Study On Degradation Efficiency Of RGO-TiO₂ Flexible Catalytic Film For Pollutants Under Simulated Sunlight

Along with rapidly development of industry,water pollution has become one of the main factors that hinder the development of the global economy.And the refractory organic pollutants and heavy metal ions frequently occurring in industrial production have become the focus and difficulty of water pollution control because of their difficult degradation and harmful effects on the environment and human body.Semiconductor photocatalytic technology is considered as the most promising water treatment technology because of its high efficiency,mild reaction conditions and applicability to most pollutants.Among many photocatalytic materials,titanium dioxide?TiO₂?has become the most widely used semiconductor photocatalytic material due to its high photocatalytic activity,stable physical and chemical properties,light corrosion resistance,non-toxic,environmentally friendly and cheap advantages.However,there are still some problems in the practical application of TiO₂,such as small spectral response range,high electron-hole recombination rate,difficulty in separation and recovery,which limit the wide application of the materials.In order to solve the above problems,graphene oxide?GO?was doped into TiO₂ to prepare reduced graphene oxide-titanium dioxide modified composite?rGO-TiO₂?.Then rGO-TiO₂ nanomaterials were immobilized on flexible thin films to obtain rGO-TiO₂ thin films,so that the photocatalytic materials could be recycled and reused.Degradation efficiency of emerging contaminants such as bisphenol A?BPA?,carbamazepine?CBZ?,sulfamethoxazole?SMX?and heavy metal ion Cr???under visible light irradiation by rGO-TiO₂ thin film were investigated.The degradation of the thin film was investigated,its catalytic performance was explored,and the large area flexibility of the catalyst was studied.And possibility of practical application were also studied.?1?rGO-TiO₂ nanocomposites were prepared by hydrothermal synthesis from commercial titanium dioxide P25 and graphene oxide?GO?.Composites with different GO doping ratios of 1% rGO-TiO₂,3%rGO-TiO₂ and 5%rGO-TiO₂ were prepared respectively.The prepared composite material was coated on a large area flexible thin film material by coating method.After calcination and fixation,rGO-TiO₂ thin film was obtained.?2?Four kinds of film were prepared,one layer pure titanium dioxide coatings,3%rGO-TiO₂ coatings,one layer,two layers and three layers.The degradation efficiency of the emerging contaminants was investigated under visible light irradiation.The film with two layers had the best degradation efficiency.By changing the amount of GO doping in titanium dioxide,1% rGO-TiO₂,3% rGO-TiO₂ and 5% rGO-TiO₂ composite nanomaterials were prepared and fixed on the film base.At the bottom,the degradation efficiency of 3%rGO-TiO₂ film is the highest;when the initial concentration of target pollutants increases,the degradation efficiency of 3%rGO-TiO₂ film decreases;when the solution pH increases,the degradation efficiency of CBZ and BPA increases,but the degradation efficiency of SMX decreases;the increase of aeration in the reaction system also promotes the degradation efficiency.However,the removal rate of target pollutants decreases when the aeration volume is 3L/min.?3?After determining the optimum combination of film thickness and GO doping amount,inorganic anions such as CO₃^2-,SO₄^2-,Cl^-,NO₃^-were added to the reaction system.The degradation rate of emerging contaminants in 3%rGO-TiO₂ film under visible light photocatalysis was inhibited and promoted to varying degrees.CO₃^2-,SO₄^2-,Cl^-all inhibited the catalytic reaction,while NO₃^-played a certain role in the degradation rate of pollutants.When the background water was changed,tap water,surface water and secondary effluent all inhibited the visible-light photocatalytic oxidation of pollutants by3%rGO-TiO₂ film.?4?The reduction ability of rGO-TiO₂ films was investigated.When 3%rGO-TiO₂thin films were used to reduce Cr???under visible light photocatalysis,the addition of citric acid promoted the reaction rate.The reaction rate constant reached the maximum at the concentration of citric acid of 1 mM.The reaction rate decreased with the increase of the concentration of Cr???;the change of solution pH affected the reduction of Cr???by 3%rGO-TiO₂ films under visible light photocatalysis.The reaction rate constant decreases with the increase of pH.