以稻壳常压制备TiO_2/SiO_2复合气凝胶的结构及传热性能研究

Microstructure and Heat Transfer Performance of TiO_2/ SiO_2 Composite Aerogels Prepared by Rice Husk at Ambient Pressure

以稻壳为原料制备硅酸钠溶液,经过阳离子交换树脂得到硅酸溶液,将纳米TiO_2与硅酸溶液混合,并以稀氨水调节其pH值,经过老化,溶剂置换,改性等工艺,最终经常压干燥制得TiO_2/SiO_2复合气凝胶。研究了TiO_2掺杂量对复合气凝胶的性能影响。结果显示,当TiO_2掺杂量为7wt%,pH值为5.5时,得到气凝胶块体,比表面积高达734.82 m2/g,密度为0.1394 g/cm^3,在波长2~8 um范围内,红外透过率明显下降。

Rice husk was used as raw material to produce a sodium silicate solution. This solution was filtered to form a silicic acid solution by cation exchange resin,and a small amount of nano-titanium dioxide（ TiO2） to form a mixture. The mixture was neutralized by weak aqua ammonia to pH = 5. 5 to form silica hydrosol. After ageing,solvent exchange,surface modification and drying under atmospheric air,TiO2/ SiO2 composite aerogels was finally obtained. The effects of the content of TiO2 and the p H on performances of the composite aerogels were investigated. The experimental results show that block silica aerogels were obtained with specific surface area of 734. 82 m2/ g,density 0. 1394 g / cm3,when doping content of TiO2 was 7wt%,pH was 5. 5. The infrared transmittance of the composite aerogels reduced obviously at a wavelength range of 2-8 μm.