Effective removal of zinc from aqueous solution by hydrocalumite

Zinc (Zn2+) from aqueous solutions was removed via synthesized hydrocalumite, and Visual MINTEQ was applied to verify the removal process in this paper. The results showed that the maximum removal capacity of Zn2+ was 7.34, 6.72 and 7.57 mmol L−1 with SO42−, NO3− and Cl−, respectively. Under an initial Zn2+ concentration of 10.2 mmol L−1 in ZnSO4 solution, the final Ca2+ concentration was equal to 5.4 mmol L−1, and the corresponding primary precipitation was ZnAl-SO4-LDHs. However, in ZnCl2 or Zn(NO3)2 solutions, released Al(OH)4− was mainly recrystallized with Zn2+ to form ZnAl-Cl-LDHs. The simulated results were consistent with the experimental ones, which revealed that Zn2+ removal was via dissolution and selective precipitation. Therefore, this research proved that hydrocalumite was an efficient Zn2+ sorbent and Visual MINTEQ could offer a novel way to validate the removal process.

Schematic of Zn2+ removal by hydrocalumite via dissolution of hydrocalumite and selective precipitation of ZnAl-LDHs under different initial Zn2+ concentrations and coexisting anions.Figure optionsDownload as PowerPoint slideHighlights
► Hydrocalumite can effectively remove Zn2+ from aqueous solutions.
► The removal process is via hydrocalumite dissolution and selective precipitation of ZnAl-LDHs.
► The precipitation products depend on different initial Zn2+ concentrations and different anions.
► Visual MINTEQ model can well validate this removal process.