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

• Published in: Applied surface science 2021-02, Vol.538, p.148054, Article 148054
• Main Authors: Zhang, Ling, Zhang, Jinghua, Li, Xinglin, Wang, Cuijie, Yu, Ajuan, Zhang, Shusheng, Ouyang, Gangfeng, Cui, Yuanyuan
• Format: Article
• Language: English
• Subjects: Adsorption mechanism; Atomic fluorescence spectroscopy (AFS); Copper hydroxy sulfate@MOF; In situ transformation; Mercury
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.148054

[Display omitted] •A core-shell CHS@Cu3(BTC)2-DMTZ prepared by a facile self-template strategy was fabricated and characterized.•The CHS served as the source of metal ion and in situ converted to MOF shell at room temperature.•The adsorption isotherms and kinetics of Hg2+ were fitted by pseudo second-order and Langmuir model.•XPS and Raman spectra verified strong interaction between Hg2+ and S/N-containing groups of CHS@Cu3(BTC)2-DMTZ. 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 Hg2+. The strategy of assembling MOF shell on copper hydroxy sulfate (CHS) core avoided the self-nucleation of MOF(Cu3(BTC)2) in the solution and complex multistep procedures by means of in situ transformation the metal source CHS into well-defined Cu3(BTC)2 crystal. The structure and properties of the DMTZ modified CHS@Cu3(BTC)2 (CHS@Cu3(BTC)2-DMTZ) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and N2 sorption–desorption isotherms (BET). The adsorption behavior followed Langmuir adsorption model and the maximum adsorption capacities for the removal of Hg2+ was up to 627.6 mg g−1. 99.96% Hg2+ was rapidly captured by CHS@Cu3(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 Hg2+ and thiol/nitrogen-containing functional groups of DMTZ on CHS@Cu3(BTC)2-DMTZ. These results manifested that this novel thiol-functionalized MOF adsorbent had superior adsorption capacity and selective for Hg2+.