Nickel-Iron Alloy Nanoparticle Characteristics Pre- and Post-Reaction with Orange G

Bimetallic nanoparticles comprised of iron and nickel were synthesized, characterized, and evaluated to optimize the ideal metal ratio for azo dye removal from water systems. Results show that changing the molar ratio of nickel to iron caused different removal rates, as well as the extent of overall elimination of azo dye from water. Lower molar ratios, from Ni1Fe10 to Ni2.5Fe10, exhibited a higher removal efficiency of 80–99%. Higher concentrations of Ni in the catalyst, from Ni3Fe10 to Ni5Fe10, resulted in 70–90% removal. The lower molar ratios of Ni exhibited a consistent removal rate of 0.11 g/L/min, while the higher molar ratios of Ni displayed varying removal rates of 0.1–0.05 g/L/min. A second order kinetic model was fit to the first twenty minutes of the reaction for all nickel to iron compositions, where there is a decrease in rate constant with an increase in molar ratio. During the last forty minutes of reaction, azo dye removal fit a zero order kinetic model. All as-synthesized nanoparticle samples were found to be structurally disordered based on the lack of distinct peaks in XRD spectra. Post-reaction samples were found to have Fe2O3 and FeOOH cubic peaks.