Chemistry

Improvement of Potentiometric Determination of Ammonium Ions in Surface Waters for the Samples with a High Concentration

The problem of choosing a technique for determining ammonium ions, in concentrations above 1 gm/cdm, in surface waters, as in complex matrix, is one of the important problems of monitoring the condition of water bodies contaminated with ammonium salts. The solution to this problem will allow us to reliably assess the ecological condition of water bodies and the degree of reduction of environmental load during pollution elimination measures.

Modified Potentiometric Sensors of Various Types for Ceftriaxone Determination

The planar unmodified and modified by polyaniline, nanoparticles and their binary mixtures potentiometric sensors of various types were manufactured on the basis of tetradecylammonium associates (TDA) with complex connections silver (I) – ceftriaxone (Ag (I) – Ceftr). In sensors of I type electroactive components (EAC) and modifiers were brought in carboniferous ink. The polyvinylchloride plasticized unmodified and modified membranes on the basis [Ag2 (Ceftr)2] 2- · 2TDA were used in the sensors of II type; C (EAC) = 1,2,3%.

The Study of the Complexation of Volatile Organic Compounds with β-cyclodextrin and Its Derivatives in Aqueous Solutions by Headspace Gas Chromatographic Analysis

Two methods of determining the complexation constants of “volatile organic compound (VOC) – 2-hydroxypropyl-β-cyclodextrin (HP-β-CD)” were tested by headspace gas chromatographic analysis. It was shown that the complexation constants of VOC with HP-β-CD calculated using 2 approaches were comparable with each other. The increase in complexation constants was observed for homologues with the increase in the molar mass and dipole moment of molecules.

Synthesis of Magnetic Sorbents Based on Magnetite Nanoparticles and Humic Acids and Their Application for Sorption of Phenolic Ecotoxicants

Fe3O4 nanoparticles coated with humic acids isolated from chernozem, sapropel, peat and brown coal were obtained using hydrothermal synthesis. The properties of the obtained sorbents were carried out using IR spectroscopy, SEM and TEM, whereas saturation magnetization was established using a vibration magnetometer. The maximum content of nitrogen-containing groups was found in humic acids obtained from sapropel, while the minimum amount was found in brown coal. The sorption properties of these polymers were checked among 12 different phenols.

Regulation of the Physicochemical Properties of Acrylic Copolymers by Graft Polymerization onto Cellulose and Starch

Scientific literature in English from 2010 to 2019, devoted to the problem of the development of sorbents based on polymeric materials, intended for collecting spilled oil and oil products from the surface of reservoirs, was scanned and analyzed. Three most numerous classes of polymeric sorbent materials (cellulosic materials, acrylate copolymers and synthetic rubbers) were identified, and the oil sorbents proposed are characterized. Prospects of using sorbents of these classes for cleaning up the surface of reservoirs from oil spills were discussed.

Viscosity Properties of Chitosan Solutions in Glycolic Acid

Viscosity properties of chitosan solutions with molecular weights of 700 and 200 kDa in 1.5% glycolic acid were studied in a wide range of polymer concentration and ionic strength of the medium by means of capillary and rotational viscometry. The concentration dependences of the specific viscosity were plotted. The influence of the molecular mass of chitosan and the NaCl-controlled ionic strength of the medium on the hydrodynamic volume of macrochains and their polyelectrolyte properties was established. The size of a polyion with an almost completely compensated charge was estimated.

Study of Rheological Properties of Sodium Salt Solutions of Carboxymethyl Cellulose

Rheological characteristics of polymer solutions not only affect their processing, but can also influence on the structure and properties of products obtained from the solutions. This work is devoted to the study of rheological properties of sodium salt aqueous solutions of carboxymethyl cellulose in water. It is shown that the studied solutions are characterized by the presence of concentration area of unstructured semi-separated solutions without network formation.

Complexation of Polymyxin B1 Derivatives with Heparin

The method of coprecipitation from aqueous solutions at a neutral pH value was used to study the interaction of polymyxin B1 derivatives with sodium heparinate. They were compared with the initial unmodified antibiotic and with the initial antibiotic in a solution of the corresponding polymer, covalently unbound with it.

Phase Equilibria and Salting Out of Butyric Acid in the Sodium Chloride – Water – Butyric Acid Ternary System

Phase equilibria in the water–butyric acid binary system in the range of −10÷0° C and in the sodium chloride–water–butyric acid ternary system in the range of 10.0÷60.0° C were studied using the visual polythermal method. The phase diagram of the water–butyric acid binary system at −9.5° C is characterized by eutectic equilibrium, the solid phases of which being ice and butyric acid crystals. The metastable delamination range was found on the ice crystallization field, bounded by a binodal curve with an upper critical solution temperature of −3.7° C.

Assessment of Growth-Regulating Activity and Ecotoxicity of Diarylidene-Substituted Cyclohexanones

The search of new biologically active substances to be used as herbicides and plant growth regulators is carried out. The two compounds were used – 2-benzylidene-6-(m-nitrobenzylidene) cyclohexanone (1) and 2-benzylidene-6-(p-fluorobenzylidene) cyclohexanone (2). They are similar in structure, but containing different functional groups in one of the benzene rings: -NO2, and -F. Their dose-dependent effect on the germination and growth of Triticum aestivum and Barbarea vulgaris was investigated.

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