Capillary electrophoresis of organic and inorganic cations with indirect UV detection

Solvent extraction of valuable metals such as copper and nickel is often carried out from ammoniacal alkaline solutions with chelating extractants, during which coextraction of ammonia is inevitable. In the present study, as a basis of modeling of the whole ammoniacal extraction process, the equilibrium distribution ratios of ammonia between a 3 mol L -1 ammonium nitrate solution and LIX84I (the active component of which is 2-hydroxy-5-nonylacetophenone oxime, HR) dissolved in a nonpolar diluent were measured as a function of pH and LIX84I concentration at 298 K. We successfully modeled the measurement results by assuming the formation of two associated species, (HR) n ･(NH 3 ) and (HR･NH 3 ) n , the aggregation of HR, and the dissociation of NH 4 + . Fourier transform infrared spectroscopy results suggested that ammonia was extracted via hydrogen bonding with HR, and these results were in accord with the proposed equilibrium model. IntroductionSolvent extraction is a commonly used method for hydrometallurgical recovery of metal ions because of its high separation efficiency and relatively low cost. Acidic solutions are the usual media for solvent extraction, but ammoniacal alkaline solutions are sometimes employed for the processing of copper and nickel, owing to the ability of these metal ions to form complexes with ammonia.This process consists of the following steps: (i) Extraction of both copper and nickel from the ammoniacal alkaline solutions with a chelating reagent such as a β-hydroxyoxime or a β-diketone; metal extraction is accompanied by ammonia extraction. (ii)Scrubbing of coextracted ammonia with dilute acid to avoid the accumulation of ammonium salts in the electrolyte in the subsequent step; these salts tend to precipitate, owing to theirSelective stripping of nickel from the organic phase with an acid at a relatively low concentration. (iv)Stripping of copper with an acid at a higher concentration and simultaneous regeneration of the extractant. Although this process has been extensively studied [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], quantitative studies of the equilibria are scarce. Flett and Melling [19] are the only investigators to have analyzed ammonia extraction; they showed good agreement between experimental results obtained with a -hydroxyoxime (LIX65N, 10 vol%) in an aliphatic diluent and the results obtained with a model that assumed the formation of a monomeric 1:1 extractant/ammonia adduct. As for metal extraction, Rice et al. [20] studied nickel extraction with SME-529 (the former brand name of LIX84I). Tanaka and Alam [21] conducted a detailed study of the equilibrium for nickel extraction with LIX84I and obtained satisfactory agreement between experimental and calculated results; however, these investigators did not consider ammonia extraction during the analysis.Our ultimate goal is to establish a quantitative equilibrium model for the ammoniacal process, including extraction of copper, nickel, and ammonia with LIX84I and their stripping or scrubbing, t...

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“…This operation is equivalent to placing a 3 mol L imidazole (pH = 4.5) buffer at +20 kV [22]. The distribution ratio of ammonia, D, is defined as…”

Section: Extraction Of Ammoniamentioning

confidence: 99%

Modeling of Equilibria for the Solvent Extraction of Ammonia with LIX84I

Wang

Narita

et al. 2017

SERDJ

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“…The separation of small ions is routinely carried out by traditional CE in silica capillaries [11][12][13][14][15][16][17][18][19], the ions being typically separated in minutes when the capillary length ranges from 10 to 80 cm. Analysis of small inorganic/ organic charged species has also been performed on microchip platforms by capillary zone electrophoresis.…”

Section: Introductionmentioning

confidence: 99%

Polyelectrolyte‐modified short microchannel for cation separation

2004

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Three alkali cations, potassium, sodium, and lithium, have been separated within 15 s in a 1 cm long polymer microchip. The separation microchannel is modified by a polycation, poly(allylammonium chloride), which makes the channel surfaces positively charged leading to a reversed electroosmotic flow (EOF) when compared to bare channels. Due to the decreased apparent mobility of the cations, the separation resolution is improved allowing the use of shorter channels.

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“…Average Na""" fluxes were in computed by pooled regression based on six experiments from different volunteers using analysis of covariance as described in (12). The accuracy of prediction was tested by plotting the predicted glucose values against the measured blood glucose in a Clark Error Grid (13).…”

Section: Data Analysis and Statisticsmentioning

confidence: 99%

Skin Bioengineering: Noninvasive Transdermal Monitoring

Guy¹

2004

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Public reporting burden for mis collection of information is estimated to average 1 hour per response, including ttie time for reviewing instaictions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burten to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and Richard H. Guy, Ph.D. PERFORMING ORGANIZATION NAMEISI AND ADDRESS(ES)University of Geneva ABSTRACT (Maximum 200 Words)The long-term objective is to develop and optimize a novel, noninvasive iontophoretic approach for metabolic monitoring via the skin. The low-level current density drives both charged and highly polar (yet neutral) compounds across the skin at rates much greater than passive diffusion. As the skin offers a uniquely accessible body surface across which information can be extracted, we hypothesize that truly noninvasive and highly sensitive devices, which exploit uniquely paired flows of at least two substances, can be developed for iontophoretic monitoring applications. Proof-of-principle targets two analytes of significant interest; specifically, glucose, and lactate. SUBJECT TERMSNo Subject Terms. The long-term objective is to develop and optimize a novel, noninvasive, iontophoretic approach for metabolic monitoring via the skin. The low-level current density drives both charged and highly polar (yet neutral) compounds across the skin at rates much greater than passive diffusion. NUMBER OF PAGESAs the skin offers a uniquely accessible body surface across which information can be extracted, we hypothesize that truly noninvasive and highly sensitive devices, which exploit uniquely paired flows of at least two substances, can be developed for iontophoretic monitoring applications. The research strategy will optimize iontophoretic and sensing technology to satisfy three key criteria for success: (a) fundamental understanding of electrotransport across the skin; (b) reproducible enhancement of transdermal permeability to identify metabolic monitoring opportunities via the skin; and (c) characterization and validation of simple, user-firiendly devices for sample collection coupled with sensitive and specific analytical tools. The specific aims of the project are:-{1} To refine understanding of electrotransport across the skin; to exploit the interactions (and independence) of solute and ion flows in the presence of an applied electric field. {2} To demonstrate that the simultaneous, 'reverse iontophoretic' extraction of a target analyte, together with an endogenous substance of essentially constant concentration within the body, can offer truly noninvasive, metaboUc monitoring. {3} To engineer simple, elegant, prototypical devices, of small volume (100 ^iL or less), into which reverse iontophoretically extracted ...

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Capillary electrophoresis of organic and inorganic cations with indirect UV detection

Cited by 202 publications

References 13 publications

Modeling of Equilibria for the Solvent Extraction of Ammonia with LIX84I

Modeling of Equilibria for the Solvent Extraction of Ammonia with LIX84I

Polyelectrolyte‐modified short microchannel for cation separation

Skin Bioengineering: Noninvasive Transdermal Monitoring

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