Excess enthalpies of binary solvent mixtures of 2-butanone with aliphatic alcohols

The molar excess enthalpies of binary solvent mixtures of 2-butanone with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-methyl-2-propanol have been measured with a flow microcalorimeter at 313.15 K. The excess enthalpies are positive over the whole composition range for all alcohols studied. The values for the primary alcohols increase with the length of the alkyl chain of the alcohol. The values for the secondary and the tertiary alcohol are slightly greater than those for the primary analogues. The partial molar excess enthalpies have also been evaluated. The results are discussed in terms of intermolecular interactions in the mixtures.     

The solvent extraction of iridium with 2-mercapto-benzothiazole

Quantitative solvent extraction of iridium is possible by formation of the yellow iridium—2-mercaptobenzothiazole complex in acetic acid medium after boiling, and extraction into chloroform. Iridium is then easily determined. The applicability of the method is shown by determining iridium in noble-metal mixtures and in a copper—nickel platiniferous sample, with satisfactory recoveries.     

Protonation and solvent extraction of N-p-tolylbenzohydroxamic acid in hydrochloric acid medium

the protonation of N-p-tolylbenzohydroxamic acid (p-TBHA) in aqueous hydrochloric acid has been investigated by determination of its distribution between cyclohexane and hydrochloric acid. The pK(a) value found was - 2.30 +/- 0.02 at 30 degrees . The solubility of p-TBHA as a function of hydrochloric acid concentration has also been determined. At lower acid concentrations the solubility decreases owing to a salting-out effect, whereas at higher concentrations it increases because of formation of the more hydrophilic protonated species and a salting-in effect. Intramolecular hydrogen-bonding observed in p-TBHA provides evidence for protonation of the nitrogen atom.     

Kinetics and mechanism of sulfite oxidation by permanganate in basic medium

The kinetics of the permanganate-sulfite redox reaction has been studied in the alkaline medium using a stopped-flow technique. In the pH range 10 to 12 the reaction was found to obey the rate expression: ?½d[MnO₄^?]/dt = (k₁ + k₂[OH^?]) [MnO₄^?] [SO₃^2?]. Mechanisms for the two paths involving the formation of a (O₃MnOSO₃)^3? complex prior to the rate-determining step are consistent with the data. © John Wiley & Sons, Inc.     

Determination of technetium-99 in environmental samples by solvent extraction at controlled valence

Distribution coefficients of technetium and ruthenium are determined under different conditions with CCl₄, cyclohexanone, and 5% tri-isooctylamine (TIOA)/xylene. A method for analyzing⁹⁹Tc in environmental samples has been developed by solvent extraction in which the valences of technetium and ruthenium are controlled with H₂O₂ and NaClO. Technetium and ruthenium which are oxidized to TcO ₄ ^– and RuO ₄ ^– by NaClO are separated by extraction with CCl₄ at pH 4. The RuO ₄ ^– is reduced to low valence and technetium is kept in the TcO ₄ ^– state with H₂O₂. Technetium, ruthenium, and other nuclides are subsequently separated by solvent extraction with cyclohexanone and 5% TIOA/xylene. The decontamination of the procedure is 1.35·10⁵ for¹⁰³Ru and 1.66·10⁵ for^110mAg. The chemical yield of technetium-99 is 55%.On leave from Institute of Atomic Energy, Beijing, China     

Kinetics and mechanism of solvent extraction of copper with kelex 100 in presence of nitrilotriacetic acid

A detailed study of the extraction kinetic behavior of copper(II) in aqueous media containing nitrilotriacetic acid (H₃Y) into chloroform solutions of Kelex 100, a high-molecular-weight alkylated 8-quinolinol, is described. The rate expression for the extraction of copper by Kelex 100, described by the expression —d[Cu²⁺]/dt = k' [Cu²⁺][HL]_o/ [HY^2-]^0.5, supports a mechanism in which the rate-determining steps are the concurrent reactions of Cu²⁺ and CuY^- with a neutral Kelex 100 molecule in the aqueous phase.     

Radiochemical solvent extraction of molybdenum/VI/ using99Mo tracer

A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using⁹⁹Mo tracer. It involves removal of^99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 g of Mo.     

Analysis of 99Tc in the radioactive liquid waste after extraction into suitable solvent

⁹⁹Tc is one of the long lived fission product with high fission yield. From radioactive waste management point of view it is very much essential to evaluate the concentration of technetium in the radioactive liquid waste in order to finalise the treatment process to extract/isolate it from the stream which is discharged to the environment. For the estimation of ⁹⁹Tc in the radioactive liquid waste stream, extraction of the stable complex of technetium-tetraphenyl arsonium chloride (TPAC) into chloroform followed by beta counting was studied. Various parameters like pH, time of equilibration, concentration of TPAC in chloroform, use of other solvent for extraction as well as interference of various other radionuclides present in the waste were also studied. The radioactive liquid waste being handled in plant contains high concentrations of salts in the form of sodium nitrate. Hence effect of salt concentration on the percentage extraction was also evaluated. The extraction behavior does not dependent on change in the pH of the solution. Almost 99.5% extraction was observed in the pH range of 1?C13.0. High concentration of salt is affecting the extraction. However, this can be taken care by diluting the radioactive waste. It takes almost 90?min time for maximum extraction. Presence of radionuclides like ¹³⁷Cs, ⁹⁰Sr are not interfering the extraction of ⁹⁹Tc. However, ¹⁰⁶Ru is getting slightly extracted along with ⁹⁹Tc. The error due to ¹⁰⁶Ru can be eliminated by taking gamma spectrum and deducting the activity from the total beta activity to get ⁹⁹Tc activity. Nitrobenzene can be used for extraction of Tc?CTPAC complex in place of chloroform.     

