Preparing Pd/Sn Modified Nickel Foam Electrode for Nitrate Removal from Aqueous Solutions

Abstract

Nitrate pollution in ground water and surface water has been becoming a worldwide problem that poses a great challenge to steady water ecosystem and human health. Electrochemical reduction of nitrate is a promising way to remove nitrate from water because of advantages. We prepared Pd/Sn modified nickel foam (NF) electrode according to a two-step electrodeposition method. The prepared NF-Pd/Sn electrode showed a micromorphology like “Karst Fengcong” with peaks, saddles and nadirs intertwined with each other. Pd 0 and Sn 0 were detected on the NF-Pd/Sn electrode and the mass ratio of Pd/Sn was 4.3/1. The NF-Pd/Sn electrode showed the highest nitrate reaction rate ( k obs : 0.543 h -1 ) and removal efficiency (94%) at the condition of 100 mg N/L, 0.05 mol/L Na 2 SO 4 and -1.6 V vs. Ag/AgCl sat. KCl. The highest N 2 -selectivity (100%) was reached at the condition of 100 mg N/L, 0.05 mol/L NaCl and -1.6 V vs. Ag/AgCl sat. KCl. The microstructure of NF-Pd/Sn electrode like “Karst Fengcong” could provide large specific surface area and lots of active sites for nitrate adsorption and electrocatalytic reduction in aqueous solution. The adsorption and the reduction reaction of NO 3 - on the surface of NF-Pd/Sn could increase the electric current response in the test system.

Keywords: Nitrate, Electrode, Palladium, Tin, Nickel foam