Dye degradation effect of rayon fibers containing titanium oxide photocatalyst

Rayon fibers containing a titanium oxide photocatalyst were prepared to examine their dye decomposition effect. Although irradiation with ultraviolet rays caused no dye decomposition when the fibers were placed in air, the irradiation readily caused dye decomposition when the fibers were placed in an aqueous dye solution. The hygroscopicity of fibers was subsequently studied to find how it affects the dye decomposition effect of fibers. Little dye decomposition effect was found when titanium oxide was added to polypropylene, which is not hygroscopic at all. The result seems to show that, because the fiber material, which completely lacks hygroscopicity, kept the aqueous dye solution from being absorbed by the fibers to prevent reactions between dye molecules and titanium oxide particles imbedded inside the fibers.