Heavy metal sequestration properties of a new amine-type chelating adsorbent

Abstract
The performance of poly(CGMAPEI), an amine-type chelating adsorbent synthesized by graft polymerization, was evaluated in a simulated waste stream containing Cu2+ and Co2+ heavy metal ions and NaNO3 salt. Comparisons of metal adsorption curves of this adsorbent with a previously synthesized cellulose-PEI and commercially available chitosan-polyamine and amberlite resins were made. The poly(CGMAPEI) exhibited the highest capacity in the absence of NaNO3. At high concentrations of NaNO3, the affinities of all the amine-type adsorbents were found to be enhanced quite tremendously. The chelating adsorbent with the highest amine content (CS-03) showed the highest improvement in capacity. This phenomenon was not observed with the ion-exchanger (amberlite IRC 50) studied. Sodium ions showed negligible affinity for poly(CGMAPEI). Competition between Na+ with Cu2+ for adsorption sites in the adsorbent was absent. Regeneration experiments revealed some reduction in Cu2+ affinity of poly(CGMAPEI) after acid treatment. Difficulty in stripping Co2+ from poly(CGMAPEI) even by strong acid was also observed.

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