Biosorption of beryllium from aqueous solutions onto modified chitosan resin: Equilibrium, kinetic and thermodynamic study

The goal of the present work is the recovery of beryllium ion from their solution by modified chitosan hydrogel. Chitosan was chemically cross-linked with glutaraldehyde to prevent its dissolution in aqueous acidic solutions. The obtained chitosan/glutaraldehyde adsorbent was reacted with chloroacetic acid to produce carboxymethyl chitosan (CMC), which was converted into sodium form by reaction with sodium hydroxide solution to increase its hydrophilic properties. The chemically synthesized chitosan adsorbent contains carboxylate group that expected to have a strong affinity to beryllium ions according to the hard-soft acid-base concept by Pearson because that beryllium ion is a hard acid and has smaller ionic radii. The synthesized adsorbent was characterized and its affinity towards beryllium ions was tested. The different experimental parameters including pH, beryllium concentration, agitation period and temperature were studied to optimize the biosorption process. The maximum biosorption values of beryllium species on the investigated biosorbent are 44.96 and 36.72 mg/g at pH 1 and 5, respectively. Kinetics and thermodynamic parameters of the biosorption process were evaluated from kinetic and biosorption experiments. The adsorbed beryllium species were eluted with a 3 M H2SO4 solution.