Removal of Cu(II) by amidoxime-modified polyacrylonitrile-grafted-cassava starch

Abstract

The presence of heavy metal ions in the environment is one of the serious threats to human health. Heavy metal pollutants have accumulating characteristics in nature, and they are non-biodegradable with high toxicity even at trace concentrations. Cu(II) is associated with kidney and liver damage, anaemia, central nervous system problem and affects enzymes in living organism due to its high affinity towards ligands containing nitrogen and sulphur donors. Adsorption is regarded as a practical treatment method due to its low cost, high capacity, easy metal recovery and reusability. In the present work, we utilized our ‘in-house’ amidoxime-modified poly(acrylonitrile (AN)-grafted (g)-cassava starch (CS)) for the removal of Cu(II) from an aqueous solution. It was found that the maximum adsorption capacity of amidoxime-modified poly(AN-g-CS) was 75.76 mgg^-1 at pH 5. The adsorption kinetic study showed that the optimum time required for the Cu(II) ions to attain saturation level was 1 h. The adsorption kinetic and equilibrium data were well fitted to the pseudo-second order model and the Langmuir isotherm, respectively.

Keywords: cassava starch; amidoxime; chemical modification; graft   copolymerization; heavy metal ions, hydroxylamine hydrochloride; ligands; oxime group; polyacrylonitrile.