Results of turbidimetry study of aggregate stability of binary SiO 2 –ZrО 2 sol and its components in 10 –3 –10 –1 M KCl solutions at рН 3.4 when ZrO 2 particles have a high positive charge and SiO 2 particles are slightly (close to zero) negatively charged are presented. The ratio of numerical concentrations of sol particles ZrO 2 to SiO 2 was 7.8 : 1. It was found that in binary SiO 2 –ZrО 2 sol both the process of heterocoagulation (mutual coagulation) of sols and coagulation of the same oxide particles occur throughout the studied range of KCl concentrations. The way of differentiation of processes of dissimilar SiO 2 and ZrO 2 particles heterocoagulation and coagulation of components is proposed. It is shown that at pH 3.4 the increase in the concentration of KCl solutions in binary SiO 2 –ZrО 2 sol leads to a decrease in the intensity of the process of ZrO 2 and SiO 2 particles mutual coagulation, which is explained by the decrease in the radius of action of attraction of dissimilar particles.

Filtration properties of a new two-sided irradiated membrane with a thickness of 20 µm (exceeding the range of the incident ion), a pore diameter of 0.20 µm, and a pore density of 1.5 × 10 8 cm −2 have been studied in comparison with a one-sided irradiated 12-µm membrane having the same pore size and a somewhat higher pore density of 2.3 × 10 8 cm −2 . An aqueous dispersion of a dye with a stable particle size distribution has been used in the experiments, with most of the particles being not larger than the pore size of the membranes. Close permeability values have been found for both membranes operating in the dead-end filtration mode, with the two-sided irradiated membrane being slightly better, and their close selective properties with some advantage of the one-sided irradiated membrane have been shown using dynamic light scattering and spectrophotometry techniques. For different dye dispersion concentrations, the mechanism of reduction in the productivity of the filtration process has been determined and differences in the limiting size of the rejected particles have been shown. It has been found that in the crossflow mode, the two-sided irradiated membrane has a certain advantage in permeability, whereas the one-sided irradiated membrane has higher rejection ability. In general, it has been concluded that the new two-sided irradiated membrane can be used in water treatment processes on a par with a one-sided irradiated membrane.

The coagulation kinetics of a monodisperse sol of Monosphere 250 silica in a 1.5 × 10–1 М NaCl solution has been studied within a pH range of 2.0–6.2. The obtained results have been used to estimate the radius of action of the structural forces for interacting SiO2 particles. It has been shown that, depending on the pH of a medium, the extension of boundary layers varies over a range of 4–8 nm, with the thickest boundary layers being observed near the point of zero charge of the particles.

Membrane filtration is one of the main methods of local water treatment. Track-etched membranes allow to obtain high-quality purified water due to their high selectivity. During the filtration, the productivity of process can decreases due to the adsorption of components in the pores, pore blockages, formation of sediment layer above the membrane. To restore the productivity, the membrane should be flushed periodically or regenerated chemically. Comparative study of the back-flushing and chemical regeneration after natural water filtration using standard 12-mu m-thick track-etched membrane and new 20-mu m-thick irradiated on both sides (with argon ions with the mileage less than the film thickness) was performed. The research was conducted with natural water from the pond "Zenit" (St. Petersburg) and the Volhov River (Leningrad region). The filtration was conducted in the dead-end mode. Water samples were analyzed by spectrophotometry, spectroturbidimetry and dynamic light scattering. The size distribution of impurity particles of studied natural water, the change in their sizes during coagulation with an aqua-aurate were determined in work. The mechanisms underlying the decrease of filtration productivity were identified. The experimental data showed that both-sided irradiated 20-mu m-thick membrane has advantages over a standard 12-mu m-thick membrane in natural water filtration with impurities that block the pores both in the direct filtration process and in back-flushing and regeneration. The possibility of regeneration and back-flushing of the 20-mu m-thick membrane allows us to recommend it for natural water filtration.

