Study On Degradation Of Formaldehyde By Nano - TiO 2 Modified By Activated Carbon Fiber

Formaldehyde as one of the most common gas of the indoor air pollution can serious influence the quality of the doors. More and more people at home and abroad pay attention to it. The photocatalytic technology friendly to the environment, but it has some disadvantages, such as the degradation efficiency is not high、the low light efficiency. Therefore in this paper on the one hand, we modified nano-TiO₂; On the other hand, we load the modified nano-TiO₂ with activated carbon fiber（ACF） which has a good physical adsorption capacity. The process can effectively improve the degradation efficiency of the formaldehyde indoors.（1）In this paper, we choose Butyl Titanate as the source of titanium which preparation of pure TiO₂、Fe³⁺ and Ag⁺ single mental doped TiO₂ respectively and Fe³⁺ and Ag⁺ co-doped TiO₂. We use the thermogravimentric（TG）、X-ray diffraction（XRD）、transmission electron microscope（TEM） and ultraviolet-visible spectrophotometer（UV-Vis DRS） to analyze our materials. By the test results, in the 500℃, Fe³⁺ and Ag⁺ single mental doped Ti O₂ and co-doped TiO₂ promote the anatase to rutile. In the condition of the m（Fe）: m（Ag）: m（TiO₂）= 0.5%: 1.5%: 1, the crystal structure、crystal morphology、distribute and particle size are optimal. Compared with the Fe³⁺ and Ag⁺ single mental doped TiO₂, the particulate reinforce and the particle size are more uniform; The grain diameter is smaller which is about 13- 18nm; The red shift of Fe³⁺ and Ag⁺ co-doped TiO₂ is more obvious which red shift from 400 nm to 500nm; Light absorption range wider and expand into visible light. The spectra of UV- Vis DRS indicate that Fe³⁺ and Ag⁺ co-doped modified TiO₂ has a certain synergy helping to improve the photocatalytic properties of the nano-TiO₂.（2）In this paper, we preparation the composition materials which the ACF load the different photocatalysis( ACF, pure TiO₂, Fe³⁺ or Ag⁺ single mental doped and co-doped TiO₂) by the dipping pulling method, discussion the degradation rate of formaldehyde by use the different composite material. By the experiment result, the degradation rate of composition materials which Fe³⁺ and Ag⁺ co-doped TiO₂/ ACF is the highest which can reach 87.3% under 10 w UV light in the three hours. So it is superior to other three kinds of composition materials. Fe³⁺ and Ag⁺ co-doped TiO₂ has a certain synergy to the degradation of the formaldehyde.（ 3） In exploring the process of preparation conditions, we know that the composition materials of Fe³⁺ and Ag⁺ co-doped TiO₂, calcination at 500℃ has the highest degradation of the formaldehyde which can reach 87.3% in the three hours. The temperature of heat treatment will directly affect the efficiency of composite degradation of formaldehyde. The best amount of Fe³⁺ and Ag⁺ single mental doped TiO₂ is 0.5% and 1.5% respectively. The best proportion of Fe³⁺、Ag⁺ and TiO₂ is m（Fe）: m（Ag）: m（TiO₂）= 0.5%: 1.5%: 1. The composite materials which load 1.35 g doping catalyst has the highest degradation rate of formaldehyde and it can reach 87.3% in the three hours. The right amount of load can improve the degradation rate of formaldehyde which can promote the physical adsorption of ACF and co-doped photocatalysis synergy effect; UV light intensity can increase the degradation rate of formaldehyde, and increasing along with the enhancement of ultraviolet light. The formaldehyde degradation rate of 10 w UV lamp is better, 87.3%, under three lamps light irradiation（6w, 10 w UV lamp and 25 w incandescent lamp）; In addition, the degradation time extended further, formaldehyde degradation rate grow slowly（3 4 h）, almost unchanged at the 3.5h.