Three-dimensional composite hydrogel based on polyamine zirconium oxide, alginate and tannic acid with high performance for Pb(Ⅱ), Hg(Ⅱ) and Cr(Ⅵ) trapping

Highlight
• Multifunctional polymer hydrogels (Zr-DETA/TS) prepared via organic–inorganic crosslinking.
• Synergistic effect of functional groups from polyamine zirconium oxide and tannic acid/alginate hydrogels.
• Three-dimensional-network structure facilitated mass transfer of metal ions.

In this study, preparation of multifunctional polymer hydrogels (Zr-DETA/TS) was achieved via organic-inorganic crosslinking to form three-dimensional network structure for application of Pb2+, Hg2+ and CrO42− extraction. The equilibrium data of Pb2+, Hg2+ and CrO42− were best described by the Langmuir isotherm, and the kinetic data were found to follow the pseudo-second-order kinetic model. It was notable that ionic exchange and complexation were the main adsorption mechanism for Pb2+ and Hg2+ while electrostatic attraction, inner-sphere complex and esterification played an important role in CrO42− adsorption. Thus, Zr-DETA/TS hydrogels could be used as a promising biomaterial for Pb2+, Hg2+ and CrO42− removal from wastewaters.

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