Adsorptive materials based on cellulose: Preparation, characterization and application for copper ions retention

Abstract

Hydrogels based on poly(vinyl alcohol) reticulated with TEMPO-oxidized cellulose (OxC25) are proposed as a highly convenient and effective adsorbent for retaining copper ions from aqueous solutions. The equilibrium of the adsorption process was described by the Langmuir model and the adsorption capacity at 20 °C was found to be 357.140 mg of Cu2+/g of hydrogel. The value of the adsorption energy (3.758 kJ/mol) less than 8 kJ/mol, obtained by processing the experimental results according to the Dubinin-Radushkevich isotherm, suggests that the retention of Cu2+ions onto the OxC25 hydrogel may be due to relatively weak coordinative bonding, van der Waals forces, dipole-dipole interactions, and electrostatic interactions between the negatively charged surface of the hydrogel and the metal ions. The corresponding kinetic model suggests that the adsorption process proceeded in two controlled steps, beginning with film diffusion and followed by intraparticle diffusion.