Composition of sodium cholate micellar solutions.
To study the composition of sodium cholate solutions, an investigation was carried out at 25 degrees C and in N(CH3)4Cl, as a constant ionic medium, at three different concentrations (W = 0.100; 0.500 and 0.800 mol dm(-3)). Electromotive force measurements of three different galvanic cells, the first involving a glass electrode for hydrogen ions, the second an electrode for sodium ions and the third a lead amalgam electrode, were performed. Independently, lead (II) cholate solubility measurements in the presence of sodium ions were performed, as well. The experimental results obtained from both approaches were explained by assuming the formation of aggregates in cholate and sodium of different composition depending on W and on the cholate concentration. The maximum aggregation found number for cholate was 24 and even aggregation numbers were markedly predominant. Only two species with odd aggregation number were found, but at a low percentage. The assumed species and the relative constants were compared with those found for the other sodium salt of cholanic acids.
Bottari
Emilio
E
Dipartimento di Chimica, Università La Sapienza, P.le A. Moro 5, Box n. 34, Roma 62, 00185 Roma, Italy. emilio.bottari@uniroma1.it
Buonfigli
Alessio
A
Festa
Maria Rosa
MR
D002793:Cholic Acids / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D007854:Lead / Q000737:chemistry; D008823:Micelles; D020358:Sodium Cholate / Q000737:chemistry*; D012995:Solubility; D012996:Solutions
D002793:Cholic Acids; D008823:Micelles; D012996:Solutions; D007854:Lead; C007036:cholanic acid; D020358:Sodium Cholate