Development of mercaptosuccinic anchored MOF through one-step preparation to enhance adsorption capacity and selectivity for Hg(II) and Pb(II).

A novel Zr-MOF adsorbent was synthesized by one-step method and was used to selectively adsorb Hg(II) and Pb(II) from wastewater. The adsorbent can reduce the concentration of mercury and lead to less than the national standard (Hg is 50 μg/L and Pb is 1 mg/L). The entire adsorption process conforms to the pseudo second-order kinetic and Hill isotherm models. At pH 4, the adsorbent removed more than 90% of mercury (to 22 μg/L) and lead (to 0.732 mg/L) in 10 min and 960 min, and the maximum adsorption capacity was 1080 mg/g and 510 mg/g, respectively. In addition, the practical application in wastewater proved that the adsorbent can selectively adsorb Hg(II) and Pb(II) from the mixed ion solution and it still meets national standards for wastewater discharge. The research of repeated experiments proves that the adsorbent can be used repeatedly. The adsorption mechanism was clarified by FTIR, XPS spectroscopy before and after adsorption, and density functional theory (DFT) calculation. In summary, the adsorbent is stable in aqueous solution and has great potential for the efficient removal of trace heavy metal ions (mercury and lead) in future treatment of wastewater. Unlabelled Image • The novel metal-organic frameworks adsorbent was synthesized using one-step method. • The adsorption capacity of Hg(II) and Pb(II) reached to 1080 mg/g and 510 mg/g at pH 4, respectively. • Both mercury and lead can be removed below international standards at low concentrations. • Adsorbent shows good reusability for Hg(II) and Pb(II). • Adsorption mechanism is chelation and the DFT calculation proved that the combination of heavy metals and sulfur is strong. [ABSTRACT FROM AUTHOR]