Purpurin functionalized amberlite XAD-2 for extraction of heavy metal ions in leachate from cement-based stabilized waste

Abstract

A new chelating resin was synthesized by functionalizing the polymer support, Amberlite XAD-2 with the chelating ligand, purpurin through an azo linkage (-N=N-). The products were characterized by scanning electron microscopy, elemental analysis, Fourier transforms infrared and Raman spectroscopy and thermal gravimetric analysis. The optimum conditions for the extraction of Cd [superscript 2+], Cr [superscript 3+] and Pb [superscript 2+] in both matrices: leachate from cement-based material and DI water; were studied by batch and column methods. The determination of the metal ions was carried out by flame atomic absorption spectrometry. The optimum pH for the extraction of all the metal ions in both matrices was at 4.0. Their sorption equilibria were reached within 1 h. The sorbed Cd [superscript 2+] and Pb [superscript 2+] were desorbed by 1% HNO [subscript 3] within 10 min with the desorption recovery of >90%. For the elution of Cr [superscript 3+] by 10% H[subscript 2]O[subscript 2] in 0.1 M NaOH was achieved within 30 min with the desorption recovery of >80%. The sorption capacity of Cd[superscript 2+], Cr [superscript 3+] and Pb [superscript 3+] onto the resin was 75.0, 68.2, 82.7 [micro]mol g [superscript -1] resin in DI water and 54.1, 46.5 and 55.7 [micro]mol g[superscript -1] resin for the leachate, respectively. The column method has a limitation for this experiment, however, the extraction efficiency can be improved using the recirculation system. This new method gave a good accuracy in batch system at 86.5 and 89.9%recovery for Cd[superscript 2+] and Pb [superscript 2+] and %RSD less than 2.3% (n = 14).