Nitric Acid In Methanol Research Articles

An Electron Microscopy Study of the Icosahedral Phase in the Aluminum-Manganese System

One of the most interesting structures to evolve from rapid solidification processing (RSP) methods is the solid metallic phase of the Al-Mn system first reported by Shechtman et al to have icosahedral symmetry. With six 5-fold rotational axes, an icosahedron defies classification as a crystallographic point lattice: it simply has no translational symmetry. Earlier work by Levine and Steinhardt showed that “quasicrystals” with 5-fold axes could be defined by extension of the Penrose tiling idea to three dimensions. These results and their recent history prompted the present attempt at structural analysis of this novel solid by a combination of convergent beam electron diffraction (CBED) and phase contrast imaging. Specimens of 74.7 at % A1 and 25.3 at % Mn were prepared by arc melting and splat quenching (hammer and anvil) followed by jet electropolishing in a nitric acid-methanol electrolyte. They were examined in both the JEM 200CX analytical electron microscope and the JEM ARM 1000 atomic resolution microscope at the National Center for Electron Microscopy.

A HREM study of the interfacial structure of γ' precipitate plates in an Al-15 wt % Ag alloy

The interfacial structure and growth kinetics of γ' and γ (Ag2Al) precipitate plates in Al-Ag alloys have been extensively studied by conventional TEM methods. Although most results have confirmed the predictions of the general theory of precipitate morphology proposed by Aaronson, some new questions have arisen. The present study is an attempt to address the specific points of contention concerning the details of ledge growth in this system.An Al-15 wt % Ag alloy was solution treated at 500°C for 30 minutes, quenched and aged for 30 minutes at 350°C. Thin foils were jet polished in a nitric acid-methanol solution and lightly ion-beam milled prior to insertion into a JE0L 200 CX microscope. A through focus series of [110] axial lattice images was taken at 200,keV, using a pointed LaB6 filament and an objective aperture of radius 0.64Å-1.Fig. 1(a) shows twoend-on γ' plates about 200Å thick and lying on {111} planes as evident from the diffraction pattern in Fig. 1(b).

The electroreduction (polarographically) of uranyl ion in nitric acid and nitric acid-methanol mixture media

The polarographic reduction of uranyl ion in nitric acid solution are found to be one electron reduction mechanism at lower acid concentration (0.1 M HNO 3) and two electron mechanism at high acid concentration (2M HNO 3). Methanol shifted the half wave potentials to more negative values and increased the free energy. The free energies of reduction of U(VI) to U(V) in these mixed solvents are inversely proportional to both the dielectric constants and Gutman's Acceptor number of methanol. The U(V) is stable at pH 3, but its dismutation increased at lower and higher pH's than pH 3.

Quantitative separation of samarium from neodymium by anion exchange chromatography in dilute nitric acid-methanol

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantitative separation of samarium from neodymium by anion exchange chromatography in dilute nitric acid-methanolF. W. E. StrelowCite this: Anal. Chem. 1980, 52, 14, 2420–2422Publication Date (Print):December 1, 1980Publication History Published online1 May 2002Published inissue 1 December 1980https://doi.org/10.1021/ac50064a043RIGHTS & PERMISSIONSArticle Views103Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (419 KB) Get e-Alerts Get e-Alerts

Method for multi-element alpha-spectrometry of actinides and its application to environmental radioactivity studies

A method is proposed for measuring simultaneously several actinide elements by α-spectrometry. The actinides in sample solutions are sorbed together on an anion-exchange column from a nitric acid—methanol mixture. After simultaneous elution and electroplating on a disc, the actinides are determined by α-spectrometry. Radiochemical yields of the procedure for Th, U, Np, Pu, Am and Cm are better than 50%, all falling within a range of ± 5%. Examples of the application of this method to various marine environmental samples such as sea-water, seaweed and marine sediment are presented.

Determination of americium and curium by using ion-exchange in nitric acid-methanol medium for environmental analysis

A method is presented for the determination of americium and curium isotopes in environmental samples, an ion-exchange clean-up procedure being used.

