Synthesis study of formation bioavtur-type hydrocarbons from waste cooking oil-derived biodiesel (FAME) through sub-micron bubbles ozonolysis reactor

The fossil fuel crisis has encouraged the development of biofuels as a renewable alternative fuel for the aviation sector. This study examines the ozonolysis method using a sub-micron bubble reactor to convert waste cooking oil-derived biodiesel (fatty acid methyl esters, FAME) into aviation fuel-range compounds. The conversion of WCO-based biodiesel to biofuel was carried out in a sub-micron bubble ozonolysis reactor equipped with an ozone generator and a ceramic disc diffuser, with a dry air flow rate of 0.2 L/min and catalyst loading of 1–3 wt% for 1–3 h of reaction time. The average bubble diameter was 578 nm, confirming the formation of sub-micron bubbles, although not within the nanobubble range (<200 nm). Nevertheless, the bubble size distribution was relatively consistent, with stable size characteristics. Several physicochemical properties, including distillation characteristics (initial and final boiling point), complied with SNI and ASTM standards, although the smoke point and product losses remained below specification. However, the flash point of the bioavtur product was slightly higher than the conventional standard. Compared to bioavtur without ozonolysis, a reduction in unsaturated compounds was observed at 1650 cm⁻ 1 , indicating that ozonolysis breaks C=C double bonds. The proportion of hydrocarbon-like compounds increased to 10.1–10.6% compared with that of WCO-based biodiesel. These findings suggest a partial transformation of methyl esters toward hydrocarbon-like compounds during the sub-micron bubble ozonolysis process, supported by the relatively fast reaction rate (k = 2.7 h⁻ 1 ).