Selective reduction of nitrate into nitrogen using Fe–Pd bimetallic nanoparticle supported on chelating resin at near-neutral pH

Abstract

Nano zero valent iron (nZVI) has emerged as a promising water treatment technology for reduction of contaminants. Unfortunately, for nitrate reduction by nZVI, near 100% of nitrate was converted to undesired ammonia (NH3) and not to nontoxic nitrogen (N2). In this study, supported bimetallic Fe–Pd nanoparticles were prepared by loading Fe and Pd on chelating resin (DOW 3N) by two different methods. The effect of the preparation method, solution pH and Pd loading on the reactivity and selectivity of Fe–Pd composites for nitrate removal was investigated at near-neutral pH in unbuffered solution. The results suggest that DOW 3N-Fe/Pd, which was prepared by loading Pd firstly and then Fe on DOW 3N, showed a remarkable nitrate removal (>95%). The selectivity to N2 was increased with the increase of Pd content and solution pH; the N2 selectivity of 69.2% was obtained at pH 6.75 using DOW 3N-Fe/Pd with 8wt.% Pd–8wt.% Fe. The high selectivity to N2 benefited from the closer contact distance between Pd and Fe on the surface of DOW 3N-Fe/Pd and low intraparticle diffusion resistance.