Investigation In Adsorbting-Photocatalytic Degradation Of Low Concentration Formaldehyde In Air

Ceramics-activated-carbon (CAT) was prepared by phenolic resin as precursor and foamed ceramics as carrier, using a combining method of KOH-activation and steam-activation, after curing and carbonizing phenolic resin impregnated on the ceramics. The effect of activation temperature, carben ignition loss rate, iodine adsorption value, BET and pore structure of activated carbon were systematically studied by orthogonal experiments. TiO2 film is deposited to CAT by sol-gel method in which CAT is dipped in sol-gel solution and heated in temperature of centigrade by use of Ti(OBu)4 as TiO2 precursor, resulting in the accomplishment of CAT-TiO2 composite catalyst. The optimized process parameters was determined through exploring the formula and process of sol-gel. It was indicated by XRD analysis and SEM analysis that the crystal size of TiO2 is 24 nm, which was distributed uniformly and was sticked firmly to the surface of CAT.Degradation of low concentration formaldehyde in air was investigated in the photocatalytic reactor with the composite catalysts. It is exhibited by the results of the degradation that maximum degradation rate could reach 87% under four UV lamps, in the humidity of 45%, at the temperature of 30℃, and at the speed of flow of 0.8m3/h, when the CAT were deposited with 2-layer film TiO2 sol and at calcining temperature of 500℃. Photocatalytically degradation could still arrive over 80%, after five times of recircle with the composite catalysts, which manifested the superiority of adsorption-photochemical synergistic action of the composite catalysts.