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Abstract: In this paper the separation factors of cadmium and zinc were determined for extraction with Amberlite LA-2 and tri-n-butyl phosphate from pure hydrochloric and hydrobromic acid solutions as well as from mixtures of any of these two acids or KI with sulfuric or orthophosphoric acids. The complex correlation of the separation factor is due to changes in the activity coefficient of cadmium and zinc with the aqueous phase composition.

Abstract: A comparative study is presented on neutron activation analysis of rock and soil samples using whole reactor neutron spectrum and epithermal neutrons with both relative and monostandard procedures. The latter procedure used with epithermal neutron activation analysis of soil samples necessitated the use of the “effective resonance integrals” which were determined experimentally. The incorporation of the β factor, representing deviation of reactor epithermal neutron flux from 1/E law, is developed in the present work. The main criteria for the choice of one or more of the procedures studied for a given purpose are also indicated. Analysis of 15 trace elements, Ca and Fe in the standard Japanese granite JC-1 using monostandard epithermal neutron activation gave results in good agreement with the average literature values.

Abstract: Separation factors of silver-cadmium and silver-zinc pairs were determined for Amberlite LA-2 and tri-n-butyl phosphate (TBP) from pure hydrochloric, hydrobromic, sulphuric and orthophosphoric acids as well as from their binary mixtures. The separation of cadmium and zinc from macroamounts of silver can be best achieved from ca. 2M H2SO4. There are many other media suitable for the separation of trace silver from cadmium and zinc matrices.

Abstract: A systematic study was performed on the extraction and separation of cadmium from iron halides in pure halo-acid solutions and their mixtures with H2SO4 and H3PO4. As solvents Amberlite LA-2, TBP, nitrobenzene and HDEHP were used. Recommended separation media for the amine are 2M HCl, 1M HBr, 1.12M HCl−2M H2SO4, 0.64M HBr−2M H2SO4, 1.12M HCl−4M H3PO4 0.64M HBr−7M H3PO4 and for TBP the medium 0.64M HBr−4M H3PO4 is the only suitable condition.

Abstract: The radioactive tracer technique was used for studying the extraction and predicting the best conditions of separation of arsenic halides by organic solvents of different nature. Sulphuric acid was found to enhance the extraction of arsenic halides. Extraction of AsI3 increases in the order cyclohexane 4 toluene 4 and is quantitative by benzene and nitrobenzene. For a given extraction increases in the order AsCl33< 3. Spectral measurements were made on some solvents; at maximum absorption there was a linearity between absorbance and AsI3 concentration up to 2·10−4 M for o-xylene and to 2.5·10−4 M for nitrobenzene.

Abstract: The extraction of Fe(III) and Fe(II) from various aqueous acidic solutions, with nitrobenzene, Amberlite LA-2, TBP and HDEHP is described. Conditions are given for the separation of Fe(III) from Fe(II). The extraction and separation of Fe(III) and Fe(II) is most adequate from HCl solutions, using the four solvents. The extraction of iron halides from H2SO4 solutions has been studied. The effect of water-miscible alcohols on the distribution of Fe(III) and Fe(II) was also studied. Extraction equilibria and mechanisms were proposed on the basis of the obtained results.

Abstract: An extraction study was performed on various concentrations of cadmium, zinc and cobalt halides in the presence of sulphuric acid. A long chain amine (Amberlite LA-2) and an organophosphorus solvent (TBP) have been investigated. In most cases the value of the distribution ratio decreases with the increase of metal concentration in the aqueous phase. The various possibilities of chemical and radiochemical separations of cadmium from accompanying metal species are reported.

Abstract: An extraction study was performed on tracer concentrations of cadmium, zinc and silver halides in absence and presence of phosphoric acid. A long chain amine (Amberlite LA-2) and an organophosphorus solvent (TBP) have been investigated. The presence of phosphoric acid was found to enhance considerably the extraction of most halides. The mechanism of extraction has been discussed in light of the obtained results.

