Facultad de Química, Universidad Nacional Autónoma de México, Mexico.
J Hazard Mater. 2012 Apr 15;211-212:233-9. doi: 10.1016/j.jhazmat.2011.12.008. Epub 2011 Dec 17.
We investigated the adsorption capacity and photocatalytic removal efficiency of formaldehyde using a hectorite-TiO(2) composite in a bench flow reactor. The same experimental conditions were applied to pure TiO(2) (Degussa P25) as a reference. The catalysts were irradiated with either a UVA lamp (365 nm) or with one of two UVC lamps of 254 nm and 254+185 nm, respectively. Formaldehyde was introduced upstream at concentrations of 100-500 ppb, with relative humidity (RH) in the range 0-66% and residence times between 50 and 500 ms. Under dry air and without illumination, saturation of catalyst surfaces was achieved after ≈ 200 min for P25 and ≈ 1000 min for hectorite-TiO(2). The formaldehyde uptake capacity by hectorite-TiO(2) was 4.1 times higher than that of P25, almost twice the BET surface area ratio. In the presence of humidity, the difference in uptake efficiency between both materials disappeared, and saturation was achieved faster (after ≈ 200 min at 10% RH and ≈ 60 min at 65% RH). Under irradiation with each of the three UV sources, removal efficiencies were proportional to the Ti content and increased with contact time. The removal efficiency decreased at high RH. A more complete elimination of formaldehyde was observed with the 254+185 nm UV source.
我们研究了在台式流动反应器中使用膨润土-TiO2 复合材料对甲醛的吸附容量和光催化去除效率。相同的实验条件适用于纯 TiO2（Degussa P25）作为参考。催化剂分别用 UVA 灯（365nm）或两种 UVC 灯（分别为 254nm 和 254+185nm）照射。甲醛以 100-500ppb 的浓度在 0-66%相对湿度和 50-500ms 的停留时间下在入口处引入。在干燥空气中且没有光照的情况下，P25 约 200 分钟后达到催化剂表面饱和，而膨润土-TiO2 约 1000 分钟后达到饱和。膨润土-TiO2 对甲醛的吸附容量比 P25 高 4.1 倍，几乎是 BET 表面积比的两倍。在存在湿度的情况下，两种材料的吸附效率差异消失，且饱和速度更快（在 10%RH 下约 200 分钟，在 65%RH 下约 60 分钟）。在三种 UV 光源的照射下，去除效率与 Ti 含量成正比，并随接触时间的增加而增加。在高 RH 下去除效率降低。用 254+185nm 的 UV 光源可以更完全地消除甲醛。
