Preparation Of Photocatalytic Materials Based On Bimetallic Oxides And Design Of Wastewater Treatment Equipment

Graphite phase carbon nitride（g-C₃N₄）is an inorganic layered photocatalyst that has become a potential photocatalyst due to its non-toxic,visible light response and good thermal and chemical stability.However,due to the small specific surface area,low photon-generated carrier separation efficiency and limited visible light absorption range,its application has been limited.The Ce-based bimetallic oxide has the ability to store and release oxygen atoms,thereby generating oxygen vacancies.The presence of oxygen vacancies can promote the migration of photogenerated carriers,so that the photocatalytic activity can be improved.In this thesis,two bimetallic oxides were used to modify g-C₃N₄ by simple heterojunction composite methods.The photocatalyst composites with different component were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,photogenesis spectroscopy（PL）,N₂ adsorption-desorption,Ultraviolet-vis absorption spectroscopy（UV-Vis）,electrochemical test,and photogenesis spectroscopy.The photocatalytic performance was evaluated by the decline of rhodamine B（Rh B）under simulated sunlight.The main research content of this thesis is as follows:Firstly,the bimetallic oxide cerium titanate（Ce Ti O₄）was prepared with cerium nitrate and titanium dioxide as raw materials,using potassium chloride and lithium chloride as molten salts.Cerium titanate/carbon nitride composites（Ce Ti O₄/g-C₃N₄）were further synthesized by a simple high-temperature solid phase method with the addition of melamine.Ce Ti O₄ nanoparticles are loaded on g-C₃N₄ layered nanosheets in large quantities,forming an interfacial heterojunction structure,which is conducive to photogenerated carrier separation.The photocatalytic activity of the as-prepared photocatalytic heterojunction composite Ce Ti O₄/g-C₃N₄ was studied with Rh B as the target pollutant.According to the experimental results,the photocatalytic degradation rate of Ce Ti O₄/g-C₃N₄ composites under simulated sunlight exposure was higher than that of single Ce Ti O₄ and g-C₃N₄.On the basis of the trap agent experiment,a possible degradation mechanism was proposed.Secondly,petaloid bimetallic oxide lanthanum cerate（La₂Ce₂O₇）were synthesized with lanthanum nitrate and cerium nitrate by a sol-gel method.Lanthanum cerate/carbon nitride composites（La₂Ce₂O₇/g-C₃N₄）were further prepared via a simple high-temperature solid phase method with the addition of melamine,forming a heterostructure with a tight interface between La₂Ce₂O₇ and g-C₃N₄ layers.With Rh B molecules as photocatalytic degradation target pollutants,the photocatalytic degradation performance of the samples under simulated sunlight in different conditions was studied.The results showed that the enhancement of photocatalytic degradation performance was mainly due to the formation of composite heterojunction,which improved the separation and migration efficiency of photogenerated carriers.Finally,the process design of the photocatalytic water treatment system was carried out.First of all,the process flow was designed,while the diagram of the photocatalytic water treatment system was drawn,and various parts of the system were introduced.The calculation was made for each process parameter,based on which,the equipment selection was completed.The main reactor aeration suspended photocatalytic reactor was designed and the engineering drawing was drawn.