1998/03/01 by Hans Christian Bruun Hansen, Christian Koch · 4 citations
Environmental Science · Materials Science · #Clay minerals and soil interactions #Layered Double Hydroxides Synthesis and Applications #Phosphorus and nutrient management
paper · doi:10.1180/000985598545453
openalex publication_date 1998/03/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
Abstract Iron(II)-containing minerals are potential inorganic nitrate reductants in soils and sediments. Specifically, synthetic green rust (Fe 4 II Fe III 2 (OH) 12 SO 4 . y H 2 O, GR) reduces nitrate to ammonium. The reaction of GR with two different nitrate salts, NaNO 3 and Ba(NO 3 ) 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 NaNO 3 and Ba(NO 3 ) 2 , respectively. However, for the latter reaction the rate of reaction is increased 40 times. Based on X-ray and M6ssbauer investigations, this acceleration of the reaction rates is attributed to the forced exchange of sulphate with nitrate in GR interlayers caused by precipitation of BaSO 4 outside the GR particles, a reaction which does not occur in the presence of NaNO 3 . 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.