Membrane filtration is one of the main methods for individual and local water supply systems. Track-etched membranes are among the types of membranes that allow to obtain high quality purified water due to their high selectivity. Ensuring the durability of track-etched membranes is one of the topical issues on their use. Comparative research of the natural water filtration process using standard 12-mu m track-etched membrane and new, more durable 20-mu m irradiated on both sides was performed. Both membranes were manufactured by NPF TreM, St. Petersburg. The pore diameter of membranes was 0.20-0.205 mu m, the pore density was 2.3 x 10(8) cm(-2) and 1.5 x 10(8) cm(-2), respectively. The research was conducted with natural water from the pond in the park, "Malinovka" (St. Petersburg, Kosygin pr.). The filtration was run in the dead-end model. Raw water and filtrate samples were analyzed by spectrophotometry and spectroturbidimetry using KFK-3.01 photoelectrocolorimeter and SF-56 spectrophotometer. The dispersion analysis of nature water was performed by dynamic light scattering on Zetatrac laser analyze. The experimental data showed the same dependences of the productivity of dead-end filtration of pond water samples upon the volume of passed water and close values of turbidity and color in filtrate samples for both membranes. The results allowed us to recommend the 20-mu m-thick membrane irradiated on both sides with a beam of argon ions having a range shorter than the film thickness for natural water purification for local water supply of individual buildings.

Based on the results of studying the coagulation kinetics of monodisperse sol of SiO2 in NaCl solutions at various pH values, it is shown that the coagulation rate, flowing in the far potential minimum while maintaining a high repulsion barrier between the particles, depends on the formation and decomposition times of the aggregates. The boundary values of the depth and power of the far potential minimum-at the excess of which sol coagulates-are determined.

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.

For Aqualat filtering material, which is supposed to be used for electroadsorption post-treatment of waters, three methods of zeta-potential determining were applied: streaming potential method, microelectrophoresis and method implemented by Zetatrac analyzer. Besides, the conductive properties of the material were determined in a wide range of electrolyte concentrations.

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 Хогга–Янга и обратимой коагуляции Муллера. Установлено, что медленная коагуляция как концентрированного, так и разбавленного золя протекает по безбарьерному механизму в дальнем потенциальном минимуме.

For an efficient post-treatment of waste water from dissolved organic impurities drawing on the example of one of the three model objects – BPhB dye, effectiveness of “Advanced Oxidation Methods” was experimentally verified. Individual impact of hydrogen peroxide and UV radiation on BPhB aqueous solutions was also.

The results of potentiometric titration and determination of the specific conductivity of mineralized oily wastewater from landfill areaand the results of the analysis of individual and combined model systems (bicarbonate, phosphate and hydrogen sulphide) at different volume ratios and a wide range of mineral saltsconcentrations were compared. Qualitative and quantitative characteristics of studied wastewater buffer system were defined.

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.

Методом поточной ультрамикроскопии исследована кинетика агрегации монодисперсного золя кремнезема (размер частиц 220 нм) в водных растворах NaCl в интервале pH 2.0–10.2. Установлено, что медленная коагуляция золя протекает по безбарьерному механизму в дальнем потенциальном минимуме, возникающем в результате сложения дисперсионных сил притяжения и структурных сил отталкивания. Продемонстрировано влияние pH и концентрации NaCl на параметры структурной компоненты энергии взаимодействия частиц SiO2.

Photometric data on the aggregation stability of Al2O3 hydrosols prepared from Aeroxide Alu C nanopowder in NaCl solutions at pH 4.5 and 5.5 have been discussed within the framework of the generalized Derjaguin-Landau-Verwey-Overbeek theory. Analysis of the pair interaction potentials in an ensemble of particles of a sol primordially containing both primary nanoparticles and their aggregates has led to the conclusion that the coagulation proceeds via the barrierless mechanism in the secondary potential minimum.

Результаты фотометрического исследования агрегативной устойчивости гидрозоля Al2O3, приготовленного на основе нанопорошка “Aeroxide Alu C”, в растворах NaCl при рН 4.5 и 5.5 обсуждены в рамках обобщенной теории Дерягина–Ландау–Фервея–Овербека. На основе анализа парных потенциалов взаимодействия в ансамбле частиц золя, содержащего изначально как первичные наночастицы, так и агрегаты наночастиц, сделан вывод о протекании коагуляции по безбарьерному механизму в дальнем потенциальном минимуме.

The aggregation kinetics of monodisperse silica sols with a particle size of 220 nm in aqueous NaCl solutions is studied by flow ultramicroscopy in a pH range of 2.0–10.2. Slow coagulation of the sols is found to occur via the barrierless mechanism in the secondary potential minimum resulting from the summation of dispersion attractive and structural repulsive forces. The influence of pH and NaCl concentration on the parameters of the structural component of the energy of the interaction between SiO 2 particles is demonstrated.