Fotocatálise heterogênea com uso de Ti/Cu2O aplicado na redução de Nitrato

Abstract

The increase of contaminants nitrate íons (NO3-) in water supplies to the use of fertilizers in agriculture (NH4NO3, Ca(NO3)2, KNO3, etc.), make them conventional methods of treatment less viable to be a chemically stable species with low potential for precipitation. Thus, the use of titanium with copper oxide film is proposed (Ti / Cu 2 O) as a new semiconductor p-type in photocatalytic treatments applied to the reduction of nitrate ions (NO3-) under ultraviolet light (UV) stirring a sample containing 15.0 mg.L-1 NO3-. The Cu2O film was electrodeposited on a titanium metal plate (5cm x 5cm) in potential of -0.4 V (vs. Ag / AgCl, KCl sat), for a period of 30 minutes at pH 9 solution containing 0.4 mol.L-1 cupric sulphate pentahydrate - CuSO4.5H2O - and 3.0 mol.L-l actic acid - C3H6O3 - maintained at 60°C. During the photocatalytic processes, aliquots in triplicates were collected at 0, 10, 15, 20, 30, 45, 60, 75 and 90 minutes (min) treatment and then analyzed. After 90 minutes of treatment, observed in the photoelectrocatalysis +0.1V a reduction 93.8% of NO3- maintained in solution 6.3% of NO3-, 7.2% of NO2- and 86.5% of NH4+ or N2. For photoelectrocatalysis +0,2V there was a reduction 77.1% of NO3- maintained in solution 22.9% of NO3-, 12.1% of NO2- and 65.0% of NH4+ or N2. These results showed that proposed electrode (Ti/Cu2O) has potential as a reducing nitrate íons in aqueous solution, with the possibility of being used in solutions with concentrations greater than 15 mg.L-1.