Preparation, characterization and application of polyurethane foam functionalized with α-naphthol for preconcentration and determination of trace amounts of nickel and copper in cast iron and granite

Polyurethane foam functionalized with α-naphthol was synthesis by covalently linking them through an NN group. The characterization of 1-naphthol bonded to polyurethane foam (1-Nap-PUF) and the sorption behaviour of Ni2+ and Cu2+ on 1-Nap-PUF have been investigated. The optimum pH ranges for quantitative sorption were 6-10. The kinetics of sorption of the metal ions by the 1-Nap-PUF were found to be fast, reaching equilibrium in few minutes (5-10 min) and followed a first-order rate equation with an overall rate constant k in the range 0.16-0.22 min−1. The numerical values of thermodynamics parameters enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG) indicated the exothermic and spontaneous nature of sorption. The sorption data followed Freundlich and Dubinin-Radushkevich (D-R) type sorption isotherms. The average value of the sorption free energy ΔE = 9.84 kJ mol−1 indicating ion exchange or chelations type chemisorption. The capacities of 1-Nap-PUF were 0.22 and 0.2 mmol g−1 for Ni2+ and Cu2+, respectively. The 1-Nap-PUF was used to determine these metal ions in iron, granite. On the basis of these parameters, the sorption mechanism was discussed.