ORIGINAL ARTICLE Chemistry Africa https://doi.org/10.1007/s42250-024-00956-9 in fuels, is an undesirable component that causes equip- ment corrosion and poisons secondary refning catalysts [4]. Therefore, the demand for low-sulfur transportation fuel is the most complex challenge in the refnery industry [5]. The compounds and nature of sulfur content change with the boiling point of petroleum derivatives. Higher boiling point fractions have the most refractory sulfur compounds [6]. The chemical structure of these compounds has a vital role in resisting desulfurization. Aliphatic structures of sulfur compounds like thiols and sulfdes are easier to remove than aromatic sulfur structures, i.e., thiophenes [7]. A complex combination of hydrocarbons generated by treating a petro- leum fraction with hydrogen in the presence of a catalyst is known as hydrotreated light petroleum distillate (LD). It is made up of hydrocarbons with carbon numbers primarily in the range of C9 through C16 and boiling points of around 150 to 290 °C. Many techniques are used for the desulfur- ization of liquid fuels. The most efcient technology for removing thiols, sulfdes, and disulfdes is hydrodesulfur- ization (HDS) [8, 9]. However, this technology is limited to treating refractory sulfur compounds such as dibenzothio- phenes (DBTs) and benzothiophenes (BTs) [10]. In addi- tion, this process requires severe conditions of temperature 1 Introduction Liquid fossil fuels contain high levels of organic sulfur compounds such as sulfdes, thiols, and thiophane, which are converted to SO x and NO x during combustion resulting in dangerous efects on health and the environment and also may leading causes of catalyst poisoning in refnery pro- cesses [1, 2]. The petroleum refning industry has progressed to the generation of fuel that satisfes the Euro-5 standard, which mandates a sulfur concentration of no more than 10 ppm in gasoline and light distillate fractions [3]. The need to reduce total sulfur concentration in refnery products stems from the widespread use of various types of hydrocarbon fuels in transportation and power generation, which pollutes the atmosphere with sulfur compound combustion prod- ucts. Furthermore, sulfur, which is found in various forms  Farooq Al-Sheikh Farooq.a.mehdi@uotechnology.edu.iq 1 Southern Oil Company, Ministry of Oil, Baghdad, Iraq 2 Chemical Engineering Department, University of Technology-Iraq, Baghdad, Iraq Abstract In this study, the combined methods using the oxidant and surfactant were utilized in reducing the sulfur content of the actual light distillate. The parameters in the oxidation of sulfur compounds were optimized statistically according to the response surface method (RSM) based on central composite design (CCD). Surfactants separated the oxidized sulfur components at optimum conditions. Basra light distillate was taken as a raw material for oxidation by hydrogen perox- ide (H 2 O 2 ) as an oxidant and acetic acid as a catalyst at a 2:1 ratio. The optimum conditions for oxidation and suitable surfactant type were studied. A remarkable 42.88% extent of oxidation desulfurization at optimum conditions with an oxidant percent of 19.99 wt% and a temperature of 48.6 °C at 87.8 min was achieved. The nonionic surfactant Tween 80 had higher desulfurization activity and reduced sulfur content to 68.6%. Cyclic ring sulfur compounds’ desulfuriza- tion rate increased after treatment with a surfactant. In contrast, oxidation desulfurization efectively removes non-cyclic sulfur compounds. The light distillate quality was studied by GC, and IREX tests after desulfurization steps were found less afected by the treatment. Keywords Light distillate · Desulfurization · Oxidation · Response surface method · Surfactant Received: 9 January 2024 / Accepted: 11 March 2024 © The Tunisian Chemical Society and Springer Nature Switzerland AG 2024 Desulfurization of Light Distillate by Catalytic Oxidation Integrated with Emulsifcation Wallaa A. Noori 2  · Ahmed A. Hantosh 1  · Farooq Al-Sheikh 2  · Adnan A. Abdul Razak 2  · Zaidoon M. Shakour 2 1 3