One-pot synthesis of hierarchical porous covalent organic frameworks and two-dimensional nanomaterials for selective removal of anionic dyes

Covalent organic frameworks (COFs) are new generation of porous materials constructed from light elements (such as carbon, oxygen and nitrogen) linked via covalent bonds. Herein, one-pot synthesis of the composite of a COF and two-dimensional (2D) nanomaterials (graphene oxide (GO), graphitic carbon nitride (g-C3N4), and boron nitride (BN)) was reported. Melamine is poly-condensed with terephthaldehyde in the presence of GO, g-C3N4, and BN leading to the formation of a series of highly cross-linked microporous hierarchical porous amine networks. The thermal behavior, surface morphology, and crystalline structure were studied using thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The prepared COF nanocomposites possessed a high surface area of 42-509 m2 g−1 with a hierarchical porous structure and high thermal stability. COF nanocomposites (COF@GO, COF@g-C3N4, and COF@BN) were explored as an adsorbent for dye removal anionic dyes (Eosin dye and fluorescein) and cationic dyes (Fuchsine, and methylene blue). The composite materials exhibit high adsorption efficiency of 100% with excellent selectivity compared to the pristine COF. The synergic effect of COF and 2D nanomaterials improves the adsorption performance of the materials.