Extractive Separation of Oxalic and Nitric Acids Using Tributyl Phosphate

Theoretical Foundations of Chemical Engineering - The extraction of nitric and oxalic acids by neutral compounds TBP, DBBP, and TBPO have been studied. The optimal conditions of their separation...     

Effect of mechanical activation on the sintering of a titanium-nickel alloy and a bioceramic TiNi composition

Mechanical activation strongly influences the sintering of pressed articles made of a powdered titanium-nickel alloy and its compositions with dental porcelain. Preliminary treatment of the powdered mixtures in a planetary ball mill suppresses the martensite transformation and removes anisotropy in the variation of linear dimensions of the pressings. The resulting samples exhibit, instead of a volume expansion related to the rupture of contacts between particles in the course of the reverse martensite transformation, a sintering-induced shrinkage whose extent increases with the sintering temperature and the duration of mechanical activation treatment.     

Novel metal carbon nanocomposites and carbon nanocrystalline material with promising properties for the development of electronics

New materials based on carbon nanocrystalline material and metal carbon nanocomposites, which have specific properties and are promising for the use in the fabrication of electron and electrochemical sensor devices and catalysts, have been suggested for the development of electronics.     

A Study of Indium Extraction with Carboxylic Acids with the Aim to Produce Scintillators for Solar Neutrino Detection by LENS Spectroscopy of Low-Energy Neutrino

The physicochemical properties of C₄-C₈ carboxylic acids (mutual solubility of carboxylic acids and water, ionization constants in water, distribution between water and 1,2,4-trimethylbenzene, dimerization constants in 1,2,4-trimethylbenzene) were studied. Since indium carboxylates are sparingly soluble in 1,2,4-trimethylbenzene and the second organic phase is formed in the system, In-containing scintillators can be prepared from C₄-C₅ acids only in the presence of neutral organophosphorus compounds. The best results were obtained with an extracting agent containing isovaleric acid (C₅) and 0.25 M triisoamylphosphine oxide. The scintillator prepared in this system contained 80 g l^?1 In and had a transparency of up to 2 m and a 40% light output. These parameters did not change when the sample was stored in tightly sealed dark glass vessels for 2 years at 12–34°C in an argon atmosphere. Acids C₆-C₈ can be used for In extraction without organophosphorus additives. The best results were obtained with methylvaleric acid (H₂MVA, C₆). The correlation between the transparency and light output of the scintillators, on the one hand, and the preparation conditions, on the other hand, was studied. The properties of scintillators prepared from solutions of polymeric indium hydroxy-2-methylvalerates in 1,2,4-trimethylbenzene { [In(2MVA)_0.8(OH)_2.2] _n (n = 9–115)} were the best. A procedure for extracting indium hydroxycarboxylates and preparing scintillators suitable for LENS experiment was developed. Scintillators with a volume of 4 1, an In concentration of 50 g l^?1, a light output more than 65%, and a 3-m transparency were prepared.     

Application of a semicountercurrent extraction method to waste solution treatment

General data and methods for calculations of the principal parameters of semicountercurrent extraction processes are presented. Examples of solving practical problems, based on application of the semicountercurrent extraction method to treatment of waste solutions containing various valuable components, are given. Deep purification of concentrated zinc chloride solutions to remove iron impurity with the aim of utilization of fluxing solutions was carried out. The process was performed in two semicountercurrent steps filled with VIK-II extractant in the form of zinc soap, through which the initial solution containing 250 g l⁻¹ ZnCl₂ and 0.25 g l⁻¹ FeCl₃ was passed (β_Fe/Zn ≥ 1500). The 100-fold amount of the solution relative to the working volume of the extractor was passed. The Fe concentration in the purified solution did not exceed 0.0025 g l⁻¹ (<10⁻⁵%). A scheme of treatment of electrolytic chromic acid solution to remove iron was developed. Technical-grade HDEHP was used as extractant (β_Fe/Cr > 200). The process was performed in one semicountercurrent step filled with a solution containing 250 g l⁻¹ chromic acid, 8.4 g l⁻¹ Cr(III), and 13 g l⁻¹ Fe(III), through which the extractant was passed in a volume equal to 0.66 of the initial aqueous solution volume. The Fe recovery was 98.5%. With W _o = V _a, the Fe recovery was as high as 99.9%. A minor fraction of Cr (<8%) coextracted with Fe can be returned to the process.     

Phytoconstituents and Bioactivity of Plants of the Genus Spiraea L. (Rosaceae): A Review

The genus Spiraea L. belongs to the Rosaceae Juss. family and includes more than 100 species distributed in the temperate zone and subtropical zone of the Northern Hemisphere at the center of species diversity in East Asia. Representatives of the genus are known as ornamental plants with many forms and varieties, are widely used in conventional medicine, and have a high resource potential. This review provides information on the diversity of phenolic compounds (flavonoids, phenolcarboxylic acids, and lignans), terpenoids, alkaloids, steroids, and other classes of secondary metabolites in the species of Spiraea worldwide. The article also presents little-known and hard-to-find data published in Russian concerning Spiraea phytochemistry. The biological activities of extracts and their fractions and of individual compounds having different types of biological activity (e.g., antioxidant, antibacterial, anti-inflammatory, and antifungal) are discussed. Data about biotechnological research on representatives of the genus Spiraea are presented too. The analysis of the literature showed that further chemical and pharmacological studies on Spiraea plants are quite promising.     

Ecological aspects of the operation of the Kiev hydroelectric station in a pumped-storage regime

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 32–34, September, 1988.     

Scintillators Based on Ytterbium Chloride Adducts with Neutral Organophosphorus Extractants for Detecting Solar Neutrino for LENS (Low-Energy Neutrino Spectroscopy) Experiment

The main features of extraction of ytterbium chloride with dibutyl butylphosphonate (DBBP) and triisoamylphosphine oxide (TIAPO) were studied. The effects of temperature, DBBP and TIAPO concentrations in 1,2,4-trimethylbenzene (TMB), and concentrations of salting-out agents LiCl and NH₄Cl and mineral acid (HCl) on the ytterbium distribution coefficient were determined. The isotherms of extraction of HCl and YbCl₃ with 50% DBBP and TIAPO in TMB were obtained. The composition of the extractable complexes of ytterbium chloride with DBBP and TIAPO (S), YbCl₃·3S, was determined by saturation and dilution methods. The saturation of 50% solutions of DBBP and TIAPO in TMB with ytterbium chloride was modeled. Two samples of scintillators with ytterbium concentration of 90 g l^{- 1} were prepared, and their physical parameters were measured. The stability of sample properties was tested for 18 months.