The Preparation Of Modified Titanium Dioxide And Its Application In Photocatalytic Degradation Of Phenol

Nano TiO₂can degrade organic pollutants in water efficiently under UV light, whichare difficult to be degraded by biologic methods. In this paper, to solve the problems, likelow catalytic capability of TiO₂and low light energy utilization rate, the optimumpreparation conditions of TiO₂photocatalyst were investigated and pure, non-metal ionsdoped and Fe-N co-doped TiO₂were prepared by sol-gel method and using phenol as amodel pollutant. The role of the transition metal ion Fe was studied in the photocatalyticsystem and the main factors including the radiation time, the TiO₂photocatalyst dosage,initial pH and initial concentration of phenol, which affect phenol degradation by using theself-made TiO₂as photocatalyst, also were discussed. The experiments show:1 The photocatalytic activity of TiO₂powers is greatly influenced by processingparameter using tetra-n-butyl titanate as the precursor, glacial acetic acid as the hydrolysisinhibitor and ethanol as solvent. The suitable condition is: the tetrabutyl titanate dosage is17 ml, glacial acetic acid is 10 ml, water is 5 ml, the anhydrous ethanol is 90 ml,calcinations temperature is 450℃and the calcination time is 2 h.2 Non-metal ions N doped TiO₂restrained the crystal size increase. We prepared Ndoped TiO₂photocatalyst by using the organic nitrogen source urea and the inorganicnitrogen source ammonium carbonate, respectively. The results indicate that usinginorganic N doped TiO₂powder as photocatalyst, the removal of phenol is obviouslyincreased under the radiation of ultraviolet and visible light; however, the catalytic activityof the organic N doped TiO₂powder is not obviously enhanced compared with undopedTiO₂.3 We prepared Fe and N co-doped TiO₂photocatalyst and researched the photocatalyticefficiency of TiO₂photocatalyst. The results show that using Fe and N as codopant canobtain the synergistic effect in proper doping proportion. The optimal doped molarfraction of Fe and N ions are 0.005 and 0.02, respectively.4 When taking Fe³⁺as doping ion to prepare TiO₂photocatalyst, calcinationtemperature and doping concentration have great impacts on the photocatalytic activity ofthe iron doped samples; When taking Fe³⁺as coexisting ion and with the same concentration of water soluble Fe³⁺in the photocatalytic system with differentphotocatalyst, different concentration of Fe³⁺can increase or decrease the photocatalyticefficiency of TiO₂photocatalyst.5 The photocatalytic activity was influenced by the radiation time, amounts of TiO₂, pHof the solution and initial concentration of phenol. The optimum condition are thatradiation time is 3 h, TiO₂photocatalyst dosage is 1.25 g/L, initial concentration of phenolis 40 mg/L and in acid surroundings. The removal efficiency of phenol with the pure TiO₂is 15% under UV light, and it is 10% under visible light.