Aminated polyacrylonitrile fibers for lead and copper removal

Aminated polyacrylonitrile fibers (APANFs) were prepared through the reaction of polyacrylonitrile fibers (PANFs) with diethylenetriamine in a solution and were used as an adsorbent to remove lead and copper ions from aqueous solutions. It was found that the zero zeta potential point of the APANFs was at about pH = 8.1, in contrast with that of the PANFs at pH = 3.6, and the APANFs had significantly higher adsorption capacities for both lead and copper ions than the PANFs. The adsorption behaviors of lead and copper ions on the APANFs depended upon the solution pH values, and greater amounts of adsorption were obtained at higher solution pH values. Scanning electronic microscopy and atomic force microscopy indicated that the APANF had a rougher surface than the PANF, and the adsorption of the metal species on the APANF made the surface even rougher. Fourier transform infrared spectroscopy revealed that the amine groups on the surface of the APANF played an important role in the removal of lead and copper ions from the solutions. X-ray photoelectron spectroscopy for the APANFs before and after lead and copper adsorption indicated that the adsorption of lead and copper ions on the APANFs can be mainly attributed to the formation of metal complexes with the nitrogen atoms in the amine groups on the surfaces of the APANFs, although the hydroxyl groups on the APANFs may also be involved in binding lead ions from the solutions.