A water-stable Cd-MOF and corresponding MOF@melamine foam composite for detection and removal of antibiotics, explosives, and anions

Water pollution has become one of the most worrisome environmental problems due to its harmful to human health and environmental safety. Thus, the design and development of robust and porous materials for detection and removal of pollutants from wastewater is extremely significant. Herein, a water-stable urea-containing 3D Cd-based metal-organic framework (MOF), {[Cd(L)0.5(bpe)0.5(H2O)]·x(solv)}n (MOF-1) (H4L = 5,5′-(((1,4-phenylenebis(azanediyl))bis(carbonyl))bis(azanediyl))diisophthalic acid) was prepared using urea-functionalized tetracarboxylate H4L ligand. The activated MOF-1 (MOF-1a) showed fast, sensitive, selective, and recyclable discrimination of nitrofurazone (NFZ) and nitrofurantoin (NFT) antibiotics, 2,4,6-trinitrophenol (TNP) explosive, as well as Cr2O72− by strong luminescence quenching and obvious red-shift of maximum emission. Unfortunately, MOF-1a has low adsorption capacity for the above pollutants owing to its small pore. To improve this disadvantage, MOF-1 crystals were in situ grown on the macroporous melamine foam (MF) by a facile one-pot solvothermal method, generating a MOF-1@MF composite with stability and high voids. The MOF-1@MF exhibited rapid, enhanced, and recyclable adsorption capacity toward NFZ, NFT, TNP, and Cr2O72− in water or even aqueous solutions with different pH values. Combination of the accessible functional sites in MOF-1 and macroporous structure of MF makes MOF-1@MF composite stand out as an excellent adsorbent in wastewater treatment. This work not only presents a water-stable MOF for selective recognition of NFZ, NFT, TNP, and Cr2O72−, but also provides a facile one-pot strategy to prepare MOF-based composites for high-performance removal of above pollutants from water, promoting their practical application in water quality monitoring and wastewater purification.