Transition metal doped TiO 2 mediated photocatalytic degradation of anti-inflammatory drug under solar irradiations

Abstract Bismuth (Bi) and Nickel (Ni) Doped Titanium Dioxide (TiO2) nanoparticles were synthesized by sol–gel method and the prepared nanoparticles were characterized by X-Ray Diffraction, Scanning Electron Microscope, UV–vis reflectance spectroscopy and Brunauer–Emmett–Teller (BET) analysis. The concentration of dopant in synthesized catalysts was varied from 0.25 to 1.0 wt%. Maximum BET surface area of 47.8 and 45.7 m2/g was observed with 0.25 wt% Bi–TiO2 and 0.5 wt% Ni–TiO2, respectively. EDX analysis has established the presence of 0.21% Bi ions and 0.36% Ni ions in 0.25 wt% Bi doped TiO2 and 0.5 wt% Ni doped TiO2, respectively. Band gap of Bi–TiO2 (0.25 wt%) and Ni–TiO2 (0.5 wt%) was obtained to be 2.99 eV, which is found to be minimum among the various synthesized catalysts. The photocatalytic activity of synthesized catalysts were tested and compared with Degussa TiO2 for degradation of Ibuprofen (IBP) as a model compound. Bi–TiO2 nanoparticles revealed higher photocatalytic activity when compared to Ni–TiO2 or Degussa TiO2 under solar irradiation, which may be attributed to increase in specific surface area, and decrease in the crystallite size. Maximum of 89% degradation was achieved with 0.25% Bi–TiO2 photocatalyst under 6 h of illuminations with a solar light, whereas, 78% degradation has been achieved under similar experimental condition with Ni doped TiO2. The kinetics of the degradation of IBP has been explained in terms of the Langmuir–Hinshelwood model and was found to follow first order kinetics with k value of 0.0064 and 0.0046 min−1 with Bi and Ni doped TiO2, respectively.