Extraction of high-quality cashew nutshell liquid using carbon dioxide-expanded hexane

Cashew nutshell liquid (CNSL) is a by–product from cashew processing industries containing four naturally occurring phenolic compounds. This study investigated an extraction approach using CO2–expanded hexane. The central composite design (CCD) was employed in experimental design to investigate the effects and interaction of CO 2 mole fractions and extraction temperature on the CNSL yield and quality (Colour) from Steamed CNSL. The dissolution power of the CO2–expanded hexane was assessed by determining the solubility of CNSL during the initial stages of extraction at different extraction conditions. Findings indicated that higher CO2 mole fractions reduced CNSL solubility, while higher temperatures enhanced it. The results also showed that higher temperatures and moderate CO2 mole fractions increased yield but led to a darker product. In contrast, higher CO2 mole fractions and lower temperatures gave a light– yellow CNSL without signs of polymerization or degradation, indicating improved quality. Optimal extraction conditions were found at a CO2 mole fraction of 0.825 and a temperature of 30 °C, resulting in a yield of 33±1.67% and a reduction of the darker colour by 55±9.54%. These findings show that CO 2–expanded hexane is a promising technique for extracting high-quality and yield CNSL as compared to the Soxhlet method.