Synthesis, characterization and dye adsorption properties of a 3-fold interpenetrated cobalt(II)-metal organic framework based on (E)-5,5'-(but-2-ene-1,4-diylbis(oxy))diisophthalate and 1,4-bis(imidazole-1-yl)butane ligands

Abstract

A new 3D cobalt(II)-metal organic framework, [Co2(μ4-L)(μ-bib)2]n(1) was synthesized with solvothermal method by using (E)-5,5'-(but-2-ene-1,4-diylbis(oxy))diisophthalic acid (H4L) and 1,4-bis(1H-imidazole-1-yl)butane (bib) in the presence of cobalt(II) ion. Compound 1 was characterized by elemental analysis, FTIR spectroscopy and single crystal X-ray diffraction (SCXRD) technique. SCXRD analysis result revealed that 1 displayed a 3-fold interpenetrated 3D framework with bbf topology. The dye adsorption ability of 1 towards methylene blue (MB) was assessed with diverse parameters (pH, the compound amount, temperature, contact time and initial MB concentration). Adsorption kinetics and isotherms fitted well with pseudo-second-order kinetic and Langmuir isotherm models. The highest adsorption capacity of compound 1 was 473.57 ​mg ​g−1 ​at pH ​= ​8.0, 20 ​°C. The adsorption ability could be due to the electrostatic interactions between cationic MB and negative charge density on 1 ​at pH ​= ​8.0. Overall, adsorption studies indicated that synthesized compound 1 may be an efficient alternative adsorbent for MB removal from aqueous solutions.