Une nouvelle technique pour le comptage des micelles d'un hydrosol à particules lyophobes

1956

Estimatioii c h i diarn6trc cles micellps d 'une suspension rolloitlale de s C 1 C n i u m par spectrophoto-P K1611aiclPar A. WATILLON e t F. VAN GRUNDERBEECK (*) (Bruxelles) S u n MARYIn a preceding paper, we proposed a counting method permitting the precise determination of particle sizes in lyophobic colloids. Results obtained by this method in the case of Selenium hydrosols were controlled by electron-microscopy. The latter technique was also used in verifying isodispersity of the suspensions.In the present paper, we propose a simple spectrophotornetric method calibrated by above mentioned absolute techniquesfor discriminating between isodispersed and poly dispersed Selenium Sols and for rapid estiniation of the average siLe of the Seleniniurn particles.

Estimation du diamètre des micelles d'une suspension colloïdale de sélénium par spectrophotométrie

1956

Preparation et Purification D'Hydrosols de Selenium Stables et Homeodisperses

Hautecler

1958

A. WATILLON, F. VAN GRUNDERBEECK et M. HAUTECLER (Bruxelles) SUMMARYHydrophobic selenium colloidal solutions prepared by Kruyt and Van Arkel's method were found to contain a large range of particle size, when verypure water was used. Moreover results were irreproducible. This is probably due to low and irregular nuclei content of the reagents used.By reducing the selenium oxide in presence of gold amicrons very homeodisperse and reproducible sols were obtained.The ionic content of the sols has been determined by a conductometric method. The sols were purified by electrodialysis using an original set up in which the water was continuously purified by ion exchange resins incorporated into the apparatus itself.

Cinétique de Coagulation et Stabilité Des Suspensions Colloidales Lyophobes De Sélénium

Romerowski

1959

Self Cite

Coagulation kinetics of homodisperse hydrosols containing spherical particles of selenium have been studied. Two independant experimental methods were used. One is based on direct observation of the sols under the ultramicroscope, the particles contained in a given volume being counted. The second method is a spectrophotometric one, based on Mie's theory. It has been possible to reproduce and to interpret the abnormally low value of R/a (R being the distance between the centers and a, the radius of the particles) observed by Kruyt and van Arkel for the rapid coagulation of selenium hydrosols. The Schultze‐Hardy rule, interpreted theoretically by Verwey and Overbeek was confirmed quantitatively. The potential values calculated by Reerink and Overbeek's equations are far too low. Notwithstanding the use of spherical particles of identical size, there was a considerable dispersion of the Van der Waals constant (2.10−14 to 25.10−14 ergs) obtained under various conditions.