Preparation, characterization and applications of polyurethane foam functionalized with resorcinol for quantitative separation and determination of silver(I) and mercury(II) from tap and wastewater

A stable chelating resin matrix was prepared by covalently linking resorcinol with polyurethane foam matrix through,a -N=N- group. Preconcentration and determination of trace Ag+ and Hg2+ ions from samples of different origin, using Res-PUF, were studied. Various conditions influencing the sorption of these metal ions onto Res-PUF were optimized. The kinetics of sorption of the Ag+ and Hg2+ by Res-PUF were found to be fast, reached equilibrium in few minutes (5-10 min) and followed a First-order rate equation with an overall rate constant k in 0.102 and 0.267/min, respectively. Study of the variation of the sorption of the tested metal ions with temperature yielded average values for DeltaG, DeltaH and DeltaS of -3.94, -22.02 and -58.37, respectively. The mean free sorption energy (E) computed from the Dubinin-Radushkevich (D-R) isotherm was found to be equal to 8.91 kJ/mol, which reflects the chelation sorption process. The capacities of the foam material were 0.15 and 0.07 mmol/g for Ag+ and Hg2+, respectively. Preconcentration factors of > 50 were achieved (RSD approximate to 5.99). The proposed preconcentration procedure was applied successfully to the determination of trace metal ions in natural and wastewater samples.