Immobilization of 2,2′-dipyridyl onto bentonite and its adsorption behavior of copper(II) ions

In this study, the immobilization of 2,2′-dipyridyl onto bentonite was firstly carried out and it was then used for the adsorption of copper(II) ions from aqueous solutions. The variation of the parameters of pH, contact time, initial copper(II) concentration and temperature were investigated in the adsorption experiments. The XRD, FTIR, elemental and thermal analyses were performed to observe the immobilization of 2,2′-dipyridyl onto natural bentonite. The adsorption data obtained were well described by the Langmuir adsorption isotherm model at all studied temperatures. The results indicated that the maximum adsorption capacity was 54.07 mg g−1 from the Langmuir isotherm model at 50 °C. The thermodynamic parameters indicated that the adsorption process is spontaneous, endothermic and chemical in nature. The kinetic parameters of the adsorption were calculated from the experimental data. According to these parameters, the best-fit was obtained by the pseudo-second-order kinetic model. The results showed that 2,2′-dipyridyl-immobilized bentonite can be used as the effective adsorbent for the removal of heavy metal contaminants.