الفهرس 
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Abstract
Immobilization of Aspergillus niger lipase on nanoparticles has a significant effect on its catalytic activity. In this study, Aspergillus niger lipase was immobilized on titanium dioxide (TiO2) nanoparticles with microspheres, nanotubes, and Nano sheets morphologies. The hydrothermal method was used to prepare all TiO2 samples. Through hydrophobic interaction, lipase-TiO2 nanocomposites were prepared via physical adsorption. FTIR, XRD, SEM, and HRTEM were used to characterize the prepared composites. At 40 ºC for 90 minutes, the catalytic activity of free and immobilized lipase was determined using sunflower oil in the presence of methanol to produce biodiesel. In comparison to lipase immobilized on TiO2 nanotubes and Nano sheets, the sample immobilized on TiO2 microspheres demonstrated the highest activity. To optimize the lipase-microsphere ratio, Aspergillus niger lipase was immobilized on TiO2 microspheres with varying W: W ratios; lipase (S: L) ratios were 1:1, 1:0.75, 1:0.5, and 1:0.25. The hydrolytic activity was found to be in the following order: 1:0.25 > 1:0.5 > 1:75 > 1:1. The immobilization yield activities of microspheres: lipase (S: L) ratios of 1:1, 1:0.75, 1:0.5, and 1:0.25 were found to be 113 %, 123 %, 125 %, and 130 %, respectively.
Keyword: TiO2 microspheres; TiO2 nanotubes; Titanate nanotubes; TiO2 nanosheets; FAME, lipase, sunflower oil.