Removal of Synthetic Azo Dye Using Bimetallic Nickel-Iron Nanoparticles

Abstract

Bimetallic nanoparticles comprised of iron (Fe) and nickel (Ni) were investigated for the removal of an azo dye contaminant in water. Morphology (core shell and alloy) and metal molar ratio (Ni2Fe10, Ni5Fe10, and Ni10Fe10) were tested as key nanoparticle properties. The shelf life of the nanoparticles was tested over a 3-week period, and the effect of initial nanoparticle concentration on dye removal was evaluated. The highest initial nanoparticle concentration (1000 mg/L) showed consistent Orange G removal and the greatest extent of dye removal, as compared to the other tested concentrations (i.e., 750 mg/L, 500 mg/L, and 250 mg/L) for the same nanoparticle morphology and metal molar ratio. The metal molar ratio significantly affected the performance of the core shell morphology, where overall dye removal was found to be 66%, 89%, and 98% with an increasing molar ratio (Ni2Fe10 → Ni5Fe10 → Ni10Fe10). In contrast, the overall removal of the dye for all molar ratios of the alloy nanoparticles only resulted in a variability of ±0.005%. When stored in water for 3 weeks, core shell nanoparticles lost reactivity with an average>17% loss in removal with each passing week. However, the alloy nanoparticles were able to continually remove Orange G from solution after 3 weeks of storage to ~97% when used at a starting nanoparticle concentration of 1000 mg/L. Overall, the Ni2Fe10, Ni5Fe10, and Ni10Fe10 alloy nanoparticles with a starting nanoparticle concentration of 1000 mg/L resulted in the greatest dye removal of 97%, 99%, and 98%, respectively. Kinetic rate models were used to analyze dye removal rate constants as a function of nanoparticle properties. Kinetic rate models were seen to differ from core shell (first-order kinetics) to alloy morphology (second-order kinetics). Alloy nanoparticles resulted in as high as X kinetic rate constant, and core shell nanoparticles resulted in as high as XX kinetic rate constant. Metal leaching from the nanoparticles was investigated; alloy nanoparticles resulted in leaching of 3% Fe and 5% Ni which is similar to core shell leaching of 3.2% Fe and 4.3% Ni from the Fe10Ni10 nanoparticles.

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

“…NiFe nanoparticles have been found to degrade Orange G through hydrogen transfer, but oxidized NiFe nanoparticles promote the generation of hydroxyl radicals leading to an oxidative pathway [8]. NiFe alloy nanoparticles are commonly found to follow pseudofirst-order reaction for azo dye removal, but our synthesized alloy nanoparticles were found to follow pseudo-secondorder [7], [8], [27], [29], [30]. The kinetic discrepancies between our work and literature lead to further investigation of surface characteristics of the nanoparticles pre-and postreaction to explain kinetic trends.…”

“…The nanoparticle dosage, pH, and temperature are factors proven in the literature to impact NiFe reactivity in the aqueous environment [7], [8], [26]- [28]. In previous work, we observed the morphology (i.e., core shell vs. alloy) of the bimetallic nanoparticles changes the kinetics of the reaction, indicating different processes controlling the reaction rate [29]. ANiFe nanoparticles promote different degradation pathways dependent on surface characteristics.…”

“…Bimetallic NiFe alloy oxide nanoparticles were synthesized via an aqueous solution-based reduction reaction, and the molar ratio of the two metals (nickel/iron) was evaluated. Nanoparticles with molar ratios ranging from Ni1Fe10 to Ni5Fe10, were chosen due to previous work conducted [29] and were tested in batch reactors for the removal of Orange G over time. The nanoparticle surface and bulk characteristics were investigated pre-and post-reaction to understand how nanoparticle chemistry changes and to explain differences in removal efficiency.…”

Green Synthesis of Nickel Nanoparticles using Fruit Peels of Citrus Paradise for Remediation of Congo Red Dye

“…After that level, the reaction rate may be decreased [24]. The possible reason for decreasing the decolorization of direct dye at a higher concentration of nickel nanoparticles is that the destruction/change in the surface of catalyst by the products of the reaction; hence declining the catalytic efficiency of nanoparticles [25].…”

Zero-Valent Iron Nanoparticles for Soil and Groundwater Remediation

“…It is important to notice that the reduction by Fe/Ni was 50−80 times faster than when using nanoiron or iron fillers [79]. In addition, Fe/Ni nanoparticles were also used to degrade dyes [84][85][86]. Lin and co-workers reported the degradation of Scarlet 4BS with Fe/Ni BNP, proposing a degradation mechanism in which iron is oxidized producing hydrogen that is adsorbed in Ni surface.…”