Naslov
The influence of adsorbed anionic and cationic surfactants on the phase transformation of calcium oxalate hydrates

Autori
Babić-Ivančić, Vesna ; Filipović-Vinceković, Nada ; Sikirić, Maja ; Füredi-Milhofer, Helga

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts - 15th European Chemistry at Interfaces Conference / - Jeruzalem, 1998

Skup
15th European Chemistry at Interfaces Conference

Mjesto i datum
Jeruzalem, Izrael, 18.10.1998. - 22.10.1998

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Sažetak
Crystalization of calcium oxalate dihydrate , CaC2O4 . (2 + xH2O ,x ? 0,5) , COD and monohydrate , CaC2O4 . H2O , COM , has been extensively studied in our group because of the importance of these compounds as the main constituents of kidney stone. It was found1,2 that micellar solutions of anionic , but not cationic surfactants can promote crystallization of COD on account of COM, when – without surfactant – the latter is the prevailing crystallizing phase. In this paper we present recent results on the phase transformation of prepared, well defined crystals of COD into the thermodynamically stable COM in micellar solutions of an anionic (sodium dodecyl sulphate, SDS) and a cationic (dodecylammonium chloride, DDACl) surfactant. To keep the experimental conditions close to those prevailing in urines, experiments were carried out at 370 C in 0,3 molar sodium chloride solutions containing 0,02 molar calcium chloride and preadjusted to pH 6.5 . Well characterized COD crystals with an average BET N2 surface area of 2,5 m2 /g were immersed into these solutions to which different concentrations of SDS or DDACl were added. Phase transformation was followed through several days by periodically withdrawing samples and identifying the solid phases formed by X-ray powder diffraction, thermogravimetric analysis and optical and scanning electron microscopy. In the blank system transformation was completed within 7 days, while in micellar solutions of both surfactants transformation was significantly inhibited. SDS was found to be a stronger inhibitor of phase transformation than DDACl, which is in accordance with the results of adsorption studies showing stronger adsorption of the anionic surfactant on both COM and COD crystal/ solution interfaces. References 1. D.Skrtic and N.Filipovic-Vincekovic, J. Crystal Growth, 88 (1988) 313 2. H. Füredi – Milhofer, L. Tunik, N. Filipović-Vinceković, D.Škrtić, V. Babić-Ivančić, N. Garti, Scanning Microscopy, 9 (1995) 1061

Izvorni jezik
Engleski

Znanstvena područja
Šumarstvo

POVEZANOST RADA