Preparation And Performance Of TiO₂ Hollow Microspheres

As a highly favored photocatalyst of environmental protection field, TiO₂ had some specific properties such as high photocatalytic activity, long-term stability, low cost and non-toxicity. However, TiO₂ also had two defects: poor utilization ratio of sunlight and being difficult to recycle, which always restricted the range of its application. Thus TiO₂ hollow materials had been synthesized because of their lower density, higher specific surface areas, and unique optical and surface properties in recent years. Internal cavities of hollow materials can not only improve its performance, but also expand the range of its application.Currently, TiO₂ hollow microspheres were mainly prepared by hard template method, hydrothermal method were rarely reported in the literature. The specific research methods and contents are shown as follows:TiO₂ hollow microspheres were prepared by a one-step hydrothermal method using TiCl₄ as precursor and H₂O₂, KBF₄ as raw materials. The morphology, structure and composition of TiO₂ hollow microspheres were characterized by SEM, XRD and EDS. The photocatalytic activity of TiO₂ hollow microspheres was investigated by the photocatalytic degradation of Rhodamine B as a model reaction. Results indicated that the product were anatase type with good crystallinity and its particle sizes were variation in1-8μm; The sample with hydrothermal reaction temperature of 200°C and reaction time of 14 h hours had the highest photocatalytic activities. when the rhodamine B solution with 20mg/L of initial mass concentration is treated under UV light using 1g/L TiO₂ hollow microspheres for 120 min, the degradation rate of rhodamine B can reach 90.3%.TiO₂ hollow microspheres were prepared by hydrothermal method using TiCl₄ as precursor and using H₂O₂, KBF₄ as raw materials and characterized by SEM, XRD, EDS. The photocatalytic activity of TiO₂ hollow microspheres was investigated by the photocatalytic degradation of Rhodamine B as a model reaction. The characterization results show that the prepared TiO₂ hollow microspheres are anatase type particles with 3μm of diameter, and they are dispersed evenly; The sample with hydrothermal reaction temperature of 180℃, reaction time of 10 h hours, KBF₄ dosage of 4mmol and H₂O₂ dosage of 0.2m L had the highest photocatalytic activities. when the rhodamine B solution with 20mg/L of initial mass concentration and 7 of pH is treated under UV light using 1g/L TiO₂ hollow microspheres for 120 min,the degradation rate of rhodamine B can reach 93.38%. The tests showed that the photocatalytic degradation of Rhodamine B after 5 times “reuse” of the TiO₂ hollow microspheres was over 93%. The results of the experiment also revealed that there were some differences between the reaction conditions of the TiO₂ hollow microspheres which was prepared using TiCl₄ as precursor and using TiCl₃. The sample prepared using TiCl₄ as precursor had higher photocatalytic activities with the degradation rate of Rhodamine B higher than the sample prepared using TiCl₃ by 3%.Ag-TiO₂ were prepared by Ag2CO3 method with the TiO₂ hollow microspheres which was prepared using TiCl₄ as precursor. XRD, EDS and SEM analysis showed that the Ag particles were successfully loaded on the TiO₂ hollow microspheres. The photocatalytic activity of Ag-TiO₂ hollow microspheres was investigated by the photocatalytic degradation of Rhodamine B as a model reaction. Results indicated that the sample with silver content of 4% had the highest photocatalytic activities. Under UV light for 120 min, the degradation rate of rhodamine B can reach 96.8%. The analysis results on the antimicrobial properties of Ag-TiO₂ hollow microspheres showed that the sample with calcination temperature of 700℃ had the best antibacterial property. at the same calcination temperature. Results also indicated that the higher silver content, the higher the antimicrobial properties of Ag-TiO₂ hollow microspheres, however, when the silver content is over 3%, the increase of silver content affect antimicrobial properties little.