Preparation Of Bismuth Oxyiodide And Its Composites And Study On Synergism Of Adsorption-photocatalysis Degradation

The rapid development of the economic and society has led to the serious environmental pollution of wastewater.Organic pollutants,as a principal water pollution,is widely existed in water because of its highly toxic,well stability and hardly degradation.It is regrettable that traditional physical,chemical and biological processes are unsatisfactory for its removal.Therefore,searching an efficient method for the removal of organic pollutants from wastewater is urgently demanded.Photocatalysis technique has attracted tremendous interest due to strong oxidation for organic pollutants degradation in environmental restoration.In the process of looking for excellent photocatalysts,bismuth oxyiodide(BiOI) shows the outstanding photocatalytic preformance in environmental remediation and energy conversion.BiOI material with unique layered strucure and narrow gap(about 1.7eV),exhibits superoir visible light response and the rapid separation of the photogenerated charge carriers.However,BiOI with small surface and inferior oxidation limits its photocatalytic performance.Several trategies have been empolyed to improve this adsorption-enrichment and photocatalytic of the pure BiOI material,such as morphology controlling,heterojunction constructing,compound with 3D compound hydrogel.Porous carbon nitride has been successfully prepared by step calcination.In comparison with bulk carbon nitride,2D porous carbon nitride exhibied not only shortened diffusion distance for photogenerated carrier transport but also large contact area for rapid interfacial charge separation,Nevertheless,it was far from satisfaction due to the poor light harvesting.Coupling 3D flower-like BiOI with 2D pCN to form heterojunction not only enhance light harvesting effiency,but also promote electron and hole separation to improving photocatalytic preformance.The photocurrent of pCN/BiOI photocatalyst is 3.6 times that of porous carbon nitride and 5.9 times that of bismuth oxyiodide.The methylene blue and the levofloxacin hydrochloride degradation ratio over the pCN/BiOI photocatalyst were 1.97?2 times for porous carbon nitride and 1.25?1.71 times for bismuth oxyiodide.The 3D/2D/3D BiOI/porous carbon nitride/graphene hydrogel(BPG) has been successfully synthesized by two step solvothermal method,not only demonstrate the effective absorption of pollutants and multidimensional substance transmission channel,but also favor separation from the reaction solution.In static system,the degradation efficiency of methylene blue(MB) and the typical antibiotic levofloxacin hydrochloride(LVF) was 7.2 and 2.7 times as high as BiOI.In flow system,the pollutants could be constantly degraded without with the removal rates about 1.54 and 1.67 times higher than those of BiOI,which kept unchanged for 30 h.Moreover,the synergistic effect of adsorption-enrichment and photodegradation of the composite hydrogel solved the problem of the adsorption saturation of the adsorbent,and improved the photocatalytic activity of the photocatalyst simultaneously,which make the BPG has a wider application prospect in the field of environmental restoration.