Photocatalytic degradation of Phenol, Catechol and Hydroquinone over Au-ZnO nanomaterials

Abstract

Au-ZnO nanomaterials were tested in photodegradation reactions performed under UV-Visible light; Phenol,  Catechol and Hydroquinone were selected as target molecules, and it was found that Hydroquinone is the most sensitive molecule to be degraded under illumination. The Au addition significantly increases the photocatalytic activity of ZnO in the degradation of the phenolic compounds and the Au content is an important factor influencing the physicochemical properties of the nanomaterials synthesized and therefore the effectiveness of the photocatalytic treatment. The highest effectiveness in the phenolic compounds elimination was achieved by using ZnO modified by the addition of 2 wt.% of gold, this is due to the highest absorption of this material in the visible region of the electromagnetic spectrum. By HPLC analyzes, it was determined that the degradation route of the phenolic compounds depends on the photocatalyst employed in the catalytic reaction and on the substrate to be degraded, thus, Phenol degradation takes place by formation of more intermediate compounds than the observed in Catechol or Hydroquinone photodegradation.