Research On Preparation And Degradation Characteristics Of Nanometer TiO₂/montmorillonite Composite Photocatalyst

Nonmetal mineral montmorillonite as the carrier of photocatalyst has been attached great importance by scholars because of its big regular channel structure as well as high specific surface area. TiO₂ is loaded on the surface or in interlayer of montmorillonite to prepare the laminar silicate nanocomposite photocatalyst. This kind of new environment amity material can be used to photodegrade organic pollutant, sterilize, disinfecte and purify air.In this research, nanocomposite photocatalyst were prepared by sol-gel method, eight factors which influence the photocatalytic active of samples, including mineral slurry concentration, the radio of Ti and montmorillonite, hydrolysis temperature, drying temperature, changing of pH , calcination temperature, positive and negative dropping order and aging time, have been discussed systematically. Through factor and orthogonal experiment the optimum synthesis have been concluded that: mineral slurry concentration is 1%; ratio of Ti and montmorillonite is 23mmol/g; positive dropping order; sol pH is 2.5; hydrolyzed at 42℃ for 2h; aging forl6h;dried at 50℃ for 2h and calcined at 300℃ for 2.5h. The orthogonal experiment indicated that the order of importance of factors affecting preparation of nanometer TiO₂/montmorillonite is: calcination temperaturo mineral slurry concentration> ratio of Ti and montmorillonite >hydrolysis temperature. Calcined at 300℃ nanocomposite photocatalyst has the best activity.Researching three kinds of montmorillonite and then prepared three nanometer TiO₂/composite photocatalysts by the optimized condition. Photodegrade azo dye wastewater on condition that initial concentration is 40mg/L, photocatalyst dosage is 0.3g/100mL, UV-light illuminating for 1h, the order of photocatalytic activity of the three nanocomposite photocatalystsis:TiO₂/Na-montmorillonite(96.28%) > TiO₂/Ca-montmorillonite(95.87%)> TiO₂/organic montmorillonite(71.07%).Modern testing methods to analyze three kinds of nanometer TiO₂/montmorillonite photocatalysts were also adopted in this study, which are XRD, IR, Raman, XPS and AFM, TEM. The result shows that :TiO₂ presented as anatase type, particle size of TiO₂ is between 12nm to 27nm. Nanometer TiO₂ crystal film on the surface of the Ca-montmorillonite develop as the monocase crystal shape cusp up-extrude; Nanometer TiO₂ crystal film on the surface of the Na-montmorillonite exists as crystal shape coenobium symmetrical covered over; Nanometer TiO₂ crystal film on the surface of the organic montmorillonite distribute as reunite state.Transition metal Co and rare metal La were chosen as doping metal to prepare nanometer TiO₂/montmorillonite photocatalyst by sol-gel method. Doping metal photocatalysts were analyzed by XRD and XPS. The result shows that: TiO₂ presented as mixed phase after doping metal ion, d(001) value of the montmorillonite augmented and thermo-stability of the composite material improved. Ti presented as the form of...