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

Abstract

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·(L)·(H2O)]·(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 μ2‐η1：η1 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 ℃ was an exothermic (△H < 0) , and spontaneous (△G < 0) process.