Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Jozefaciuk, G. Search for Related Content GeoRef GeoRef Citation

EFFECT OF ACID AND ALKALI TREATMENTS ON SURFACE-CHARGE PROPERTIES OF SELECTED MINERALS

Institute of Agrophysics of the Polish Academy of Sciences, ul. Dowiadczalna 4, 20-290 Lublin, Poland

^* E-mail address of corresponding author: jozefaci{at}demeter.ipan.lublin.pl

Bentonite, biotite, illite, kaolin, vermiculite and zeolite were treated with 0.1, 1.0 and 5.0 mol. dm^–3 HCl or NaOH. Suspensions of Na homoionic forms of the initial and the treated minerals were back titrated with 0.1 mol. dm^–3 NaOH. From back-titration data variable surface charge, Q_V, vs. pH dependencies and apparent surface dissociation constant distribution functions were estimated. Variable charge vs. pH curves were scaled against cation exchange capacity at pH 7.2 to obtain actual charge, Q_A, vs. pH plots. In general both treatments led to an increase of Q_V, while the Q_A value increased and decreased depending on the mineral and the treatment. Products of 5 mol dm^–3 NaOH action on zeolite and of 1 and 5 mol. dm^–3 NaOH on kaolin apparently developed a positive surface charge below pH ~3.7 and below ~4.3, respectively.

The heterogeneity of charge-generating surface groups was observed in natural minerals. During acid treatment, the number of weakly-acidic surface functional groups increased while the number of groups of stronger acidic character decreased. The opposite was found for alkaline treatment: the number of surface groups of intermediate acidity increased and that of low acidity decreased.

Key Words: Acidification • Alkalization • Surface Charge • Surface Dissociation

This article has been cited by other articles:

				J. MADEJOVA, S. ANDREJKOVICOVA, J. BUJDAK, A. CEKLOVSKY, J. HRACHOVA, J. VALUCHOVA, and P. KOMADEL Characterization of products obtained by acid leaching of Fe-bentonite Clay Minerals, December 1, 2007; 42(4): 527 - 540. [Abstract] [Full Text] [PDF]