Hydrophobic modification of sintered glass filters for the separation of organic solvents and gasoline from water as well as emulsified water

Sintered glass filters are used in chemical plants and laboratories to separate particulate matter from liquids. This paper reports their hydrophobic modification to render an additional function: the separation of water-immiscible organic liquids (oils) from water as well as emulsified water. To coat the filters, chlorodimethyloctadecylsilane and a 5 kDa poly(dimethyl siloxane) sample bearing an epoxy end group, PDMS-Ep, are covalently grafted onto the filter pore walls. Investigated are how varying the hydrophobic coating agent, its solution concentration, water content in the emulsion, and the filter pore size affects oil separation. While the oil flux increases with the filter pore size and pressure drop across the filter, the tilting of a filter from its horizontal position or the stirring of the feed emulsion also increases the separation flux presumably due to reduced pore blockage by the settling water. Based on the knowledge gained through this study, a prototype funnel for the household purification of wet gasoline is constructed. Such a funnel is shown to completely remove water droplets from wet gasoline, which contrasts with the inadequate performance of a commercial funnel sold specifically for this application. The developed filter should have applications in the treatment of wet gasoline and in the separation of organic phases from water in chemical laboratories and plants.