Available online at www.sciencedirect.com Chemical Engineering Research and Design journal homepage: www.elsevier.com/locate/cherd Choline chloride-based deep eutectic solvents for ultrasonic-assisted oxidative desulfurization of actual heavy crude oil Mohammed Y. Mohammed, Alaa M. Ali, Talib M. Albayati ⁎ Department of Chemical Engineering, University of Technology-Iraq, 52 Alsinaa St., PO Box 35010, Baghdad, Iraq a r t i c l e info Article history: Received 7 February 2022 Received in revised form 18 March 2022 Accepted 26 March 2022 Available online 29 March 2022 Keywords: Extractive desulfurization Real heavy crude oil Ionic liquids Environmental treatment Separation process abstract Deep eutectic solvents (DESs) are acquiring increasing interest as ionic liquid analogues because of their wide application, low-cost characteristics and environmentally friendly. In this study, choline chloride-based (ChCl) as a type of DESs were synthesized using polyethylene glycol (PEG), and applied to reduce sulfur content of actual heavy crude oil with sulfur content 37900 ppm (3.79 wt%). The synthesized DESs were characterized using Fourier-transform infrared spectroscopy (FTIR), as well as viscosity and density mea- surements. The DESs were evaluated for extractive ultrasound-assisted oxidative de- sulfurization (EUAODS), with 30 wt% H 2 O 2 as the oxidant and formic acid as the catalyst. This study looked at the effects of oxidative desulfurization (ODS) and single ODS under ultrasonic treatment. Different systems for DESs were tested to fnd the desulfurization selectivity of the better reaction system; and it was found that extractive desulfurization (EDS) removed 24.57% of the sulfur, followed by extractive and ultrasonic-assisted de- sulfurization (EUADS) at 26.78%, then ODS at 37.28%, with ultrasonic-assisted oxidative desulfurization (EUAODS) providing the best result of 62%. According to the comparison trials, combining DESs with ultrasonic treatment improved processing. This study con- tributes to the body of information on the use of ultrasonic treatment in heavy crude oil desulfurization. © 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved. 1. Introduction In the past few years, the clean fuels production has become a key research topic around the world. Crude oil is one of the primary sources of energy. Environmental pollution pro- blems caused by exhaust emissions have received increasing attention worldwide with the development of society. To prevent air pollution from vehicle emissions, the main trend has been to decrease the sulfur content from the source (Yusra et al., 2020; Kadhum et al., 2021; Kalash and Albayati, 2021; Khadim et al., 2022). As a result, rigorous sulfur content limitations for fuels have been set, with levels required to be below 10 ppm in most countries (Al-nayili et al., 2022; Abd Al- Khodor and Albayati, 2020; De Luna et al., 2018). Presently, the classic technology of hydrodesulfurization (HDS) in in- tegration with carbon rejection technologies (e.g., fuid cat- alytic cracking [FCC] and coking), are the predominant methods utilized industrially for the desulfurization of heavy oil (Tahir et al., 2021; Andevary et al., 2020; Saleh et al., 2020). Nevertheless, heavy crude oil makes it diffcult to achieve ultra-low sulfur levels, and the carbon footprints are sub- stantial because of the negative impact on refractory sul- fdes, such as; dibenzothiophene (DBT) and its derivatives (Nozarie, 2019; Das et al., 2020; Díaz de León et al., 2019). Moreover, current DES processes consume hydrogen in huge amounts and operate at harsh conditions, which result in signifcant capital expenditures (Astle et al., 2019; Shafq et al., 2020). Thus, the present desulfurization technology https://doi.org/10.1016/j.cherd.2022.03.047 0263-8762/© 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved. ]] ]] ]]]]]] ⁎ Corresponding author. E-mail address: Talib.M.Naieff@uotechnology.edu.iq (T.M. Albayati). Chemical Engineering Research and Design 182 (2022) 659–666