Abstract: A metals-adsorbent PAN fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. No ester groups are present. The inventive fiber is used for removing metals, including toxic metals, from fresh water, including rivers, streams, lakes, ponds, drinking water from wells and other sources, and industrial discharge waste waters, in a pH range of 3-10, and preferably at slightly acidic conditions in the range of pH 5-6. Metals that can be removed include heavy and toxic metals, such as Sc, V, Mn, Fe, Co, Ni, Cu, Sr, Yb, Cd, Cs, Pb, La, Ce, Nd, Eu, Zn, Tb and U. The adsorbed metals can be removed from the fiber by acidic elution and recovered. The fiber can be rinsed and reused.

Abstract: Extraction of platinum-group elements, e.g. Pd, by adsorption from acidic aqueous solutions, using chelating acrylic fibers having amidoxime substituents followed by recovery by elution with an HCl-thiourea solution. From about 10% to 100% of the acrylic fiber CN are converted to amidoxime by reaction with NH2OH (hydroxylamine) in H2O/MeOH solution in the range of 30° C.-90° C. for from 15 min to 72 hrs. The adsorptive loading of elements onto the fiber and the efficiency of elution therefrom is substantially 100%, in multiple cycles of adsorption/elution. The novel fiber/extraction process is rapid, lending it to a continuous recovery operation. A portion of the CN groups of may be converted to carboxylate groups by reaction with NaOH. Short lengths of fiber are loaded into a vertical column and the pregnant solution introduced. Upon breakthrough, the fibers may be eluted, washed and recycled hundreds of times without removal from the column.

Abstract: A metals-adsorbent PAN fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. No ester groups are present. The inventive fiber is used for removing metals, including toxic metals, from fresh water, including rivers, streams, lakes, ponds, drinking water from wells and other sources, and industrial discharge waste waters, in a pH range of 3-10, and preferably at slightly acidic conditions in the range of pH 5-6. Metals that can be removed include heavy and toxic metals, such as Sc, V, Mn, Fe, Co, Ni, Cu, Sr, Yb, Cd, Cs, Pb, La, Ce, Nd, Eu, Zn, Tb and U. The adsorbed metals can be removed from the fiber by acidic elution and recovered. The fiber can be rinsed and reused.