Highly Efficient and selective Hg(II) removal from water by thiol-functionalized MOF-808: Kinetic and mechanism study

By Chenghan Ji, Yi Ren, Hang Yu, Ming Hua, L. Lv, Weiming Zhang. Chemical Engineering Journal, 2021

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Abstract Mercury pollution poses a serious threat to the ecological environment and public health due to its high toxicity and persistence, but there is still a lack of rapid and effective Hg(II) removal technology, especially emergency response of Hg(II) leakage. Herein, an effective metal-organic framework adsorbent, MOF-808-SH, was fabricated by grafting thioglycollic acid on MOF-808 for Hg(II) removal. The MOF-808-SH demonstrated high adsorption capacity of 977.5 mg/g, impressively ultrafast adsorption kinetics (C0 = 10 mg/L, removal > 99 % in 10 s) with a rate constant k of 36.89 g mg-1 min-1, which is dozens of times faster than that of ever reported Hg(II) adsorbents. Batch experiments show that MOF-808-SH exhibits high selectivity toward Hg(II) with a distribution coefficient Kd as high as 5.0 ×106 mL/g. Moreover, MOF-808-SH exhibits excellent recyclability with a negligible loss of capacity after 6 adsorption-regeneration cycles. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometry (XPS) unveil that the –SH groups in MOF-808-SH are the key adsorption sites, and specific inner-sphere coordination with Hg(II) is responsible for the high selectivity. In addition, large surface area, well-developed porous structures and high –SH loading of MOF-808-SH reasonably explains ultrafast kinetics and high adsorption capacity for Hg(II). This study indicates the potential of MOF-808-SH to remove Hg(II) from wastewater.

Subfields: Inorganic Chemistry, Materials Chemistry, Water Science and Technology

View Paper: https://www.semanticscholar.org/paper/6912f73bb098657c36f4cea318710d52800066d6