This study presents a groundbreaking composite adsorbent, STB@MOF-808-SH, developed through the innovative amalgamation of thiol-functionalized metal-organic framework material (MOF-808-SH) with sulfur-doped C3N4 tubular bundles (STB), targeting the effective elimination of toxic mercury [Hg(II)] ions from polluted water. Our investigation explores crucial determinants of the adsorption process, including pH, initial Hg(II) concentration, and the impact of coexisting ions, while revealing the significant enhancement in mercury ion removal efficiency and adsorption capacity due to the synergistic interaction between STB and MOF-808-SH. Remarkably, under optimal conditions at pH 4.0, STB@MOF-808-SH achieves a removal rate of 91.35% and an impressive adsorption capacity of 228.38 mg/g. These outcomes suggest that the development of the STB@MOF-808-SH composite adsorbent introduces a novel and efficacious approach to tackling water pollution issues, highlighting its potential as a cost-effective and efficient solution for the remediation of toxic Hg(II) ions in wastewater.
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 (C 0 = 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 K d as high as 5.0×10 6 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.