Two-Dimensional Copper-Based Metal-Organic Framework for Efficient Removal of Methylene Blue from Wastewater

Metal-organic frameworks (MOFs) can effectively remove methylene blue (MB) from wastewater due to their abundant adsorption sites and multi-level pores. In this paper, a copper-based MOF: {[Cu & sdot; (L) & sdot; (H2O)] & sdot; (DMF)}(n) (1) (H2L=2-hydroxyterephthalic acid; DMF=N,N-dimethylformamide), was synthesized by hydrothermal synthesis method. X-ray single crystal diffraction showed that a two-dimensional structure was formed by the carboxyl group of L2- in 1 took mu(2)-eta(1) : eta(1) bridged two adjacent Cu(II). In this two-dimensional structure, the coordinated water molecules and hydroxyl group on L2- were distributed on the surface of 1. Thus, it had abundant adsorption sites. The transmission electron microscopy (TEM) of copper-based MOF nano adsorbent showed that the particle diameter of the nano adsorbent prepared by a cell fragmentation apparatus was about 50 nm. The performance of the copper-based MOF nano adsorbent in adsorbing MB indicated that the optimal adsorbent dosage was 0.20 g/L and the solution pH was 6. Under the optimal experimental conditions, its maximum adsorption capacity for MB was 143.3 mg/g, which was superior to most MOFs adsorbents. The adsorption thermodynamic analysis showed that the copper-based MOF nano adsorbent at 25-45 degrees C was an exothermic (Delta H<0), and spontaneous (Delta G<0) process.