The aggregation kinetics of OX50 sols in aqueous NaCl solutions (10–4–2 × 10–1 M) has been studied for 15 days or more by dynamic light scattering. The following set of characteristics has been considered to quantitatively estimate the coagulation intensity in the disperse systems: the particle size corresponding to the maximum in the differential particle size distribution curve, the height of the maximum, the polydispersity index, and the average diameter of the intensity distribution. It has been found that slow sol coagulation proceeds via the barrierless mechanism in secondary potential minimum, which arises from the predominance of the dispersion attractive forces over structural and electrostatic repulsive forces.
Методом фотометрии исследована кинетика агрегации монодисперсного золя кремнезема (средний размер частиц 220 нм, численная концентрация частиц n0 = 1010 см-3) в водных растворах NaCl и BaCl2 при рН = 6.2. Прямым методом поточной ультрамикроскопии исследована устойчивость разбавленного золя (n0 = 107 см-3) в растворах NaCl. Результаты проанализированы с позиции теории безбарьерной коагуляции ХоггаЯнга и обратимой коагуляции Муллера. Установлено, что медленная коагуляция как концентрированного, так и разбавленного золя протекает по безбарьерному механизму в дальнем потенциальном минимуме.
The aggregation kinetics of a monodisperse silica sol with an average particle size of 220 nm and particle number concentration n 0 = 1010 cm−3 in aqueous solutions of NaCl and BaCl2 at pH 6.2 is studied with the help of photometry. The stability of diluted sols (n 0 = 107 cm−3) in NaCl solutions is investigated by the direct method of flow ultramicroscopy. The results obtained are analyzed in terms of the theories of the Hogg-Yang barrierless coagulation and the Muller reversible coagulation. It is established that the slow coagulation of both concentrated and diluted sols proceeds via the barrierless mechanism in the secondary potential minimum.
Aggregation kinetics of monodisperse silica sol (with particle size of 250 nm) in aqueous NaCl solutions at pH 2.0 and 3.0 were studied by the method of flow ultramicroscopy. Slow sol coagulation was found to proceed according to a barrierless mechanism in subsequent potential minimum, caused by the predominance of attraction dispersion forces over the forces of structure repulsion at relatively large distances between particles.
Dielectric permeability of the urine from healthy subjects and patients with various types of urolithiasis was studied using millimeter electromagnetic waves. The urine from healthy subjects and patients with urolithiasis differed in dielectric properties, specific water content, and structure of water. A relationship was revealed between aggregation stability of urine colloids and dielectric properties of the urine in millimeter-wave electromagnetic radiation.
