Mechanistic and kinetic studies of crystallization of birnessite

Journal Article · Mon Feb 21 04:00:00 EST 2000 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic990456l· OSTI ID:20017569

Luo, J; Zhang, Q; Suib, S L

Kinetic and mechanistic features have been studied for the crystallization of birnessite in aqueous systems via different synthesis methods: the oxidation of Mn{sup 2+}, reduction of MnO{sub 4}{sup {minus}}, and redox reaction between Mn{sup 2+} and MnO{sub 4}{sup {minus}}. For oxidation methods, a topotactical conversion from Mn(OH){sub 2} to birnessite via feitknechtite ({beta}-MnOOH) is observed. In reduction methods, birnessite evolves from the initially produced amorphous manganese oxide (AMO gel). For redox methods, both mechanisms exist, with the latter prevailing. A liquid mechanism is proposed to describe the reduction and redox synthesis, which comprises three stages: an induction period, a fast crystallization period, and a steady-state period. The redox method is accompanied by the formation and phase transformation of feitknechtite to birnessite. A method combining IR and XRD quantitation is proposed to detect nuclei in the induction period. Crystallization rates and apparent energies of activation of crystallization for reduction and redox methods are determined.

• Research Organization: Univ. of Connecticut, Storrs, CT (US)
• Sponsoring Organization: US Department of Energy
• OSTI ID: 20017569
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 4 Vol. 39; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTALLIZATION
MANGANESE OXIDES
REACTION KINETICS
REDOX REACTIONS
SYNTHESIS