High-performance Zn-based coordination polymers selectively adsorb mercury ions from aqueous solutions

Mercury ions pose a serious threat to human health and there is an urgent need to control mercury pollution. In this study, we explored a new adsorbent (defined as Zn-IDC-AMT) to achieve the purpose of controlling mercury pollution. Batch experiment showed that the optimal pH, maximum adsorption quantity and thermodynamics of Zn-IDC-AMT were 3.0, 2763.87 mg/g and spontaneous endothermic, respectively. The adsorption type was chemisorption and was consistent with the pseudo-second-order kinetic model and Hill isothermal model. The selectivity of Zn-IDC-AMT to mercury ions was investigated by selective experiments. The stability of Zn-IDC-AMT was studied by XRD analysis under different pH and three adsorption-desorption experiments. The results showed that Zn-IDC-AMT had excellent stability and good repeatability (the removal rate of all three times was more than 85%). In addition, XPS analysis, DFT calculation and frontier molecular orbital theory (FMO) were used to investigate the reaction mechanism, and the results confirmed that the reaction between Zn-IDC-AMT and mercury ions was chelation and ion exchange, which depended on the N and S atoms reacting with mercury ions together, and the reaction product containing N–Hg bond was more stable. In short, the Zn-IDC-AMT could be a promising adsorbent for effectively treating mercury pollution. • A novel adsorbent functionalized by 2-amino-5-mercapto-1, 3, 4 thiadiazole was synthesized. • The adsorbent has a large adsorption capacity of 2763.87 mg/g. • The adsorbent showed excellent selectivity and high stability for removal of mercury ions. • The adsorption mechanism was studied by DFT calculation and frontier molecular orbital theory.