Adsorption of bisphenol a: Characterisation of ZIF-8, UiO-66(Zr) and MIL-88(Fe) metal-organic frameworks (MOFs)

Abstract

The characteristic properties of three metal-Organic Frameworks (MOFs); zinc imidazole frameworks (ZIF-8), zirconium terephthalate (UiO-66(Zr)) and iron terephthalate (MIL-88(Fe)) were studied using Nitrogen adsorption- desorption analysis, field emission scanning electron microscopy (FESEM), X-Ray Diffraction (XRD) and Fourier- transform infrared spectroscopy (FTIR). The MOFs possessed highly microporous structure with uniformly distributed surface particles sizes. The specific Brunauer-Emmett-Teller (BET) surface area of the MOFs was 1229, 1242 and 1421 m2/g for the ZIF-8, UiO-66(Zr) and MIL-88(Fe) respectively. Thus, they have demonstrated higher adsorption efficiency towards the adsorption of bisphenol A (BPA) from the aqueous medium. The adsorption of the BPA onto the UiO-66(Zr) was said to occur via monolayer formation according to the Langmuir isotherm model, whereas that of the ZIF-8 and MIL- 88(Fe) has been found to proceed with multilayer formation according to the Freundlich model. These findings have indicated the suitability of the MOFs for BPA adsorption from the environmental waters.