Abstract: Many industrial sectors generate different forms of solid waste that threaten the environment. The slag of the Basic oxygen furnace, which is considered in the steel industry as a by-product, is one of these solid wastes. The main aim of this study is Using this solid waste to be included in applications related to chemical engineering. The process of producing of the biodiesel would be the main use of this waste in this study. As it is known that the energy is essential for survival of human being, most of the sources of energy used worldwide are non-renewable sources and are produced as products from oil, coal, petroleum and natural gas, also their use impact on the environment is negative. As these resources will soon run out, the sources of renewable energy should take place as replacement. Mainly the aim of this paper is biodiesel production, which is a renewable, clean, diesel with high cetane numbers, Waste cooking oil was used as the feedstock and the basic oxygen furnace slag as the catalyst beside using the methanol in a transesterification reaction. With respect to the data that come out from the experimental work, the yield of biodiesel produced could reach 90.16% if the optimum parameters for this reaction is used which states that the methanol to oil ratio should be 20:1, while the catalyst loading should be 5%, also the temperature of the reaction should be 57oC, in addition to a 750rpm stirring rate, and the reaction time to be one hour.

Keywords: Biodiesel; Solid waste; Slag; Renewable energy.

| DOI: 10.17148/IARJSET.2025.12619