【作者】 刘倩倩；

【导师】 朱爱民；

【作者基本信息】 大连理工大学 ， 化学工程与技术， 2012， 硕士

【摘要】 甲醛是一种常见的室内空气污染物,光催化氧化将其转化成无害的C02和H20具有广阔的应用前景。Ti02是一种性质稳定,无毒的光催化剂,在光催化氧化脱除有机污染物方面得到广泛的研究。本文采用大气压介质阻挡放电在玻璃基底上沉积Ti02薄膜,对其均匀性及沉积量进行了表征,并在连续流动的平板式光催化反应器中开展光催化氧化脱除模拟空气中ppm级甲醛的研究。主要考察停留时间、甲醛初始浓度、光强、气体湿度及光源等因素对光催化过程的影响,并对光催化反应进行了动力学分析。结果表明：1.薄膜平面上五个测试点的UV-Vis吸收光谱基本重合,说明所制备的Ti02薄膜是均匀的。由薄膜定量分析结果计算得薄膜的Ti02沉积量为74μg·cm-2.2.对于焙烧前的Ti02薄膜,254nm光照下,线速度大于7.1cm·s-1时,光催化反应总包过程由反应控制,可看作一级反应。在反应控制下,得到如下结果：在考察的光强范围(0.72～1.78mW·cm-2)内,-ln(1-X)=kIτ,k=0.78cm2·mJ-1；在考察的甲醛初始浓度范围(23～56ppm)内,甲醛转化率基本不随初始浓度变化；湿度在0.04～1.06vo1%之间时,湿度对甲醛转化率的影响不大,湿度在1.06～1.85vo1%之间时,转化率随湿度增加而降低。3.对于450℃焙烧2小时后的薄膜,254nm光照下,线速度大于9.1cm·s-1时,光催化反应总包过程由反应控制,可看作一级反应。在反应控制下,得到如下结果：光强对光催化反应的影响表明,-1n(1-x)=kInτ当0.21mW·cm-2<Ⅰ<0.98mW·cm-2时,n=1,k=2.1cm2.mJ-1当0.98mW·cm-2<Ⅰ<1.78mW.cm-2时,n=0.4,k=2.1cm08·mW-04·s-1；湿度在0.04～0.50vol%之间时,甲醛转化率随湿度增加而增大；湿度在0.50～1.10vol%之间时,转化率对湿度的变化不敏感；湿度在1.10～1.63vol%之间时,转化率随湿度增加稍有降低。365nm光照下对于焙烧后的薄膜,在实验考察范围(线速度大于3.3cm·s-1)内,总包反应均为反应控制。湿度在0.04～0.80vol%之间时,甲醛转化率随湿度增加而增大；湿度在0.80～1.66vol%之间时,转化率对湿度的变化不敏感。更多还原

【Abstract】 Formaldehyde is a common air pollutant. Photocatalytic oxidation that can translate it into harmless CO2and H2O has extensive application prospects. TiO2has been widely researched as a photocatalyst for its chemical stability and non-toxic. TiO2thin film was deposited by atmospheric pressure dielectric barrier discharge chemical vapor deposition and its uniformity and quality were characterized. The degradation of ppm levels of formaldehyde in the simulated air by the film was carried out in a continuous flow flat-plate photocatalytic reactor under UV irradiation in this paper. Residence time, light intensity/source, initial concentration of formaldehyde and humidity were investigated as process variables. The photocatalytic reaction kinetic was analyzed. The results are as follows:3. UV-Vis absorption spectra of5testing points on surface of the TiO2film were in good agreement, which showed the uniformity of the TiO2thin film. Quantitative analysis showed that the film has a TiO2quality deposition of74μg·cm-22. Under the irradiation of254nm UV lamp for as-deposited film, overall rate was controlled by reaction when the linear velocity exceeded7.1cm-s-J. Under the control of reaction, the results are as follows:As0.72mW·cm-2<Ⅰ<1.78mW·cm-2,-ln(1-X)=kⅠτt, k=0.78cm2·mJ-1;In the range of the initial concentrations of HCHO investigated (23-56ppm), the reaction rate changed little with the initial concentration variation;In the range of the humidity from0.04vol%to1.06vol%, photocatalytic conversion of HCHO to CO2kept almost constant, while in the range of the humidity from1.06vol%to1.85vol%, photocatalytic conversion of HCHO to CO2decreased with increasing the humidity.3. Under the irradiation of254nm UV lamp for the film calcined at450℃for2hours, overall rate was controlled by reaction when the linear velocity exceeded9.1cm·s-1and under the control of reaction, the results are as follows:The effect of light intensity showed that-ln (1-X)=klτ:As0.21mW·cm-2<Ⅰ<0.98mW·cm-2, n=1, k=2.1cm2· mJ-1As0.98mW·cm-2<Ⅰ<1.78mW·cm-2,n=0.4, k=2.1cm0.8· mW-0.4·s-1;In the range of the humidity from0.04vol%to0.50vol%, photocatalytic conversion of HCHO to CO2increased with increasing the humidity, in the range of the humidity from0.50 vol%to1.10vol%, photocatalytic conversion of HCHO to CO2kept almost constant, in the range of the humidity from1.10vol%to1.63vol%, photocatalytic conversion of HCHO to CO2decreased with increasing the humidity.Under the irradiation of365nm UV lamp for the calcined film, overall rate was controlled by reaction within the scope of the inspection (linear velocity>3.3cm·s-1). In the range of the humidity from0.04vol%to0.80vol%, photocatalytic conversion of HCHO to CO2increased with increasing the humidity, while in the range of the humidity from0.80vol%to1.66vol%, photocatalytic conversion of HCHO to CO2kept almost constant.更多还原