Extraction of mercury from aqueous iodide solutions by trilaurylamine N-oxide and its subsequent determination by atomic absorption spectrometry

A solvent extraction technique using 0.01M solution of trilaurylamine N-oxide in benzene as extractant has been used to concentrate mercury efficiently from water solutions with or without the presence of 0.02M KI in weakly acidic media. In addition to unmodified aqueous solutions, mercury can be extracted quantitatively from aqueous iodide solutions that are up to 1M in HCl, H₂SO₄, and HNO₃ in a single equilibration. Distribution coefficients and separation factors of several elements relative to mercury(II) are reported for media that contain 0.1 M HCl and 0.02M KI. The reagent is superior to aliphatic amines and quaternary amines for the extraction of mercury from aqueous iodide solutions.     

Extraction of heterometallic complexes of ruthenium and nonprecious metals by phosphorylmethylated calix[4]arenes from nitrate solutions

Synergetic extraction of [RuNO(NO₂)₄OH]^2? by calix[4]arene phosphine oxides (L) in the form of Ru/M heterometallic complexes was studied in the presence of nonprecious metals (M²⁺). The main extraction laws were recognized for [M(NO₃)₂L _n ] and [RuNO(NO₂)₄OH])ML _m ], where M²⁺ = Zn²⁺, Cu²⁺, Co²⁺, or Ni²⁺ and n, m = 1 or 2; extraction constants were determined for these metals. The variation row of the extraction constants with varying metal (Zn²⁺ > Cu²⁺ > Co²⁺ > Ni²⁺) coincides with the Irving-Williams row. Two or three PO groups of extractant L and the OH and NO₂ groups of the ruthenium anion are coordinated to the M²⁺ atom in Ru/M complexes. The conditions for generation of the Ru/Zn complex and its complete extraction were optimized as applied to the extraction of fission ruthenium from nitrated nitric acid and imitation solutions.     

Selective extraction of Hg(II) from aqueous mineral acid solution containing iodide ions using 2-benzylpyridine in benzene

A method for the selective extraction of mercury has been developed. The extraction of Hg(II) by 2-benzylpyridine (BPy) in benzene from dilute mineral acid solution containing iodide ions has been investigated, and variables such as concentration of acids, iodide and the extractant have been optimized. The optimum conditions for the extraction of Hg(II) by 0.1M BPy/benzene are: 0.01M (HCl, HNO₃, H₂SO₄)+0.01M KI. The distribution coefficients and separation factors of 19 elements relative to Hg(II), have been reported. Effect of anions such as ascorbate, acetate, citrate, oxalate and thiosulfate has also been studied. The method developed could find useful applications in selective extraction of small amounts of mercury from environmental samples.     

Studies of the solvent extraction of cadmium and silver dithizonates

An extensive study was made of the solvent extraction of cadmium and silver dithizonates into chloroform A few extractions of silver dithizonate were made into carbon tetrachloride. In most cases extraction curves of PH versus % metal extracted were obtained and reported in terms of the PH of 50% extraction. The shift of the extraction curves to higher PH values due to the effect of ions in the aqueous phase which complex with the cadmium or silver ions was investigated An equation was developed which would predict the PH of 50% extraction for the extraction from the solutions containing these complexing ions The effects of chloride, bromide and iodide ions on the extraction of cadmium and the effects of chloride, bromide, iodide, thiocyanate and thiosulfate ions on the extraction of silver. Extraction constants for the various extractions were determined.     

Tri-n-octylphosphine sulfide: : A selective organic extractant

Tri-n-octylphosphine sulfide (TOPS) has been investigated as the stationary phase in reversed-phase partition paper Chromatographie separations using nitric or hydrochloric acids as the mobile phase. TOPS has also been studied as an extractant for metal ions. Silver, mercury (II), and palladium (II) were found to have RF values of zero when nitric acid was used as the mobile phase. These same ions were also selectively extracted from aqueous nitric acid solutions. Gold(III), mercury(II), palladium (II), and platinum (IV) were found to have RF values of zero when hydrochloric acid was used as the mobile phase. However, only gold(III) and mercury(II) were extracted from aqueous hydrochloric acid solutions in liquid-liquid extraction systems. Several separations were successfully performed from 1 M nitric acid.     

