Study On Synthesis And Dye Removal Of CeO₂·xH₂O And CeO₂@C

Water resources are the focus of attention all over the world.However,due to the rapid development of industrialization,more and more water is polluted.China is the largest dyestuff country in the world,accounting for more than 70%of the world's output.Many printing and dyeing enterprises have discharged a large amount of dye wastewater in the process of production and manufacture,which has caused a lot of troubles to biology and human daily life.With the wide application of semiconductor photocatalyst in the field of environment,Researchers have developed a series of semiconductor catalysts,such as TiO2?ZnO?CdS,etc.CeO2 can exhibit catalytic properties similar to TiO2:low cost,stable properties,but potential absorption of visible light,which has attracted wide attention in the field of photocatalysis.Because CeO2 itself has limited absorption of visible light,In order to increase the absorption of visible light by CeO2,to increase the yield of photogenerated electrons and holes induced by visible light,and to improve the photocatalytic efficiency,Researchers usually improve the photocatalytic performance of CeO2 by improving its structural properties or preparing complexes.Adsorption is an important factor affecting photocatalysis.In this paper,we change the experimental conditions of synthesis and the way of adding biological carbon.The preparation of CeO2,which has a high adsorption capacity for dyes,has been studied in detail,including the adsorption and photocatalytic degradation of the dyes.The main contents of the study are as follows:1.CeO2@BC materials with high adsorption and photocatalytic properties were synthesized from orange peel as carbon source.CeO2·xH2O@OPP materials with different OPP content were prepared by chemical precipitation method.The alkali treated orange peel powder(OPP)was compounded with Ce(NO3)3·6H2O.The results showed that CeO2 xH2O@OPP exhibited excellent adsorption performance for acid orange 7(A07)and that 90%of the dyes could be adsorbed by 5 min.With the increase of OPP loading,the adsorption capacity of the dyes decreased,which may be due to the excessive binding of opp to hydroxyl sites on the surface of the materials.The number of active sites that bind to dyes decreases.UV-Vis analysis showed that the visible light absorption of the calcined CeO2@BC material increased.The photocatalytic experiment showed that the photocatalytic activity of CeO2@BC calcined with 0.1 g OPP was the highest,and the photocatalytic activity of CeO2@BC was the highest after 50 min irradiation.The A07 degradation rate of 0.2 mmol/L was 97%;The detection of active species showed that O2·-and h+ was the active species for A07 degradation.2.Synthesis of CeO2·xH2O and its adsorption on dyesA series of CeO2·xH2O adsorbents were prepared by chemical precipitation method.The relative factors affecting their adsorption properties were investigated,such as aging temperature,time,pH value of reaction system,etc.The results showed that the pH of solution was larger when the aging temperature was too high.When the aging time is long,the content of NH4+?OH-on the surface of the material decreases,which is not conducive to the adsorption of AR14,the oxygen vacancy on the surface of the material promotes the adsorption,the maximum adsorption capacity of CeO2·xH2O for AR14 is 541.4 mg/g It is also found that the adsorption efficiency of CeO2·xH2O for different acid dyes is different,which may be due to the different content of-SO3-in dye molecules.3.Preparation of CeO2@C with dyes as carbon source and its photocatalytic propertiesWith CeO2·xH2O as adsorbent,different concentrations of dyes were adsorbed and the adsorbed materials were calcined at 600 ? to form CeO2@C material.The results showed that the absorption of visible light increased with the increase of dye concentration;XPS analysis showed that the content of Ce3+ on the surface of CeO2@C increased first and then decreased.The results of photocatalytic experiments showed that the adsorption and photocatalytic activity of CeO2@C was better than that of CeO2 and the photocatalytic activity of CeO2@C was related to the content of Ce3+ on the surface;With the increase of carbon content,the visible light absorption increases,but when the carbon content increases to a certain extent,the photocatalytic efficiency decreases,which may be due to the increase of surface carbon layer thickness,which results in the absorption of most incident light by carbon layer.The light intensity available for CeO2 is reduced.The photocatalytic efficiency of the CeO2@C-2 calcined by adsorption 0.2 mmol/L A07 can reach 74.7%after 20 min photocatalysis of 0.4 mmol/L AO7,which is higher than the photocatalytic efficiency of the related materials.