الفهرس 
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Abstract
Pure and x mol% Ln3+ modified TiO2 nanomaterials (Ln3+ = Eu3+ or Sm3+ ions, x = 0, 0.007, 0.020, 0.050, 0.070 mol%) synthesized by a sol–gel at pH = 2. Structure and surface properties of the photocatalysts were characterized by XRD, UV-vis/DR, FT-IR, XPS and N2 adsorption–desorption at 77 K measurements. The prepared lanthanide doped TiO2 nanomaterials have anatase phase and exhibit Ti–O–Ln bond. The absorption spectra of the prepared samples reflect the increasing photoresponse of doped samples to visible light over pure TiO2 and commercially available P25. Surface area is remarkably increased due to lanthanide ion-doping. XPS analysis confirms the presence of Eu3+ and Sm3+ ions in the doped samples (Eu3+/TiO2 and Sm3+/TiO2) in addition to the Ti4+ and O. The prepared pure and Ln3+ modified TiO2 nanomaterials, as well as, commercially available P25 were applied for photocatalytic generation photobiogas/hydrogen from acetic acid under N2 atmosphere. The main gaseous products of CH3COOH decomposition using these nanomaterials were CH4 and CO2. Trace amounts of C2H6 and H2 were also detected in the reaction mixture. Moreover, it was observed that the quantities of all identified gases increased with elongation of irradiation time. The most active photocatalysts towards CH4 and H2 generation were Ln3+/TiO2 containing 0.050 and 0.02 mol. % of Sm and Eu, respectively. In addition, these nanomaterials were also applied for photocatalytic degradation of textile dyes from water under atmospheric condition. Remazol red RB 132 (RR) and brilliant blue (BB) were selected as examples of textile dyes which already used for dying in many factors. The results show that the Ln doping brought about remarkable improvement in the adsorption efficiency and photocatalytic activity over pure TiO2. The optimal UV light reactivity of the photocatalysts for dyes decolorization was achieved for 0.02 and 0.05 mol% of Eu3+ and Sm3+ ions, respectively. The results revealed that the Ln3+ modification can improve the effectiveness of the photocatalysts compared to pure and commercially available TiO2 provided that a proper amount of modifying ions is used. Other important parameters which influenced the effectiveness of photobiogas/hydrogen generation and textile wastewater purification in case of Ln3+ modified samples were high surface area and low crystallite size of anatase. Furthermore, the presence of lanthanide oxide on the surface of TiO2 creates a charge imbalance. Therefore, the hydroxide ions would be adsorbed on the surface as we can see from XPS measurements. The hydroxide ions act as hole traps that inhibit electron/ hole pairs recombination as well.