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.