Removal of rubidium ions by polyaniline nanocomposites modified with cobalt-Prussian blue analogues

Abstract

Nanocomposite (NC) adsorbent made of polyaniline (PANI) and modified with Cobalt-Prussian blue analogues (Co-PBA) was prepared by the chemical precipitation method, and its application for adsorption of rubidium ion (Rb+) from aqueous solutions was investigated. First, the adsorbent was characterized by the FTIR, XRD, BET and SEM analyses. The effect of the experimental parameters affecting Rb+ sorption onto the PANI/Co-PBA/NC, such as the pH, adsorbent amount, contact time, the initial concentration of Rb+, and temperature was studied. The Co-PBA is shown to play an important role in the adsorption process. Adsorption increased rapidly within the first two hours of the process. In order to probe the sorption behavior, pseudo-first-order and pseudo-second-order kinetic models were studied. The latter fit accurately the data for the Rb+ ions adsorption. The equilibrium data were fitted to the Freundlich and Langmuir isotherm models, with the isotherm accurately best describing the experimental data. The maximum adsorption capacity was 98mgg−1 at room temperature, whereas at the maximum temperature of 60°C the adsorption capacity was 125mgg−1. The thermodynamic parameters, such as the various energies, were computed. They indicate that sorption of Rb+ onto the PANI/Co-PBA/NC is endothermic and spontaneous.