Boosted capture ability of Rhodamine B by a core-shell composite equipped with spherical porous carbon and copper-based metal-organic framework

Abstract

Copper-based metal-organic framework (e.g. Cu-BTC) suffer from water instability issue, restricting its practical applications in the adsorptive removal of dyes from aqueous solution. In this exploration, a innovative core-shell porous composite with spherical porous carbon (SPC) and Cu-BTC units, boosting its water stability and Rhodamine B (RhB) uptake capacity. Those novel Cu-BTC@SPC composites have undergone comprehensive characterization, and their structural features have been further evaluated through various analytical techniques, including N2 adsorption-desorption tests, X-ray diffraction analysis, scanning electron microscopy image, Fourier transform infrared spectroscopy analysis, X-ray photoelectron spectroscopy, etc. Remarkably, the structural integrity of the Cu-BTC@SPC composite remained intact even after being immersed in water for a duration of 7 days or subjected to boiling water for 6 h. Through a series of batch tests, we observed that the Cu-BTC@SPC composite exhibited a high capacity for RhB adsorption. The observed phenomenon can be ascribed to the synergistic effects of π-complexation and acid-base interactions present within the SPC and Cu-BTC components. The maximum RhB uptakes over Cu-BTC@SPC can reach 81 mg/g, exceeding some other adsorbents prior publications. Especially, the RhB uptakes capacity of Cu-BTC@SPC decreased by less than 10% after the fifth cycle. The distinctive core-shell structure of Cu-BTC@SPC might be a hopeful adsorbent for dye (e.g. RhB) removal from water.