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Polysaccharide-based adsorbents prepared in ionic liquid with high performance for removing Pb(II) from aqueous systems

Rufato, Késsily B., Almeida, Vitor C., Kipper, Matt J., Rubira, Adley F., Martins, Alessandro F., Muniz, Edvani C.
Carbohydrate polymers 2019 v.215 pp. 272-279
X-ray photoelectron spectroscopy, adsorbents, adsorption, alginates, chitosan, infrared spectroscopy, ionic liquids, ions, lead, nuclear magnetic resonance spectroscopy, scanning electron microscopy, sulfates, zeta potential
Alginate/chitosan (ALG/CHT) and alginate/N,N-dimethyl chitosan (ALG/DMC) polyelectrolyte complex (PEC)-based adsorbents with high capacities for removing Pb(II) from aqueous systems are produced in [1-hydrogen-3-methylimidazolium hydrogen sulfate ionic liquid ([Hmim][HSO4―]). The [Hmim][HSO4―] is recovered, characterized by 1H NMR and reused to yield novel polysaccharide-based adsorbents. As-obtained PEC materials are characterized through infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Zeta potential measurements. Kinetic and equilibrium adsorption studies reveal that the pseudo-second-order Kinetic, as well as the Redlich-Peterson isotherm, provide the best fits for the experimental data, respectively. CHT/ALG and DMC/ALG adsorbents promoted maximum adsorption capacities (qm) of 529.4 mg g−1 and 560.2 mg g−1, respectively. After adsorption, the materials are characterized by infrared spectroscopy and X-ray photoelectron spectroscopy, confirming that the chemisorption prevails upon Pb(II) removal. Also, PECs produced in the recovered [Hmim][HSO4―] have good capacities for removing Pb(II) ions from aqueous systems as well. This study showed that the [Hmim][HSO4―] is an alternative solvent to prepare novel and eco-friendly PEC-based adsorbents.