Quantitative separation of beryllium from magnesium, calcium, aluminium, iron and other elements by cation-exchange chromatography in nitric acid-methanol

Beryllium is separated from Mg, Ca, Mn(II), Fe(III), Al, Co(II). Zn. U(VI), La and Gd by elution with 2.0 M nitric acid in 70 % methanol from a column of AG50W-X8 sulphonated polystyrene cation exchanger, while the other elements are retained quantitatively. Sr, Ba, Sc, Y, the other lanthanides, Zr, Hf, Th, Ga, In, Cd and Ni(II) should also be separated according to their distribution coefficients or elution behaviour. Separations are sharp and recoveries quantitative from millimolar amounts down to 10 μg of beryllium. The separation of Ti(IV) and Cu(II) from beryllium is not satisfactory and requires rather large columns. Bi(III), Pb(II), Hg(II) and the alkali metals are eluted together with beryllium, but can be separated by other methods. Typical elution curves and results for the quantitative separation of binary synthetic mixtures are presented.

Anion-exchange isolation of rare-earth elements from apatite minerals in methanol-nitric acid medium

Batch distribution coefficients, K d, of rare-earth elements (REE) and other elements were determined radiochemically for a strongly basic nitrate anionexchange resin Dowex 1-X8 100–200 mesh, in nitric acid-methanol media of varying composition. This method was developed for the separate recovery of REE from apatite minerals. Calcium and other common elements of the apatite are eluted by a 5% (v/v) 7 M nitric acid-95% methanol mixture, while the REE are retained. The REE are recovered and separated into two fractions; the heavier REE by elution with a 45% nitric acid-55% methanol mixture, and a very clean fraction of La, Ce, Pr, Nd by elution with water.

Separation of lithium from sodium, beryllium and other elements by cation-exchange chromatography in nitric acid-methanol

Lithium can be separated from sodium, beryllium and many other elements by eluting lithium with 1 M nitric acid in 80% methanol from a column of AG50W-X8 sulphonated polystyrene cation-exchange resin. The separation factor is not quite as large as that in 1 M hydrochloric acid in 80% methanol, but many elements, such as Zn, Cd, In, Pb(II), Bi(III) and Fe(III), which form chloride complexes in 1 M HCl-80% methanol are retained quantitatively together with Na, Be, Mg, Ca, Mn(II), Al, Ti(IV), U(VI), and many other elements, when 1 M HNO3-80% methanol is used for elution of lithium. A method for the accurate determination of traces of lithium in rock samples is described, and some results obtained are presented together with relevant distribution coefficients, elution curves and results for the analysis of synthetic mixtures.

Barium and Strontium Determination in Biological Materials by Atomic Absorption Spectroscopy

Ashed samples of diet, excreta, soft tissue, and bone were measured for trace amounts of stable barium and strontium by atomic absorption spectroscopy after classical chemical separation and anion exchange chromatography. Barium, strontium, and calcium were separated from silica by dehydration, the alkali metals by phosphate collection, and magnesium, the transition metals, and phosphate by nitrate precipitation. Barium was separated from strontium and calcium by absorption on Bio-Rad AG 1-X8 (100–200 mesh) anion exchange resin in methanol—nitric acid mixed solvent. Barium-133 and strontium-85 tracers were added to the samples to correct radio-metrically for losses during the chemical method. Atomic absorption measurements for barium and strontium were made at the resonance lines of 5536 and 4607 Å, with nitrous oxide—acetylene and air—acetylene flames, respectively. Radiometric yields of barium-133 and strontium-85 ranged between 85%–95% and 75%–99%, respectively, with an average coefficient of variation of 5%–6%.

Determination of Sodium Carboxymethyl Cellulose in Household Detergents by Anthrone-Naphthalenediol Method

Ordinarily, the household detergents contain about 1% of sodium carboxymethyl cellulose (CMC) to prevent redeposition of soil. For the determination of CMC itself, nitric acid-methanol method is usual. This method is not applicable for the determination of CMC in household detergents, as the components which are insoluble in 80% methanol solution are added to CMC.Anthrone or naphthalenediol method is used for the determination of CMC in household detergents. In the both methods, however, intensity of color development is influenced by the degree of substitution of hydrogen of hydroxy radicals by carboxymethyl radicals. If the degree of substitution isunknown, the content of CMC can not be found unless the degree of substitution is assumed. Furthermore, intensity of color development is influenced by ingredients of detergent.Authors noted that intensity of color development of these methods indicate reverse relationship with the degree of substitution, and found that combination of these two method is available to determine both the content and the degree of substitution. At the same time, the measuring conditions were investigated for. As a result, this method is useful for the determination of CMC in household detergents.

