Sustainable Surfactants From CNSL Waste: Oxyacetic Acid and Salt Derivatives for Formulation Applications

Cashew nut shell liquid (CNSL), an abundant agro‐industrial byproduct, was valorized into nonionic and anionic surfactants. Oxyacetic acid derivatives were synthesized with high yields (94%) and assessed for their physicochemical properties. Sodium oxyacetate from crude CNSL exhibited a critical micelle concentration at 25°C (CMC) of 0.0146 wt.%, while the one from pure anacardic acid showed a CMC of 0.0468 wt.%. The hydrophilic lipophilic behavior of surfactants was quantified by determining the change of the phase inversion temperature of a reference system (PIT‐slope method). These results confirmed that the CNSL derivatives are less hydrophilic than those obtained from pure anacardic acid, likely due to the presence of cardanol‐based compounds in CNSL, which contain only a single carboxyl group. Emulsions stabilized with CNSL oxyacetic acid remained stable for over 21 days. In addition, the foaming properties of sodium oxyacetate from CNSL were comparable to those of the benchmark Texapon N70 (sodium laureth sulfate), with 73.2% foam stability after 1200 s and smaller bubble sizes at similar concentrations. These results highlight the potential of crude mixture CNSL‐derived surfactants as cost‐effective, sustainable alternatives to petrochemical surfactants for formulation applications in detergents and personal care products, contributing to waste valorization and circular economy strategies.