Experimental and computational studies on isolation of cardanol from cashew nut shell liquid using diethanolamine‐based deep eutectic solvent at different molar ratios

Abstract

BACKGROUNDAmine‐based deep eutectic mixtures composed of choline chloride with DEA‐based hydrogen bond donor in various mole ratios like 1:2, 1:3, 1:4, 1:5, 1:6, and 1:7 for isolation of cardanol from cashew nut shell liquid.RESULTSIn this study, green techniques were created to extract cardanol from cashew nut shell liquid (CNSL) by utilizing a deep eutectic solvent based on diethanolamine with various mole ratios (hydrogen bond acceptor: hydrogen bond donor) in 1:2, 1:3,1:4,1:5, 1:6 and 1:7. To enhance cardanol's solubility in DES, promote phase separation, and increase cardanol yield, ethyl acetate (EA) and isobutyl methyl ketone (IBMK) could be utilized as co‐solvents. At temperatures ranging from 293 to 343.15 K and 1 atm, the density of various mole ratios of DES was determined. Additionally, the prepared DES pH behaviour as well as the relationship between pH and temperature. For all investigated DES temperature increases caused a decrease in pH value. By using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), the similar mole ratios of amine‐based DES were studied for their thermal stability in terms of decomposition temperature, mass loss, and melting temperature. The melting temperature and thermal stability were both increased in this case when the HBD increased. The thermal stability of DES, which mostly depends on intermolecular interactions, is greatly influenced by HBD. Finally, at T = 298.15 K and 1 atm, cardanol was extracted from 50 mL of CNSL using different volumes of various mole ratios of DES (100 mL, 75 mL, 50 mL, and 25 mL) together with 25 mL of IBMK and 25 mL of EA. By using FT‐IR and GC–MS spectra, the extracted cardanol was evaluated.CONCLUSIONIt was observed that the yield of cardanol from each prepared mole ratios ratio of 100 mL DES was 96.57%, 95.38%, and 92.87%, respectively. In this study, the sigma potential and sigma profile of chosen HBA and HBD were determined using the conductor‐like screening model for real solvents (COSMO‐RS), and analyze the interactions between the molecules during the extraction process. The findings demonstrated the viability of using the chosen DES as extracting solvents for the polyphenol extraction process.This article is protected by copyright. All rights reserved.