Study On The Preparation And Properties Of Polyethylene Photocatalytic Membranes Loaded With TiO₂ Or TiO₂/BaSO₄

Nano photocatalyst has been widely used in air purification,sewage treatment and other environmental fields because of its high catalytic activity,mild reaction conditions and low secondary pollution.However,there are two restrictions on the extensive application of nano photocatalyst:(1)the high cost of single phase catalyst hinders its large-scale application,(2)the easy aggregation and high loss of the catalyst powder in its application process cuases to difficult recycling and reusing the nano catalyst.In view of these,we propose a method to load the nano catalyst onto the suitable carrier surface to improve the properties of catalyst.In this paper,commercial TiO2 and TiO2/BaSO4 were loaded on polyethylene film to prepare photocatalytic thin films via blow molding and deposition methods,respectively.The photocatalytic degradation of rhodamine B on the resultant catalysts loaded on PE film was investigated.Firstly,a commercial TiO2 was loaded on polyethylene film by blow molding and deposition method respectively.The morphology of the film,the crystal structure of the TiO2 on the film surface and the photocatalytic activity of the film were characterized.The technique for TiO2 loading on PE film were discussed.The results show that TiO2 has been successfully loaded onto the surface of polyethylene film via both blow molding and deposition methods without changing the crystal structure of TiO2.The TiO2-loaded PE film obtained via blow molding method shows a good photocatalystic property for Rhodamine B degradation with a degradation rate of 67.9%,though the value is slightly lower than that of TiO2 powder of 77.3%.However,the photoactivity of the prepared film decreases rapidly in recycling run.On the other hand,The TiO2-loaded PE film obtained via deposition method shows higher adsorption capacity,better photocatalytic degradation property for Rhodamine B with a better recycling feature.The degradation rate of rhodamine B is as high as 99.8%at the first run and is 82.8%even if at fifth run.All prepared TiO2-loaded PE films give higher photoactivity for Rhodamine B degradation than as recieved TiO2 powder.Secondly,The TiO2/BaSO4 catalyst was prepared by loading the TiO2 on BaSO4 surface via the hydrolysis precipitation method using tetrabutyl titanate as a titanium source and BaSO4 as a carrier.The effect of TiO2 dosage,calcining time and calcining temperature on the activity of TiO2/BaSO4 catalyst was studied.The results show that the TiO2/BaSO4 catalyst with 12%TiO2 obtained by calcinating at the temperature of 400 ℃for 3h possesses the highest photocatalytic activety for Rhodamine B degradation.The degradation rate of rhodamine B is 75.1%under the irradiation of visible light for 180 min.The value is slightly lower than that of the homemade pure TiO2 catalyst(79.9%).Finally,The TiO2/BaSO4 catalyst was loaded onto the surface of the polyethylene film by the deposition method.The resultant photocatalytic films have excellent adsorption performance,high photocatalytic activity and recycle performance.The degradation rate of rhodamine B is as high as 94.8%for the first run,and decreases to 69.4%at the fifth recycling run.The photocatalytic activety at fifth recycling run is,with the increase of recycling times,slightly lower than that of the same content of catalyst powder.