The blowout of the Deepwater Horizon drilling rig resulted in discharge of 4.9 million barrels of light crude oil into the Gulf of Mexico. The primary cleanup strategy employed was emulsification of the oil using the surfactant Corexit®. About 1.84 million gallons of the surfactant was dispersed in the affected regions of the gulf. Later it was shown that Corexit® causes the emulsified oil to sink decreasing its bacterial decomposition. We focused on enhancing oil bioremediation using clay nanotubes for the emulsification.<br/> An oil emulsification with naturally occurring halloysite nanotubes enhances bacterial decomposition by the hydrocarbon degrading bacteria <i>Alcanivorax borkumensis.</i> Halloysite is an allotropic form of kaolin rolled in a hollow tubular structure with a lumen diameter of ca. 12 nm and length of 0.5-2 micron. We have demonstrated that the addition of 0.5 - 1 wt. % of halloysite to a mixture of water and model oil (naphthalene 10 %, decane 40 %, hexane 50 % by wt.) results in the formation of stable emulsions known as Pickering emulsion with diameters ranging 5-50 microns. Dry halloysite was added to a mixture of oil and water (1:3), sonicated and vortexed for 1-3 minutes. The droplet size distribution and stability studies were investigated by microscopy followed by the image analysis of digital photographs. Clay nanotubes form a network on the droplet interface, and optimization of the tube hydrophobicity through silanization gave emulsions stable in model sea water. The formation of a bacterial biofilm on the oil-water interface was observed in case of halloysite emulsified oil. We believe that rougher surface of the droplets facilitates adhesion of the bacterial cells resulting in enhanced bacterial decomposition of oil.

Oil spill remediation through halloysite Pickering emulsification with enhanced bacterial decomposition

251st National Meeting (2016)

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