Research On The Preparation And Properties Of The Visible Light Responsed TiO₂/Fly Ash Cenospheres

To overcome the weaknesses of nano-titanium dioxide’s wide energy gap which makes its utilization of sunlight extremely low, and the small particle size which makes it difficult to separate and easy to reunite in practical application. Besides, to solve the problem that the high value utilization of solid waste-fly ash is still low and the excessive emissions of fly ash cause serious environmental pollution. In this paper, nano-Ti O2 particles were successfully coated on the cenospheres by using the hydrolysis of Ti OSO4.This paper discussed the effect of the coating process parameters on the morphology and the photocatalytic activity of Ti O2/fly ash cenospheres. The p-n heterostructure Ag2O/Ti O2 and the n-n heterostructure WO3/Ti O2 were built on the cenospheres to study their effects on the UV and visible photocatalytic activities of Ti O2/fly ash cenospheres.The results showed that high quality composites were available when the parameters were set as below: hydrolysis temperature at 85℃, the capacity of Ti O2 at 30%, 10%wt Na OH in 5m L, CTAB content at 2g, stirring speed at 150r/min, and the calcination temperature at 750℃. The 50-200 nm coating particles of the Ti O2/fly ash cenospheres were anatase Ti O2, they combined closely with cenosphere matrix, and the Si-O-Ti bonds had built between the coating particles and the cenospheres. Besides, the surface area of Ti O2/fly ash cenospheres had been increased more than 5 times to nano-Ti O2 particles, that made it have better adsorptivity.According to the degradation of the 20 ppm methylene blue solution, the Ti O2/fly ash cenospheres had good UV photocatalytic activity. Building the p-n heterostructure Ag2O/Ti O2 on the cenospheres improved the UV photocatalytic activity of Ti O2/fly ash cenospheres, and the absorption edge occurred red shift, that made Ag2O/Ti O2/fly ash cenospheres have good visible light photocatalytic activity. While the m(Ti O2:Ag2O) was 4:1 to 1:1, the MB solution was degraded completely after 30 min UV light on.While the m(Ti O2:Ag2O) was 1:6, the degradation of MB solution exceed 80% after 4h visible light on. But the building of n-n heterostructure WO3/Ti O2 had nothing to do with improving the UV light or the visible light photocatalytic activities.Conversely, with the increasing amount of WO3, the degradation of MB decreased. It was due to the strong adsorptivity of WO3 affected the Ti O2 degradation.The results proved that the submicro-sized Ti O2/fly ash cenospheres can be easily recovered, and achieved the goal of the waste treatment by another waste.The p-n heterostructure Ag2O/Ti O2 was better than the n-n heterostructure WO3/Ti O2 in improving the UV and visible photocatalytic activities of Ti O2/fly ash cenospheres.