solar light-induced decolorization of safranin o using unmodified and gold-modified semiconductor oxides

Unmodified and gold-modified semiconductor oxides were used for the complete decolorization of non-buffered aqueous safranin o solutions. photocatalytic properties of commercially available zno and tio2 (anatase nanopowder) were compared with those of gold-modified zno (au/zno). au/zno was obtained from commercial zno powder through direct current sputter coating. zno-based catalysts show significantly higher decolorization power in comparison with tio2. au/zno show slightly higher activity than unmodified zno. decolorization of safranin o using au/zno was additionally tested in different types of mineral water. the decolorization efficiency in mineral waters was negatively correlated with the dry residue content (180 °c) and in all cases was less than in distilled water. the inhibiting effect of hydrogen carbonate was additionally investigated.