Adsorptive capacity of polyacrylonitrile modified with triethylenetetramine for removal of copper and cadmium ions from aqueous solutions



A simple method was developed for modification of polyacrylonitrile with triethylenetetramine (PAN-TETA) as absorbent of copper and cadmium ions. PAN-TETA and its metal complexes were characterized by FT-IR and SEM. FT-IR studies confirmed the presence of metal ions in the metal-PAN-TETA complexes. The obtained aminated polyacrylonitrile was evaluated for chelating of Cu(II) and Cd(II) ions. Batch adsorption studies were carried out on the effect of experimental parameters including pH, amount of adsorbent, contact time, initial concentration of metal ions, and temperature. Adsorption efficiency increased with increasing metal ions concentration, initial pH, and temperature. The adsorption kinetics followed pseudo-second-order kinetic model with correlation coefficients of 0.999. Experimental data were analyzed by model equations such as Langmuir and Freundlich isotherms. It was found that Langmuir isotherm model was better fitted with the adsorption data. The maximum sorption capacity of 109.26 and 99.67 mg g−1 for copper and cadmium ions were achieved in pH = 6, respectively. The negative value of ΔGº indicated the spontaneous nature of the adsorption. The competitive tests verified that PAN-TETA had good adsorption selectivity for Cu (II) with the coexistence of copper and cadmium ions. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1139–1147, 2014