Hydrazine-Functionalized guar-gum material capable of capturing heavy metal ions.

This research demonstrates the capability of guar-gum modified with salicylhydrazine to remove Ni2+, Co2+ and Cr3+ from aqueous solution. Structural characterization showed that aldehydes guar gum was grafted with salicylhydrazine with morphology. The as-prepared nanocomposite had a large surface area and hydrophobicity, which ensured its good sorption ability and convenience of separation. The sorption equilibrium data were well fitted to the Langmuir model, and uniquely high adsorption capacities for nickel, chromium and cobalt, which are 1272.4 mg•g-1, 748.86 mg•g-1 and 521.81 mg•g-1, remarkably, were achieved. The thermodynamic parameters for the sorption were also determined, and ΔG and ΔH values indicate exothermic behavior. Adsorption mechanism of capturing cation with GG-SH has been demonstrated through 1H NMR titration experiments of model molecular and metal ions. The features make this carbohydrate-based material suitable in water purification and separation treatment.