Influence of the polyethyleneimine grafting on the adsorption capacity of chitosan beads for Reactive Black 5 from aqueous solutions

The adsorption capacity of chitosan hydrogel beads generated by alkali (CB) and sodium dodecyl sulphate (CSB) gelation was investigated after polyethyleneimine (PEI) grafting for adsorption of Reactive Black 5 (RB5) from aqueous solutions. The adsorption capacities of PEI-grafted CB (PEI-CB) and CSB (PEI-CSB) were varied with the amount of PEI used during grafting. The maximum adsorption capacity values of PEI-CB (709.27 mg/g) and PEI-CSB (413.23 mg/g) obtained from the Langmuir isotherm model were higher than those of CB (201.90 mg/g) and CSB (168.07 mg/g), indicating that the adsorption performance of CB and CSB could be highly enhanced by PEI grafting. All of the adsorption systems showed better fits to the Langmuir isotherm model than the Freundlich isotherm model, except PEI-CSB. The kinetic data of the adsorption systems showed better fits to a pseudo-first-order rate model than a pseudo-second-order model. (C) 2010 Elsevier B.V. All rights reserved.