High-Efficiency Organic Contaminants Remover Based On Modulated Self-Assembly Of Cobalt Metal-Organic Frameworks

The pollution of the water environment affected by organic dyes has been become an increasingly serious and concerning environmental problem. Metal-organic frameworks (MOFs), as an excellent adsorbent, have afforded a good platform for the removal of organic dyes from an aqueous system. Herein, four new cobalt-organic frameworks (Co-MOFs), namely, {Co-4(HL)(2)(H2O)(4)}(n) (1), {[Co-2(HL)(H2O)(5)]center dot H2O} n (2), {[Co-4(HL)(2)(4,4'-bibp)5(H2O)(2)]center dot 4,4'-bibp}(n) (3), and {[Co-4(HL)(2)(4,4'-bibp)(4)(H2O)(2)]center dot 4H(2)O} n (4) (H5L = 3,5-bis(3,5-dicarboxylphenoxy)benzoic acid, 4,4'-bibp = 4,4'-bis(imidazolyl)biphenyl), have been successfully synthesized and characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, thermogravimetric analysis, and powder X-ray diffraction. All of them show polynuclear Co(II) 3D frameworks and afford three unique topological networks. The adsorption performances of MOFs 1-4 for organic dyes have been investigated, and 3 and 4 display excellent selective adsorption property for an anionic dye (MO) against a cation dye (MB). The adsorption kinetics, selective adsorption, and adsorption isotherms of 3 and 4 for MO dye have been studied in detail.