Application of a new chitosan derivative for adsorption of copper (II) and oxyanions of chromium (VI)

Abstract

This study describes the synthesis of a new bioadsorbent from chitosan using ethylenediaminetetraacetic dianhydride (EDTAD) as a modifying agent and its successful application for removal of a cationic ion (copper (II) (Cu2+)) and oxyanions of chromium (VI) (Cr6+) from single-component aqueous systems. The new multifunctionalised chitosan derivative (C1) was produced through chemical modification of the primary hydroxyl function of chitosan with EDTAD to introduce carboxylic and tertiary amine functional groups, maintaining the secondary amines on the chitosan surface. Such a transformation was important not only to increase the adsorptive potential of chitosan but also to allow C1 to be used in acidic media, thus solving the problem of solubility of most chitosan derivatives. C1 was characterised by spectroscopic methods. The effects of solution pH, contact time and initial solute concentration on the removal of copper (II) and chromium (VI) by C1 were investigated in aqueous solutions. C1 showed an experimental maximum adsorption capacity of 106 mg/g for copper (II) and 194 mg/g for chromium (VI).