Application of chitosan/poly(vinyl alcohol)/CuO (CS/PVA/CuO) beads as an adsorbent material for the removal of Pb(II) from aqueous environment

The utilization of CS/PVA/CuO as a novel adsorbent for the removal of Pb(II) from aqueous solution has been examined in a batch adsorption process with several experimental conditions including initial solution pH, dose, contact time, initial metal ion concentration, and temperature. The new and novel material was characterized by structural (XRD), spectral (FTIR), morphological with elemental (SEM with EDS), and size of the nanoparticles (TEM) analyses. The pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations were used to analyze the kinetic data of the adsorption process and the data was fitted well with the pseudo-second-order kinetic model with R-2 values (close to the unity). Equilibrium isotherms for the adsorption of Pb(II) were analyzed by the Langmuir, Freundlich, and D-R isotherm models. The best interpretation for the equilibrium data was given by Langmuir isotherm, and. the maximum adsorption capacity was 116.84 mg/g at pH 5, and adsorbent dose of 100 mg at 323 K. Different thermodynamic parameters namely, Gibbs free energy change (-8.436, -9.167 and -9.723 kJ/mol for 303,313 and 323 K respectively), enthalpy change (11.61, 11.52 and 11.62 kJ/mol, and entropy change (0.0661 J/mol k), were also evaluated from the temperature dependence, and the results suggest that the adsorption reaction is spontaneous and endothermic in nature. (C) 2016 Elsevier B.V. All rights reserved.