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

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.