Catalyzing the Hydrogenation of Nitro Group to Amino Group using Greenly Synthesized Fe3O4 Nanoparticles for Water Purification

Abstract

This study investigates the synthesis, characterization, and catalytic application of Fe3O4 nanoparticles (NPs) derived from the Euphorbia milii leaf extract. The nanoparticles were synthesized by reducing iron salts (FeSO₄ and FeCl₃) in the presence of the plant extract, with the formation of Fe3O4 confirmed through UV–visible, FTIR, and SEM analyses. The catalytic activity of Fe3O4 NPs was evaluated through the reduction of 4-nitrophenol (4NP) to amino phenol in the presence of sodium borohydride (NaBH4). The reaction exhibited a high reduction in efficiency, achieving 82.63% conversion at 20 min at a 0.1 mM 4NP concentration. The reduction reached 80.36% at 0.2 mM 4NP after 24 min, highlighting the influence of substrate concentration on the reaction rate. Optimization of reaction conditions revealed that a 2.0 mM NaBH4 concentration achieved the highest reduction, with a 90.68% conversion within 14 min. Kinetic studies indicated that the reduction followed pseudo-first-order kinetics with an apparent rate constant (kapp) of 0.0962 min⁻1 and an R2 value of 0.9424. The recyclability of the catalyst was also evaluated, showing that Fe3O4 NPs maintained 82.63% reduction efficiency in the first cycle, which decreased to 71.09% in the third cycle. These findings highlights the potential of Fe3O4 NPs for environmental and industrial applications, particularly in catalytic remediation of organic pollutants.

Keywords: Functional Group Transformation, Fe3O4, Euphorbia Milli, 4NP, Kinetic Studies, Catalysis