Nitrogen Fixation Into Water by Pulsed High-Voltage Discharge

Nitrogen in the bubbling gas was directly fixed into water by pulsed high-voltage discharge. When the discharge occurred, nitrogen could be dissociated to form active N species to take part in the aqueous chemical process. Nitrous acid (HNO
₂
) was primarily produced, which was further converted into nitric acid (HNO
₃
). With the formation of HNO
₂
and HNO
₃
, the pH of the liquid decreased. The decrease in pH sped up the conversion from HNO
₂
into HNO
₃
, thus resulted in an increase in the NO
₂

^-
concentration at first and a decrease after a turning point. The nitrogen fixation rate with bubbling nitrogen was faster than that with bubbling air in distilled water. By discharge for about 30 min, HNO
₂
was converted into HNO
₃
as the final products. Its concentrations were 1.96 mmol . L
^-1
with bubbling air and 2.34 mmol . L
^-1
with bubbling pure nitrogen. The energy efficiencies were 2.08 times 10
^-9
and 2.48 times 10
^-9
mol . J
^-1
, respectively.