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

摘要

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~1,Hg~(II) and Pb~(II) 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~I,Hg~(II) and Pb~(II),respectively.The capacities of Al-Puf were 4.2,2.5 and 2.4 mmol/g for Ag~(I),Hg~(II) and Pb~(II),respectively.The detection limit was about 4 ng/ml for preconcentration factor of 50 has been achieved (rsd - 3.46%).The kinetics and thermodynamics of the sorption of the tested ions onto Al-Puf have been studied.The sorption of Ag~I,Hg~(II) and Pb~(II) 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 (AG) for the sorption of Ag~(I),Hg~(II) and Pb~(II) 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.