Enhanced adsorption of Cr(VI) from water by guar gum based composite hydrogels

Composite hydrogels were prepared by in situ incorporation of a natural macromolecule guar gum and nano sized bentonite clay in an acrylic network during copolymerization of acrylic acid, N,N-methylenebisacrylamide (MBA) and hydroxyethyl methacrlylate (HEMA) in water. The structure of the hydrogels was characterized and the hydrogels showing the best results in mechanical and swelling properties were used for the removal of low (5–50 mg/L) and high (100–800 mg/L) concentration of Cr(VI) ions from water. The composite hydrogel showed a high removal of 97.8% (4.89 mg/g gel) and 91.4% (182.4 mg/g gel) at an initial feed metal ion concentration of 5 mg/L and 200 mg/L, respectively.