The Study On Preparation Of Bentonite Composite Photocatalyst And Its Photocatalytic Ability

The composite photocatalyst has become a photocatalyst research focus because of its good stability, high photocatalytic activity and recoverability. Bentonite is suitable for the support of photocatalytic composite because of its interlayer size adjustability, large surface area, strong absorbability, good stability, large reserves, and low price. So it has a broad prospective future preparing bentonite composite photocatalyst with high photocatalytic activity.With bentonite as the support, H3PW1204o/organobentonite and H3PW1204o/Ti02/bentonite were made by backflow adsorptive process and sol-gel process respectively. Those composites were characterized by methods of SEM, XRD, UV-VIS, EDS, were also analyzed on the properties of photocatalytic degradation to the methyl orange wastewater. The study results were as follows:1、The study of preparation of H3PW12O40/organobentonite and its photocatalytic ability to the methyl orange wastewater in UV-H2O2system.The major preparation technology factors influencing the photocatalytic ability of H3PW12O40/organobentonite composite photocatalyst were reaction time, reaction temperature, roasting temperature and roasting time. The optimum preparation technology of H3PW12O40/organobentonite was determined when reaction time was4h, reaction temperature was80℃, roasting temperature was200℃and roasting time was2h. Then the H3PW12O40/organobentonite prepared as described above was used to process10mg-L-1methyl orange wastewater in UV-H2O2system. The study indicated that too much H3PW1204o/organobentonite was not favorable for photocatalyst reaction and in UV-H2O2system the H3PW1204o/organobentonite had rather broad pH adaptive range to methyl orange. When pH=2, reaction time was2h, and dosage of H2O2was10mmol-L-1, the degradation rate of the methyl orange was up to90%. When the composite photocatalyst was used repeatedly for6times, the degradation rate was still as high as80%. In addition, the XRD analysis indicated that the layer space of composite photocatalyst had increased, and the EDS analysis indicated that H3PW12O40was successfully supported to the organobentonite.2^The study of preparation of H3PW1204o/Ti02/bentonite and its photocatalytic ability to the methyl orange wastewater in UV system.The major preparation technology factors influencing the photocatalytic ability of H3PW12O40/TiO2/bentonite composite photocatalyst were roasting temperature, mass ratio of TiO2and bentonite, and doping concentration of H3PW12O40. The optimum preparation technology of H3PW12O40/TiO2/bentonite was determined when roasting temperature was200℃, ratio of TiO2and bentonite was1:1, doping concentration of H3PW12O40was0.5%, reaction time was3h, and ageing time was12h. The H3PW12O40/TiO2/bentonite composite photocatalyst prepared under optimum preparation technology was used to photocatalytically degrade10mg·L1methyl orange wastewater in UV system. The study indicated that the H3PW12O40/TiO2/bentonite had high photocatalytic activity, good stability, and had rather broad pH adaptive range to methyl orange in UV system. When pH=2, reaction time was2h, composite phtocatalyst dosage was0.8g·L-1, and composite dosage was1g·L-1, the degradation rate of the methyl orange was up to90.63%. It was not significantly decreased even after the composite photocatalyst was repeatedly used for5times. In addition, with3mmol·L-1H2O2added the degradation rate achieved98.05%. What is more, the XRD analysis indicated that there was anatase TiO2formed in the H3PW12O40/TiO2/bentonite composite photocatalyst. The UV-VIS analysis indicated that the H3PW12O40/TiO2/bentonite had better light absorption intensity than the Na-bentonite in250～800run and appeared red shift phenomenon. The EDS analysis indicated that H3PW12O40and TiO2were successfully supported on the bentonite.