Removal of divalent manganese from aqueous solution using glycine modified chitosan resin

• The removal ability of G@Chs for Mn(II) is largely affected by solution pH.
• Uptake mechanism is the chelate interaction between Mn(II) and modified adsorbent.
• The temperature study confirmed the endothermic nature of Mn(II) adsorption.
• Desorption and regeneration studies showed its good reusability.

Removal of Mn(II) ions from aqueous solution through adsorption on glycine modified chitosan resin (G@Chs) has been studied. Experiments were carried out as a function of pH, concentration of metal ion and contact time. Optimum Mn(II) uptake was observed at pH 6 and most of the Mn(II) were sorbed within 150 min. The isothermal data correlated with Langmuir model better than Freundlich model. Thermodynamic data indicated that adsorption process is exothermic and spontaneous reaction, while the kinetic data indicated that the adsorption follows the pseudo second order kinetics. The adsorption capacity of glycine onto modified chitosan resin was found to be 1.3 mmol/g, at 25 °C ± 1. Due to their outstanding adsorption capacities, G@Chs resin is an excellent adsorbent for the removal of Mn(II) ions. The resin regeneration was greater than 93% with 1.0 M HCl, and G@Chs could be repeatedly utilized for Mn(II) removal with negligible loss in sorption capacity.