Clean synthesis of rock candy-like metal–organic framework biocomposite for toxic contaminants remediation

A green methodology was considered to expeditiously synthesize a new class of microporous zeolitic imidazolate framework-8 (ZIF-8) crystals associated with ZnO nodes (denoted ZIF-8/ZnO) based on the eggshell membrane (ZIF-8/ZnO@ESM) supporting bed, to study the Malachite green (MG) and tetracycline removal. Several characterization methods were applied to analyze the properties of the materials, including FTIR, XRD, BET–BJH, and SEM/EDS/Mapping. The BET–BJH analysis validates the efficiency of the applied synthesis approach in the preparation of a high specific surface area (1498.07 m2/g) and high porous (0.061 cm3/g) ZIF-8/ZnO. Also, the N 2 adsorption/desorption analysis verifies the microporous structure of synthesized ZIF-8/ZnO in the pure and composite form regarding mean pore diameters of 1.8802 and 1.6579 nm, respectively. The MG dye removal ability of ZIF-8/ZnO@ESM nanocomposite was tested and it showed better performance in comparison with the pure ZIF-8/ZnO and ZIF-8. The results indicate that the Langmuir adsorption isotherm could explain the obtained equilibrium data with a maximum adsorption capacity of 833.33 mg/g with high accuracy (R 2 = 0 .997). Kinetic study showed that the pseudo-second-order model was capable to fit the experimental data with high correctness. Reusability test was confirmed excellent regeneration ability of ZIF-8/ZnO@ESM even after 5th cycle (<13% diminished).