Energy-efficient separation of cardanol, cardol, and 2-methyl cardol from biowaste using solvent extraction

Cardanol is yielded from cashew nutshells, known as a biowaste of cashew nut processing, and is used in the production of epoxy resin, polyurethane, surfactants, and various polymer materials. This study proposes solvent extraction as an energy-efficient separation technique for cardanol, cardol, and 2-methyl cardol from cashew nutshell liquid as an alternative to energy-intensive thin-film distillation. To develop the proposed process, the liquid-liquid equilibrium (LLE) was experimentally measured and supplemented by quantum chemical molecular dynamics simulations, enabling the formulation of the thermodynamic model necessary for the extraction process design. The molecular dynamic simulation results provided radial distribution functions (RDFs), which described the molecular interactions between pairs of molecules, clarifying the selective extraction of cardanol with hexane. For the development of the separation process, a sequential solvent introduction of pure and mixed solvents was proposed, and the separation products were examined using gas chromatography/mass spectrometry. Finally, an extractor design for cardanol recovery from an aqueous ammonia solution using hexane is presented.