Surfactant-coated carbon nanotubes as pseudophases in liquid–liquid extraction

The advantages of surfactant-coated carbon nanotubes (CNTs) as coadjutants in liquid–liquid extraction are systematically considered. The effect of the CNT state (dispersed or suspended in an aqueous medium) is characterized by the single-component solid–liquid isotherms exemplified for benzene. Adsorption isotherms are obtained by means of a headspace-GC–MS method, the recommended instrumental combination when very volatile compounds are involved. Adsorption studies are completed using toluene and n-undecane as model analytes of aromatic and linear hydrocarbons, respectively. The potential of using dispersed carbon nanotubes to improve liquid–liquid extraction is finally evaluated. The liquid–liquid distribution of the two model analytes between an organic phase (n-heptane) and the aqueous dispersion of CNTs is studied via batch extraction and subsequent analysis of the organic phase by GC–MS. A prospective application of this methodology is also given.