Study Of Photocatalytic Degradation Of Organic Pigments And Surfactants

Photocatalytic degradation of organic pigments and surfactants in the presence of TiO₂ under UV irradiation was investigated in the present study. We chose Lingt Fast Searlet BBN (48:1, BBN) and Toluidine Red (TR), and the surfactants including cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecylbenzensulfonate (DBS). Our main purpose is to examine the effect factors on the degradation of BBN as well as the interaction mechanism of the bicomponents, and the adsorption model between substrate and catalyst in TiO₂ suspensions.The mixture of organic pigments, surfactants, TiO₂ and deionized water was added to a 500mL beaker. After stirred for 1h in the dark, the mixture was irradiated with a high pressure Hg lamp (100W,λmax 365nm).In single component system of BBN degradation, the better discoloration rate of BBN was with 4g/L of catalyst amount. Increase in the light intensity can accelerate the discoloration rate of BBN. The degradation ratio was faster in acid or alkaline medium. The fading ratio of BBN decreased with the increase of the BBN amount.The alkaline medium were favorite the degradation of BBN and CTAB. The degradation of CTAB were slightly slower than that without BBN in alkaline (pH=9.2). When the concentration of CTAB was 1cmc, the degradation rate of BBN and CTAB were the fastest. The degradation of the two compounds system was faster than each organic compounds individely in neutral condition (pH=6.8). In the system of BBN/DBS, the degradation rate of BBN was slightly increased by adding DBS. When the concentration of DBS was 1cmc, the degradation rate of BBN was much faster. The degradation rate of DBS was faster in alkaline medium, but the discoloration rate of BBN was faster in acidic medium.TR was stable in single compontent system and hard to photocatalytic discolored. The photocatalytic degradation of TR was enhanced after the addition of H2O2. When the concentration of H2O2 was 5%, the discoloration rate of TR was 70.2% after 8h. It was more effective in alkaline medium for the system of TR/H2O2/TiO₂.The activities of photocatalytic oxidation of ZnFe2O4 doped TiO₂ depended on the adulterate amount.