Reduction of nitrate by bimetallic Fe/Ni nanoparticles

Abstract

Bimetallic Fe/Ni nanoparticles were synthesized and their nitrate reduction capacity was studied. Nitrate (354 mg L⁻¹, equal to 5.71 mmol L⁻¹) reduction was performed using Fe/Ni nanoparticles with various Ni contents (1.0, 5.0, 10 and 20%) in an unbuffered condition. Optimum nitrate reduction rate () was obtained with 5.0% nano-scale Fe/Ni, while only 25% nitrate () was transformed by nano-scale Fe⁰ within the same reaction time, which means that these bimetallic nanoparticles are obviously more reactive than mono-metallic nano-scale Fe⁰. For this bimetallic system a near-neutral initial pH (6.5) is more favourable than an acidic condition (2.0 and 4.0). Relatively air-stable nano-scale Fe/Ni particles were developed by slowly aging them for 22 h and exhibited similar reactivity to freshly synthesized nano-scale Fe⁰. Although undesirable transformation of nitrate (91.0±0.37% ) to ammonium was observed in this study, Fe/Ni particles showed a much higher nitrate reduction rate and an optimum reduction rate at near-neutral pH, which may have important implications for nitrate-contaminated site remediation.

Keywords:

• Fe/Ni
• Fe⁰
• nanoparticle
• nitrate
• reduction
• stability

Acknowledgements

This study was sponsored by the Fundamental Research Funds for the Central Universities (2010ZD14, 2010ZD13), National Program of Control and Treatment of Water Pollution (2009ZX07424-002), Program for New Century Excellent Talents in University (NCET-07-0769) and China Geological Survey (Ke 2011-01-66-07).