Influence of Pd–Cu on nanoscale zero–valent iron supported for selective reduction of nitrate

Abstract

Selective reduction of nitrate over nanoscale zero–valent iron (nFe0) modified metals (Pd and Cu) was investigated. Parameters of modified metal loading, metallic ratio (Pd:Cu), and H2 gas supplying were investigated on the influence of nitrate reduction. Metal (Cu, Pd) deposited onto nanoiron was proven to be effective in promoting the formation of nitrogen gas and, on the other hand, suppressing the NH4+ formation. Hydrogen gas feeding appeared to have a synergistic effect on nitrate removal and on nitrogen gas selectivity in all types of catalytic reductants. A catalyst with a loading of 10% of (Pd–Cu)–nFe0 with a ratio of Pd:Cu of 2:1, and H2 feeding showed the highest selective to N2: NH4+ formation (51:42), compared to the others ((Cu–Pd)–nFe0, Cu–nFe0, Pd–nFe0 and nFe0). The significant improvement in initiating the formation of N2, on the other hand suppressing the formation of NH4+, was referred to an indirect electron–transferring process of nFe0 to Cu and to Pd, consequently. In addition, kinetic evaluations on each catalyst was evaluated and used to postulate the selective reduction of nitrate phenomena.