Effective Removal of Copper(II) Ion from Polluted Water Using Ferric Oxide-Chitosan Composite: Kinetic, Equilibrium and Adsorption Mechanism Studies

Abstract

In the current research, ferric oxide-chitosan composite (FOCC) was synthesized by loading chitosan with ferric oxide which was obtained from a kind of ferrous sulfate waste liquid by chemical precipitation, and FOCC was used to adsorb the copper(II) ion from polluted water. The effects of copper(II) ion adsorption experimental factors including initial pH, FOCC dosage and contact time on the removal efficiency were determined, and the related copper(II) ion adsorption mechanism was discussed. The copper(II) ion adsorption optimization study was performed through Box–Behnken design (BBD), and the maximum efficiency of copper(II) ion removal reached 99.23% under the optimized adsorption conditions of initial pH = 5.57, FOCC dosage = 2.5 g/L, contact time = 15 min. The kinetics of copper(II) ion adsorption by FOCC fits well with the pseudo-second-order model (R² > 0.9920), indicating that the copper(II) ion adsorption process belongs chemisorption. The maximum adsorption capacity of FOCC for copper(II) ion is 14.81 mg/g when the temperature is 55 °C. Under the above temperature, the isothermal experiments show that the Langmuir model (R² > 0.9920) is more suitable for describing copper(II) ion adsorption process than the Freundlich model(R² > 0.9504). The adsorption of copper(II) ion onto FOCC is endothermic(\({\Delta H}^{^\circ }<0\)) and spontaneous(\({\Delta G}^{^\circ }<0\)). In general, the study demonstrates FOCC is a quite promising material for copper(II) ion removal from polluted water.