using high surface area (50-370 m(2)/g) and high porosity (>90 %) filter media fabricated by combining aerogels and glass fiber mats. Specifically, high surface area, porous gels of syndiotactic polystyrene (sPS) and silica are developed inside glass fiber mats via dip coating in corresponding sol followed by sol-gel transition. The resultant materials are supercritically dried to obtain aerogel-coated separation media. The abundant meso-and macropores of the aerogel network and the different surface energy of sPS and silica produce cooperative functioning of the mechanisms of size exclusion, coalescence filtration, surfactant adsorption, and volumetric water absorption for removal of emulsified water droplets from ultralow sulfur diesel fuel under continuous flow conditions. The role of each separation mechanism is elucidated in this paper. The results reveal high water separation efficiency of similar to 92 % compared to similar to 30 % for the glass fiber mats.