posted on 2019-12-20, 20:39authored byAzeem Farinmade, Olakunle Francis Ojo, James Trout, Jibao He, Vijay John, Diane A. Blake, Yuri M. Lvov, Donghui Zhang, Duy Nguyen, Arijit Bose
The use of chemical dispersants is a well-established
approach
to oil spill remediation where surfactants in an appropriate solvent
are contacted with the oil to reduce the oil–water interfacial
tension and create small oil droplets capable of being sustained in
the water column. Dispersant formulations typically include organic
solvents, and to minimize environmental impacts of dispersant use
and avoid surfactant wastage it is beneficial to use water-based systems
and target the oil–water interface. The approach here involves
the tubular clay minerals known as halloysite nanotubes (HNTs) that
serve as nanosized reservoir for surfactants. Such particles generate
Pickering emulsions with oil, and the release of surfactant reduces
the interfacial tension to extremely low values allowing small droplets
to be formed that are colloidally stable in the water column. We report
new findings on engineering the surfactant-loaded halloysite nanotubes
to be stimuli responsive such that the release of surfactant is triggered
by contact with oil. This is achieved by forming a thin coating of
wax to stopper the nanotubes to prevent the premature release of surfactant.
Surfactant release only occurs when the wax dissolves upon contact
with oil. The system thus represents an environmentally benign approach
where the wax coated HNTs are dispersed in an aqueous solvent and
delivered to an oil spill whereupon they release surfactant to the
oil–water interface upon contact with oil.