Adsorption, photocatalytic degradation, and their mechanisms of methylene blue on three-dimensional Cu-MOF

Herein, we report the structure, adsorption and photocatalytic degradation properties of a novel metal-organic framework [Cu-3(ppda)(3)(tib)(2)(H2O)(4)]center dot 6H(2)O (Cu-MOF) by the selection of the flexible 1,4-phenylenediacetic acid (H(2)ppda) and the rigid 1,3,5-tris(1-imidazolyl) benzene (tib). In Cu-MOF, ppda(2-) and tib ligands alternately link Cu ions to form 2D polymeric layers, the layer and layer interpenetrate each other by trans-ppda(2-) to form a stable 3D structure. Cu-MOF has excellent thermal stability and semiconductor properties, so it can be used as a catalyst. Cu-MOF had the best catalytic effect on methylene blue (MB), with a catalytic efficiency of up to 97% and the highest reaction rale constant of 0.019 7 min(-1). The main photocatalytic degradation mechanism is the separation of the photogenerated electron and hole pair of the catalyst under the light excitation, and the redox reaction occurs to produce the active species to degrade the dye and eventually decompose into carbon dioxide and Water. Cu - MOF exhibited high adsorption capacity after adding NaCl (200 g center dot L-1) to MB solution (87.23 mg center dot g(-1)). The adsorption process is a spontaneous monolayer chemisorption process illustrated by the pseudo-second-order kinetic and Langmuir isotherm models and thermodynamic studies. CCDC: 2219373.