Poly(acrylic acid)-graft-biopolymer towards ammonium adsorption: A comparative study on chitosan and cellulose

Poly(acrylic acid)-graft-biopolymer was copolymerized from acrylic acid and chitosan (or cellulose), and then cross-linked to N,N’-methylene-bis-acrylamide with the aim at removing ammonium from an aqueous solution. The chitosan-based copolymer showed higher adsorptive capacity of ammonium than that of the cellulose-based material, thanks to the effectiveness of copolymerization on both free amino and hydroxyl groups, as proven by Fourier-transform infrared spectroscopy. In comparison with copolymer, bentonite-blended material (10% wt. bentonite) improved the ammonium removal (up to 80.0% efficiency) at a neutral pH condition, reaching the equilibrium after 30 min and obeying both the Langmuir and the Freundlich isotherms, along with the maximum adsorption capacity of 40.32 mg/g at room temperature.