Photocatalytic Transesterification of Palm Oil Using TiO2-K: Synthesis, Characterization, and Kinetic Modeling

Potassium-modified titanium dioxide (TiO2–K) was synthesized and evaluated as a heterogeneous photocatalyst for fatty acid methyl ester (FAME) production from palm oil under UV irradiation. The catalyst was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS). Potassium modification preserved the TiO2 crystalline framework while producing marked changes in morphology and a significant decrease in surface area. Photocatalytic transesterification was optimized using a central composite design, evaluating the effects of catalyst loading and the methanol-to-oil molar ratio on FAME yield. The quadratic response surface model adequately described the experimental data and predicted an optimum FAME yield of approximately 98.96% under the evaluated conditions. Kinetic analysis showed that the reaction profile was well described by an apparent pseudo-first-order model, consistent with the use of excess methanol, while the Avrami–Weibull equation provided a flexible empirical representation of the conversion profile. Control experiments confirmed that irradiation and catalyst presence were required for measurable FAME formation. Overall, this study demonstrates the potential of TiO2–K as a photocatalyst for light-assisted biodiesel production and provides an initial framework for process optimization and kinetic interpretation.