Synthesis and Characterization of Calcium Oxide Impregnated on Silica from Duck Egg Shells and Rice Husks as Heterogeneous Catalysts for Biodiesel Synthesis. Baghdad Sci.J [Internet]. 2023 Oct. 28 [cited 2024 May 12];20(5(Suppl.). Available from: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/7895