Reduction rate of sodium nitrate by lead drops with wet-ballmilling

Kazuyo Kikuchi, Miho Uchida, Toshiaki Yoshioka, Akitsugu Okuwaki

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Reduction of sodium nitrate solution by lead drops with wet-ballmilling is studied in order to remove concentrated NO3- from wastewater. Metal oxides forming on the lead drops surfaces in a ballmill reactor was continuously removed by inter-ball contacting In the 5-80°C temperature range, initial concentration of NaNO3 0.05-0.1 M, and ballmill rotation speed, ω , 80-180 rpm, NO3- is rapidly reduced to NO2-, then slowly to N2 and NH3. NO3- is reduced to NO2- 32-100% in 10 h, but the reduction rate of NO2- is very slow, so the maximum percentages of N2 and NHs from NO2- are only 6 and 10 %, respectively. Above 40°C, NO3- is reduced under zero-order reaction and NO2- is formed corresponding to the reduction stoichiometry. The reduction rate is proportional to ω1/2 [rpm1/2], and the apparent activation energy is 27.5 kJ·mor-1, but independent of the NO3- concentration. These results suggest that the rate determining step is the peeling of PbO layers on the particle surface. Below 25°C, the reduction rate decreases with reaction time as the surface is not covered completely with PbO due to the lowering of the rate.

Original languageEnglish
Pages (from-to)553-554
Number of pages2
Journalkagaku kogaku ronbunshu
Volume23
Issue number4
DOIs
Publication statusPublished - 1997

Keywords

  • Chemical reaction
  • Lead
  • Nitrate reduction
  • Wet-ballmilling

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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