The extraction of niobium (V) and Tantalum (V) by Octylarsinic acid in chloroform

Dioctylarsinic acid (HDOAA) in chloroform solution extracts Nb(V) and Ta(V) efficiently from solutions containing oxalate and oxalic acid at hydrochloric acid concentrations greater than 1M.The extraction coefficients are 92.5 at 7M hydrochloric acid and 251 at 6M hydrochloric acid for niobium and tantalum, respectively. These metals can be extracted even more efficiently from sulfuric acid solutions. The results of the reagent- and pH-dependence studies suggested that a trimeric, monobasic oxoacid of niobium, associated with ten HDOAA molecules, is extracted. Tantalum appears to be present in the organic phase as (H₂DOAA)⁺ [Ta(C₂O₄)₃ (HDOAA_n] (n=l or 2).     

Extraction of thorium(IV), lantanum(III), and yttrium(III) nitrates with a composite solid extractant based on a polymeric support impregnated with trialkylamine

Extraction of Th(IV), La(III), and Y(III) from aqueous solutions containing 0–4 M sodium nitrate with a composite solid extractant based on a polymeric support impregnated with trialkylamine (Alamine-336) was studied. The extraction isotherms were analyzed assuming that lanthanides and thorium are extracted with the solid extractant in the form of complexes (R₃HN)₃[Ln(NO₃)₅] and (R₃HN)₂[Th(NO₃)₆], respectively. The extraction constants were calculated. The joint extraction of Th(IV) and La(III) [Y(III)] with the solid extractant from aqueous salt solutions was studied.     

Extraction of Th(IV), La(III), and Y(III) nitrates with a composite solid extractant based on a polymeric support impregnated with trialkylmethylammonium nitrate

Extraction of Th(IV), La(III), and Y(III) from aqueous solutions containing 0–4 M sodium nitrate with a composite solid extractant based on a polymeric support impregnated with trialkylmethylammonium nitrate (Aliquat-336) was studied. The extraction isotherms were analyzed assuming that lanthanides and thorium are extracted with the solid extractant in the form of complexes (R₄N)₂[Ln(NO₃)₅] and (R₄N)₂[Th(NO₃)₆], respectively. The extraction constants were calculated. The joint extraction of Th(IV) and La(III) [Y(III)] with the solid extractant from aqueous salt solutions was studied.     

Preconcentration and separation of copper (II) with solvent extraction using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane

Preconcentration and separation with solvent extraction of Cu(II) from aqueous solution using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane (H₂L) as the new extractant has been studied. Separation of Cu(II) from other metal ions such as Cd(II), Ni(II), Zn(II), Pb(II), Cr(III), Co(II) and Mn(II) at aqueous solutions of various pH values and complexing agent H₂L, has been described. The possible extraction mechanism and the compositions of the extracted species have been determined. The separation factors for these metals using this reagent are reported while efficient methods for the separation of Cu(II) from other metal ions are proposed. From the loaded organic phase, Cu(II) stripping was carried out in one stage with different mineral acid solutions. The stripping efficiency was found to be quantitative in case of HNO₃ and HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complex extracted is the simple 1:1 chelate, CuL. The extraction constant has a value of logK_ex=−4.05±0.04.     

Rhenium(VII) extraction with Versatic hydrazides and <Emphasis Type="Italic">N',N'</Emphasis>-Dialkylhydrazides

Rhenium(VII) and molybdenum(VI) extraction with kerosene solutions of α-branched tertiary carboxylic Versatic acids derivatives containing hydrazide C(O)NHNH2 and C(O)NHNCH₃)₂ fragments instead of carboxyl group has been studied. Optimal extraction conditions have been determined depending on H₂SO₄, HCl, and extractant concentrations and composition of extracted complexes has been established. The mechanism of extraction and back extraction of perrhenate ion with ammonia solutions has been suggested.     

Solvent extraction of lead,silver, antimony and thallium with zinc dibenzyldithiocarbamate and its application to the separation of bismuth from large amounts of lead

Solvent extraction of lead, silver, antimony and thallium from various acid solutions was investigated with zinc-DBDTC as chelating reagent. These metals were quantitatively extracted over a wide range of acidity with 0.03% zinc-DBDTC solution in carbon tetrachloride. A separation procedure for bismuth from large amounts of lead was developed; bismuth was extracted from 1 M nitric acid with zinc-DBDTC and was separated from lead by subsequently washing the organic phase once with 3.5 M hydrochloric acid or twice with 3 M hydrochloric acid. Satisfactory results were obtained in separating microgram amounts of bismuth from 1 g of lead.     

