DMF promoted embedded of melamine inside HKUST-1 for efficient Hg(II) adsorption with regenerability

In response to the growing problem of Hg(II) pollution in water environment, highly efficient HKUST-1@melamine adsorbent for Hg(II) removal was synthesized by in-situ growth post-synthesis modification method. Under the regulation of DMF, melamine embedded inside the HKUST-1 pore, which guaranteed the high loading rate. Based on theoretical calculation, DMF lowered the energy barrier for melamine to enter the HKUST-1 pore (2.79 eV to 0.21 eV). Meanwhile, water stability and skeleton structure were also be strengthened. The -NH2 on melamine in the pores would coordinate with Hg(II), and the corresponding Eads of the composite with Hg(II) was calculated-3.49 eV, confirming the spontaneous adsorption reaction. Under the optimal conditions, HKUST-1@melamine showed the best adsorption of Hg(II) with a removal rate of 99.41 % within 90 min. The maximum adsorption capacity qm of 1557.38 mg/g, which was several times more than the existing MOF-based adsorbents. And the good selectivity and anti-interference realized the following practical application in real samples. In addition, the material achieved 85.3 % of qm after 4 regeneration cycles with 5 % thiourea. This research would provide a theoretical basis for rapid and efficient nanomaterials-based treatment of heavy metals pollution in water.