Fibrous Iminodiacetic Acid Chelating Cation Exchangers with a Rapid Adsorption Rate

Abstract

Fibrous chelating cation exchangers were derived from chloromethylstyrene-grafted polyethylene-coated polypropylene filamentary fiber and its nonwoven cloth. Ligand contents and acid capacities of the resulting chelating filamentary fiber (FIDA-f) and cloth (FIDA-c) were ca. 2 mmol/g and ca. 4 mequiv/g, respectively. A distribution study by using FIDA-c clarified that the selectivity sequence of divalent metal ions is Mg(II) ∼ Ca(II) < Co(II) ∼ Zn(II) < Cd(II) ∼ Ni(II) < Pb(II) < Cu(II). Capacities of FIDA-c in mmol/g at around pH 5 were as follows: for divalent ions, Ca(II) = 0.91, Mg(II) = 0.98, Cd(II) = 1.5, Ni(II) = 1.5, Pb(II) = 1.6, and Cu(II) = 1.8; for trivalent ions, La(III) = 0.75, Gd(III) = 0.92, and Lu(III) = 1.0. A column-mode study using a FIDA-f packed column revealed that breakthrough capacities for Cu(II) (ca. 1 mmol/g) were not dependent on flow rates up to 200−300 h-1 in space velocity but slightly decreased with a further increase in the flow rate. Conditioning-adsorption-elution oper...