Synergistics dispersion force:hydrogen bonding interactions between choline-based deep eutectic solvents with naphthenic acid for deacidification process

Naphthenic acids (NAs) are organic compounds found in heavy crude oil that cause various problems in industrial processes. They contribute to corrosion, emulsion formation, reduced oil quality, and refinery corrosion. Ionic liquids (ILs) are a new type of solvent currently explored for NA extraction that offers advantages such as high selectivity, chemical stability, non-volatility, and wide liquid range, making them a promising alternative, but the high cost and toxicity of ILs limit their application in this field. In this study, two deep eutectic solvents (DES) are synthesized to become an alternative to overcome the drawbacks of ILs as extractants in NA extraction by using Choline Chloride (ChCl) as hydrogen bond acceptor (HBA) while Ethylene Glycol (EG) and Phenol as hydrogen bond donor (HBD). NA and dodecane are used to prepare the model oil. The DESs structures are confirmed by Fourier transform infrared (FTIR) spectroscopy. Their thermal properties are evaluated using TGA and DSC. A computational study using COSMO-RS is done to study the molecular properties of DESs and the interaction of DES with NA to understand the result. The results showed that ChCl:Phenol which has an aromatic HBD with one hydroxyl group perform better than ChCl:EG which has an aliphatic HBD with two hydroxyl groups. Thus, this shows that the formation of dispersion force together with hydrogen bonding between DES and NA gives higher influence in extracting NA as compared to hydrogen bonding only. In optimizing the extraction process, the result shows that the extraction efficiency increases with DES to model oil weight ratio involved, where 0.07 is found to be the optimized ratio. For reaction temperature and reaction time, the extraction efficiency increases with temperature and time, which 80 & ring;C and 100 min were indicated as the optimized temperature and optimized time, respectively. In conclusion, the findings prove that DES has high potential to be an extractant for NA removal.