N. Jordanov

Separation of tellurium(IV) by solvent extraction methods

A critical review is given of the contemporary state and the perspectives for development of solvent extraction methods for the separation of tellurium(IV). The literature (150 references) is covered up to the end of 1973.

New chelating sorbents based on pyrazolone containing amines immobilized on styrene-divinylbenzene copolymer-I Synthesis and analytical characterization.

A series of new cheating sorbents has been prepared by modification of styrene-divinylbenzene copolymer with different pyrazolone-containing amines. The substances were characterized by elemental analysis and infared spectroscopy. The complexation ability of the sorbents towards alkali, alkaline-earth, transition and precious metals has been studied. The new sorbents may successfully be applied to the simultaneous preconcentration of alkaline-earth and transition elements in neutral medium and to the selective separation of precious metals in acidic medium.

Substituted ethan phosphonic acid esters as reagents for the separation of molybdenum from rhenium by solvent extraction.

New esters of the ethan phosphonic acids have been synthesized and their extraction properties studied with respect to Mo(VI), Re(VII), Fe(III),Au(III),Tl(III) and Sb(V). A possibility is shown for the analytical separation of molybdenum from rhenium (beta = 700). The state of these new extraction agents in carbon tetrachloride solution, and the mechanism of the extraction processes, have been investigated by means of infrared spectra.

Study of liquid–liquid extraction of perrhenate with cyclohexanone in different media

A study has been made of the extraction of ReO(4)(-) from the following media: nitric, hydrochloric, sulphuric and phosphoric acids, and sodium nitrate, chloride, sulphate, carbonate and hydroxide solutions. The extraction curves were obtained and hydration and solvation numbers determined. It is concluded that in acidic medium the extraction follows a hydratosolvate mechanism; in neutral and alkaline medium only a solvate mechanism is observed. Similar investigations were carried out with molybdenum(VI). The separation of rhenium and molybdenum is discussed.

Selective separation of tin(IV) by solvent extraction with n-benzoyl-n-phenylhydroxylamine

Abstract The solvent extraction of tin(IV) with chloroform solutions of BPHA in hydrochloric acid medium is described. Maximum extraction was obtained from 0.2–0.5 M hydrochloric acid. The distribution coefficient of tin was increased 100 to 150 times when BPHA was introduced in the aqueous phase with ethanol, acetic acid or chloroacetic acid. Under the optimal conditions for extraction of tin(IV), Ti(IV), V(V), Cr(VI), Zr, Hf, Nb(V), Ta(V), Mo(Vl), W(VI), Ce(IV) and Sb(V) interfered. When hydrogen peroxide and tartaric acid were added as masking reagents, tin(IV) could be separated from these ions in ratios from 1:50 to 1:100.

Determination of copper, cadmium, lead and bismuth in phosphoric acid solutions by atomic-absorption spectrometry after extraction with diethylammonium diethyldithiocarbamate and butyl acetate

The possibility of applying diethylammonium diethyldithiocarbamate and butyl acetate for the extraction of copper, cadmium, lead and bismuth from molar solutions of orthophosphoric acid, and from solutions containing up to 55% pyrophosphoric acid and 20% tripolyphosphoric acid has been investigated. Some characteristics of the various diethylammonium diethyldithiocarbamate-butyl acetate-phosphoric acid systems are described. Suitable conditions have been found for flame atomic-absorption spectrometric determination of the ions extracted. This extraction/AAS approach has been used to determine copper, cadmium, lead and bismuth in some iron-, aluminium- and tin-containing samples dissolved in concentrated orthophosphoric acid. The same approach is used for determining 10(-5)-10(-6)% copper, cadmium and lead in orthophosphoric acid and in alkali-metal mono and dihydrogen phosphates.

Gas-chromatographic determination of selenium as an organo-selenium compound with acetophenone.

A gas-chromatographic method with electron-capture detection is presented for the determination of selenium after reaction with acetophenone to obtain an organo-selenium compound. This compound is extracted into benzene and chromatographed on an alumina column. The relative standard deviation for the average value (5 mug) is +/-6% (n = 8, P = 95%). The method has been applied to the determination of selenium in metals, alloys, ores and biological samples.

Improved specific separation of selenium by solvent extraction with saturated monoketones

Acetophenone is the most suitable ketone for extraction of selenium into chloroform. Methods are given for determination of selenium in copper concentrates and metallic tellurium.

Electrothermal AAS determination of bismuth, antimony and tin in high-purity WO3

SummaryFour methods for the bulk trace determination of Bi, Sb and Sn in WO3 were developed and tested. In all cases, the final determination is carried out by graphite furnace atomic absorption spectrophotometry. The limits of detection range from 1 μg/g for a very fast and simple method to 50 ng/g for a method comprising a trace-matrix separation by sorption and complexation on activated carbon powder loaded with TMDTC. A way of preparation of standard reference WO3-samples doped with varying amounts of Bi, Sb and Sn traces is also described.

Solvent extraction of uranium(VI) with trioctylphosphine oxide in the presence of fatty acids

The influence of fatty acids on the extraction of uranium(VI) with solutions of TOPO in different diluents was studied. The fatty acids used were valeric acid, capric acid, pentadecanoic acid, palmitic acid, and margaric acid. The effect of the acids on the distribution of uranium is antagonistic up to pH 1.9 and synergic above pH 1.9. (LK)