负载TiO_2的泡沫镍网光催化降解甲醛的膜厚优化

Optimal film thickness of TiO_2 coated on foam nickels for the photocatalytic degradation of formaldehyde

采用负载TiO2的泡沫镍网光催化降解甲醛,考虑内部和外部质量传递,建立了可预测优化催化剂膜厚的数学模型.分析了TiO2膜厚对光催化降解甲醛的影响,并在模型基础上分析了催化剂层内光的衰减系数和污染物的有效扩散系数对最优催化剂膜厚的影响.结果表明,随着催化剂膜厚的增加,甲醛的降解先增加而后趋于平缓;最优催化剂膜厚受UV光衰减系数的影响较大,受污染物的有效扩散系数的影响较小;由于TiO2催化剂对254nmUV光的强烈吸收,优化的催化剂膜厚只有80nm左右.该模型对实验数据拟合较好.

Based on the internal and external mass transfers, a mathematic model was proposed to optimize the film thickness of TiO2 coated on foam nickels for the photocatalytic degradation of formaldehyde. The effect of the film thickness of catalysts on the degradation of formaldehyde was investigated. The effects of the optical attenuation coefficient in catalyst lay and the effective diffusion coefficient of contamination on the optimal film thickness of catalysts were analyzed based on the model. The degradation of formaldehyde increased at first with the increase of the film thickness of catalysts and then reached a plateau. The optimal film thickness of catalysts mainly depended on the optical attenuation coefficient, while less depended on the effective diffusion coefficient of contamination. The optimal film thickness of catalysts was only about 80 nm due to the strong absorption of 254nm photons by TiO2 catalysts. This model was consistent with the experimental data.