In the present study, heterogeneous acid catalysts for fatty acid esterification reactions were synthesized using agro-industrial waste from murumuru kernel shells.

Heteropolyacids (HPA) with Keggin structures, such as H₃PMo₁₂O₄₀ (H₃PMo), have been described as efficient catalysts in trans/esterifications of high-acid feedstocks due to their tolerance to water and free fatty acids contents.

This study aims to synthesize a WO₃/CuFe₂O₄ catalyst through a wet impregnation method and use it as a new magnetic acid catalyst in the transesterification process of waste cooking oil (WCO).