TiO_2催化Cr(Ⅵ)-氯代苯酚共存体系中Cr(Ⅵ)的光致还原

Photo-Induced Cr(Ⅵ) Reduction in Cr(Ⅵ)-4CP Coexist Pollution System in the Presence of TiO_2 Photocatalyst

Cr( )离子在 Ti O2 光催化剂表面的暗态吸附 ,受 Cr( )离子浓度及体系酸度的影响较大 .4-氯代苯酚( 4 CP)的存在 ,对 Cr( )离子吸附没有影响 .Cr( ) - 4CP- Ti O2 体系中 ,Cr( )离子的紫外光致还原主要包括Cr( )与 4CP之间的均相反应以及 Cr( )离子在 Ti O2 表面的光催化还原反应 .Cr( )的还原为零级反应 ,并且受体系酸度影响较大 .4CP的存在对光催化还原过程有促进作用 .在一定波长紫外光或太阳光照射下 ,可排除Cr( ) - 4CP- Ti O2 体系中的均相反应 ,并证实了 4CP对 Cr( )离子光催化还原反应的促进作用 .

The dark adsorption of Cr(Ⅵ) ion on the surface of TiO 2 photocatalyst is mainly dependent on Cr(Ⅵ) concentration and the system acidity. The presence of 4CP has no interference on Cr(Ⅵ) adsorption. Under UV irradiation, reaction in Cr(Ⅵ) 4CP TiO 2 system is much complicated and two different reactions contribute to the overall Cr(Ⅵ) reduction: photo induced homogeneous reaction between Cr(Ⅵ) and 4CP, and photocatalytic reduction of Cr(Ⅵ) ion by TiO 2, an efficient semiconductor photocatalyst, which is promoted by another photocatalytic half reaction: 4CP oxidation and degradation. Cr(Ⅵ) is indirectly reduced by obtaining electrons from Ti 3+ . Obvious photocatalytic reduction of Cr(Ⅵ) ion on TiO 2 under the sunlight irradiation is observed in both Cr(Ⅵ) TiO 2 and Cr(Ⅵ) 4CP TiO 2 systems. When the homogeneous reactions is excluded, the promotion effect of 4CP on photocatalytic reduction of Cr(Ⅵ) ion is discriminated and confirmed. The results obtained under the sunlight irradiation indicate that the direct use of solar energy is efficient for the photocatalytic decontamination.