During the photocatalytic reaction

the VB hole has been scavenged by isopropyl alcohol and the electron accumulated in CB of TiO2 has been used for the reduction of decabromodiphenyl（PBB209） under anoxic condition.The experiment reveals that PBB209 has been rapid degradated by TiO2

and the kinetics is fitted by pseudo-first-order process

giving a rate constant of（0.11±0.01） min-1（t1/2=6.5 min）.The degradation of kinetics of PBB209 has been affected by different conditions

such as various solvents

the presence of H2O

acids or bases.The experimental results indicate that the degradation has been accelerated in the presence of base

but been greatly depressed by acids and H2O.The degradation of PBB209 has been observed in acetonitrile and isopropyl alcohol solution.But in the hexane and toluene solution

where the adsorption of PBB209 is weak

the degradation scarcely occurs.The photocatalytic mechanism was further proposed on the basis of experimental results.