Muhammad Fareez Naufal FadilahBalqis Adlina OmarFarah Wahida HarunSalina Mat RadziNurul Jannah Abd Rahman2025-06-252025-06-2520252025-6-25Muhammad Fareez Naufal Fadilah, Balqis Adlina Omar ,Farah Wahida Harun, Salina Mat Radzi,and Nurul Jannah Abd Rahman. (2025). Synthesis and characterization of magnetized Fe 3 O 4 -ZrO 2 catalysts for methyl ester production from waste cooking oil. Malays. J. Anal. Sci, 29, 1–12. https://mjas.analis.com.my/mjas/v29_n2/pdf/Fadilah_29_2_1311.pdf1394-25062521-16https://oarep.usim.edu.my/handle/123456789/27071https://www.scopus.com/pages/publications/105005723058Indexed by Scopus (Tier 2)Biodiesel is an efficient, clean, and renewable alternative to petroleum-based fuels. Biodiesel production typically requires heterogeneous catalysts. However, the usage of traditional heterogeneous catalysts faces challenges like difficult recovery and catalyst loss. To address these challenges, this study aims to synthesize and characterize magnetized Fe3O4-ZrO2 catalysts for direct transesterification of waste cooking oil into biodiesel. Fe3O4 was first synthesized via co-precipitation of FeSO4·7H2O and FeCl3·6H2O, resulting in black precipitate. ZrO2 was then impregnated with 10-30 wt.% Fe3O4 using the incipient wetness impregnation method. The catalysts were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller analysis (BET) to assess thermal stability, functional groups, morphology, surface area, and porosity. The catalysts were tested for methyl ester production using 12:1 methanol to waste cooking oil ratio and 5 wt.% catalyst loading at 60°C for 5 hours. The 20Fe-Zr catalyst showed superior performance (13.13%) compared to 10Fe-Zr and 30Fe-Zr catalysts. The enhanced catalytic activity of the 20Fe-Zr catalyst is attributed to its mesopore connectivity, high pore volume, and large surface area. Additionally, its magnetic properties enable easy catalyst separation and demonstrate potential for reuse, making the process more cost-effective and environmentally friendly.en-USmethyl estermagnetize heterogeneous catalystwaste cooking oiltransesterificationtext::journal::journal article112292