Studies on the interaction of mercury(II) and uranyl(II) with modified chitosan resins

Chitosan polymer was cross-linked using glutardialdehyde. The resin obtained was chemically modified through the reaction with ethylenediamine and (3-amino-1,2,4-triazole-5-thiol) to produce chitosan/amine and chitosan/azole resins, respectively. The resins obtained were tested for the uptake of Hg2+ and UO22+ from their aqueous solutions. The chitosan/amine resin showed higher uptake towards Hg2+ and UO22+ compared to chitosan/azole. This was attributed to the fact that the azole moiety does not furnish efficient attachment to the metal ions compared to the amine active sites which are more compact. Selective separation of Hg2+ from UO22+ was achieved at pH < 2. This was explained by the ability of Hg2+ to adsorb on chitosan resin through ion-exchange in the acidic media while UO22+ would not. Uptake values up to 2.0 and 1.7 mmol/g were reported for Hg2+ and UO22+, respectively, on chitosan/amine. Application of the Langmuir model to the adsorption data indicated a higher binding of Hg2+ to the resin compared to UO22+. The adsorbed Hg2+ or UO22+ on the studied resins was eluted using H2SO4 and HCl, respectively.