Targeted and Stimulus-Responsive Delivery of Surfactant to the Oil–Water Interface for Applications in Oil Spill Remediation

Abstract

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.

Halloysite nanotubes filled with salicylic acid and sodium diclofenac: effects of vacuum pumping on loading and release properties

“…Accordingly, the vacuum pumping allows the overall pressure to approach the vapor pressure of the solvent, which evaporates faster, thus leaving empty space to be filled by the guest molecules that are forced to enter and gather inside [66]. Literature reports several studies on the loading of halloysite from organic solvents by using the vacuum assisted procedure [43,67,68]. Nevertheless, the physico-chemical insights of this mechanism have not been studied.…”

Sepiolite-Hydrogels: Synthesis by Ultrasound Irradiation and Their Use for the Preparation of Functional Clay-Based Nanoarchitectured Materials

“…S BET (m 2 g −1 ) S EXT (m 2 g −1 ) V micro (cm 3 g −1 ) V meso (cm 3 g −1 ) 2019b; Lo Dico et al, 2019;Lisuzzo et al, 2020a;Farinmade et al, 2020;Saleh et al, 2020;Stavitskaya et al, 2020). Moreover, this clay does not show toxic effects and it is biocompatible (Fakhrullin and Lvov, 2016;Rozhina et al, 2020;Rozhina et al, 2021).…”

A Decade of GoMRI Dispersant Science: Lessons Learned and Recommendations for the Future

“…Other interesting new concepts in dispersant science include the formulation of dispersants from food grade emulsifiers such as Tween and lecithin, which have been found to be more effective at stabilizing emulsion droplets than Corexit (Athas et al, 2014;Riehm et al, 2015) and the use of engineered particles at the oil-water interface (Omarova et al, 2018). Synergistic aspects of both particles and surfactants have been reported in the design of novel tubular clays (halloysite) containing surfactants within their tubes (Farinmade et al, 2020). Here, the clays act to stabilize the oil-water interface and release surfactant that reduces interfacial tension and decreases droplet size.…”