Waste organic dye removal using MOF-based electrospun nanofibers of high amine density

Abstract

The exceptional structural stability of UiO-66 metal–organic framework (MOF) and ligands' functional groups render UiO-66 as a versatile candidate for multiple applications, including wastewater treatment. The possibility of a broad spectrum of post-synthetic modification of UiO-66 further expands its prospective uses. However, commercial applications of UiO-66 have been hindered by the polycrystalline nature of the powder. In this research, modification to obtain UiO-66-NH2 and post-processing with nanofibers comprising chitosan and polyvinyl alcohol (PVA) were applied to faciliate deployment as a suitable option for water decontamination. MOF nanoparticles were post-synthetically modified with 2,4,6-trichloro-1,3,5-triazine (TCT) and 5-phenyl-tetrazole (PT) to produce high-amine containing UiO-66, thus introducing active nitrogen-containing functional groups that enhanced the removal efficiency of targeted molecules from aqueous media. A systematic study was undertaken to optimize the supporting nanofibers and to demonstrate that even a low MOF functionalization, of up to 7- wt%, offered a maximum methyl orange adsorption capacity of 619 mg/g, superior to most adsorbents reported so far. Furthermore, selectivity, regeneration ability, and the effect of ambient conditions were demonstrated.