Ion exchange equilibria of heavy metals in aqueous solution on new chelating resins of sporopollenin

Studies have been conducted on the sorption of several heavy metal ions Cu(II), Ni(II), Zn(II), Cd(II) and Al(III) from aqueous solutions on the new chelating exchangers of sporopollenin (Lycopodium clavatum) as a function of pH at several temperatures between 20 and 50°C. The novel metal-ligand exchange resins possessing oxime and carboxylic acid side arm functionality were prepared through the reaction of diaminosporopollenin with dichloroantiglyoxime and bromoacetic acid. The sorption of all metals increased considerably in the range of pH 6–10 and was observed in sequence as: Cu ≥ Ni > Zn > Cd > Al for carboxylated-diaminoethyl-sporopollenin (DAEC) and Ni ≥ Cu > Zn > Cd > Al for bis-diaminoethyl-glyoxime-sporopollenin (bDAEG). The level of pH of the aqueous medium had a large influence on the sorption capacity, and the uptake of metals, except Al(III), was found to be 90% or more. The metal-form resins afforded complete recovery of the sorbed species by acid stripping. Both resins also showed high stability towards concentrated acids and bases and retained their high capacity for heavy metals.