| Abstrakt: |
Meta-benziporphodimethene (meta-BPDM) ligand immobilized in polyacrylamide/ carboxymethyl guar gum (PAM/CMG) hydrogel was used for selective removal of Zn2+, Cd2+ and Hg2+ ions from water. This hydrogel appears to be a competitive sorbent and has been successfully applied to efficient removal of Zn2+, Cd2+ and Hg2+ ions from water in the presence of others. Batch adsorption experiments with respect to pH, initial metal ion concentration and contact time were also investigated. The selectivity towards Zn2+, Cd2+ and Hg2+ is due to meta-BPDM ligands and other functional groups incorporated in hydrogel. Adsorption on hydrogel was found to be pH dependent and maximum adsorption was found to be at pH 6.5. The sorption equilibrium for Zn2+, Cd2+ and Hg2+ ions was achieved in 8 h, 12 h and 6 h contact time at room temperature, 250 rpm and 500 ppm initial metal ion concentration, respectively. The percentage removal of Zn2+, Cd2+ and Hg2+ was found to be 78.8%, 67.6%, and 80.4%, respectively. Maximum removal was observed with respect to Hg2+ (Hg2+ > Zn2+ > Cd2+) and this can be explained by the hard-soft acid base principle. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Thermogravimetry analysis were employed to monitor changes that have occurred in the hydrogels after the sorption of metal ions. Inductively coupled plasma mass spectroscopy (ICP-MS) and atomic absorption spectroscopy (AAS) analysis were employed to estimate the residual metal ion concentrations in water. Parallel adsorption and comparative studies indicated that the hydrogel has better adsorption capacity and selectivity. [ABSTRACT FROM AUTHOR] |
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