Removal of hazardous cationic organic dyes from water using nickel-based metal-organic frameworks

The adsorption activity of a layered two-dimensional (2D) nickel-based metal-organic framework (Ni-MOF) was investigated for the removal of the harmful methylene blue dye (MB) from water. NiCu-BTC, which has high surface area, was selected as a comparable adsorbent. The morphology and structure of MOF adsorbents were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA)-differential thermal analysis (DTA), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption/desorption, field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The adsorption studies of MB included kinetic and equilibrium approaches. Nanosheets of Ni-MOF showed analogous adsorption capacity (765.5 mg/g) in comparing with highly porous NiCu-BTC (798.0 mg/g). The adsorption activity of Ni-MOF may be attributed to its layered structure that facilitate the diffusion of dye species to the predominate exposed facet of (100) plane. The adsorption of dye fitted with the Langmuir isotherm and followed the pseudo-second-order kinetic model. (C) 2017 Elsevier B.V. All rights reserved.