Adsorption behavior and mechanism of Hg (II) on a porous core-shell copper hydroxy sulfate@MOF composite

Herein, a porous core-shell copper hydroxy sulfate@metal-organic framework decorated by 2,5-dimercapto-1,3,4-thiadiazol (DMTZ) was synthesized via a facile self-template strategy for the capture of Hg 2+ . The strategy of assembling MOF shell on copper hydroxy sulfate (CHS) core avoided the self-nucleation of MOF(Cu 3 (BTC) 2 ) in the solution and complex multistep procedures by means of in situ transformation the metal source CHS into well-defined Cu 3 (BTC) 2 crystal. The structure and properties of the DMTZ modified CHS@Cu 3 (BTC) 2 (CHS@Cu 3 (BTC) 2 -DMTZ) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and N 2 sorption–desorption isotherms (BET). The adsorption behavior followed Langmuir adsorption model and the maximum adsorption capacities for the removal of Hg 2+ was up to 627.6 mg g −1 . 99.96% Hg 2+ was rapidly captured by CHS@Cu 3 (BTC) 2 -DMTZ within 10 min from 40 mg L -1 to 0.014 mg L -1 . Meanwhile, not only X-ray photoelectron spectroscopy (XPS) but also Raman spectra verified the selective and strong interaction between Hg 2+ and thiol/nitrogen-containing functional groups of DMTZ on CHS@Cu 3 (BTC) 2 -DMTZ. These results manifested that this novel thiol-functionalized MOF adsorbent had superior adsorption capacity and selective for Hg 2+ .