Publication Date:
2009-09-01
Description:
A series of Cu-substituted goethites, single and co-substituted with Cr, Zn, Cd and/or Pb was prepared, having molar ratios equal to 2.00, 3.33 and 5.00 mol%. All the samples contained only goethite, except Cu-, (Cu,Zn)- and (Cu,Pb)-samples synthesized at 5.00 mol% where hematite was also formed. The presence of Cr/Cd suppressed the hematite-forming effects of Cu. The general sequence of metal entry into the single-metal-substituted goethites was Zn = Cr 〉 Cd 〉 Cu 〉 Pb and in di- (5.00 mol%) and tri- (3.33 mol%) metal-substituted goethites was Cu 〉 Zn 〉 Cd 〉 Cr 〉〉 Pb. Cu incorporation increased all the unit-cell parameters in single-metal-substituted goethite, and these parameters increased in combination with other metals as follows: Cd 〉 Zn 〉 Cr 〉 Pb in the multimetal-substituted goethites. The Cu-substituted goethite dissolved faster than pure goethite. Co substitutions of Cr/Pb reduced the dissolution rate (kFe), while substitutions of Cd/Zn increased kFe.
Print ISSN:
0009-8558
Electronic ISSN:
1471-8030
Topics:
Geosciences
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