Preparation Of Pleated Mesoporous Silica Supported Titanium Dioxide Nanomaterials And Their Photocatalytic Properties

Nano-titanium dioxide exhibits remarkable advantages including low-cost, strong activity, chemical stability and environmental friendliness, etc., and is wildly utilized as promising photocatalyst, which plays a major role in treating wastewater and waste gas. Generally, nano-scale Ti O₂, owing to its relatively low surface area, often encounter practical problems?easily aggregation, poor dispersion, poor adsorption ability and difficult to separate and recycle?. Mesoporous silica materials have attracted great attention due to its high adsorption capacity, strong chemical stability, adjustable pore size and easy surface modification, thus attaching nano-TiO₂ to it may successfully solve the above-mentioned problem. Herein we attempt to load nano-TiO₂ onto the inside and outside surface of three different radial wrinkle mesoporous silica spheres via the coordination from their surface organic functional groups, respectively. These three mesoporous silicas possess varied surface area, pore size and surface wrinkles density. However, they all have the same center-radial open pores, which have more accessibility for various sized molecules to enter into the internal surface of the particles, and are in favor of the loading and high dispersion stability of nano-TiO₂. Firstly, mesoporous silica can effectively restrain the grain growth of TiO₂ with stable crystal form and prevent aggregation between the particles; secondly, high adsorption capacity of mesoporous silica will sharply accelerate the speed of charge transfer between dye molecules in excited state and catalyst TiO₂; meanwhile, enriched electrons in the inner and outer surfaces of mesoporous silica pores can effectively inhibit the recombination of electron and hole from TiO₂, leading to the easy capture of dye molecules and improving photocatalytic efficiency in the sewage purification process.Using three different wrinkle mesoporous silicas as carrier, highly dispersive surface functional groups?-OH/-COOH? can effectively anchor tetrabutyl titanate?TBOT? molecules on its surface and guarantee the excellent dispersion of nano-TiO₂. Then the photocatalytic performance of the obtained samples was investigated in detail. The current work contains the following three parts:?1? Mesoporous silica with surface area of 438.32 m2/g and medium wrinkle density was prepared through sol-gel method at room temperature by using cetyltrimethylammonium?CTAB? as template, tetraethoxysilane?TEOS? and 3-aminopropyltriethoxysilane?APTES? as silica source, diethyl ether as solubilizer. TiO₂ particles were dispersedly locked on its surface via direct impregnation or surface modification method, respectively. It turns out that nano-TiO₂ particles prepared by surface modification method exhibit better size distribution without agglomeration and better photocatalytic performance to Rhodamine B?Rh B?. The result showed that the optimal catalytic effect can be obtained by adjusting the amount of TBOT to 0.5 mL with Ti O₂ content of 30.66% and calcination temperature of 750?, that 0.1 g dosage can degrade 100 m L 20 ppm Rh B completely within 30 min much better than P25?which need 1 h?, and can be reused.?2? Mesoporous silica with a specific surface area of 954.41 m2/g and small wrinkle density was prepared through sol-gel method at room temperature by using CTAB as template, TEOS as silica source, diethyl ether as solubilizer. Similarly, Nano-TiO₂ particles were dispersedly locked on its surface without agglomeration. The result showed that the optimal catalytic effect can be abtained by adjusting the amount of TBOT to 0.5 mL with Ti O₂ content of 24.14% and calcination temperature of 750?, that 0.1 g dosage can degrade 100 mL 20 ppm Rh B completely within 40 min better than P25?which need 1 h?, but poor reusability.?3? Mesoporous silica with a specific surface area of 664.58 m2/g and large wrinkle density was prepared at 70? by using cetylpyridinium bromide?CPB? as template, TEOS as silica source, n-pentanol as cosolvent. Nano-TiO₂ particles locked on its surface existed agglomeration with poor dispersion and was easy to form precipitation. The result showed that the optimal catalytic effect can be abtained by adjusting the amount of TBOT to 0.5 mL with TiO₂ content of 37.36% and calcination temperature of 750? or 950?, that 0.1 g dosage can degrade 100 m L 20 ppm Rh B completely within 40 min better than P25?which need 1 h?.?4? All three kinds of samples have better photocatalytic performance than P25 under sunlight irradiation.