Sodium Nitrate Medium Research Articles

EXTRACTIVE PROPERTIES OF TRI-N-OCTYLPHOSPHINE OXIDE TOWARDS THORIUM (IV) AND EUROPIUM (III) IONS IN AQUEOUS NITRATE MEDIA

Phosphoryl containing ligand tri-n-octylphosphine oxide (TOPO) in dichloromethane has been used as an extracting agent for tetravalent thorium and trivalent europium ions from their 1 M sodium nitrates. The equilibrium data reveal that both ions are extracted as the complexes at 1:3 metal/ligand ratio. The values of conditional extraction equilibrium constant (Kex) show the superior extractive properties of the ligand towards thorium than europium ions. The effects of solvent, type and concentration of the salting-out agent on the extraction abilities of the ligand are investigated. The influence of the temperature on the extraction of these ions from the sodium nitrate medium into 1,2-dichloroethane by TOPO is studied as a function of temperature in the range 20-40 oC. The results show that the distribution ratios of thorium and europium ions decrease with the increase in temperature. Free energy (Go), enthalpy (o) and entropy (So) changes associated with the extraction process are evaluated from the distribution measurements.

Solvent extraction of thorium (IV) and europium (III) ions by diphenyl-N,N-dimethylcarbamoylmethylphosphine oxide from aqueous nitrate media

The extractive properties of a CMPO-type extractant, diphenyl- N , N -dimethylcarbamoylmethylphosphine oxide (DΦDMCMPO) in dichloromethane, have been investigated towards thorium (IV) and europium (III) ions in nitrate media at 20 °C. The conventional log–log plot analysis of the extraction equilibrium data reveals that the thorium and europium ions are extracted as complexes characterized by a metal/ligand ratio of 1:3 and 1:2, respectively. The effects of solvent, type and concentration of salting-out agent on the extraction abilities of the ligand were studied. The comparative extraction experiments in nitric acid medium showed that DΦDMCMPO exhibits higher efficiencies than tri- n -octylphosphine oxide (TOPO). The influence of temperature on the extraction of the studied ions from 1 M sodium nitrate medium into 1,2-dichloroethane by DΦDMCMPO was tested as a function of temperature in the range 20–40 °C. The distribution ratios of europium ions decrease when raising the temperature, while with thorium ions the opposite phenomenon was observed. From the distribution measurements, thermodynamic parameters such as the free energy (Δ G °), enthalpy (Δ H °) and entropy (Δ S °) changes associated with the extraction processes could be evaluated.

Column chromatographic separation of thorium (IV) from associated elements using poly-(dibenzo-18-crown-6) from sodium nitrate medium

A simple column chromatographic method has been developed for the separation of thorium from associated elements using poly-(dibenzo-18-crown-6). The separations are carried out from sodium nitrate medium. The adsorption of thorium was quantitative from 0.1-0.5M sodium nitrate. Amongst the various eluents tested, 1.0-8.0M HCl, HBr, H2SO4 and 3.0-8.0M HClO4 were found to be particularly efficient for e elution of thorium. The capacity of poly-(dibenzo-18-crown-6) for thorium was found to be 1.034 mmole/g of crown polymer. Thorium was arated from number of elements in binary mixtures in which most of the elements showed a very high tolerance limit. It was possible to separate tium from a number of elements in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand and ga: artles. The method is very simple, rapid, selective and has good reproducibility (approximately±2%).

ChemInform Abstract: Hydrolysis of the Zinc(II) Ion in Sodium Nitrate, Chloride and Perchlorate Medium: The Effect of the Anionic Medium.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Stability Constants of Complexes of Thorium (IV) with Phenolate Ions

The complex formation equilibria between Th(IV) and phenolate and p-nitrophenolate ions have been studied potentiometrically. The stability constants of the 1:1 complexes formed were evaluated in an aqueous sodium nitrate medium of unit ionic strength at 25.0°C.

SOLVENT EXTRACTION OF URANIUM( VI) AND THORIUM( IV) FROM NITRATE MEDIA BY CARBOXYLIC ACID AMIDES

ABSTRACT A series of nineteen N-alkyl carboxylic acid amides (R.CO.NHR') has been prepared, in which the alkyl groups R and R' have been varied in order to introduce different degrees of steric complexity into the compounds. A smaller number of N,N-dialkyl amides (R.CO.NR2) and non-substituted amides (R.CO.NH2) has also been prepared for comparison purposes. These amides were characterized by measurement of their boiling points, melting points, refractive indices and densities.|The solvent extraction of uranium(VI) and thorium(IV) from sodium nitrate media by solutions of the amides in toluene was studied. Increasing steric bulk of the alkyl groups R and R' was found to cause a marked decrease in the extraction of thorium, with a much smaller effect on the extraction of uranium, thus considerably enhancing the separation between these metals. Vapour pressure osmometry studies indicate that the N,N-alkyl amides are self-associated in toluene solution, with aggregation numbers up to about 2.5 for 0.6 M solu...

