Fast and selective removal of silver(I) from aqueous media by modified chitosan resins

Chitosan resin was cross-linked using ethylene glycol diglycidyl ether and modified through the reaction with ethylenediamine and 3-amino-1,2,4-triazole-5-thiol to produce chitosan/amine (R-en) and chitosan/azole (R-az) resins, respectively. The adsorption behavior of the chelating resins towards Ag(I) from aqueous media was studied. Better adsorption behavior was achieved for Ag(I) by R-en resin. The chelating matrix obtained from ethylenediamine showed uptake capacity of 1.13 mmol/g in 20 min and at 25 °C. These resins were evaluated for their recovery of Ag(I) from aqueous solutions using batch methods and column techniques. Various parameters such as pH, agitation time, Ag(I) concentration and temperature had been studied. The kinetics and thermodynamic behavior of the adsorption reaction were defined. The obtained resins achieved promising results in the selective separation of Ag(I) from other metal ions. Both kinetics and thermodynamic parameters of the adsorption process were obtained. The data indicated that the adsorption process is an exothermic reaction and kinetically proceeds according to pseudo-second order model. Regeneration and durability of the loaded resin towards the successive cycles were clarified. These parameters indicated that the resins can be applied in the removal of Ag(I).

► Ethylenediamine and 3-amino-1,2,4-triazole-5-thiol modified chitosan were prepared.
► Removal of Ag(I) from aqueous media was studied by batch and column methods.
► The kinetic and thermodynamic properties of the adsorption process were studied.
► The studied resin showed high affinity and selectivity for Ag(I) adsorption.
► The regeneration of the resins for repeated use was done successfully.