Attachment of a Hydrophobically Modified Biopolymer
at the Oil–Water Interface in the Treatment of Oil Spills
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Abstract
The stability of crude oil droplets
formed by adding chemical dispersants can be considerably enhanced
by the use of the biopolymer, hydrophobically modified chitosan. Turbidimetric
analyses show that emulsions of crude oil in saline water prepared
using a combination of the biopolymer and the well-studied chemical
dispersant (Corexit 9500A) remain stable for extended periods in comparison
to emulsions stabilized by the dispersant alone. We hypothesize that
the hydrophobic residues from the polymer preferentially anchor in
the oil droplets, thereby forming a layer of the polymer around the
droplets. The enhanced stability of the droplets is due to the polymer
layer providing an increase in electrostatic and steric repulsions
and thereby a large barrier to droplet coalescence. Our results show
that the addition of hydrophobically modified chitosan following the
application of chemical dispersant to an oil spill can potentially
reduce the use of chemical dispersants. Increasing the molecular weight
of the biopolymer changes the rheological properties of the oil-in-water
emulsion to that of a weak gel. The ability of the biopolymer to tether
the oil droplets in a gel-like matrix has potential applications in
the immobilization of surface oil spills for enhanced removal