Adsorption characteristics and behavior of a graphene oxide-Al-13 composite for cadmium ion removal from aqueous solutions

摘要

Graphene oxide-Al-13 (GO-Al-13) composites were synthesized by a hydrolysis method on the basis of graphite oxide and were characterized by XRD, FT-IR and SEM. The adsorption of Cd2+ onto the GO-Al-13 composite was investigated as a function of pH, temperature and adsorbent dose. Langmuir and Freundlich models were employed to describe the adsorption equilibrium. The adsorption kinetic was investigated by the pseudo-first-order, pseudo-second-order and the intraparticle diffusion models. The results showed that the GO-Al-13 composite has excellent adsorption capacity, and the Cd2+ removal rate could reach 98.92% at the optimum conditions. The adsorption isotherm fitted the Langmuir model well and the adsorption process was found to fit the pseudo-second-order rate equation. Also, the thermodynamic parameters including free energy (Delta G(circle minus)), enthalpy (Delta H-circle minus) and entropy (Delta S-circle minus) of adsorption were calculated. These experimental data suggested that the adsorption of Cd2+ on GO-Al-13 composite was an endothermic and spontaneous process.