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

Abstract

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.