Hydrolysis of the zinc(II) ion in sodium nitrate, chloride and perchlorate medium: the effect of the anionic medium

Hydrolysis of the zinc(II) ion in 0.5 mol dm–3(Na)NO3, (Na)Cl or (Na)ClO4 solution was studied by the electromotive force method at 25 °C. The data cover the zinc(II) concentration range 2.5–40 mmol dm–3 within the pH range 2.0–6.0. The general least-squares treatment of the data indicates the formation of only mononuclear complexes. The complex [Zn(OH)]+ was found in all three media, while Zn(OH)2(aq) was found only in perchlorate solution. This, as well as the differing values for the stability constant of [Zn(OH)]+, demonstrate the effect of the anionic medium on both complex formation and stability of the hydrolytic species.

Study of the Catalytic Polarographic Pre-Wave of Nickel(II) Induced by Cimettdine

Abstract We carried out a comprehensive study of the Ni(II) pre-wave induced by cimetidine in sodium veronal - nitric acid - sodium nitrate media using various polarographic techniques in order to establish the mechanism of the electrode process. This was found to involve the formation of catalytic complexes of the aquo-Ni(II) and veronal-Ni(II) ions with deprotonated cimetidine adsorbed on the electrode surface, which was followed by reduction of the Ni(II) in the complexes and the consequent release of the catalytic ligand. The pre-peak obtained by differential pulse polarography for the 5 l0−4M Ni(II) - 5 10−3M sodium veronal-HNO3-NaNO3 system (pH 8.5, ionic strength 0.4 M) can be exploited for the quantitative determination of cimetidine over the concentration range 1-10−6 -1 105 M.

ChemInform Abstract: Hydrolysis of Aluminum(III) Ion in Sodium Nitrate Medium.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Hydrolysis of aluminum(III) ion in sodium nitrate medium

Hydrolysis of aluminum(III) ion in 3.0 M (Na)NO3 medium was studied by emf method at 25° C. Data cover the range 1–78 mM Al(III) within the pH range of 2.0–4.5. At a definite pH, the extent of hydrolysis increases with increasing aluminium concentration, thereby indicating the presence of polynuclear hydrolysis products. The least squares treatment of the data indicates the formation of polynuclear hydrolytic complexes [Formula: see text] [Formula: see text] and [Formula: see text] With the reactions written in the form[Formula: see text]the stability constants obtained were log (β2,2 = −7.55 ± 0.21, log β2,4 = −16.41 ± 0.13, and log (β3,4 = −13.24 ± 0.08. Distribution curves indicate that the complex [Formula: see text] is predominant. Key words: hydrolysis, aluminum(III) ion, hydrolytic complexes, aluminum(III) ion hydrolysis.

The complexation of iron(III) with sulphate, phosphate, or arsenate ion in sodium nitrate medium at 25 °C

The complexation and hydrolysis of iron(III) has been investigated potentiometrically using a glass electrode at 25 °C in the presence of sulphate ion in 1.0 mol dm–3 sodium nitrate. The formation constants of the species which are defined as [Fep(OH)q–r(SO4)r]=βspecies[Fe]p[H]–q[HSO4]r(charges ignored for brevity), expressed as log βspecies′ are: log βFe(OH)=–3.01 (0.01), log βFe2(OH)2=–3.09 (0.01), log βFe3(OH)4=–6.92 (0.03), log βFe(SO4)= 0.41 (0.01), and log βFe3(OH)4(SO4)=–5.44 (0.02). These results required the independent determination of the second dissociation constant of sulphuric acid (pK2), which was found to be 1.104 (0.005). The complexation of iron(III) with phosphate and arsenate ion has also been investigated in the same manner at 25 °C in 3.0 mol dm–3 NaNO3. No significant hydrolysis was observed because of the low pH values (<2.0) involved. The formation constants of the species which are defined as [FepH3r–q(PO4)r]=βspecies[Fe]p[H]–q[H3PO4]r, are: log βFe(HPO4)= 1.28 (0.03) and log βFe(PO4)= 0.78 (0.01). The corresponding results for the iron(III)–arsenate system are: log βFe(HAsO4)= 0.11 (0.02) and log βFe(AsO4)=–1.34 (0.03). The first dissociation constants of phosphorus(V) and arsenic(V) acids were found to be 1.763 (0.002) and 2.128 (0.002) respectively.