The solvent extraction of zinc with dithizone

The extraction of 10^-5M zinc ion from aqueous solution into an organic solvent 1.8 . 10–3m in dithizone has been investigated. The effects of pH, other ions in the aqueous phase including ions which complex with zinc, and various organic solvents have been investigated. Ions which complex with zinc (citrate, oxalate, nitrilotriacetate, ethylenediaminetetracetate) change the position and/or shape of the extraction curve. Changes in the organic solvent alter the position of the curve, this alteration being qualitatively related to the solubility of dithizone in the organic solvent. Spectra for dithizone and for zinc dithixonate in several organic solvents have also been determined.     

Membrane extraction of pertechnetate with quaternary ammonium salts comparison with solvent extraction

The liquid membrane extraction (MX) and the solvent extraction (SX) of pertechnetate with Aliquat 336 as a carrier has been studied. From the results of SX the percentage of pertechnetate in the inner solution in experiment with LM was proposed. It has been found that the pertraction of pertechnetate depends on the inner solution used and the most effective solutions were those with ClO ₄ ^– and SCN^–. Effects of the carrier concentration in membranes and outer phase composition have been studied too. The results of these experiments were kinetic curves with a minimum, which may be interpreted as a result of competing processes in the systems.     

Regularities of Pd/C-catalyzed reduction of trichlorobiphenyls with 2-propanol in basic medium

Reduction of a series of trichlorobiphenyls with 2-propanol in basic medium catalyzed by Pd/C has been studied. Regioselectivity of the reduction has been determined. In the studied cases, the chlorine atom in para or meta positions of the more substituted ring has been more reactive. Using isotope labeling, it has been demonstrated that the reaction occurs via the stage of 2-propanol dehydration on palladium catalyst, followed by catalytic hydrogenation of the polychlorinated biphenyls.     

Catalytic effects in solvent extraction

Catalytic phenomena in solvent extraction of metals with hydrophobic chelating extractants are reviewed. Interface modification by adsorption of additives, phase transfer catalysis, formation of micelles, reversed micelles and microemuslions are discussed and examples are given.     

Salt effects in the synergistic solvent extraction of Co2+

The extraction of Co²⁺ by mixtures of acetylacetone (acac) and either pyridine (Py), benzylamine (ba), triethylamine (tea) or tripyridylamine (tpa) bases in xylene solvent was investigated from an aqueous phase containing salts of LiCl, NaCl, KCl, RbCl and CsCl in concentrations varying up to 3M. The different hydration properties of the alkali metal cations is show to affect very slightly the synergistic solvent extraction of Co²⁺. This result, together with previously obtained thermodynamic data indicating the nonexistence of water molecules in the extracted synergistic species, may explain the fact that these salts have no effect on the extraction of Co(acac)₂ (N-base)₂.     

The solvent extraction of Ir(III) with 2-mercaptobenzothiazole into chloroform

Ideal conditions for the extraction of Ir(III) with 2-mercaptobenzothiazole (2-HMBT) into chloroform have been established. The effects of various parameters such as pH, time of equilibration, time of heating, solvents, cation and anion interferences have been studied. The stoichiometry of metal to reagent has been evaluated.     

Solvent effects in the synergistic solvent extraction of Co2+

The extraction of Co²⁺ from a 0.1M ionic strength aqueous phase (Na⁺, CH₃COOH) of pH=5.1 was studied using thenoyltrifluoroacetone, HTTA, in eight different solvents and HTTA+trioctylphosphine oxide, TOPO, in the same solvents. A comparisons of the effect of solvent dielectric constants on the equilibrium constant shows a synergism as a result of the increased hydrophobic character imparted to the metal complex due to the formation of the TOPO adduct.     

The solvent extraction of UO 2 2+ and Th4+ with petroleum sulfoxide

The influence of the concentration of nitric, hydrochloric and phosphoric acids, petroleum sulfoxides (PSO), salting-out agent, kind of diluent and temperature on the distribution ratio of U(VI) and Th(IV) has been systematically studied. It is found that the extraction regularity of PSO is similar to that of TBP. The distribution ratio in phosphoric acid is lower, but it increases with the increase of hydrochloric acid concentration and reaches a high value. The U(VI) exhibits the maximum distribution ratio at 3–4 mol/l HNO₃. The distribution ratio of U(VI) and Th(IV) increases rapidly in the presence of a salting out agent. The extracted compounds are determined to be UO₂(NO₃)₂2PSO and Th(NO₃)₄2PSO. The extraction enthalpies of U(VI) and Th(IV) with PSO were also calculated.     

Metal complexes and solvent extraction properties of isonitrosoacetophenone 2-aminobenzoylhydrazone

Three types of copper complexes as well as an oximate-bridged nickel complex with isonitrosoacetophenone 2-aminobenzoylhydrazone (H(2)L) have been prepared in ethanolic solution and characterized by elemental analyses, IR, (1)H NMR, UV-vis and magnetic susceptibility measurement. IR spectra show the ligand coordinates as a neutral, monoanionic and dianionic O,N,N-tridentate acylhydrazoneoxime ligand depending reaction conditions and metal salts employed. The elemental analyses results, spectroscopic and magnetic data are consistent with the formation of mononuclear copper complexes and binuclear complexes with both copper and nickel. The effects of varying pH and solvent on the absorption behavior of both ligand and complexes have been investigated. The extraction ability of acylhydrazoneoxime ligand has been examined by the liquid-liquid extraction of selected transition metal [Cu(2+), Ni(2+), Co(2+), Cr(3+), Hg(2+), Zn(2+), Cd(2+) and Mn(2+)] cations. The ligand shows strong binding ability toward copper(II) ion.