Research On The Catalytic Ozonation Of Aniline In Aqueous Solution By Nano-tio₂/fly Ash

The aniline waste water with strong toxicity and low biodegradability has been treated by photo-catalytic oxidation process, using the anatase TiO2/fly ash combining with ozone and ultraviolet radiation. The effect of wastewater treatment by TiO2/fly ash is higher than that of general biochemistry oxidation, due to the completely degradation of aniline. The low-cost TiO2/fly ash catalyst is easy to be prepared, the crystal style is also controllable. The TiO2/fly ash catalyst also shows a potential application in wastewater treatment, resulting from its good stability, supernal catalyst activity, which can repeatly use.Firstly, the removing effect of aniline waste water by ozone has been studied. Results show a low TOC degradation rate by ozone i.e. 38% after 20 mins reaction. The effect of degradating aniline by sole ozone gradually increases with the increasing pH and temperature.Secondly, TiO2/fly ash catalyst was prepared by sol-gel process, the crystal phase of TiO2 and morphology of TiO2/fly ash were investigated by IR, XRD and SEM. Results show that, TiO2 are distributed symmetrically on fly ash, an average crystal grain size, prepared in 550℃, is 11.12nm, containing 80% anatase TiO2. The removing rate of anline increases with the increasing ozone flow, temperature,pH value and TiO2 content, decreasing initial concentration. The degradation of aniline is strongly restrained by the tert-butyl alcohol. The TiO2/fly catalyst with higher catalytic activity and stability can be used for 3~7 times. The removing rate of anline reachs 97% with 8 mins reaction time and the removing rate of TOC reachs 63% with 20 mins reaction time, respectively. This is about 25% higer than that of sole ozone. According to the removing of TOC, the degradation of aniline by both ozone and TiO2/fly ash accords with the rule of first reaction kinetics.Finally, the intermediate of nitrobenzene, polyaniline and organic acid are identified by GC-MS(purge& trap) and the machnism of aniline degradation by OH? is dicussed.