Dilute Solution Reactions of the Nitrate Ion as Applied to Water Reclamation

摘要

A new and unexpected partial denitrification of dilute nitrate ion solutions (10 to 50 ppm NO3(-)-N) has been achieved by treatment with 8 moles of ferrous sulfate per mole of nitrate in unbuffered alkaline reactions. The nitrogen loss, which probably represents evolution of N2 or N2O, has been as high as 50%. Total reduction to lost nitrogen plus nitrite and/or ammonia has approached 100%. The reduction takes place in the presence of partially oxidized black iron hydroxides, and requires catalytic quantities of cupric ion. Denitrification is suppressed by phosphates, as well as by several other factors, some as yet unidentified. Silver ion catalysis or a 16-fold excess of the ferrous salt permits reduction to ammonia in the presence of phosphate, but there is no accompanying denitrification. (Author)