Preparation Of Fe Based Magnetic Porous Materials And Their Adsorption And Photocatalytic Degradation Of Dyes

Nowadays,the water pollution caused by dye wastewater has become one of the most urgent problems to be solved by human beings.Traditional dye wastewater treatment methods such as physical adsorption,chemical degradation are more or less limited.Metal Organic Frameworks（metal-organic Frameworks,MOFs）has become a high quality candidate material for dye wastewater treatment due to its high specific surface area and adjustable pore size.Moreover,the photocatalytic degradation performance of MOFs on Organic dyes by virtue of its quasi-semiconductor properties has attracted much attention.However,it is difficult to solve the problem of recycling after using MOFs,which makes the recycling use of MOFs materials greatly limited.In order to solve the above problems,this paper uses Fe₃O₄ as the magnetic matrix,transition metal element Cu as the metal center,and polycarboxylic acid as the organic ligand to construct a porous material that combines superparamagnetism,light responsiveness and water stability.The adsorption performance and photocatalytic degradation performance of the dye were studied,and the adsorption cycle ability and photocatalytic degradation cycle ability of the dye were studied.The main research contents are as follows:（1）With Fe₃O₄ as the magnetic matrix and Cu²⁺as the metal coordination center,three polycarboxylic acids with similar structures,tri-（p-carboxyphenyl）-m-triphenyltriamide（H₃L）,and tri-（4-carboxy-3methyl）were selected.Three kinds of Fe-based magnetic porous materials Fe₃O₄ were synthesized by using phenyl)-m-trimethylene triamide（H₃L-2-CH₃）and bis（3,5-2 carboxyphenyl）terephthalamide（H₄L）as organic ligands.Fe₃O₄@Cu-H₃L,Fe₃O₄@Cu-H₃L-2-CH₃,and Fe₃O₄@Cu-H₄L.The three materials were characterized and tested by X-ray diffraction,FTIR and TGA.The results show that three kinds of magnetic MOFs materials are successfully prepared,all of which have certain thermal stability,and the addition of Fe₃O₄nanoparticles has a certain protective effect on the overall framework of the material,which can appropriately enhance the thermal stability of MOFs.（2）The adsorption properties and photocatalytic performance of the three magnetic MOFs prepared on cationic turquoise blue X-GB were studied.It was found that all three have good adsorption performance and photocatalytic degradation performance for small molecule linear cationic turquoise blue X-GB.Among them,Fe₃O₄@Cu-H₃L and Fe₃O₄@Cu-H₃L-2-CH₃ have higher adsorption and removal rate of cationic turquoise blue X-GB,and Fe₃O₄@Cu-H₄L has faster adsorption rate for dyes.Under the experimental conditions,the final degradation rate of three kinds of magnetic MOFs for cationic turquoise blue X-GB is very high（corresponding to the degradation rate of 98.29%,99.97%and 98.58%respectively）,and after the experiment,the magnetic MOFs can all move directionally through the external magnetic field.In addition,the effect of Fe₃O₄ addition on the adsorption and photocatalytic degradation of cationic turquoise blue X-GB by MOFs was studied.The results show that Fe₃O₄ can reduce the final adsorption rate of Cu-H₄L to cationic turquoise blue X-GB from 85.81%to 79.86%,and increase the Eg value of H₃L-2-CH₃ from 2.34ev to 2.40ev,but has little effect on the overall adsorption performance and photocatalytic degradation performance.Finally,it is found that the optimal p H value of Fe₃O₄@Cu-H₃L-2-CH₃ for degradation of cationic turquoise blue X-GB solution is 8.（3）The water-stable properties of the three materials were studied.The results show that all three materials have certain water stability,and Fe₃O₄@Cu-H₃L-2-CH₃has the best water resistance stability.Fe₃O₄@Cu-H₃L-2-CH₃ was used to study the adsorption cycle and photocatalytic degradation cycle of cationic turquoise blue X-GB.It was found that Fe₃O₄@Cu-H₃L-2-CH₃ exhibited excellent adsorption cycle and photocatalytic cycle performance for cationic turquoise blue X-GB,and the framework structure and superparamagnetism of the material could be preserved after five cycles.Compared with traditional recycling methods,the magnetic recycling capacity of magnetic MOFs greatly shortens the recycling time and reduces the recycling cost.（4）The adsorption capacity and photocatalytic degradation capacity of Fe₃O₄@Cu-H₃L-2-CH₃ for reactive turquoise blue KN-G were studied.It was found that Fe₃O₄@Cu-H₃L-2-CH₃ did not adsorb the complex macromolecular reactive dye reactive turquoise blue KN-G.Moreover,Fe₃O₄@Cu-H₃L-2-CH₃ sensitized by cationic turquoise blue X-GB showed a certain photocatalytic degradation ability and good photocatalytic degradation cycle ability against the hardly degradable reactive turquoise blue KN-G.After the second cycle experiment,the percentage of catalytic degradation only decreased by 5.38%,and the original structural framework and superparamagnetism of the material were retained.In addition,the addition of Fe₃O₄ decreased the degradation rate of Cu-H₃L-2-CH₃photocatalytic degradation of reactive turquoise blue KN-G by only 1.99%.