Synthesis and application of Alizarin red S bonded polyurethane foam for separation and preconcentration of trace amounts of some metal ions in wastewater

Abstract

A stable chelating resin matrix was prepared by covalently linking Alizarin red S with polyurethane foam, through a -N=N-group, and identified through UV/Vis and IR. The resin was used in batch and column techniques for the separation and preconcentration of Ag I , Hg I I and Pb I I from wastewater. The various parameters affecting the retention efficiency of the tested metal ions from aqueous media by the Alizarin red S bonded polyurethane foam (Al-Puf) were examined, e.g. pH, contact time, sorption isotherm, flow rate and breakthrough capacity. Extraction was accomplished during 5-15 min at pH 9, 2-4 and 4-6 for Ag 1 , Hg I I and Pb I I , respectively. The capacities of Al-Puf were 4.2, 2.5 and 2.4 mmol/g for Ag I , Hg I I and Pb I I , respectively. The detection limit was about 4 ng/ml for preconcentration factor of 50 has been ashieved (rsd - 3.46%), The kineties and thermodynamics of the sorption of the tested ions onto Al-Puf have been studied. The sorption of Ag I , Hg I I and Ph I I onto Al-Puf follow a first order rate equation, with the rate constant, k, to be 0.211, 0.448 and 0.207 mim - 1 , respectively. The values of Gibbs free energy (ΔG) for the sorption of Ag I , Hg I I and Ph I I were -4.29, -2.73 and -3.43 kJ mol - 1 , respectively at 298 K. The proposed method has been successfully applied to the assay of tested metal ions in waste -water.