PREPARATION OF POLYACRYLOAMIDOXIME CHELATING CLOTH FOR THE EXTRACTIONOF HEAVY-METALS FROM WATER

Woven polyacryloamidoxime cloth was prepared from the polyacrylonitril e precursor via reaction in methanolic hydroxylamine. Preparation was controllable and reproducible and the reaction conditions were optimiz ed with respect to the time of conversion, the concentration of NH2OH . HCl, and the temperature of conversion. The cloth produced had a lar ge capacity for Cu(II) and Pb(II) of 71.2 and 450 mg g(-1) (1.12 and 2 .17 mmol g(-1))respectively, and adequate physical properties suitable for rigorous use. Sorption profiles of Pb (II) and Cu(II) were simila r to those of chelate ion exchange resins and fibers containing the am idoxime group. The rate of uptake of metals by the cloth was found to be dependent on the percent surface area converted to amidoxime groups , the concentration and type of metal being tested for, and the time o f exposure. Anomalous kinetics of sorption for Pb(II) and Cu(II)by clo th of increasing amidoxime group content were explained by a two-part sorption mechanism. Distribution coefficients of 3.5 x 10(6) and 1.5 x 10(6) for Cu(II) and Pb(II) were observed, and the average rates of u ptake for Cu(II) and Pb(II) were 600 and 200 mu g g(-1) day(-1) (9.4 a nd 0.96 mu mol g(-1) day(-1)), respectively, from dilute solution ([Cu ] = 5.9 mu g L-1, [Pb] = 2.8 mu g L-1). Treatment of the cloth with aq ueous NaOH did not improve the capacities for Pb(II) and Cu(II). (C) 1 997 John Wiley & Sons, Inc.