Effects of noble metal particles and salts on the light stability of Safranin O

Abstract

Organic dyes are used in many industrial and chemical analytic fields. They are easily degraded under severe light and heat owing to be organic materials even though they could have good chromogenic ability. If the colors of organic dyes were faded or discolored, the dyes would be no use as coloring agents by degradation. While inorganic materials have strong light and heat stability in their own properties, organic materials usually have poor fastness of light and heat. Each material used in this research has remarkably different physical and chemical properties. Hence It was investigated how organic dye as organic materials would be affected by noble metals as inorganic materials. In this study H2O2 were added to the Safranin O aqueous solution. H2O2 might serve a part as pseudo catalyst of dye degrading reaction. We applied noble metal nanoparticles such as Ag, Au, Pt in colloidal condition and AgNO3, HAuCl4, H2PtCl6 as the noble metal salts. The Safranin O solutions containing noble metal and H2O2 were irradiated by UV lamp (λ=254nm). The effects of noble metal nanoparticles and salts on the light stability of Safranin O were investigated. Effect of pH was also considered. HCl and NaOH were used to control the pH of the solution. Optical properties of the noble metal and organic dye were investigated by UV-vis spectroscopy and naked eyes as time went. The complexes between noble metals and the organic dye were confirmed by TEM and Raman spectroscopy.