One-dimensional coordination supramolecular polymer [Cu(bipy)(SO4)]n as an adsorbent for adsorption and kinetic separation of anionic dyes

A coordination supramolecular polymer, [Cu(bipy)(SO 4 )] n , was prepared as an adsorbent. It has a molecular structure of one-dimensional chain with dense adsorption sites. Three divalent dyes including Congo red, Orange G and Reactive Brilliant red X-3B were tested as pollutants in the adsorption study. The adsorbent showed extraordinary adsorption capacity for all three dyes, reaching 2429   mg/g, 915   mg/g and 1333   mg/g for Congo red, Reactive Brilliant red X-3B and Orange G, respectively. The Langmuir isotherm model can well describe the adsorption isotherm. In kinetic study, all of the three dyes presented a model of pseudo second-order. According to the kinetic rate constants, the adsorption processes are very fast and different for three dyes. The difference can be attributed to the divalent character and the different structure of the dye’s molecule. Based on their discrepancy of adsorption velocity, separation of dyes was attempted through kinetic separation between Congo red and X-3B. A separation coefficient was developed, which can well describe the separation performance results. The results show that the two dyes can be separated quickly and efficiently by [Cu(bipy)(SO 4 )] n .