Preparation Of Basic Bismuth Nitrate Based Heterojunction And Its Application In Dye Wastewater Photodegradation

Dye wastewater is a great threat to the water environment due to its color,hard to degradation and high toxicity.In recent years,advanced oxidation technology,especially the photocatalysis oxidation technology has shown great promise for the dye wastewater degradation.Photocatalysis technology has advantages of simplicity,can degrade low concentrations of wastewater with no secondary pollution formed.Bismuth based semiconductor has become an ideal catalyst for dye wastewater photodegradation due to its high valance potential and good oxidation ability.It is important to research of the influence factor of bismuth based semiconductor and design simple,efficient bismuth based heterojunction for enhanced photocatalytic activity.Through the research of this thesis,it shown that building a heterojunction based on basic bismuth nitrate is an efficient way to boost the photocatalytic performance of bismuth based semiconductors.?0 0 1?and?0 1 0?facet-dependent BiOX?X=Cl,Br?was prepared through adjusting the pH of the solution by a hydrothermal method.The effect of different facet-dependent to the photocatalytic performance of BiOX was tested by using Rhodamine B as the target contaminant.The experimental results showed that the BiOX with exposed?0 1 0?facets exhibit better photocatalytic activity than?0 0 1?facets.It showed better light absorption capability and faster separation of electrons and holes.Bi₆O₆?OH?₃?NO₃?₃.1.5H₂O/BiOCl?BHN/BiOCl?heterojunction was prepared by adjusting the ratio of Bi?NO₃?₃ and NaCl in solution through hydrothermal method.Through SEM and TEM characterization,it can be seen that the BHN added has effect on the morphology of the heterojunction catalyst,so that the original sheet becomed a self-assembled flower.The dye Rhodamine B was used as a target contaminant to evaluate the photocatalytic activity of the prepared heterojunction catalyst.The experimental results showed that the photocatalytic performance of the heterojunction was much better than BiOCl.The UV-Vis,EIS and PL characterizations indicated that the added BHN can enhance the light absorption capacity of the heterojunction,beneficial to reduce the surface resistance of the material and facilitate the transfer of electron and hole pairs.The capture agent experiments showed that the active species during the photocatalytic oxidation of dye Rhodamine B were superoxide radical and holes.Bismuth molybdate was used as the visible light response semiconductors,about 10 nm basic bismuth nitrate was in situ growth on the nanosheets of bismuth molybdate by adjusting the ratio of Bi?NO₃?₃ and Na₂MoO₆ in solution through hydrothermal method.The experimental results showed that after adding 4.4%basic bismuth nitrate to bismuth molybdate,and the degradation rates of the heterojunction are 8.5 times than that of the pure bismuth molybdate.Moreover,a mechanism for the efficient transfer of photogenerated electrons and holes was proposed.The heterojunction also exhibits a good stability performance through recycle experimental.