Removal of Cu2+ from wastewater by modified xanthan gum (XG) with ethylenediamine (EDA)

Abstract

Herein, a new adsorbent was synthesized by modifying xanthan gum for the removal of Cu²⁺ from wastewater. Xanthan gum was first successfully modified with thionyl chloride followed by ethylenediamine. The modified xanthan gum was characterized via Fourier transform infrared spectrometry (FTIR), carbon nuclear magnetic resonance (¹³C NMR), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and thermogravimetry (TG) for a better understanding of its Cu²⁺ removal efficiency. In addition, the effects of pH, contact time, adsorbent dosage, initial concentration of Cu²⁺ and coexisting ions on the adsorption of Cu²⁺ were investigated via batch adsorption studies. Results suggest that the adsorption process of Cu²⁺ follows a pseudo second order kinetics model with an equilibrium time of 120 min. The experimental data could be fitted with the Langmuir isotherm better than the Freundlich model. The adsorption capacity of Cu²⁺ by the modified xanthan gum reached up to 46.95 (mg g⁻¹). The adsorbent could be easily regenerated by only the addition of 0.1 M HCl. Also, the adsorption effect of other divalent cations by XG-NH₂ was preliminarily investigated.