| Indoor air quality is closely related to human health.It is of great significance to use active purification technology to rapidly and efficiently degrade gaseous formaldehyde.In this project,a new filter material is explored to improve the purification efficiency of gaseous formaldehyde.Firstly,a new type of TiO2-GR/ACF composite purification material was synthesized by combining ACF and TiO2-GR.The composites were characterized by scanning electron microscopy,X-ray diffraction and specific surface area.Then,an experimental platform was built to investigate the degradation performance of TiO2-GR/ACF composites for gaseous formaldehyde.Then,the basic law of formaldehyde degradation of TiO2-GR/ACF composite was explored under the condition of changing the influencing factors.Finally,combined with Langmuir Hinshelwood model,the mathematical model of material adsorption photocatalytic degradation of formaldehyde was established,and the reaction rate constant K'was calculated.The reaction mechanism of formaldehyde degradation process was deeply analyzed,and the correlation between four related factors and K'was summarized.The main work of this project is as follows:1.Three kinds of TiO2-GR/ACF composites with different TiO2-GR loading ratios(22.4%,43.6%,59.4%)were synthesized.The synthesized TiO2-GR/ACF composites were characterized and analyzed by characterization methods.The results show that the composite with 43.6%load ratio has a good load condition,the load film on the fiber is uniform,and the gully structure is clearer.After loading,the phase structure and crystal form of the composite were not destroyed.The specific surface area of TiO2-GR/ACF composite was 893.08 m2/g,which not only retained the adsorption advantage,but also increased the photocatalytic properties;2.Combined with the material performance evaluation test,the influence of ACF material thickness and TiO2-GR photocatalyst load on the adsorption photocatalytic performance of TiO2-GR/ACF composite was explored.The results showed that the ACF material with thickness of 6 mm and TiO2-GR photocatalyst with mass ratio of 43.6%were the most suitable for the synthesis of the composite.The composite had better gas-phase formaldehyde degradation ability,and the formaldehyde removal rate reached 76.58%in 120min.The conclusion corresponded with the characterization results.At the same time,the TiO2-GR/ACF composite was compared with the commercial filter screen.The results showed that under the irradiation of UV lamp,the removal rate of formaldehyde by TiO2-GR/ACF composite was better than that of commercial filter(pure TiO2:66.2%,granular activated carbon:63.2%)within 120 min,and about 50%of formaldehyde could be reduced after 30 min of UV lamp irradiation;3.The basic law of multi factors on the degradation of gaseous formaldehyde by TiO2-GR/ACF was explored through experiments.The results showed that the degradation rate of formaldehyde in gas phase increased at first and then tended to be stable with the extension of time.Within the scope of this experiment,the removal efficiency of formaldehyde increases with the increase of irradiance.When the irradiance is 19.9 w/m2for120 min,the removal efficiency of gaseous formaldehyde is the highest,reaching 84.90%.The purification efficiency of gaseous formaldehyde is positively correlated with the air supply volume.The formaldehyde degradation rate is 84.87%under the condition of 183 m3/h air supply volume,and it only takes 8 minutes for the formaldehyde mass concentration from0.5 mg/m3to 0.4 mg/m3.With the decrease of the initial concentration of formaldehyde,the removal rate of formaldehyde slows down.The three working conditions discussed in the experiment show the same law.There was a negative correlation between the relative humidity and the degradation efficiency of formaldehyde.The highest degradation rate of formaldehyde was 84.87%(RH:27%).The results show that the degradation kinetics of formaldehyde by TiO2-GR/ACF composite filter material is in accordance with Langmuir-Hinshelwood first-order reaction kinetics;4.The regression relationship between the four factors and the first-order reaction rate constant K'was analyzed.The results show that the initial concentration,irradiance and supply air volume have a significant positive effect on K',and the relative humidity has a significant negative effect on K',and the order of correlation between the four factors and the first-order reaction rate constant K'is:initial concentration>supply air volume>irradiance>relative humidity. |
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