A new stable and reusable nanoscale Cu(II) coordination polymer as an efficient dye adsorbent

Abstract

A new two dimensional nanoscale Copper(II) coordination polymer (CP), [Cu2(pydc)2(bpy)(H2O)2]n (1), where pydc = pyridine-2,5-dicarboxylic acid and bpy = 4,4ʹ-bipyridine, was synthesized using a sonochemical method. CP1 was characterized by scanning electron microscopy (SEM), elemental analysis, FT-IR spectroscopy and X-ray powder diffraction (XRD) and its solid-state structure was determined using the single crystal X-ray diffraction technique. In CP1, each Cu atom is connected to two other Cu atoms through two pydc2− ligands resulting in a 1D helix chain in the b direction, which is then interlinked to the other chains via bpy ligands and produces a 2D coordination polymer. Considering the low cost and availability of CP1, its adsorption performance for dye removal specifically for the dye Congo red (CR), was examined. The maximum mono-layer adsorption capacity of CP1 towards CR could reach 833 mg.g−1, which is higher than most reported CPs. CP1 was successfully recovered using a green sonochemical method for five cycles of adsorption-desorption. The effects of various parameters including pH, initial concentration of CR, reaction time, and adsorbent dose were evaluated. Based on the above results, nano-CP1 could be considered as a potential candidate for the treatment of the pollutions arising from the production and application of dyes.