Nitrate removal from water using iron nanoparticles produced by arc discharge vs. reduction

Methods of fabrication of zero valent iron nanoparticles (FeNps) are found to affect their efficiency in nitrate removal from water. Application of a 50 A/cm2 current to a pair of iron electrodes, in distilled water, renders FeNps (37 nm) which show twofold efficiency over FeNps (30 nm) produced via the reduction of FeSO4 by NaBH4. The approximation of crystallite sizes of FeNps through application of the Scherrer equation to the XRD data suggests a larger size of 39 nm (37 nm by TEM) associated with the more efficient arc fabricated FeNps, compared to the FeNps produced by the reduction (30 nm). On the other hand, scanning electron microscopy (SEM) recommends a higher dispersity for the arc discharged FeNps compared to those produced by NaBH4 reduction. In addition, the XRD pattern of the arc discharge FeNps confirms their purity, whereas Fe3O4 appears as an impurity with the reduction product. Higher concentrations of nitrate retards FeNps produced by reduction while exerts less effect on the arc fabricated FeNps. Hence, using the latter brand is recommended for water sources containing higher concentration of nitrate.