| China is a big energy consumer,and coal plays an irreplaceable role in the operation of thermal power plants.The flue gas produced during coal burning contains mercury.Mercury can cause serious pollution and harm in people's daily production and life.The treatment of mercury is an important subject,and it is urgent to study the technology of removing mercury from the flue gas.Photocatalytic technology has many advantages,such as strong oxidation ability,no secondary pollution,low cost,high efficiency,etc.,which has attracted the attention of scientific workers day by day.Titanium dioxide is a kind of semiconductor material with good photoreactivity,non-toxic and cheap,but its shortcomings such as wide band gap and strong carrier recombination limit its catalytic ability.Bismuth oxyiodate has a layered structure and a suitable forbidden band width,which is conducive to the continuous progress of the photocatalytic reaction.After being combined with titanium dioxide,it can significantly inhibit the recombination of carriers,and the catalytic efficiency is high.The TiO2-BiOIO3 composite material has a simple preparation process and low cost,and is a catalyst with potential for photocatalysis applications.The TiO2-BiOIO3 composite material was prepared by hydrothermal and calcination methods.The photocatalytic mercury removal efficiency of TiO2-BiOIO3 in the presence of water and sulfur dioxide was studied.XRD,XPS,TEM,PL,TPD,FTIR,Characterization methods such as ESR and UV-vis reduced the physical properties of TiO2-BiOIO3,and proposed the reaction mechanism of photocatalytic removal of pollutants.Characterization shows that TiO2-BiOIO3 has an excellent heterojunction structure,which effectively reduces the recombination of photogenerated electrons and holes,and improves the catalytic performance.The calcination will cause the catalyst to form defects and easily form the capture sites and active sites of photogenerated carriers.which strongly promotes the efficiency of photocatalytic removal of pollutants.The mercury removal efficiency is divided into two kinds of efficiency,one is physical removal,that is,the photocatalyst physically adsorbs mercury,and the other is chemical removal,that is,the photocatalytic oxidation of Hg0 to HgO.The method of using tin tetrachloride solution to reduce HgO successfully calculated the efficiency of physical and chemical mercury removal under each working condition.In exploring the working conditions of different sulfur dioxide concentration and moisture,the reaction gas was collected using a serpentine tube and isopropanol,and the presence of SO3 was detected by the analysis of ion chromatograph.Through XPS analysis of the photocatalyst before and after the reaction,by discovering the movement of Bi 4f and I 3d points before and after the reaction,it is proposed that the presence of water will affect the electron transfer mode in the photocatalytic reaction.Through experimental analysis,water molecules and sulfur dioxide molecules will compete with Hg0 for active sites on the surface of the photocatalyst,and the higher the concentration of water and sulfur dioxide,the more intense the competition and the lower the mercury removal efficiency.SO2 is oxidized to SO3.It does not adhere to the surface of the catalyst,but leaves with the flue gas flow.TiO2-BiOIO3 composite material is conducive to the flow of photogenerated electrons,has a strong response to light,high catalytic efficiency,and has a broad application prospect. |
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