Synthesis and characterization of goethite and goethite-hematite composite: Experimental study and literature survey

Marek Kosmulski, Edward Maczka, Elzbieta Jartych, Jarl B. Rosenholm

Tutkimustuotos: LehtiartikkeliArtikkeliTieteellinenvertaisarvioitu

108 Sitaatiot (Scopus)

Abstrakti

Aging of synthetic goethite at 140 °C overnight leads to a composite material in which hematite is detectable by Mössbauer spectroscopy, but X-ray diffraction does not reveal any hematite peaks. The pristine point of zero charge (PZC) of synthetic goethite was found at pH 9.4 as the common intersection point of potentiometric titration curves at different ionic strengths and the isoelectric point (IEP). For the goethite-hematite composite, the common intersection point (pH 9.4), and the IEP (pH 8.8) do not match. The electrokinetic potential of goethite at ionic strengths up to 1 mol dm -3 was determined. Unlike metal oxides, for which the electrokinetic potential is reversed to positive over the entire pH range at sufficiently high ionic strength, the IEP of goethite is rather insensitive to the ionic strength. A literature survey of published PZC/IEP values of iron oxides and hydroxides indicated that the average PZC/IEP does not depend on the degree of hydration (oxide or hydroxide). Our material showed a higher PZC and IEP than most published results. The present results confirm the allegation that electroacoustic measurements produce a higher IEP than the average IEP obtained by means of classical electrokinetic methods. © 2003 Elsevier Science B.V. All rights reserved.
AlkuperäiskieliEnglanti
Sivut57-76
Sivumäärä20
JulkaisuAdvances in Colloid and Interface Science
Vuosikerta103
Numero1
DOI - pysyväislinkit
TilaJulkaistu - tammik. 2003
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

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