MOF derived novel zero-valent iron @ graphitic carbon-based nanoreactors for selective reduction of hazardous 4-nitrophenol

Fabrication of stable and efficient zerovalent non-noble metal-based nanostructured catalyst has emerged as the hot area of research for wastewater treatment due to their low cost and facile natural source availability. In this work, the rationally controlled calcination of iron-terephthalate MOF has produced the magnetically active zerovalent iron-based nanostructured catalyst. Unlike other synthesis approaches, MOF's temperature-controlled calcination has offered highly effective and stable metallic iron nanoparticles encapsulated in few-layered porous graphitic carbons. The developed nanostructured catalyst was applied for room temperature conversion of hazardous 4-Nitrophenol (4-NiP) to a value-added industrial intermediate 4-Aminophenol (4-AP) by exploiting sodium borohydride as a hydrogen donor agent. The synthesized zerovalent iron-based nanostructured catalysts were thoroughly investigated and characterized by powder X-ray diffraction (pXRD), infrared and Raman spectroscopy, thermogravimetric analysis (TGA), energy dispersive X-Rays (EDS), X-ray photoelectron (XPS) spectroscopy, and transmission electron microscopy (TEM). The UV-Vis spectroscopy was used for the monitoring of the conversion of the 4-NiP into 4-AP. The conversion analysis result has shown that the MOF-based precursors' calcination temperature has played a critical role in the potency of the catalyst for converting the 4-NiP into 4-AP. The outer porous architecture provided the facile adsorption and desorption of the 4-NiP on the active nanostructured metallic iron catalyst. The maximum degradation of 4-NiP into 4-AP has taken place in a short time of 3 min at a rate constant of 0.0149 s(-1). In terms of economic perspective and high catalytic efficiency, the developed low coast nanostructured catalyst is the right choice over the reported noble metal-based catalyst for the room temperature conversion of 4NiP to a value-added product.