Influence of Co(II), Ni(II), tartrate, and ethylenediaminetetraacetic acid on Cu(II) adsorption onto a polyvinylidene fluoride-based chelating membrane

Abstract

A 3-aminopropyltrimethoxysilane-diethylenetriaminepentaacetic acid/polyvinylidene fluoride (APTMS-DTPA/PVDF) chelating membrane was employed to remove Cu(II) from an aqueous solution. The influence of Co(II), Ni(II), tartrate, and ethylenediaminetetraacetic acid (EDTA) on the sorption of Cu(II) was investigated by a series of dynamic adsorption tests and by density-functional theory (DFT) calculations. Isotherms and kinetics of the membrane sorption process towards Cu(II) in the presence of the two other cations and the two complexing reagents were elucidated. The DFT descriptors, such as chemical potential, electronegativity, electrophilicity index and charge transfer, and the complexation energy, were calculated. Cu(II) showed higher electrophilicity than Co(II) and Ni(II), and the sorption of Cu(II) by the chelating membrane in the absence of tartrate and EDTA was stronger than in their presence. Ni(II) tended to form a more stable complex with the complexing ligand than Co(II). EDTA interfered more strongly with Cu(II) uptake than tartrate. Adsorption isotherms and adsorption kinetics were fitted to the Langmuir and the Lagergren second-order models. The [Cu(APTMS-DTPA)]2− complex exhibited higher charge transfer and a more negative complexation energy than [Co(APTMS-DTPA)]2−, [Ni(APTMS-DTPA)]2−, Cu-tartrate, and Cu-EDTA.