Photocatalytic reduction of nitrate in wastewater using ZnO nanopowder synthesized by solution combustion method

ZnO nanopowder was synthesized by a unique method which is called solution combustion method (SCM). This nanopowder was used for a photocatalyst to decompose nitrate that is a toxic pollutant in wastewater. It has been known that TiO2, the most popular photocatalyst, does not decompose the nitrate. In this paper, however, the SCM ZnO nanopowder decomposed about 13% of nitrate. Furthermore, adding methanol as a hole scavenger, the decomposition rate was enhanced by about 5 times. On the other hand, it has been reported that the photocatalytic reduction reaction of nitrate produces ammonia as a final product. The present results, however, suggest that the final product is non-toxic nitrogen gas rather than the toxic ammonia. These results would be very valuable for drinking water purification.