Fig. 6From: Production of biodiesel from waste cooking oil using mesoporous MgO-SnO2 nanocompositea XPS spectrum of MgO-SnO2 nanocomposite and XPS spectra of b Mg 1s core level, c O 1s core level, and d Sn 3d core level for MgO-SnO2 nanocompositeBack to article page