S. A. Dolenko

Association and colloid-chemical properties of humic acids in aqueous solutions

Colloid-chemical properties of humic acids in aqueous solutions have been studied as functions of their concentration, medium pH, and counterion nature. It has been established that, at pH < 4, Na-form humic acids exist in aqueous solutions as 30–120-nm aggregates. At pH > 4, the state of humic acids depends on the solution concentration. At low concentrations, they exist as individual molecules; as the concentration is increased, they associate to form supramolecular structures at 5 mg/dm3 and micelles at 8 g/dm3. An increase in the counterion charge has been shown to decrease the critical concentration of supramolecular structuring. Supramolecular structures have increased adsorbability on clay minerals and promote the manifestation of solubilizing properties of humic acids in solutions even at a concentration of 5 mg/dm3, which is three orders of magnitude lower than the critical micelle concentration (8 g/dm3).

Sorption-photometric determination of anionic surfactants in water

The adsorption of Crystal Violet, anionic surfactants, and their ion associates on nonionic hydrophobic polymer adsorbent Amberlite XAD-16 was studied. A procedure for the sorption-photometric determination of anionic surfactants in water was developed with a detection limit of 0.001–0.003 mg/L at a sample volume of 50 mL.

Impact of a pulse corona discharge on the formation of hydrogen peroxide in different types of water

Using an example of detecting hydrogen peroxide the article showed the possibility of generation of highly active radicals in various types of water (high-resistance, distilled and tap) in their treatment by a pulse positive corona discharge. The article has established the impact of the conditions for the formation of plasma, time of treatment and temperature of the solution at the output of hydrogen peroxide and also for the change of some physicochemical properties of investigated water samples.

Sorption-photometric method for determination of sodium dodecyl sulfate with methylene blue in the presence of non-ionic surfactant

The extraction of sodium dodecyl sulfate with methylene blue by polyurethane foam in the presence and absence of non-ionic surfactant additives was investigated using diffuse reflectance spectrophotometry method. The sorption-photometric method for determining sodium dodecyl sulfate in water of various types was developed. The linearity of calibration curve with the test sample volume being 25 cm3 was kept within the range of 0.04–6.0 mg/dm3.

The use of cationogenic SAS in pressure-driven processes of purification of water contaminated with Cr (VI) salts

The article has investigated the impact of cationogenic SAS on purification of contaminated waters of Cr (VI) by the methods of ultra and nanofiltration. We have determined the impact on these processes of the pH of the medium working pressure, and concentration of SAS concentration. The most effective results of water purification of Cr (VI) were obtained at pH 5 and SAS concentration close to its critical concentration of micelle formation.

Sorption of methylene blue on polyurethane foam and its use for determination of anionic SAS

The article has studied sorption of the main dye of methylene blue on polyurethane foam and influence on it of sodium dodecyl sulfate additives. We have developed a sorption-photometric technique of determining 5–30 μg of sodium dodecyl sulfate at the sample volume 25 cm3.

The impact of water-soluble humic acids on extraction-photometric determination of anionic SAS with methylene blue in natural waters

The estimation of possible applications of the standard extraction-photometric method for determining anionic SAS by using methylene blue has been performed during the analysis of dyed natural waters. It is shown that humic acids significantly affect the adequate determination of anionic SAS by the specified method. The ways of eliminating the harmful influence of humic acids during the analysis of natural objects are also proposed.

The use of vacuum ultraviolet radiation for investigationof water samples with different salt content

The paper gives the results of experimental research in photolysis of water samples using vacuum ultraviolet radiation at the wavelength 185 nm. Differences in the kinetics of formation of hydrogen peroxide for different waters found are explained by changes in the structural state of water, which was confirmed in defining sizes of clusters by the method of dynamic light scattering.

Sorption-photometric determination of sodium dodecylsulfate with methylene blue on polyurethane preliminary treated by organic solvent

The paper has investigated the possibility of using preliminary treatment of polyurethane tablets by organic solvents for determination of anionic SAS. A technique has been developed of their sorption-photometric determination in waters with a detection limit 0.004–0.144 mg/dm3 depending on the wave length.

Absorption of organic anions from aqueous solutions by layer silicates substituted with a cationic electrolyte

The paper has conducted adsorption and spectral research of interaction of organic dyes of anionic nature with the substituted cationic polyelectrolyte (hydrochloride polyhexamethylene guanidine) layer silicates (kaolinite and hydromica). It has been proved that modifying results in an increased adsorption capacity of minerals to organic anions owing to the formation of the sorbent surface of the sorbate/modifier ionic associates. Selectivity of the sorbents being investigated to anionic compounds increases with an increase of hydrophobicity of the latter.