pH值对聚合钛离子/蒙脱石复合结构及其TiO_2纳米粒子的影响研究

Effects of pH Value on Composite Structure of Poly-titanium-ion/Montmorillonite and Its TiO_2 Nano-particle

采用水解-插层复合法,以TiOSO4.2H2O为TiO2的前驱体,蒙脱石为复合基体,通过控制蒙脱石悬浊液pH值,制备了不同的蒙脱石复合结构样品.采用XRD研究了样品的结构、物相、晶粒大小等属性的变化.结果表明,蒙脱石悬浊液的pH值对TiOSO4.2H2O水解属性有较大的影响,从而影响水合氧化钛/蒙脱石的复合结构特性,当蒙脱石悬浊液pH为0.5时,电价较低且聚合度较小的聚合钛离子易于进入蒙脱石层间域,对蒙脱石结构层的分散剥离作用最好;经700℃热处理的TiO2/蒙脱石复合结构样品中,锐钛矿晶粒尺寸最小达到13.4 nm;经1100℃热处理后,复合结构中锐钛矿相对含量达到35%;与纯纳米TiO2样品相比,TiO2/蒙脱石复合结构中的TiO2具有更高的锐钛矿相向金红石相转变的温度及更小的晶粒尺寸.蒙脱石结构层对TiO2的相转变和晶粒长大都具有明显的阻滞作用.

The montmorillonite composite structure samples were prepared using a hydrolysation-intercalation composite method with TiOSO4·2H2O as a precursor of TiO2 nano-particles and montmorillonite as substrate by controlling the pH value of the montmorillonite suspension. The changes of the structure, phase and crystal size of the samples were characterized by X-ray diffraction method. The results show that the pH value of montmorillonite suspension has a significant influence on the hydrolyzation of TiOSO4·2H20, so the composite structure of hydratedtitanium-oxide/montmorillonite is affected. When the pH value of montmorillonite suspension is 0.5, the poly-titanium-ions are with the lower electrovalence and extent of polymerization and easily intercalate the interlayer space of montmorillonite, moreover, the structural layers of montmorillonite are separated best. The crystal size of anatase in the TiOE/montmorillonite composite samples calcinated at 700℃ is smallest and reaches 13.4 nm. After calcination at ll00℃, the relative content of anatase in the composite structure reaches 35%. Compared with pure TiO2 nano-particle sample, TiOE/Montmorillonite composite sample has a higher phase transition temperature from anatase phase to rutile phase and smaller crystal size of TiO2. Montmorillonite structure layer has a significant blocking effect on the TiO2 phase transformation and grain growth.