DOI: https://doi.org/10.55373/mjchem.v28i2.339

Keywords: Oxidative-extractive desulfurization, deep eutectic solvent, glutaric acid, fuel purification

Abstract

The removal of sulfur compounds from fuel oil is a key challenge in petroleum refining, as hydrodesulfurization (HDS) is ineffective for sterically hindered species such as dibenzothiophene, benzothiophene, and thiophene. This study explores oxidative extractive desulfurization (OEDS) using deep eutectic solvents (DESs) as sustainable alternatives. Three DESs were synthesized from glutaric acid, β-alanine, and polyethylene glycol (PEG). FTIR confirmed successful formation, while toxicity analysis suggested safe application. Experimental and COSMO-RS studies identified β-alanine–PEG as the most effective extractant, outperforming glutaric acid–PEG and glutaric acid–β-alanine–PEG. Response surface methodology (RSM) was employed to optimize thiophene extraction using β-alanine–PEG, considering temperature (25–100 °C), DES-to-oil ratio (0.2–1), and oxidant-to-sulfur ratio (1–15). DES dosage was the dominant factor, with optimal performance at 60 °C, DES-to-oil ratio of 1, and oxidant-to-sulfur ratio of 12, achieving 93.4% extraction efficiency. The solvent retained activity for at least five cycles. These findings demonstrate OEDS with DESs as a promising, energy-efficient, and environmentally friendly alternative to HDS.