二氧化钛改性硅胶的光催化和吸湿特性

Photocatalytic Activity and Hygroscopic Property of Titanium Dioxide Modified Silica Gels

为提高硅胶吸附剂的氮氧化物去除性能,并且不影响其水蒸气传质性能,选择光催化性能优异的二氧化钛为改性材料,通过浸渍法制备不同二氧化钛含量的硅胶-二氧化钛复合材料。对复合材料的紫外透射性能、氮氧化物光催化性能和水蒸气吸附性能进行了实验研究。研究结果表明:随着二氧化钛含量的增加,复合材料透射光谱趋向二氧化钛·复合材料的氮氧化物去除率最高可较纯硅胶提升8倍以上。在0.3~0.6的中低相对湿度区间,二氧化钛对硅胶的吸湿性能基本无影响,但在高湿条件下,有一定负面影响。最后,基于吸附势理论对最佳复合材料的等温吸湿曲线进行拟合,得到吸附平衡方程,可用于模拟计算复合材料在后续新风净化除湿系统应用时的吸附性能。

In order to improve NOx removal rates and not to influence the mass transfer performance of silica gel, titanium dioxide with high photocatalytic activity was selected as the support material.Composite materials with different content of titanium dioxide were fabricated by impregnation method. UV-Visible spectroscopy, photocatalytic activity and mass transfer performance of these composites were investigated. Results showed that transmittance spectra of composite materials shift towards titanium dioxide with the increase of TiO2 amount. Nitrogen oxides removal rates of composites improved greatly as compared to pure silica gel, and increased with the increase of titanium dioxide content. Moreover, the highest rate was 8 times more than that of non-modified silica gel. Water vapor absorption research showed that in the middle and lower relative humidity(RH)range(0.3~0.6), titanium dioxide had no effect on the hygroscopic property of silica gel. However,when RH is high, water uptake of the composite was smaller than that of pure silica gel. Besides,sorption characteristic curves of the best composite and pure silica gel were fitted based on Polanyi potential theory. Adsorption equilibrium equations were obtained, and can be used in simulating dehumidification performance in our later research.