INFLUENCE OF THE ACETATE MEDIUM ON THE EXTRACTIONOF Co(II) BYDI-2ETHYLHEXYL PHOSPHORIC ACID

The distribution of Co(II) between aqueous sodium nitrate medium or acetate-buffered medium and kerosene solutions of di-2-ethylhexyl phosphoric acid has been studied. Under these conditions it has been possible to observe that the ions existing in the aqueous medium play a significant role in the extraction of metal. Thus, the main species extracted from nitrate medium is Co(DEHP)2(HDEHP)2, whereas in the presence of low concentrations of acetate a dimerized species (CoAc)2 (DEHP) 2 (HDEHP)4 is extracted, but (Co2Ac3DEHP) (HDEHP)3 at high acetate concentrations.

Hydrolysis of the thorium(IV) ion in sodium nitrate medium

The hydrolysis of the thorium(IV) ion in sodium nitrate medium was studied by the emf method at 25 °C. The data show that the extent of the thorium hydrolysis depends both on the concentration of thorium and the sodium nitrate medium. Thus, at a definite pH, the extent of the hydrolysis of thorium increases with increasing its concentration, but decreases with increasing concentration and the hydration energy of the medium ions. The stability constants of complexes Th2(OH)26+, Th3(OH)57+, and Th6(OH)159+ also slightly differ going from one concentration of sodium nitrate to another. The observed effect of the medium is in agreement with the linear free energy relationship proposed for the metal ion hydrolysis.

Hydrolysis of the uranyl ion in sodium nitrate medium

AbstractThe hydrolysis of the uranyl ion in sodium nitrate medium was studied by the emf method at 25°C. The data show that the extent of the uranyl ion hydrolysis depends both on the concentration of uranium and the sodium nitrate medium. Thus, at a definite pH, the extent of the hydrolysis of uranium increases with increasing its concentration, but decreases with increasing concentration of the medium ions. The composition of the hydrolytic complexes and their stability constants also indicate the effect of the ionic medium. The obtained data imply the generality of the linear free energy relationship proposed for the medium effect in the field of hydrolysis of the metal ions.

Potentiometric studies on the complex formation between methylmercury(II) and some keto- and amino-carboxylic acids

The protonation of pyruvic and laevulinic acid, l-serine, l-cysteine, l-methionine and l-asparagine, and their complex formation with methylmercury(II) ions, have been studied by a potentiometric method, in 1.0 M sodium nitrate medium at 25°. The protonation and equilibrium constants were evaluated by using the computer program LETAGROP—ETITR. The limitations of the experimental method are explained. The participation of different functional groups of the ligands in binding methylmercury(II) and the biological significance of the complex formation are discussed.

On the complex-formation between Cd(II) and EDTA

The complex-formation between cadmium and EDTA has been studied at 25° in 1.0 M sodium nitrate medium, by measuring with a glass electrode the hydrogen-ion concentrations of a series of solutions containing varying amounts of cadmium and EDTA, and the free concentration of cadmium with a cadmium-amalgam electrode. The experimental data, which were analysed by using the ETITR version of the general error-minimizing computer program LETAGROP, may be explained satisfactorily by assuming the formation of the species CdL, CdHL, CdH 2L and Cd 2L in the pH range 1.8–6.5. The equilibrium constants for the formation of these species are also reported.

Solvent extraction separation of hafnium with 4-methyl-3-pentene-2-one

A new method for the extractive separation of hafnium from zirconium is presented. Zirconium is extracted with pure mesityl oxide from 4 M nitric acid/4 M sodium nitrate medium, followed by extraction of hafnium with mesityl oxide from 0.4 M hydrochloric acid/2 M ammonium thiocyanate medium. It is possible to accomplish clean separations of Hf from Zr in ratios from 1:20 to 1:200. The separation of hafnium from commonly associated elements such as scandium, yttrium, uranium, thorium, alkali and alkaline earth metals in 500:1 weight ratio to hafnium is also possible.

Characterization of a red pigment‐antibiotic produced by Streptomyces sp. strain NRC‐C7

The streptomycete strain NRC-C 7 isolated from some Egyptian soil samples, produces a red-coloured pH indicator antibiotic active against gram positive bacteria. The producing organism belongs to the grey series of the genus Streptomyces and has grey coloured aerial mycelium with violet pigmented substrate mycelium, the violet pigment does not diffuse into the agar medium. Glucose sodium nitrate medium proved the most suitable medium for the production of this antibiotic. The pigment was extracted from the broth and purified. The solubility, Rf values, minimal inhibiting concentrations, optical rotation, UV, and IR spectra were studied. Melting point 180, elemental analysis: carbon 51.71%, hydrogen 6.25%, and oxygen 42.04%.

Hydrolytic precipitation of iron(III) in 1 M sodium nitrate medium

Hydrolytic precipitation of iron(III) in 1 M sodium nitrate medium