TiO₂ Films Prepared With Vacuum Deposition And The Degradation Of Phenol On Them

TiO₂ films were prepared with vacuum deposition coating on different kinds of substrates.The films were characterized by EDS and SEM.One of the most typical and difficultly degradated aromatic compounds--phenol was the objective substance.The photocatalytic and electrochemically assisted photocatalytic degradation of phenol on TiO₂ films were studied.The photocatalytic activity and stability were estimated.Also the effects of some factors were investigated.The result indicated:The surfaces of the TiO₂ films prepared with vacuum deposition are fine,without crack. The distribution of TiO₂ in the films is well-proportioned.An excellent photocatalytic property is investigated,which could degradate phenol in aqueous solution effectively.Different from substrate,the photocatalytic activity is different to some extent.TiO₂/Ti, TiO₂/steel and TiO₂/glass have almost the same activity,while the activity of TiO₂/Cu is much lower,only 1/2 of that of the formers.The TiO₂ films have higher photocatalytie activity than commodity TiO₂ power which was used as the material of the films.The degradation rate of phenol on TiO₂/glass is 57%,when C₀=100mg/L,t=4h,while that of the powered TiO₂ is just 20%.The difference of the granularity may be the reason.In the experiment conditions,the photocatalytic and electrochemically assisted photocatalytic degradations of phenol on TiO₂ films both follow apparen first-order reaction kinetics.The rate of electrochemically assisted photocatalytie quicker than that of photocatalytic.The change of pH inflences both photoeatalytic and electrochemically assisted photocatalytic.The optimal initial pH of photocatalytic is 3 while that of electrochemically assisted photocatalytic is 7.In acidic condition the rate of electrochemically assisted photocatalytic is slower than photocatalytic;In alkaline and litmuless conditions the rate of electrochemically assisted photocatalytic is quicker than photocatalytic.The phenol degradation rate gets the maximum at U=1.0 V.When U＜1.0 V,the rate of electrochemically assisted photocatalytic gets more and more quicker;When U＞1.0 V, turning up the anodic bias the rate gets slower.There is no inference to photocatalytic when the solution contains NO₃^- or SO₄^2-.While C1^-,SO₃^2-,C₂O₄^2- or CO₃^2- may cut down the rate of photocatalytic degradation.All of these ions including NO₃^- and SO₄^2-may have effect on electrochemically assisted photocatalytic,the extent was NO₃^-＜C1^-,SO₄^2-,C₂CO₄^2-＜SO₃^2-,CO₃^2-.