Study On The Photocatalytic Degradation Of Methyl Orange By TiO₂ Nanoparticales

TiO2 photocatalysis is emerging as a promising technology for wastewater treatment and water purification. The advantages of this technique over the traditional wastewater treatment include complete mineralizaion, high degradation efficiency, low cost, good stability, and the potential to utilize sunlight as UV source. The TiO2 nanoparticales were prepared by novel chlorination technology, and the degradation and decolorization of methyl orange (MO) in nano-TiO2 aqueous slurries was studied. The effects of light source, catalyst amount, initial concentration of solution, reaction time and temperature on the degradation rate of methyl orange were investigated under the irradiation of high pressure mercury lamp,and the same investigations were also did in the dark. The results of optimum parameters were as following: the mass concentration of nano-TiO2 5.0g/L ~13.0g/L; the initial concentration of MO 100 mg/L ~ 700 mg/L; the reaction time 30~60 min; the reaction temperature 0℃～30℃. The results indicated that light source shows a little influence on the decolorization rate of MO. When the initial concentration of MO was 100 mg/L, the solution color removal achieved 91.1% in 30 minutes of irradiation,and in the dark after 30 min reaction the solution color removal achieved 86.9%. Further investigations were indicated that this nano-TiO2 has good absorbability for MO, and it could decolor the MO much more efficiently than Degussa P-25 TiO2, which was not only because of its good adsorbability for MO. The ESR study justified whether the nano-TiO2 was irradiated under the ultraviolet light or in the dark, the surface of this nano-TiO2 will produce ·OH free radicals, which perhaps do some effect on the degradation of MO.