Impact of the Hydrophobicity of the Particles on the Formation and Behavior of Oil Particle Aggregates (OPA)

Oil droplets in marine environment interact with particles to form oil particle aggregates (OPA). As it was argued that the hydrophobicity of particles impacts the formation of OPA and subsequently the entrapment of oil and the transport of OPA, this study altered the hydrophobicity of kaolinite through the addition of chitosan and the contact angle was increased from 28.8° to 57.3°. Modified kaolinite was mixed with 500 mg/L crude oil in 200 rpm for 3 hours, then bottom layer was separated and extracted. Observations of the settled OPA microscale structure and calculations of oil trapping efficiency (OTE) were accomplished. Results indicated that with higher hydrophobicity of kaolinite, oil droplets were maintained in larger sizes in OPAs. This could increase the buoyancy of formed OPAs, thus decrease the amount of settled OPAs.