Sulfur compounds in fuel is converted to SOx when burnt, which is detrimental for the environment. That is why the sulfur compounds are removed from crude oil before it gets to market. The conventional way of desulfurization is through hydrodesulfurization (HDS), which is a high pressure, high temperature process. This makes HDS expensive as well. Again, for waste valorization and decreasing reliance on fossil fuel hydrothermal liquefaction (HTL) has become very popular in recent years. However, HTL too is a high temperature, high pressure process. So, researchers have been looking for other methods for desulfurization and extractive desulfurization is one of them. But the organic solvents often used for the extractive desulfurization process are often volatile and harmful for the environment. However, a new class of solvents, called hydrophobic deep eutectic solvents (HDES) can be used for the process. In this study, the effect of alkyl chain length and accompanying anion in the hydrogen bond acceptors (HBAs) on the extraction of benzothiophene, a model sulfur compound found in biocrude, from n-hexadecane, model oil compound was assessed. The HBAs used were tetraethylammonium chloride/bromide, tetrabutylammonium chloride/bromide, tetrahexylammonium bromide and tetraoctylammonium chloride/bromide. Octanol-1 was the hydrogen bond donor (HBD). First, conductor like screening model for real solvents (COSMO-RS) was used to get the suitable combination of HBA and HBD for the process. Then the extractive desulfurization was evaluated experimentally. The experimental determination of benzothiophene in n-hexadecane was carried out using ultra-violet visible spectroscopy (UV-VIS). Furthermore, the research explored the HBA to HBD ratio, initial loading, extraction temperature and time.
