Effect of precursor concentration on the characteristics of nanoscale zerovalent iron and its reactivity of nitrate

Differing precursor concentrations, 1.0, 0.1, and 0.01 M FeCl3·6H2O, were performed to produce nanoscale Fe0 and the results were discussed in terms of the specific surface area, particle size and electrochemical properties. The results indicated that the nanoscale Fe0 prepared by 0.01 M FeCl3 had absolutely reduced in size (9–10 nm) and possessed the greatest specific surface area (56.67 m2 g−1). These synthesized nanoscale Fe0 particles were attempted to enhance the removal of 40 mg-N L−1 unbuffered nitrate solution. The first-order degradation rate constants (kobs) increased significantly (5.5–8.6 times) with nanoscale Fe0 prepared by 0.01 M precursor solution (Fe0.01M0). When normalized to iron surface area concentration, the specific rate constant (kSA) was increased by a factor of approximately 1.7–2.4 using Fe0.01M0 (6.84×10−4 L min−1 m−2 for Fe0.01M0, 4.04×10−4 L min−1 m−2 for Fe0.1M0 and 2.80×10−4 L min−1 m−2 for Fe1M0). The rise of reactivity of the reactive site on the Fe0.01M0 surface was indicated by the specific rate constant (kSA) calculation and the i0 value of the electrochemical test.