Photocatalytic activity of TiO2, ZnO and Nb2O5 applied to degradation of textile wastewater

Abstract In this work, photocatalysis was employed in the treatment of textile effluent from industrial laundry jeans using the catalysts TiO 2 P25 (commercial), TiO 2 , ZnO and Nb 2 O 5 , under artificial UV irradiation. The parameters investigated were: pH of the solution and catalyst concentration. The photocatalytic activity was evaluated by means of kinetic efficiency (rate constant and half life time), thermodynamic (absorbance reduction at 228, 254, 284, 310, 350, 500 and 660 nm), COD reduction, mineralization in terms of the formation of inorganic ions (NH 4 + , NO 3 − , NO 2 − , SO 4 2− and Cl − ) and toxicity reduction (bioassays using Artemia salina ). The photocatalytic degradation of textile effluent at pH 3.0 and catalyst concentration of 0.250 g L −1 showed the best results, being found 95.91%; 87.35%; 86.95% and 59.18% of absorbance reduction at 660 nm (λ max ) after 300 min of artificial irradiation with TiO 2 P25, Nb 2 O 5 , TiO 2 and ZnO, respectively. TiO 2 and Nb 2 O 5 were responsible for the reduction of approximately 70 and 66% of COD and the photocatalytic activity of TiO 2 was very close to TiO 2 P25. In this sense, Nb 2 O 5 becomes a promising alternative to replace the commercial TiO 2 P25. Bioassays with Artemia salina confirmed the efficacy of the treatment, indicating that after photodegradation there was an expressive decrease in effluent toxicity for up to 3 times.