With the aim to improve the features of surfactant solutions in terms of sustainability and renewability we propose the use of hydrogenated natural and sustainable plant-derived cardanol as an additive to commercial surfactants. In the present study we demonstrated that its addition, in amounts as high as 10%, to commercial surfactants of different charge does not significantly affect surfactant properties. Conversely, the presence of hydrogenated cardanol can strongly affect spectrophotometric determination of CMC if preferential interactions with the dyes used take place. This latter evidence may be profitably exploited in surfactant manufacturing by considering that the concurrent presence of a rigid organic molecule such as Orange OT and 10% hydrogenated cardanol decreases the CMC of CTAB up to 65 times.
