Research On The Photocatalysis Of Formaldehyde In Indoor Air And Designing Of Air Purifier

The photocatalytic technology of air purification using nanometer TiO₂ as photocatalysthas been a topic of major in the world. Contrast with other conventional techniques,nanometer photocatalytic technology has more advantages such as higher treatment efficiency,lower energy consumed, more easily controlled, no secondary pollution etc.The purpose of this disquisition is to remove the formaldehyde in indoor air byphotocatalytic oxidation technology.The contents of research include the preparation ofnanometer photocatalyst, designing and manufactureing the photocatalytic reactor, appraisingthe efficiency of photocatalytic reactor and the analysis of the influence of different factors onthe efficiency of photocatalytic oxidation.The nanometer Co²⁺-SiO₂-TiO₂ photoctalyst was prepared by Sol-Gel method, pH of thesol-gel, coating cycle, drying method, calcining temperature, codoped dosage of Co²⁺ werestudied in order to make the photocatalyst have the best photocatalysis. Scanning electronmicroscope (SEM) and X-ray reflection diffraction spectra (XRD) had been used toinvestigate the structural properties and surface morphology of the Co²⁺-SiO₂-TiO₂. Theresults show that particle of Co²⁺-SiO₂-TiO₂ was dried by microwave oven is more finer anduniformer than that dried by oven. The sol-gel was composed of by Ti(OC₄H₉)₄, Si(OC₂H₅)₄and Co(NO₃)₂ when the molar ratio was 1:0.05:0.01. Coating the sol-gel on glass fiber bydipping-drawing way then drying it by microwave oven, repeating those process 4～5 timesbefore calcining it at 500～550℃for 1 hour, then the 1%Co²⁺-5%SiO₂-TiO₂ was obtainedwhich has the highest photocatalytic efficiency of 88% when the initial concentration offormaldehyde is 2.2mg/m³, its photocatalytic ability is about 10% higher than that ofSiO₂-TiO₂.At the basis of above study, the interior construction of photocatalytic air purifier wasoptimized designed, a new construction of gear shape has been brought forword. Comparedwith constructions of cascade and cylinder, the new construction can provide adequatelyContacting between photocatalyst and formaldehyde and ultraviolet radiation, it shows goodefficiency. The effect of humidity on the removal efficiency, and the stability of air purifierhad aiso been studied. As this new photocatalytic air purifier has good performance and 30%cheaper than that sold on the market, it would have enormous market space in the future.