Surface properties of hydrous manganite (-MnOOH): A potentiometric, electroacoustic, and x-ray photoelectron spectroscopy study
2004 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, no 19, 8224-8229 p.Article in journal (Refereed) Published
The acid-base characteristics of the manganite (-MnOOH) surface have been studied at pH above 6, where dissolution is negligible. Synthetic microcrystalline particles of manganite were used in the experiments. From potentiometric titrations, electrophoretic mobility measurements, and X-ray photoelectron spectroscopy (XPS), a one pKa model was constructed that describes the observed behavior. The data show no ionic strength effect at pH < 8.2, which is the pH at the isoelectric point (pHiep), but ionic strength effects were visible above this pH. To explain these observations, Na+ ions were suggested to form a surface complex. The following equilibria were established: =MnOH2+1/2 =MnOH-1/2 + H+, log 0 (intr.) = -8.20; =MnOH2+1/2 + Na+ =MnOHNa+1/2 + H+, log 0 (intr.) = -9.64. The excess of Na+ at the surface was supported by XPS measurements of manganite suspensions containing 10 mM NaCl. The dielectric constant of synthetic manganite powder was also determined in this study.
Place, publisher, year, edition, pages
2004. Vol. 20, no 19, 8224-8229 p.
Chemical Sciences Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:umu:diva-14028DOI: 10.1021/la0496338OAI: oai:DiVA.org:umu-14028DiVA: diva2:153699