Highly active and stable magnetically recyclable CuFe2O4 as a heterogenous catalyst for efficient conversion of waste frying oil to biodiesel

Abstract For the first time, this work investigates the performance of cuprospinel CuFe2O4 nanoparticles as a heterogeneous catalyst for effective and sustainable biodiesel production via waste frying oil (WFO) transesterification process. The catalyst is successfully synthesized by two methods; co-precipitation (to produce CS1) and combined co-precipitation and hydrothermal (to produce CS2). The cuprospinel catalysts were characterized by TGA, SEM, EDX, HR-TEM, FT-IR, Raman spectroscopy, nitrogen adsorption–desorption and VSM. The hydrothermal treatment increased the catalytic activity of the synthesized CS2 much higher than CS1 which is synthesized by co-precipitation only. The experimental investigations show that the optimum operating conditions are 30 min reaction time, 18:1 methanol to oil molar ratio, 3% wt. of catalyst and 300 rpm reaction speed at 60 °C to produce 90.24% biodiesel yield using CS2. Besides, the kinetic study of the experimental results was in line with the pseudo-first-order and the low activation energy of 37.64 kJ/mole. The thermodynamic parameters suggested that the transesterification is a non-spontaneous endothermic process. The CS2 catalyst was easy recoverable, reusable, and its activity was very stable for 5 times reusing. Therefore, utilizing of CuFe2O4 as a novel heterogeneous catalyst would provide a good manner for biodiesel production.