Removal of Cu2+ ions from aqueous solution by amino-functionalized magnetic sawdust composites

In this study, amino-functionalized magnetic γ-Fe₂O₃/sawdust composites (MSC-NH₂) were investigated as biological absorption materials for removing Cu²⁺ ions from aqueous solution. These composites were fabricated by precipitated γ-Fe₂O₃ nanoparticles on sawdust substrate and then functionalized with 1,6-hexanediamine. Characterization of MSC-NH₂ was performed by means of SEM, TEM, XRD, FTIR, BET, MPMS and XPS analysis to discuss the uptake mechanism. As a result, the amino groups are grafted upon the sawdust surfaces. The MSC-NH₂ could be effectively used to remove Cu²⁺ from aqueous solution and be separated conveniently from the solution with the help of an external magnet. Batch experiments show that the adsorption equilibrium is achieved in 150 min, and the adsorption capacity is 7.55 mg/g at pH 6 and room temperature. The isotherm analysis indicates that the sorption data could be represented by Langmuir isotherm models. The kinetics is evaluated utilizing the Lagergren pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models. Thermodynamic parameters reveal the spontaneous, endothermic and chemical nature of adsorption.