About Us | Help Videos | Contact Us | Subscriptions



This article in JEQ

  1. Vol. 5 No. 3, p. 320-325
    Received: Oct 24, 1974

Request Permissions


Chemical Reduction of Nitrate by Ferrous Iron1

  1. R. J. Buresh and
  2. J. T. Moraghan2



Knowledge concerning the chemical reduction of NO3 to gaseous products, a process of potential practical significance as an antipollution device, is sparse. The influence of pH on chemical reduction of NO3-N (approximate concentration 25 ppm) by Fe2+ in the presence and absence of Cu2+ was studied over a pH range from 6 to 10. After 24-hours of controlled pH incubations under a helium atmosphere NO3, NO2, N2O, NO, N2, and NH4+ were determined. The initial Fe2+/NO3 mole ratio was 8. Reduction of NO3 was negligible in the absence of Cu2+, but was pronounced above pH 7 in the presence of approximately 5 ppm Cu2+. Formation of NH4+ increased with pH and was the dominant process at pH 9 and 10. Nitrous oxide and N2 accumulations were greatest in the pH range from 8 to 8.5 and negligible at pH 6 and 10. Nitrite formation was small except at pH 9 and 10. Trace quantities of NO accumulated during incubation if the pH was allowed to drop below 6.

Levels of Cu2+ and Fe2+ influenced the extent and nature of NO3 reduction at pH 8. Maximum reduction of NO3 (93%) and maximum gas production (equivalent to 61% of the original NO3) occurred when the Fe2+/NO3 mole ratio was 12 and the Cu2+ level was approximately 10 ppm. The N2O/N2 mole ratio in the evolved gases decreased as the Cu2+ level was increased from approximately 1 to 10 ppm and as the Fe2+/NO3 mole ratio was increased from 8 to 12. Nitrate was relatively stable at a Cu2+ content of 0.1 ppm irrespective of the Fe2+/NO3 ratio.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © .