Using titanium dioxide nanoparticle-deposited whey protein isolate amyloid fibrils to photocatalyze the degradation of methylene blue

Titanium dioxide nanoparticles (TiO2NPs) have been widely used in photocatalytic reactions, but their tendency to aggregate reduces their photocatalytic activity. Recent studies have suggested that whey protein isolate amyloid fibrils (WPI-AFs) serve as promising catalyst carriers due to their structural stability and high surface area. This study is aimed at applying WPI-AFs to improve the dispersibility and photocatalytic activity of TiO2NPs. One-dimensional composites, TiO2NP-deposited WPI-AFs (TiO2NP/WPI-AFs), were synthesized via the hydrothermal method. The concentration of TiO2NPs on WPI-AFs’ surface was determined through inductively coupled plasma optical emission spectroscopy (ICP-OES). TiO2NP/WPI-AFs were characterized via transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In addition, the photocatalytic activities of bare TiO2NPs and TiO2NP/WPI-AFs were assessed by monitoring the degradation of methylene blue (MB) using UV-vis spectrophotometry. TiO2NP/WPI-AFs showed improved dispersibility and narrow band gap compared to TiO2NPs. The photocatalytic activity of TiO2NP/WPI-AFs was superior to that of bare TiO2NPs. The mechanism of TiO2NP/WPI-AFs photocatalyzed-MB degradation was examined by fitting the kinetic data with Langmuir–Hinshelwood and modified Elovich models. The results of activation parameters showed that TiO2NP/WPI-AFs lowers the activation energy, and the photocatalytic MB degradation is an endothermic and energetically unfavorable reaction.