Extraction of uranium (VI) from sulfuric acid solution with TOPO

The extraction of uranium(VI) from sulfuric acid medium with tri-octylphosphine oxide (TOPO) in n-heptane was studied. Accompanied with the increase in the concentration of H₂SO₄, the distribution coefficient of uranium(VI) increased in the region of dilute sulfuric acid. When the concentration of H₂SO₄ surpassed 3.5 mol·dm⁻³, the distribution coefficient of uranium(VI) was at maximum. This result was due to the competition extraction between uranium(VI) and H₂SO₄. From the data, the composition of extracted species and the equilibrium constant of extraction reaction have been evaluated, which were (TOPOH)₂UO₂(SO₄)₂ (TOPO) and 10^7.6±0.15, respectively.     

Extraction recovery of vanadium(V) from sulfuric acid solutions

The IR and electronic absorption spectra of di-2-ethylhexyl hydrogen phosphate (HDEHP) extracts of vanadium(V) and sulfuric acid and of vanadium(V) solutions in sulfuric acid were studied. The composition of the extractable complex was determined, and the equation of vanadium(V) extraction with HDEHP was suggested. The equilibrium constant of vanadium(V) extraction from concentrated sulfuric acid solutions was found.     

TOPO萃取色谱分离钨,钼的研究

研究了用TOPO的二甲苯溶液从盐酸水溶液中单取分离钨、钼的条件,测定了萃取配合物的组成及萃取平衡常数,提出了分离钨、钼的萃取色谱法,并用于合金钢及地球化学样品中钨和钼的测定。     

Extraction of palladium and platinum with trioctylphosphine oxide (TOPO) in various solvents from hydrochloric and hydrobromic acid media

The extraction of palladium and platinum with trioctylphosphine oxide (TOPO) in cyclohexane, chloroform, methyl isobutyl ketone (MIBK) and 2,2′-dichlorodiethyl ether (DCDE) from hydrochloric and hydrobromic acids in dependence on the concentration of the acids and the extractant has been investigated. The obtained relation have been discussed and the possibilities of the separation of palladium, platinum, gold and their simultaneous extraction have been pointed out.     

Reactions of methylcyclohexanones with concentrated sulfuric acid

Conclusions In reaction with concentrated sulfuric acid 2-, 3-, and 4-methylcyclohexanones undergo autocondensation and simultaneous intramolecular cyclization with formation of furan compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 1958–1963, November, 1966.     

Reaction of sphene with sulfuric acid solutions

The kinetics of titanium(IV) extraction from sphene with boiling 4–6 M sulfuric acid was studied. The rate constants of the sphene dissolution were determined. The influence of the particle size of the starting mineral on the rate of its dissolution was established. The feasibility of performing sphene dissolution by a liquid-phase procedure yielding stable titanium-containing sulfate solutions suitable for the synthesis of multifunctional composite materials was examined.     

Reaction of cycloheptanone with concentrated sulfuric acid

Treatment of cycloheptanone or 2-cycloheptylidenecycloheptanone with concentrated sulfuric acid, leads to self-condensation accompanied by intramolecular rearrangement and cyclization to give substituted tetrahydrofurans, viz. 2-methyl-2, 3-cyclohexano-4, 5-cyclohepteno-(⁵)-2, 3, 4, 5-tetrahydrofuran and 2-methyl-2, 3-cyclohexano-5-hydroxy-4, 5-cycloheptano-2, 3, 4, 5-tetrahydrofuran. Self-condensation of ketones with 6-membered rings under the action of concentrated sulfuric acid, proceeding via carbonium ions, and accompanied by contraction to a 5-membered ring, is also characteristic of cycloheptanone, the 7-membered ring of which isomerizes to a 6-membered one.     

Extraction chromatographic separation of thorium (IV) with tri-n-octylphosphine oxide (TOPO)

Thorium was extracted from a mixture of nitric acid and NaNO₃ of 0.01M each at pH 2.2 on a column of silica gel coated with TOPO. Thorium was separated from alkalis, alkaline earths, chromium, iron, cobalt, nickel, zinc, cadmium, mercury, lead, trivalent rare earths, platinum group metals, chloride, phosphate and acetate in binary mixtures by selective extraction of thorium. Thorium was separated from cerium (IV), zirconium, uranium and molybdenum by selective elution of thorium with 0.01M H₂SO₄. The method was extended for the analysis of thorium in monozite ore.     

Interaction of single-walled carbon nanotubes with sulfuric acid

An increase in the radiation yield of paramagnetic centers in H₂SO₄ + nanotubes (NTs) solutions was evidence of the sensitizing influence of NTs on the low-temperature radiolysis of sulfuric acid, that is, on excitation energy and charge transfer. Under the conditions selected, the influence of NTs extended to distances of 100–300 nm. The presence of NTs also influenced the interstice nanodiffusion of atomic hydrogen by decreasing kinetic heterogeneity of the vitrified matrix surrounding NTs. No chemical interaction between atomic hydrogen and carbon NTs was observed at 77–120 K. The diffusion of radical-base anions occurred following the vacancy mechanism and was independent of the presence of NTs. Nanotubes did not form a separate phase as sulfuric acid solutions were cooled to 77 K. The transition from the vitreous to supercooled liquid state was observed as irradiated and nonirradiated solutions were heated to 175 K; no phase transitions occurred over the temperature range 180–300 K. For the first time, substantial changes in the electronic spectra of sulfuric acid solutions of NTs with time were observed: an intense additional absorption band at 320 nm appeared in the spectra in several days. This band was supposedly related to the formation of complexes between H₂SO₄ molecules and the surface of NTs.     

