Dye encapsulated hierarchical porous zeolitic imidazolate frameworks for carbon dioxide adsorption

It is important to tune the pore properties of zeolitic imidazolate frameworks (ZIFs) to improve their performance for gas adsorption. Herein, the synthesis of dye encapsulated hierarchical porous ZIF-8 (Dye@ZIF-8) is reported for cationic dyes such as rhodamine B, and methylene blue. The procedure offers a one-pot method and requires a short reaction time (30 min). The materials were characterized using X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and nitrogen adsorption-desorption isotherms. Data confirm the formation of pure and crystalline phases of ZIF-8 containing hierarchical porous structure. Dye@ZIF-8 was used as an adsorbent for carbon dioxide (CO2) gas at 273-323 K. Dye@ZIF-8 exhibited a superior CO2 capacity of 1.46 mmol g(-1) at 273 K, which is 42 % higher than that of ZIF-8 (0.84 mmol g(-1)) under the same conditions. The presence of a dye molecule into ZIF-8 crystals improves its adsorption capacity toward CO2. This study may open new avenues for the synthesis of an efficient adsorbent for gases.