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

In this work, photocatalysis was employed in the treatment of textile effluent from industrial laundry jeans using the catalysts TiO2 P25 (commercial), TiO2, ZnO and Nb2O5, 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 (NH4+, NO3-, NO2-, SO42- 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 gL(-1) showed the best results, being found 95.91%; 87.35%; 86.95% and 59.18% of absorbance reduction at 660 nm (lambda(max)) after 300 min of artificial irradiation with TiO2 P25, Nb2O5, TiO2 and ZnO, respectively. TiO2 and Nb2O5 were responsible for the reduction of approximately 70 and 66% of COD and the photocatalytic activity of TiO2 was very close to TiO2 P25. In this sense, Nb2O5 becomes a promising alternative to replace the commercial TiO2 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. (C) 2016 Elsevier B.V. All rights reserved.