Thin-layer chromatographie separation of alkaline earth metals on diethylaminoethyl cellulose

Thin-layer Chromatographic behaviour of magnesium, calcium, strontium and barium on diethylaminoethyl cellulose has been investigated in methanol-nitric acid mixtures. R f values are in the order magnesium > calcium > strontium > barium. The differences in R f values are large enough to allow good separations of the four metal ions from each other. The best separation is obtained by the ascending technique with methanol-8 M nitric acid (20:1, v v ).

Cation exchange separation of thorium from rare earths and other elements in methanol-nitric acid medium containing trioctylphosphine oxide

Cation exchange separation of thorium from rare earths and other elements in methanol-nitric acid medium containing trioctylphosphine oxide

Adsorption of the rare-earth elements on an anion-exchange resin from nitric acid-acetone mixtures

The distribution coefficients on Dowex I-X8 anion-exchange resin were determined for all the rare earths at various proportions of concentrated nitric acid and acetone, using radioactive tracers of the metallic ions. In the range 4–40% nitric acid, the distribution coefficients decrease with increasing content of nitric acid, and at a given ratio of acid to acetone, they decrease with increasing atomic number in the lanthanum series. The value for yttrium is close to that of thulium; scandium is much less adsorbed. Literature data for aqueous systems and other mixed solvent systems are discussed. The distribution of scandium between Dowex I-X8 and conc. nitric acid-methanol, ethanol or acetone systems is described. The separation power of the nitric acid-acetonc system at different acid concentrations is analysed. Dowex I-X8 resin with a nitric acid-acetone solvent is shown to be sufficient for separation of the rare-earth elements by ion-exchange chromatography.

Anion-exchange separation of beryllium, vanadium and other elements from large amounts of uranium

A method is described for the anion-exehange separation of small quantities of beryllium, vanadium, magnesium, calcium, aluminium, gallium and indium from gram-amounts of uranium. For this purpose, a medium consisting of 95 % methanol and 5% 5 M nitric acid is passed through a resin bed of Dowex 1, X8. By subsequent washing of the resin with a methanol-nitric acid mixture of the same composition, these metal ions are preferentially eluted from the column, whereas uranium is still retained by the anion exchanger. In the eluates the elements are determined by means of spectrophotometric or titrimetric procedures.

Determination of scandium, yttrium, samarium and lanthanum in standard silicate rocks, G-1 and W-1, by neutron-activation analysis

Neutron-activation analysis results for four rare earth elements in standard silicate rocks, G-1 and W-1, are reported. An anion-exchange method for the separation of scandium, yttrium, samarium and lanthanum in good radiochemical purity has been developed. The method is based on the chromatographic elution of these elements from a Dowex 1 × 8 (nitrate form) resin column using methanol-nitric acid mixtures. The results obtained by this method are compared with values already available.

Structure of Anodic Layers on the (100) Face of Aluminum

The structure of coherent anodic layers grown on the {100} faces of aluminum in tartaric acid—ammonia electrolytes has been studied by replicas and transmission electron microscopy. At pH 5.5 these layers are pore-free to the limit of our sensitivity (10–15 Å) and faithfully replicate the original surface formed during electropolishing. The hillock structure, characteristic of perchloric acid polishing baths, can be considerably reduced by electropolishing in a nitric acid—methanol bath at −20°C. The metal—oxide interface in this instance is featureless to within 20 Å. Anodic layers grown at pH 2.0 or 10.5 are highly porous and an electropolishing action takes place. An ultrastructure with characteristic spacing 50 Å is observed on surfaces polished in perchloric acid mixtures. The structure is also seen on the electrolyte interface of the anodic layer. It is proposed that this structure is not an artifact of the shadowing, and that it may correspond to particles of aluminum hydroxide formed during growth of the anodic layer.

Anion Exchange Resin Separation of the Rare Earths, Yttrium, and Scandium in Nitric Acid-Methanol Mixtures.

The adsorption of the rare earths, yttrium, and scandium from nitric acid--methanol solutions was studied using strongly basic anion exchange resins. Adsorption measurements were made at room temperature using the column elution technique and employing emission spectrographic analysis. Distribution coefficients were a function of both the volume percentage of alcohol and of the nitric acid concentration. The rare earths were eluted from a column in order of decreasing atomic number with little individual than terbium had relatively large separation factors. Yttrium behaved like lutetium, while scandium was not adsorbed to an appreciable extent. Application of the system for macro separations was demonstrated in the preparation of extremely pure rare earths and for fractionation of crude rare earth mixtures. Finally, the simplicity of operation is attractive for analytical separation of trace impurities.