Nanoscale nickel metal organic framework decorated over graphene oxide and carbon nanotubes for water remediation

Abstract

In this report, highly crystalline and well-dispersed nano-sized nickel metal organic framework (MOFs) was decorated over graphene oxide (GO) and carbon nanotubes (CNTs) platforms to form hybrid nanocomposites. These as-synthesized hybrid nanocomposites were synthesized through a one-pot green solvothermal method. The prepared nanocomposites were characterized by SEM, TEM, EDS, XRD, FT-IR, Raman and TGA techniques. XRD analysis revealed the crystalline structure of the hybrid nanocomposites. Morphological and elemental studies also verified successful decoration of nickel-benzene dicarboxylate (Ni-BDC) MOFs over GO and CNT platforms. Chemical analysis collected through IR, and thermal analysis collected through TGA technique, illustrated the presence of all the components in the hybrid nanomaterials. Methylene blue (MB) was used as a model organic pollutant to analyze the adsorption capacity of the prepared nanocomposites. According to the findings, a strong interaction exists between the MB molecule and the developed adsorbents at which due to the synergistic effect, the hybrid nanocomposites show several times higher adsorption capacity compared to that of parent materials. This improvement can be due to several reasons: high surface area of the MOFs in the composites resulting from the smaller size of MOFs, presence of the pores formed between the MOFs and the platforms and different morphological characteristic of Ni-BDC MOFs in hybrid nanocomposites, compared to bare Ni-BDC MOFs. Furthermore, the isotherm and kinetic studies revealed that the adsorption of MB onto the newly prepared adsorbents could best be explained by the Langmuir and Pseudo-second order kinetic models. A regeneration study demonstrated the highly stable nature of the hybrid nanocomposites.

Keywords: CNTs; Graphene oxide; Hybrid nanocomposites; Methylene blue; Nano-sized Ni-BDC MOFs; Water remediation.