Equilibrium structure of sulfuric acid

The equilibrium structure of the more stable conformer of H2SO4, of C2 symmetry, has been calculated ab initio using the CCSD(T) method and taking into account the core correlation correction. The accuracy of this structure has been checked by comparing it to that of similar molecules and by estimating the effects of basis set enlargement and of diffuse functions. Furthermore, the quadratic, cubic, and quartic force fields have been calculated at the MP2 level of theory using a basis set of triple-zeta quality. The spectroscopic constants derived from the force field are in satisfactory agreement with the experimental ones. The resulting band origins are compared to literature infrared values, including those for overtone and combination bands. Normal modes of vibration are pictured. Using this force field, semiexperimental equilibrium rotational constants are determined which allows us to check the accuracy of the ab initio structure and to refine it using a mixed regression method.     

Mechanism of the reaction of triterpenoids with sulfuric acid

The single maximum of triterpenoids in sulfuric acid solutions at 310 nm is due to the formation of a carbocation. Under the action of sulfuric acid, oleanolic acid undergoes lactonization at the COOH group and the Δ¹² C=C bond. Pyatigorsk Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 647–651, September–October, 1980.     

Fluidization of cation exchangers with regenerating sulfuric acid solution

Dependences of the bed expansion of cation exchangers (weakly acidic Lewatit CNP 80 and strongly acidic KU-2×8) on the flow velocity, temperature, and concentration of the regenerating sulfuric acid solution were determined. An equation describing the dependence of the bed expansion of cation exchangers on the flow velocity, temperature, and concentration of sulfuric acid, common to the two ion exchangers, was derived, which allows a priori determination of the extent of bed expansion in regeneration of cation exchangers in the fluidization mode.     

Interaction of ethyl alcohol vapor with sulfuric acid solutions

We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approximately 40 to approximately 80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients (gamma) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approximately 70 wt % and in dilute solutions colder than 220 K, the gamma values approached approximately 0.07. We also determined the effective solubility constant of ethanol in approximately 40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.     

Interaction of activated carbon electrodes with sulfuric acid solutions

Impedance and potentiodynamic studies have been carried out to investigate reversible processes on the surface of electrodes based on activated carbon (AC). Relationships have been found between the reversible capacity and true resistance, on the one hand, and the potential, on the other. Stoichiometric characteristics of AC charging in sulfuric acid have been obtained. A mechanism of the reversible surface process is suggested. It is concluded that Faraday pseudocapacity makes a considerable contribution to charging of AC electrolytes. The amount of gas liberated in the course of AC wetting in electrolyte has been measured. It is assumed that the amount of liberated gas depends on the amount of active oxygen involved in the current-forming reaction. Based on the data obtained, a redox surface reaction is substantiated in general form.     

Microwave investigation of sulfuric acid monohydrate

The complex H2SO4-H2O has been observed by rotational spectroscopy in a supersonic jet. A-type spectra for 18 isotopic forms have been analyzed, and the vibrationally averaged structure of the system has been determined. The complex forms a distorted, six-membered ring with the water unit acting as both a hydrogen bond donor and a hydrogen bond acceptor toward the sulfuric acid. One of the H2SO4 protons forms a short, direct hydrogen bond to the water oxygen, with an H...O distance of 1.645(5) A and an O-H...O angle of 165.2(4) degrees. Additionally, the orientation of the water suggests a weaker, secondary hydrogen bond between one of the H2O hydrogens and a nearby S=O oxygen on the sulfuric acid, with an O...H distance of 2.05(1) A and an O-H...O angle of 130.3(5) degrees. The experimentally determined structure is in excellent agreement with previously published DFT studies. Experiments with HOD in the jet reveal the formation of only isotopomers involving deuterium in the secondary hydrogen bond, providing direct experimental evidence for the secondary H...O interaction. Extensive isotopic substitution has also permitted a re-determination of the structure of the H2SO4 unit within the complex. The hydrogen-bonding OH bond of the sulfuric acid elongates by 0.07(2) A relative to that in free H2SO4, and the S=O bond involved in the secondary interaction stretches by 0.04(1) A. These changes reflect substantial distortion of the H2SO4 moiety in response to only a single water molecule, and prior to the proton transfer event. Spectral data indicate that the complex undergoes at least one, and probably more than one type of internal motion. Although the sulfuric acid in this work was produced from direct reaction of SO3 and water in the jet, experiments with H2(18)O indicate that about 2-3% of the acid is formed via processes not normally associated with the gas-phase hydration of SO3.