Comparison of effectiveness of removal of nuisance anions by metalloligs, metal derivatives of Octolig.

The present study describes the effectiveness of removal of selected aqueous anions by several metalloligs, i.e., metal derivatives of a commercially available immobilized ligand, IMLIG, Octolig. This material consists of polyethylenediamine moieties covalently bound to a high-surface area silica gel (CAS Registry number = 404899-06-5). The metals involved are copper, cobalt, iron, nickel, manganese, and thorium. The nuisance anions, studied as aqueous solutions, were arsenate, orthophosphate, selenite, sulfate, nitrate, and nitrite. All six metalloligs tested were able to remove arsenate (280 ppb, > 99% removal) effectively. The effectiveness for other anions varied, but all anions were removed by one metallolig or another. For example, for Colbaltilig, in deionized water samples, removal was 96% for 20.9 ppm NO(3)-N, 98% for 29.6 ppm sulfate (as sodium sulfate). For Cuprilig, removal was 98% for 9.82 ppm boron as boric acid, > 99% for Cr as 212 ppm dichromate, 97% for P as 10 ppm HPO(4)-P, and 90% for sulfate as 29 ppm sulfate. Removal of nitrate by Cobaltilig appeared to be adversely affected by the presence of sulfate. Manganilig and Nickelig were able to remove > 97% of 10 ppm P as Na(2)HPO(4). Mechanisms of interaction are proposed that suggest six types of behavior and several classes of materials are represented by these metalloligs.