Adsorption of heavy metal ions from aqueous solution onto chitosan entrapped CM-cellulose hydrogels synthesized by irradiation

The application of novel environment-conscious hydrogels as an adsorbent for heavy metal ions adsorption from aqueous solutions was examined. Chitosan was blended with highly concentrated carboxymethylated cellulose (CM-cellulose) solution to form CM-cellulose/chitosan physical hydrogels, which were crosslinked by additionless irradiation technique. The adsorptive properties of the blend hydrogels against some divalent heavy metal ions were investigated by batch adsorption method. It was found that the addition of chitosan increased the crosslinking degree and the adsorption capacity of the blend hydrogels. As a typical example, experimental data of Cu(II) ion were exploited for kinetic and isothermal evaluations. Copper adsorption process was found to be initially transport-controlled, and its adsorption isotherm can be fitted well into the Langmuir equation. Cu(II) adsorption mechanism can be viewed as the complexation of the Cu(II) with carboxyl groups and amino groups on the CM-cellulose/chitosan gel during the adsorption. From these preliminary evaluations, it is possible to conclude that the CM-cellulose/chitosan blend hydrogels have great potential for applications in water treatment for the removal of heavy metal ions.