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ABSTRACT:A chelating fibrous polymer with metal complexing ability was prepared by partial conversion of the nitrile groups of melana (an acrylonitrile-based synthetic fiber) into amidoxime groups -C(NH 2 ) ϭ NOH using a solution of 3% hydroxylamine in methanol by refluxing at 80°C. The molar ratio of NH 2 OH/CN and the reaction time were adjusted to values of 0.9 and 2 h, respectively. The amidoximated polyacrylonitrile fiber with a 2.89 meq/g ionexchange capacity functions as an efficient chelating adsorbent for palladium ions. The pH dependence, the contact time, and the temperature of palladium ion retention from a model solution on amidoximated acrylic fiber were studied.The fibrous chelating adsorbent exhibited high affinity for palladium ions in acidic solution (pH ϭ 2-6) at high temperature (50 -60°C). The values of parameters q m and K L (from the Langmuir equation) determined at different temperatures of adsorption and the thermodynamic quantities ⌬G, ⌬H, and ⌬S were calculated. The adsorbed palladium ions can be quantitatively desorbed by elution with a 0.3% hydrochloric solution of thiourea.

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