Surface and Solubilisation Activities of 1-Amino-2-alkyloxynaphthalene-4-sodium Sulphonates

Abstract

A series of 1-amino-2-alkyloxynaphthalene-4-sodium sulphonates was prepared by using octyl bromide, dodecyl bromide and cetyl bromide, respectively, with the sodium salt of 1-amino-2-naphthol-4-sulphonic acid in sodium ethoxide solution. The surface tensions, interfacial tensions and emulsifying efficiencies of the surfactants thus synthesised were studied in relation to the length of their hydrophobic chains. The critical micelle concentration (CMC), effectiveness (π CMC ), maximum surface excess (Γ max ) and minimum surface area (A min ) of the synthesised surfactants were also investigated. The effect of the chain lengths of these surfactants on the solubilisation rate (δS/δt) of paraffin oil in their micellar solutions was determined. The results revealed that different factors relating to surfactant structure have a considerable influence on solubilisation, particularly the hydrophilic/lipophilic balance (hlb) and the minimum area occupied by a molecule.