UV–VIS photocatalytic degradation of nitrobenzene from water using heavy metal doped titania

Abstract

The photocatalytic degradation of nitrobenzene (NB) under UV–VIS irradiation with un-doped TiO2 and various heavy metals doped TiO2 powders were studied for aerated solutions. The dopant type (Fe, Co, Ni) and its concentration (0.5–5 wt.% TiO2) influence on pollutant degradation efficiency were investigated. The photocatalyst with lowest Fe content (0.5 wt.%) showed a considerable better behaviour in respect to pollutant degradation than catalyst with higher Fe content and Co and Ni doped titania catalysts. The experiments were carried out for solutions with (0.37–8.45) x 10-4 M NB initial content, using 50–250 mg/L catalyst dose, at various pHs (4–10) and irradiation time between 30 and 240 min. The kinetics of NB degradation and organic nitrogen mineralization was assessed and pseudofirst order rate constants were calculated. For optimum working conditions (0.5 wt.% Fe doped-TiO2 loading of 250 mg/L, 2.52 x 10-4 M pollutant initial concentration, pH = 7 and 240 min irradiation time) NB removal and organic nitrogen mineralization efficiencies were 99% and 85%, respectively. It was also demonstrated that degradation process occurs on catalyst surface, so experimental results are in accordance with Langmuir–Hinshalwood model.