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Molybdate sorption by oxides of aluminium and iron
Author(s) -
Ferreiro E. A.,
Helmy A. K.,
de Bussetti S. G.
Publication year - 1985
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.19851480513
Subject(s) - sorption , molybdate , chemistry , inorganic chemistry , hematite , goethite , aluminium , adsorption , mineralogy , organic chemistry
The sorption of molybdate by goethite, hematite, bayerite and α‐Al 2 O 3 was studied as a function of molybdate concentration and pH. The sorption isotherms exhibited double sorption plateaus in which the amount of Mo sorbed in the second plateau was double that in the first. This was attributed to the polymerization of molybdates as the concentration increases. Furthermore Mo sorption was found to be associated with a cosorption of Na cations, probably present to maintain electroneutrality in the surface zone. The sorption showed high sensitivity towards the pH, attaining a maximum at pH 4. For the iron oxides the decrease in sorption was much less pronounced on the acid side of the pH maximum and occured at lower pH values than that of the Al oxides. Molybdate sorption is explained in terms of a ligand exchange reaction between molybdate and surface hydroxyls.