Application Of MOFs Materials Based On Nitrogen-Containing Carboxylic Acid Derived Ligands In Catalysis

Persistent organic pollutants（POPs）and other pollutants with poor biodegradability and large molecular weight are difficult to remove through natural environmental remediation and existing science and technology.Some pollutants that are difficult to mineralize could be converted by advanced oxidation process（AOP）into non-toxic small molecular substances.Metal-organic frameworks（MOFs）reflects unique structural advantages in designing catalytic materials due to their ultra-high porosity and specific surface area.Function-oriented design of controllable and tunable MOFs is also critical for the synthesis of target materials.Crystalline materials are constructed by organic carboxylic acid ligands and nitrogen-containing ligands as linkers and prepared by adjusting the types of solvents.The strategy of in situ carbonization to synthesize novel metal/carbon materials extends the application of MOFs in catalytic filed.In this paper,the preparation process of MOFs crystalline materials and their derivatives and their performance in catalytic degradation of pollutants were studied.（1）Two novel three-dimensionally structured cobalt-based crystalline MOFs（CUST-560 and CUST-561）were successfully prepared using solvothermal methods.The degradation efficiency of anionic and cationic dyes（Rhodamine B,methylene blue,acid red,acid yellow 17）can reach more than 90%within 20 minutes.The rate constants and activation energies are calculated by first-order kinetic equation and the Arrhenius equation respectively.Factors affecting the degradation process,such as different crystal amounts,PMS volume and other factors were explored.The trapping experiments of free radicals confirmed that SO₄^?ˉplays a major role in the system.（2）Three-dimensional CUST-563 was used as a sacrificial template to prepare the carbon materials preparation.A novel crystalline material[Co₂（H₃bpt）（DPE）（H₂O）]was synthesized by solvothermal method using H₃bpt and DPE.The carbon-coated cobalt magnetic nanomaterial Co@C-T（T=500,600,700,800）was prepared by calcination at different temperatures using synthesized the precursor.Co@C-600 showed excellent catalytic activity towards PMS in the degradation experiments of various antibiotics.The influencing factors such as catalyst and OTC concentration,p H and anion,etc.on the OTC degradation process were discussed.After 10 cycles,it still maintains high stability and degradation rate.The free radical quenching experiment combined with EPR test confirmed the coexistence of free radical pathway and non-radical pathway in the system,and proposed the possible mechanism of the reaction process.（3）Three-dimensional CUST-564 was prepared by hydrothermal method,and its composition and structure were characterized.The properties of CUST-564 in catalytic activation of PMS to remove tetracycline（TC）were explored.The experimental results showed that the degradation efficiency of TC could reach 90%after 30 minutes of reaction.Experiments show that the catalyst dosage,PMS concentration and temperature in the reaction system can promote the degradation of TC.The quenching experiments of free radicals showed that SO₄^?ˉacted with other reactive oxygen species to degrade TC.