Experimental Study On Catalytic Purification Of Indoor Formaldehyde By TiO₂-AC/Resin/Zeolite

With the development of modern technology and economy,various decoration,decorative materials and some daily necessities slowly release formaldehyde gas,making indoor air pollution more and more serious.Formaldehyde,molecular formula HCHO,an aqueous solution commonly known as formalin,is a colorless,highly pungent odor.Exposure to low concentrations of formaldehyde can cause dizziness,headache,nausea,etc.Exposure to high concentrations of formaldehyde or prolonged exposure to formaldehyde can cause fetal malformations,damage to the nervous system,increase the likelihood of cancer,and even death.Therefore,indoor formaldehyde purification is an urgent task and a hot topic and focus of research for a long time.In the current formaldehyde removal technology,TiO₂ photocatalytic technology has a good development prospect because of its advantages of high efficiency,easy operation and no secondary pollution.However,TiO₂ tends to agglomerate during photocatalysis,reducing the contact area between TiO₂ and contaminants,and affecting its degradation ability.In order to improve the photocatalytic ability of TiO₂,it is improved by compounding and loading,and its photocatalytic activity is increased.In this paper,the experimental platform for photocatalytic purification of formaldehyde was built by ourselves.The activated carbon,cationic resin and self-made zeolite were mixed with TiO₂.Activated carbon/TiO₂,zeolite/TiO₂ were prepared by sol-gel method,and cationic resin/TiO₂ was prepared by ion exchange method.Taking the degradation efficiency of formaldehyde as the index,the effects of different temperature,relative humidity and ultraviolet irradiance on the photocatalytic performance of the composite catalyst were investigated and the three composite catalysts were compared and analyzed to confirm the optimal composite catalyst.The results show that the formaldehyde removal rate of activated carbon/TiO₂,resin/TiO₂,zeolite/TiO₂ is compared with activated carbon,resin and zeolite under the experimental conditions of system temperature 18?,air relative humidity 30%and wind speed 1.7m³/min.There is a significant increase.Among them,the formaldehyde removal rate of activated carbon/TiO₂ is 37.9%higher than that of activated carbon,the formaldehyde removal rate of resin/TiO₂ is 6.3%higher than that of resin,and the formaldehyde removal rate of zeolite/TiO₂is 2.0%higher than that of zeolite.When the relative humidity is controlled to 30%and the ultraviolet irradiance is 18.5?W/cm²,the experimental temperature is changed.It is found that the removal rate of formaldehyde by activated carbon/TiO₂,resin/TiO₂ and zeolite/TiO₂increases with the increase of temperature.At the temperature of 35?,the formaldehyde removal rate reached the maximum,48.5%,68.3%,79.2%.When the control temperature is18?and the ultraviolet irradiance is 18.5?W/cm²,the relative humidity of the experiment is changed.As the relative humidity increases,the formaldehyde removal rate first increases and then decreases.Activated carbon/TiO₂,resin/The removal rate of formaldehyde was the highest when TiO₂ was 60%relative humidity,which was 72.5%and 86.6%,respectively.When the control temperature is 18?and the relative humidity is 30%,the ultraviolet illuminance is changed.It is found that the formaldehyde removal rate increases with the increase of the ultraviolet radiation,and the ultraviolet illuminance is 18.5?W/cm².The maximum formaldehyde removal rates were 84.9%,68.3%,and 76.2%,respectively.On this basis,the good performance of photocatalytic material for formaldehyde removal was proved and the optimal reaction conditions for photocatalytic purification of formaldehyde were provided,which provided a reference for the development of TiO₂ degradation of formaldehyde.