Chondrules. Contained Silver Nano-tio <sub> 2 </ Sub>-al <sub> 2 </ Sub> O <sub> 3 </ Sub> Photocatalytic Indoor Formaldehyde

Indoor air pollution is one of the most concerned environmentalproblems. Air pollutant formaldehyde is a colorless and strongly incentivepoisonous gas, which is harmful to human health. Some methodsfrequently used to treat the pollution of indoor HCHO are adsorption,photocatalytic degradation, o₃/catalysis, non-equilibrium plasma andplant removal. But every one of them has some drawbacks and its effectis not strong.The experiment based on the principle of adsorption andphotocatalysis was conducted by combining excellent adsorbingcapability of alumina with photocatalytic capability of nano-TiO₂improved by Ag⁺ to produce an adsorbing and photocatalysising silverloaded spheroid of TiO₂-Al₂O₃. It could be used to degradateformaldehyde by photocatalysising and the achievements obtained in thisstudy were as follows:1) Al₂O₃ and SiO₂ are primary materials with some helping sinterreagent (MgO), holing reagent (NH₄HCO₃) and felting reagent (CMCNa)in the product. Under the content of Al₂O₃, SiO₂, MgO, NH₄HCO₃ andCMCNa 60ï¼…, 10ï¼…, 5ï¼…, 20ï¼…and 5ï¼…respectively, diameter ofspheroid 5mm treated at 1150℃, an excellent adsorbing capability ofalumina particle was achieved successfully and then loaded TiO₂ on thespheroid by thermal treated at 400℃. There were many different shapesof small uniformal holes present in alumina particle. The holes weredistributed in the interior and exterior facies. Aperture showed three seriesdistribution, small hole constitute with two parts and decomposingNH₄HCO₃ and mineration reagent bring about the large hole.2) It was found in this study that the factores influencingphotocatalytic degradation were strength of light, activated temperatureand activated time. The result showed the silver loaded spheroid ofTiO₂-Al₂O₃ had fairly good quality and the degradation percentage offormaldehyde was over 90ï¼…after treated at 400℃and silver loaded just1ï¼…. Silver loaded could prevent complex between electrons and cavitys, which improved photocatalytic capability of nano-TiO₂.3) Tish paper delivered an elementarily discussion about themechanism of the alumina granule adsorbing and photocatalyticdegrading formaldehyde. There are three status in adsorption isotherm ofHCHO on the surface of Al₂O₃. (â… ) The pressure is strongly affected theadsorption capacity under low pressure condition. (â…¡) Adsorptioncapacity increases and transition appears at high pressure. (â…¢)Adsorption isotherm gets to a high level when the pressure becomes highenough, and then the adsorption is in saturated condition. The chang ofconfiguration of adsorption isotherm attributes to achievement of thesingle molecule adsorption. HCHO is photocatalytically degraded to CO₂and H₂O through the middle outcome HCOOH.