Hg2+ removal from wastewater by anchoring nitrogen/sulfur active center onto metal-organic framework via Schiff-base reaction: Synthesis, characterization, and experiment

Remediation of Hg 2+ pollution in wastewater is imminent. Herein, a Metal-Organic Framework hybrid Uio-DBD-x was designed and synthesized via rational introducing the 5-Diamino-1,4-benzenedithiol Dihydrochloride (DBD) molecule onto parent Uio-66-NH 2 . By optimizing the synthesis conditions, the material exhibited better adsorption performance when x = 1. The characteristics including crystallinity, morphology, and pore size were analyzed. 12.64 nm for pore diameter and 493.73 m 2 /g for surface areas of Uio-DBD-1 were obtained. Subsequently, the adsorption performance of Uio-DBD-1 towards Hg 2+ was studied under different pH, dosage, concentration, and time. The corresponding maximum adsorption capacity of 423.10 mg/g and equilibrium time of 10 min was achieved. Remarkably, Hg 2+ concentration could be reduced below the emission limit (0.05 mg/L). Furthermore, the selectivity and reusability of the adsorbent were investigated, and the results manifested that Uio-DBD-1 maintains high removal efficiency (82.10%) after 6 times recycles. The possible adsorption mechanism could be ascribed to the strong interaction (chelation, proton exchange, and coordination) between Hg 2+ and –NH 2 /-SH groups. This work breaks new ground in functional material design and paves the way for wastewater treatment.