Efficient Cu2+, Pb2+ and Ni2+ ion removal from wastewater using electrospun DTPA-modified chitosan/polyethylene oxide nanofibers

Abstract

Diethylenetriaminepentaacetic acid-modified chitosan/polyethylene oxide nanofibers (CS-DTPA/PEO NFs) were developed for enhanced heavy metal ion adsorption. These nanofibers were prepared by electrospinning, and their morphology and structure were investigated by scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR), respectively. The ability of CS-DTPA/PEO NFs to removing copper (Cu2+), lead (Pb2+) and nickel (Ni2+) ions from aqueous solutions was tested at room temperature. The effects of [DTPA]/[NH2] molar ratio, pH and initial concentration of metal ions on their absorption capacity were investigated to optimize process conditions, using pseudo-first and apparent-second-order, Boyd and intraparticle diffusion models to determine the rate-limiting step of metal ions adsorption. In turn, Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherm models were used to describe the experimental data. The results demonstrate a decrease in the ability of CS-DTPA/PEO NFs to adsorb metal ions in the following order: Cu2+>Pb2+>Ni2+. The adsorption equilibrium is established after 90 min from the first contact with solutions containing the metal ions, and data are described using the Langmuir isotherm model. The maximal adsorption capacities of CS-DTPA/PEO NFs for Cu2+ , Pb2+ and Ni2+ions were 177, 142, 56 mg g−1, respectively. The stability and reproducibility of CS-DTPA/PEO NFs were determined after five adsorption–desorption tests.