| With the rapid development of industrial technology,technological products have caused various pollutions to the ecological environment.Formaldehyde is one of the main organic pollutants in the room.It has a wide source and high content,and it can seriously cause death.It is the most polluted organic pollutant and has been classified as the first type of carcinogen.The management of formaldehyde is an urgent matter.Photocatalytic technology for the degradation of formaldehyde is economical,efficient,and pollution-free.The most common one is TiO2,which is currently the hot spot and the most extensive application.However,TiO2 is easy to agglomerate during use,the specific surface area is small,the contact area with formaldehyde molecules is small,so the photocatalytic purification effect is not obvious.So TiO2 is supported on the porous material carrier,the adsorption technology is combined with the photocatalytic purification technology to improve the removal efficiency of formaldehyde.In this paper,porous coconut shell activated carbon?AC?,AC modified by 2mol/L,4mol/L,6mol/L HNO3 and fly ash zeolite molecular sieve?ZMS?are used as carriers.Using butyl titanate as the titanium source and the sol-gel method as the preparation method to prepare the composite photocatalyst TiO2/AC,TiO2/AC-4,TiO2/ZMS.X-ray diffraction?XRD?,scanning electron microscopy-energy spectroscopy?SEM-EDS?and specific surface area?BET?characterization tests were carried out on the composite photocatalyst materials,the photocatalytic mechanism was analyzed,and ultraviolet photocatalytic purification tests on formaldehyde were conducted.To study the effect of three different factors,such as light time,ultraviolet radiation intensity,and air humidity,on the removal efficiency of formaldehyde,the removal rate of formaldehyde from the composite photocatalyst of porous materials was used as a benchmark.The three factors were controlled as time 0min,30min,60min,90min,120min,150min,ultraviolet radiation intensity is 0,3.7?W/cm2,7.4?W/cm2,11.1?W/cm2,14.8?W/cm2,18.5?W/cm2,the air humidity is 30%,40%,50%,60%,70%,80%.Comparing the purification effect of formaldehyde under different conditions,the reaction mechanism and influencing factors of physical adsorption-photocatalysis combined technology were analyzed,and the best materials were also found.The main conclusions are as follows.1.The study results show that the sol-gel method was used to successfully prepare TiO2,TiO2/AC,TiO2/AC-4,TiO2/ZMS.The synthesized anatase TiO2 was effectively loaded on the porous material carrier,supported on the surface of the AC,and coated on the surface of the ZMS.It has no effect on the adsorption of AC,reducing the adsorption of the ZMS.The AC treated with 4mol/L HNO3?AC-4?has the best adsorption performance.The ZMS has the best adsorption performance among the three materials.2.The experiment conditions were system temperature 18?,relative humidity 30%,and air volume 1.7m3/min.With the increase of ultraviolet radiation intensity and the increase of light time,the removal rate of formaldehyde from the three composite photocatalysts gradually increased.When the ultraviolet radiation intensity is 18.5?W/cm2,and the irradiation duration is150min,the removal rate of formaldehyde by TiO2/AC,TiO2/AC-4,TiO2/ZMS is better than AC,AC-4 and ZMS,which is obviously better than TiO2 powder.Among them,the removal rate of formaldehyde by TiO2/AC reached 84.9%,which was 37.9%higher than AC and 58.2%higher than TiO2.The removal rate of formaldehyde by TiO2/AC-4 reaches 92.1%,which is27.1%higher than AC-4 and 65.4%higher than TiO2.The removal rate of formaldehyde by TiO2/ZMS reaches 76.24%,which is 1.98%higher than that of ZMS and 49.54%higher than that of TiO2.3.The experiment conditions were system temperature 18?,ultraviolet radiation intensity 18.5?W/cm2,and air volume 1.7m3/min.The removal rate of formaldehyde of the three materials increased first and then decreased with the increase of humidity.The peak appeared at a relative humidity of 60%.The removal effect of TiO2/ZMS was the best,but only2.42%higher than that of TiO2/AC-4.4.The experiment conditions were system temperature 18?,relative air humidity 30%,and air volume 1.7m3/min,ultraviolet radiation intensity 18.5?W/cm2,irradiation duration150min.Among the three materials,TiO2/AC-4 has the best photocatalytic performance for formaldehyde.It has a reference value for the research and development of new composite photocatalytic materials and the development of formaldehyde purification technology in indoor air. |
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