Synthesis of Fe-TiO2/Al2O3 nanocatalyst for photocatalytic reduction of nitrate ion from aqueous solution under visible light and UV irradiation

In this study, different nanocatalysts of Fe-TiO2, Al2O3/TiO2, Fe-TiO2/Al2O3 were synthesized by sol-gel technology. In order to study the performance of synthesized catalysts, the photocatalytic degradation of nitrate ion under visible light and UV was investigated. To optimize the content of Fe-TiO2/Al2O3 in nanocatalyst powder and to obtain the optimum conditions for nitrate ion reduction experiment, design-expert software was implemented, in which the RSM method with the central composite design was used. The parameters of doping amount of iron ion to titanium ion (wt.% Fe3+/Ti4+), the amount of alumina relative to TiO2 (TiO2/Al2O3), and the formic acid ratio (as the electron donor or hole scavenger) to the nitrate ion were simultaneously examined at three levels. The concentration of catalyst and initial concentration of nitrate ion were 1 g/L and 100 ppM NO3--N, respectively. The highest photocatalytic activity for powdered nanocatalyst with content of 6.23 wt.% Fe-TiO2/(1:0.13) wt.ratio Al2O3, with the ratio of formic acid to nitrate ion 5.14 M/M under visible light, was obtained equal to 16.97% in 360 min. All experiments were performed at ambient temperature of (25 +/- 0.5) degrees C. The optimum nanocatalysts obtained in powder form were studied by UV irradiation to reduce nitrate ion and was obtained equal to 87% under a period of 120 min. In the third step, the optimum contents of synthesized nanocatalyst in powder form were deposited over a glass substrate in the form of a thin-film three-layer. The maximum photocatalytic reduction efficiency of nitrate ion by this nanocatalyst was obtained equal to 13.4% under irradiation visible light in 360 min.

Automated summary

Different nanocatalysts were synthesized using sol-gel technology and their performance in photocatalytic degradation of nitrate ion under visible light and UV was investigated. Design-expert software was used to optimize the experimental conditions and obtain the highest photocatalytic activity. The synthesized nanocatalysts were further studied by UV irradiation and deposition on a glass substrate.