Preparation and characterization of polyamidoxime chelating resin from rubberwood fibre-g-polyacrylonitrile

Grafted rubberwood fibre was converted to polyamidoxime ion-exchange resin in order to remove heavy metal ions from aqueous solution. The cation-exchange resin existed predominantly in the syn-hydroxyamino form. The water uptake by the resin was ca. 31 g/g dry resin while its hydrogen ion capacity was 3.6 mmol/g. The adsorption capacity of the resin towards different metal ions from wastewater was determined at different pH values within the range 1-6. The prepared chelating ion-exchanger exhibited the highest adsorption capacity towards Cu²⁺ ions (3.83 mmol/g), followed by Cd²⁺, Fe3+, Pb²⁺, Ni²⁺ and Co³⁺ ions, respectively. The results showed that the adsorption capacity depended on the solution pH. Polyamidoxime ion-exchange resin was also used to separate Co³⁺ and Ni²⁺ ions from Cu²⁺ ions using a column technique. On passing Cu²⁺/Ni²⁺ and Cu²⁺/Co³⁺ ion mixtures through the resin at pH 3, Cu²⁺ ions were adsorbed by the resin but no sorption of Ni²⁺ or Co³⁺ ions was detected. Approximately 98% of the Cu²⁺ ions could be desorbed from the resin. FT-IR spectroscopy was used to confirm the conversion of polyacrylonitrile-g- rubberwood fibre to polyamidoxime.