Modeling Formation and Removal of Limescale in Water Treatment Systems

Doklady Mathematics - Modeling the processes of formation and removal of limescale formed in water treatment systems is considered to develop closed-loop technologies. Solid deposits that form over...     

Phase and extraction equilibria in the antipirin-pyrocatechol-water system

Solubility isotherms of the antipirin-pyrocatechol-water ternary system at 25 and 50°C were constructed. A field where two liquid phases are present in equilibrium which results from the protolytic interaction between the components was revealed. The various-composition chemical compounds that formed were isolated preparatively. Interphase distribution of a series of metal ions was studied. The half-extraction pHs of rare-earth metals were found to be linearly related to their ionic radii.     

Study of intermolecular interactions in aqueous solutions by millimeter spectroscopy

The absorption of millimeter electromagnetic radiation (v=1.4, 1.71, and 5 cm⁻¹) by aqueous solutions of glycine (pH 6.1–6.2) in the concentration range of 0.5–2.5 mol L⁻¹ was measured. It was found that the absorbing ability of the water present in the solutions, is higher than that of pure water. This phenomenon is explained by the presence of a center of negative hydration in the structure of the glycine zwitterion, which results in an increase in the rotational mobility of water molecules immobilized in the hydrate shell of the glycine zwitterion. For Part 5, see Ref. 1. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1305–1307, July, 1997.     

Phase and extraction equilibria in water–polyethyleneglycol ethers of monoethanolamides of synthetic fatty acid–ammonium chloride systems

Phase equilibria in layering systems of water, polyethyleneglycol ethers of monoethanolamides of synthetic fatty acids (SFAs) (synthamide-5), and ammonium chloride are studied. The possibility of using such systems for the liquid extraction of metal ions is evaluated. The effect the nature of salting-out agents has on the processes of segregation of the systems has been considered.     

Systemic approach to design of liquid cleaning compositions and practical implementation of the method

The scientific basis of the development of liquid cleaning compositions is physicochemical analysis of multicomponent systems that comprise the major components of detergents. The method was implemented in Optimum software for the sulfirol-8–isobutanol–turpentine–water four-component system. After solubility in the system was studied, homogeneous mixtures were optimized by their physicochemical and functional properties (viscosity, density, refractive index, pH, detergency, and corrosion activity). The compositions having the highest detergency and neutral pH and not causing corrosion on titanium and aluminum alloys were selected and recommended for use as technical detergents.     

Efficient Synthesis of 3-(4-Carboxyphenyl)pyridine-2,6-dicarboxylic Acid

Russian Journal of Organic Chemistry - An efficient synthetic approach to 3-(4-carboxyphenyl)pyridine-2,6-dicarboxylic acid has been developed on the basis of “1,2,4-triazine”...     

Micronization of levofloxacin by supercritical antisolvent precipitation

The process of micronization of levofloxacin (LF, an antibacterial agent of the fluoroquinolone group) by the supercritical antisolvent precipitation technique (SAS) was investigated. It was shown that LF particles of different sizes (from 1 to 10 μm) and of various morphologies (from thin plates to elongated parallelepipeds) can be produced depending on the type of solvent used for conducting micronization. Investigation of the micronized LF preparations using the methods of IR-Fourier spectroscopy, Raman scattering, and circular dichroism showed that the LF micronization caused neither changes in its chemical structure nor racemization. Micronization of LF significantly affects the rate of its dissolution in model systems exhibiting effects dependent on the type of the solvent used for micronization. For example, the highest rate of dissolution at pH 4 was observed for LF preparations micronized with the help of chlorohydrocarbons. It was shown that the rate of dissolution of all micronized LF preparations was higher by 15–30% in comparison with the initial LF, which likely was related to the changes in the degree of crystallinity/amorphousness, as well as of morphologies of microparticles formed in the SAS process.     

Phase equilibria in water-alkali metal (ammonium) sulfate-Oxifos B systems

Solubility in the H₂O-(NH₄)₂SO₄ (Li₂SO₄, Na₂SO₄)-Oxifos B (potassium bis(alkylpolyoxyethylene) phosphate, [C _n H_{2n + 1}O(C₂H₄O) _m ]₂POOK, n = 8−10, m = 6) ternary systems at 25°C is reported. A two-phase liquid-liquid equilibrium in the systems is observed in a wide pH range (at inorganic acid concentrations of 2 to 10 mol/l). These separating systems are suggested for use in liquid-liquid extraction of metal ions.