Application of natural polysaccharide-based hydrogel materials in heavy metal pollution in water environment

Author(s): Wei Zhang
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Institution or organization of origin: Changsha University of Science and Technology
Country: China


Heavy metal pollution, such as Cu(II) but not other priority toxic heavy metal, yet becomes lake water security problem not admitting ignoring. In present work, novel natural plant polysaccharide-based hydrogel sorbents derived from grapefruit peel have been prepared by a facile physically-crosslinked method using alginate and pectin as entrapment agent and biochar as functional additive for enhanced Cu(II) removal from water. FTIR, SEM-EDS, XRD, TGA and XPS, etc. were applied for characterization analysis. The synergistic reinforcing effect of polymer matrix and biochar fillers improved the adsorptive performance and environmental adaptability of hydrogel sorbents. Factors like component contents of biochar and pectin, pH, contact time, adsorbate concentration and coexisting substances were systematically investigated in batch and dynamic modes. To clarify the heavy metal adsorption mechanism of these hydrogel sorbents, adsorption capacity was investigated from the adsorption isotherms, kinetics, and thermodynamics points of view. Thomas model was fitted with breakthrough curves under different initial Cu(Ⅱ) concentration, bed height and flow rate in a column system. Moreover, they also showed better environmental adaptability in the presence of inorganic salts or organic ligands and actually polluted lake water as well as good adsorption potential for other heavy metal [e.g. Pb(II)]. Crucially, the hydrogels showed good regeneration ability in batch/dynamic sorption experiments. It proved that cation-exchange, complexation, reduction of Cu(II) to Cu(I), Cu-π bonding, micro-precipitation and porous-effect enhanced Cu(II) removal. The tailored hydrogel sorbents with exceptional adsorption performance are low-cost and eco-friendly, which potentially be feasible for some certain water treatment.

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