Nitrate removal by Fe⁰/Pd/Cu nano-composite in groundwater

Abstract

Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe⁰/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe⁰/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe⁰/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe⁰/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe⁰/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe–6.0%Pd–3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe⁰ alone or Fe–Cu, nano-Fe–6%Pd–3%Cu composites showed a better selectivity to N₂.

Keywords:

• nitrate reduction
• nano-Fe⁰/Pd/Cu
• ammonia
• groundwater
• anion