Modification Of Metal-organic Skeleton UiO-66 And Its Composite Materials For The Study Of Photo-assisted Fenton Catalytic Degradation Reactions

In recent decades,water pollution has become more and more serious.The photocatalytic oxidation technology and the Fenton oxidation technology are highly respected for their high efficiency and environmental protection,and the Fenton oxidation performance is enhanced to a certain extent under light.In this thesis,UiO-66 has been chosen as the research object,and as the substrata to synthesize a composite catalyst with multiple components.That can maximize the advantages of UiO-66 to achieve effective activation of PMS under light assistance and improve its catalytic performance.Based on literature research,three systems have been studies in this paper.In the second chapter of this thesis,cobalt ions are doped into the metal-organic skeleton UiO-66.A series of cobalt-doped UiO-66 with different Cocontents were prepared by hydrothermal synthesis method.In the presence of xenon lamp irradiation and PMS,the degradation efficiency of RhB by composite catalyst is much higher than that of pure UiO-66,and even slightly higher than that of homogeneous Co²⁺/PMS system.The high catalytic efficiency can be ascribed to the large channel of UiO-66 and the effective separation of photo-generated charges in cobalt-doped UiO-66.The catalyst with 4%Coin mass in UiO-66（4%Co-UiO-66）showed the highest degradation efficiency.The trapping agent experiment and EPR data showed that sulfate radical was the main active species.Based on experimental investigation and related literature,a possible reaction mechanism is proposed.Finally,the stability of Co-UiO-66 is proved to be excellent by cyclic experiment.In chapter 3 of this thesis,Co₃O₄/UiO-66 composite catalysts with different atomic mole ratios of Zr/Cowere synthesized by hydrothermal method and calcination method.The catalytic degradation performance of Co₃O₄/UiO-66 is higher than that of pure UiO-66 and pure Co₃O₄ by activating PMS under xenon lamp light.The catalytic degradation efficiency reached the highest when Zr:Cois 0.8.The trapping agent and EPR experiments showed that sulfate radical was the main active radicals.A feasible reaction mechanism was proposed based on experimental investigation and related literature,and the stability of the composite catalyst was proved by cyclic experiments.In chapter 4,the p-type semiconductor CoWO₄ is compounded with n-type semiconductor UiO-66（Ce）.CoWO₄/UiO-66（Ce）composite catalysts with different Ce/CO atomic mole ratios were prepared.The catalytic performance of CoWO₄/UiO-66（Ce）is higher than that of pure UiO-66（Ce）and CoWO₄ in the presence of both xenon lamp irradiation and PMS.It may due to the p-n heterojunction formed between UiO-66（Ce）and CoWO₄,and the effective separation of photoelectron-hole pairs is realized due to energy band staggered.The catalytic degradation efficiency reached the highest when Ce:Cois 0.3.The quenching experiment showed that sulfate radical was the main active radicals.According to experimental investigation and related literature,a possible reaction mechanism was proposed,and the excellent stability of the composite catalyst was proved by cyclic experiments.In this thesis,three kinds of Fenton catalysts were prepared using metal-organic framework UiO-66 as the substrate by ion doping and semiconductor recombination.The Fenton-like effect of these catalysts can be enhanced by illumination,and their high catalytic activity and excellent stability have great potential application value in the field of catalytic degradation of pollutants.