Design,Synthesis And Dye Removal Performance Of MOFs Based On Benzene Polycarboxylic Acid

In the last two decades,considerable research efforts have been devoted to the study of metal-organic frameworks?MOFs?,not only owing to their intriguing fascinating structure with rich topology,adjustable aperture and extremely large specific surface area,but aslo due to their potential applications in gas adsorption,separation,catalysis and so forth.Some MOFs have been used to remove organic dyes from nonaqueous solution,considering their poor moisture susceptibility.Most likely because preventing the hydrolysis-induced collapse of porous structure is challenging.Our efforts are focused on utilizing rigid and semi-rigid ligands of benzene polycarboxylic acid to assemble stable MOFs for dye removal in aqueous solution.Therefore,according to the principles of crystallography and topology networks,MOFs with different topological structures and pore sizes were prepared and selected out water stable MOFs for using in dye sorption,separation and photodegradate.The specific works in this thesis are as follows:?1?The identical crb topology of complexes 1 and 2 were prepared under solovthermal conditions.And the complex 3 was fabricated under ureathermal conditions.The mixed nitrogen-containing ligand and rigid terephthalic acid can be used to assemble Cd-based MOFs-4.Among of them,CoOF-1 is instable,but complexes 2-4 all have better water stability,so they are applied to photodegradate the methylene blue?MB?,rhodamine B?RhB?and methyl orange?MO?dyes in aqueous soltion.The experimental results show that the anionic 3D framework of complex 2 can degradate cation MB/RhB in aqueous solution,while the neutral framework of complexes?3 and 4?have certain degradation effect on the anionic dye?MO?.?2?It is generally accepted that the shape and size of the pores of MOFs have important influence on dye adsorption and selective separation.Two novel isoreticular cadmium based MOFs of 5 and 6 with sra topologic networks have been constructed based on C-C bond-rotatable ligand of H₄BPTC and Cd?II?ingeniously to form neutral MOF under diverse reaction conditions.The structure of 5 exhibits 1D consistent rhombic channel which possesses dimensions of 8.80×11.11?²,but 6 possesses the inconsistent rhombic channels with dimensions of which are about 8.96×11.37?² and 9.53×9.53?²,respectively.The two MOFs exhibit distinct uptakes and good selectivity for cationic methylene blue?MB?molecules.The pseudo-second-order kinetic model and Langmuir isothermal model were utilized to elaborate the behavior of MB adsorption onto 5 and 6.And,these results indicate that their adsorptions are chemisorption,and adsorption isotherms follow monolayer adsorption.In addition,the adsorption capacity and adsorption kinetic constant of 6 are greater than those of 5,showing the importance of porosity and pore size during the adsorption.Moreover,two MOFs both show effectively degradation of rhodamine B and methyl orange?MO?organic dyes under UV light irradiation.Therefore,They are rare multifunctional materials that can adsorb,separate and photocatalytic degradate dyes at the same time.?3?There is no denying that metal active sites of MOFs may mediate the effection of the adsorption and separation of dyes.Two isomeric In-OFs 7?unt?,8?PtS?and a new pentanuclear zinc clusters?ZnOF-9?were discovered.These materials were easily prepared as a pure phase via the solventhermal preparation.As a result of all these,these 3D fremework of7-9 were observed that pseudo-second-order kinetic and the Langmuir monolayer adsorption isotherm model are suitable to fit the experimrntal data for dyes sorption and photocatalysis.These complexes 7-9 all dispaly good ability of selectively adsorb and separate MB.Prominently,the MB adsorption capacity of 9 is reached to 175.24 mg g^-1?which is equivalent to that of MOF-235?.At the same time,they both degrade RhB and MO organic dyes.Therefore,they are rare porous materials which suggest their promising application in dyes adsorbtion,separation and photocatalytic degradation at the same time.