Abstract: A systematic study is presented on the extraction of Sn(IV) and In(III) halides with benzene, toluene, o-xylene, nitrobenzene, cyclohexane, n-hexane, CHCI 3 and CC14 from H2SO4 solutions. While no extraction of the chlorides of the two elements by these solvents takes place, the extraction of their bromides and iodides is considerable (In) or very high (Sn). In case of Sn(IV), maximum extraction is obtained at 12.6M H~SO4 for the bromide and at 7 9M H 2SO 4 for the iodide. It is easy to separate SbCI 3 from SnCI by extraction with one of the first 3 solvents, and SnBr 4 from InBr~ by extraction with n-hexane. Extraction mechanism of Sn(IV) halides was discussed in view of the results for the above solvents, TBP and amberlite LA2.

Abstract: A preliminary liquid-liquid extraction study of ferric and ferrous ions has been undertaken using the radioactive tracer technique with59Fe as an indicator of iron. Various solvents were studied and suitable media and solvents were selected for the separation of the two oxidation states of iron. Such separation was used to study the effect of ascorbic acid and other reducing agents on the reduction of ferric ions. The oxidation of ferrous ions to the ferric state under the effect of gamma radiation from60Co has also been investigated in the absence and presence of ascorbic acid, using spectrophotometry. In addition, a calculation of the amount of iron oxidized by gamma radiation is given with a discussion of its mechanism and possible effects on the metabolism of iron in the human body.

Abstract: In this study the cleaning time and fate of phosphoric acid on human dental enamel and dentin has been investigated, using the radioactive tracer technique with32P as an indicator of phosphorus. Twenty seconds were found to be sufficient for cleaning the enamel from phosphoric acid, which is used for conditioning, and from formulations produced from its interaction with enamel. It was also found that dentin protection is necessary before conditioning with phosphoric acid due to the retention penetration of the latter through subsurface dentinal tubules. In addition, there seems to be an interaction between phosphoric acid and Ca(OH)2 leading to the formation of a sparingly soluble compound.

Abstract: The extraction of mercury by inert solvents has been investigated as a function of the hydrochloric and sulfuric acid concentration in the aqueous phase. It was found that the extraction of mercury with kerosene is adequate at low hydrochloric acid concentrations but decreases with the increasing acid concentration. In the case of sulfuric acid a maximum and/or a minimum are noticed. The presence of trace halides in the aqueous phase changes the shape of the relation between the distribution of mercury and the sulfuric acid concentration in the aqueous phase. The extraction of mercury by neutral, anion and cation exchange reagents was also investigated.

Abstract: A systematic study is presented on the extraction of60Co and65Zn bromides and chlorides from H2SO4 with tri-n-butyl phosphate (TBP) and Amberlite LA-2. It has been found that the presence of a little HBr or HCl enhances the extraction of the two isotopes with both solvents. The extractions of60Co and65Zn have been studied as functions of the acidity (HBr, HCl or H2SO4) in the aqueous phase, and of the diluent and solvent concentrations in the organic phase. The presence of water-miscible alcohols or acetone enhances extraction. A suggested extraction mechanism is presented in the light of the obtained results.

Abstract: A systematic investigation was carried out on the extraction of Sb(III) and (V) with HDEHP from various acidic, neutral and alkaline solutions. Antimony(III) is best extracted from neutral or slightly acidic solutions, and the E values are nearly the same in the forward and backward extractions. Antimony(V) extraction is high only from concentrated HCl and HClO4, and the E values are much larger in the backward direction. Extraction and separation of Sb(III) and (V) was studied as a function of acidity, alkalinity, anion and water-miscible organic additives in the aqueous phase, as well as the diluent used and HDEHP molarity. Separation factors obtained for Sb(III) and (V) were higher than when using isopropyl ether as solvent, which was hitherto used for this purpose.

Abstract: A new approach is presented for neutron activation analysis using the monostandard (single comparator) method. Elements to be determined are classified into two groups; those with σo>Io are activated with whole neutron spectrum (without Cd-cover), using a standard of the same group (e.g. Sc), while elements with Io>σo are activated with epithermal neutrons (under Cd-cover) using a standard of the same group (e.g. Au or Co). Epithermal activation increases the number of determinable elements and its coupling with the monostandard method has the advantage of using a small Cd-cover. The σo and I0 values of some elements were determined to test this approach.