Affiliations: Guangdong Institute of Eco-Environment and Soil
Science,Guangzhou 510650, China. E-mail: fbli@soil.gd.cn | College of Chemical Engineering, South Technology
University, Guangzhou510642, China
Abstract: The photo-catalytic degradation pathway and degradation products of
methylene blue, rhodamine B, methyl orange, and malachite green in aqueous
TiO_2 suspension irradiated by high pressure mercury lamp by means of
UV-visible absorption spectra and ion chromatography were investigated. The
photo-catalysis degradation of dye solutions with charges was greatly affected
by pH value owing to the electrostatic model. The photo-degradation rate of
dyes anion increased with the decrease of pH value, in contrast, the
photo-degradation rate of dyes cation increased with the increase of pH value.
And the absorption peaks diminished with a blue shift. After illuminated for 30
minutes, a part of dye chemicals were completely mineralized and transferred
into inorganic species including chloride ion, ammonium ion, nitrate ion,
sulfate ion. And the addition of 100 mmmol/L H_2O_2 promoted the formation of
inorganic species. In this study, the quantity of ammonium ion was much more
than that of nitrate ion. That indicated the formation of nitrate is from
ammonium. The purification rate of COD in four kinds of dye solution was
71.7%-88.7%. The decrease of COD of dyes solution implies the feasibility of
the environmental application of photo-catalyzed process.
