Metal organic framework UiO-66 and activated carbon composite sorbent for the concurrent adsorption of cationic and anionic metals

A composite sorbent for the simultaneous removal of both Hg2+ and SeO32− from aqueous media was produced from the solvothermal synthesis of a zirconium metal organic framework, UiO-66, in the presence of activated carbon. The composite sorbent has a large surface area of 1051 m2 g−1 with crystalized porous structures and has strong thermal stability up to 600 °C. The contaminant uptake of the sorbent follows a Langmuir adsorption isotherm with maximum sorption capacity of 205 mg g−1 and 168 mg g−1 for Hg2+ and SeO32−, respectively. Scanning electron microscopy-energy dispersive spectroscopy results show that the Se regions overlap exclusively with Zr-rich regions suggesting that SeO32− adsorption depends entirely on the exposed UiO-66 surface. In addition, X-ray photoelectron spectroscopy spectra of Se 3d and Hg 4f showed the association of SeO32− and Hg2+ on the UiO-66 and carbon surfaces, respectively. The sorbent could facilitate the development of a single process for the simultaneous removal of cationic Hg and anionic Se as well as other similar ionic metals with opposite charges from aqueous media. [Display omitted] •A UiO-66 and activated carbon composite sorbent is synthesized and characterized.•Adsorption experiments indicates that the sorbent removes dissolved Hg2+ and SeO32- effectively.•Langmuir isotherm best describes the adsorption of Hg2+ and SeO32- to the composite sorbent.•The adsorption of SeO32- is localized to UiO-66 while Hg2+ adsorption is not site specific.