Adsorption Kinetics and Equilibrium of Cu(II) from Aqueous Solution by Polyaniline/Coconut Shell-Activated Carbon Composites

Polyaniline/coconut shell-activated carbon (PANI/GAC) composites were fabricated by chemical oxidative polymerization of aniline monomers with GAC as the supporting materials. These prepared PANI/GAC composites were characterized by scanning electron microscopy, N2 adsorption-desorption analysis, and Fourier transform infrared spectroscopy. The effects of various parameters, including aqueous pH, contact time, the initial concentration of Cu(II), and temperature (288-323K) on the Cu(II)'s adsorption, were investigated in detail. Results showed that the adsorption maximum occurs at around pH 5.5 and adsorption equilibrium was achieved in 90min at 400mgL-1 Cu(II) concentration. The adsorption process followed the pseudo second-order kinetics, and the adsorption equilibrium data fit well with the Langmuir isotherm. Thermodynamic parameters indicated that the adsorption processes were endothermic, spontaneous, and more favorable at a higher temperature.