| In this paper,pure tetragonal,pure monoclinic and mixed-phase nano-zirconia were prepared by hydrothermal method,using Zr(NO3)4 as zirconium source,and high concentration NaOH and different kinds of quaternary ammonium salt as surface modifiers,achieving the controlled synthesis of different tetragonal/monoclinic ratio of nano-zirconia.The characteristics of the nano-zirconia were investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),Raman spectra and differential scanning calorimetry(DSC),the experimental condition,such as the kinds and content of quaternary ammonium salt,aging temperature and aging time had been further researched,which had an effect on the crystal phase of nano-zirconia,and the growth mechanism of nano-zirconia was analyzed under the TMAC modifying.The research showed that the chlorinated and long-chain quaternary ammonium salt had a better effect on crystal phase of zirconia than brominated and short one.The research of aging experiments with TMAC suggested that short aging time made for the formation of metastable monoclinic-zirconia nucleus,but with the extended aging time,the metastable monoclinic-zirconia nucleus transformed into tetragonal completely.The photocatalytic activity of nano-zirconia of different crystalline phases was investigated by degradation of Rhodamine B(RhB),and the results suggested that the maxed-phase zirconia which contain 66%monoclinic and 34%tetragonal showed the highest photocatalytic activity;we explored the effects of the catalyst dosage,pH values of solution,the initial concentration of RhB and the gas identity blowing into the solution,the experimental results indicated that the best dosage of catalyst was 70mg/L,the nano-zirconia show the higher photocatalytic activity under acidic condition and with air;finally,the removal kinetics of RhB had been studied,the results showed that the decline of RhB concentration in the solution followed a one-order kinetics. |
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