Skip to main content

Reduction of nitrate to ammonium by sulphate green rust: activation energy and reaction mechanism

Buy Article:

$13.61 plus tax (Refund Policy)

Abstract:

Iron(II)-containing minerals are potential inorganic nitrate reductants in soils and sediments. Specifically, synthetic green rust (FeII4FeIII2(OH)12SO4.yH2O, GR) reduces nitrate to ammonium. The reaction of GR with two different nitrate salts, NaNO3 and Ba(NO3)2, has been compared. The reaction stoichiometry and the reaction order with respect to Fe(II) in GR does not change in the examined temperature range (15-50°C), irrespective of the nitrate salt used. Activation energies of 83.9 ± 7.6 kJ mol-1 and 90.5 ± 6.9 kJ mol-1 have been determined for the reaction of GR with NaNO3 and Ba(NO3)2, respectively. However, for the latter reaction the rate of reaction is increased 40 times. Based on X-ray and Mössbauer investigations, this acceleration of the reaction rates is attributed to the forced exchange of sulphate with nitrate in GR interlayers caused by precipitation of BaSO4 outside the GR particles, a reaction which does not occur in the presence of NaNO3. This difference in anion exchange behaviour is confirmed by anion exchange experiments with the redox-inactive GR-analogue, pyroaurite. A reaction model initiated by nitrate electrostatically bound at positively charged sites of GR is proposed.

Document Type: Research Article

DOI: http://dx.doi.org/10.1180/000985598545453

Affiliations: Chemistry Department, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C., Denmark

Publication date: March 1, 1998

More about this publication?
minsoc/cm/1998/00000033/00000001/art00009
dcterms_title,dcterms_description,pub_keyword
6
5
20
40
5

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
UA-1313315-23
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more