Solubilization of oleophilic compounds in gelatin solutions containing surfactant

Solubilization of benzene (C6H6) and Sudan ‘Yellow’ (SY) in solutions of gelatin modified with ionic surfactants sodium dodecylsulfate (SDS) or cetylpyridinium chloride (CPC) has been investigated by refractometry and photocolorimetry. Biopolymer gelatin modified with low-molecular-mass surfactant can be regarded as a new surfactant whose properties are defined by the degree of its binding with gelatin. The mixtures of gelatin with SDS or CPC in a specific range of component ratios were found to exhibit synergism in solubilization of oleophilic compounds in the temperature range 295–318 K. The solubilizing capacity and volume of hydrophobic areas in the gelatin–surfactant complex were shown to attain their largest values at the isoelectric point. The thermodynamic parameters of solubilization (ΔG, ΔH, ΔS) were determined. The process is accompanied by a slightly negative change in the Gibbs energy and favored largely by an increase in entropy.