Tandem on-line continuous separations for atomic spectroscopic indirect analysis: Iodide determination by ICP-AES

A sensitive and selective indirect determination of iodide by inductively coupled plasma emission spectrometry (ICP-AES) based on the principle of tandem on-line continuous separations as an alternative means of introducing samples into plasmas is proposed. Iodide is continuously extracted as an ion-pair into xylene by mixing the sample with Hg(II) and dipyridil solutions. The organic phase (containing the analyte in [Hg(Dipy)₂]I₂ form) is on-line continuously mixed with NaBH₄ (in DMF) and acetic acid solutions. Mercury vapour continuously generated from this organic phase is separated in a classical U-type gas-liquid separation device. The system has been optimized for the continuous extraction of KI, for the direct generation of cold mercury vapour from xylene and for the final ICP-AES determination of mercury. The optimised method has been applied to the determination of iodide (detection limit 20 ng/ml of iodide) in table salt and in synthetic samples. Very good agreement between found and certified results was observed. The usefulness and convenience of such alternative sample chemical pretreatment/presentation to the ICP is thus demonstrated for indirect determinations to be carried out by atomic spectroscopy methods.     

Extraction of mercury(II) ions with antipyrine and its derivatives from chloride solutions to chloroform

The extraction of 0.01 mol/L mercury(II) ions from chloride solutions to chloroform is studied in the presence of antipyrine (AP) and its condensed derivatives (diantipyrylmethane (DAM), propyldiantipyrylmethane (PDAM), and hexyldiantipyrylmethane (HDAM)). The optimal mercury extraction conditions are determined for AP and its derivatives. The composition of the extracted complexes is determined. With respect to their pH_1/2 and extraction capacities, the extractants are arranged in the following order: AP < DAM < PDAM < HDAM. The calculation of partial equilibrium constants and approximate partition constants is proposed.     

Ion-selective carbon-paste electrodes for halides and silver(I) ions

The behaviour of a simple type of ion-selective electrode for halogens and silver has been studied. The electrode consists of a plastic body filled with carbon paste, the surface of which can be easily renewed. The paste composition is based on carbon-nujol (5:1, w/v) or carbon-paraffin wax (3:1,w/w) containing a prepared mixture of silver halide-silver sulphide (1–30%). The electrodes have low ohmic resistance and show a rapid Nernstian response (within 2–5 mV) for halide and silver ions down to 5·10^-5M chloride, 1·10^-5M bromide and 5·10^-7M iodide with the respective electrodes. Ions forming very stable complexes with halide or silver and those having strong oxidizing or reducing action interfere.     

Synthesis, transport, and ionophore properties of α,ω-biphosphorylated azapodands: VIII. Solvent extraction of the metal ions with N,N′-bis(dioctylphosphorylmethyl)-1,8-diamino-3,6-dioxaoctane

Liquid extraction from the aqueous solutions of perchloric acid with neutral azapodand extractant N,N′-bis(dioctylphosphorylmethyl)-1,8-diamino-3,6-dioxaoctane has been highly efficient in the cases of uranyl ions and some metals of groups II and III. To estimate the synergic effect of organophosphorus extractants, the neutral extractant was applied in the mixture with an acidic component, bis(pentadecyl)phosphoric acid. The synergic effect has exclusively been observed in the extraction of zinc and cadmium ions.     

Studies of radioactivity and heavy metals in phosphate fertilizer

The extraction of mercury(II) from chloride and thiocyanate solutions has been studied by tracer techniques using bis(2-ethylhexyl) sulphoxide (B2EHSO) in benzene as an extractant. These extraction data have been analyzed theoretically by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexation in the organic phase. The results demonstrate that Hg(II) is extracted as HgX₂ and HgX₂·nB2EHSO (where X=Cl^– or SCN^– andn=1 or 2). The effect of the foreign ions on the extraction of Hg(II) has also been investigated.     

Extraction of trivalent lanthanide cations by diphenyl phosphinic acid

The distribution of trivalent lanthanides between solutions of diphenyl phosphinic acid, (ϕ)₂PO(OH), in chloroform and aqueous phases containing nitrate ions was investigated radiometrically. The distribution ratio was studied as a function of mineral acid and salt concentrations in the aqueous phase and extractant concentration in the organic phase, for all lanthanides except Pm. The compositions of the extracted complexes were investigated by the usual slope analysis. The results obtained for a given set of conditions indicate that none of the anions present in the aqueous medium are present in the extracted complex species. For these conditions, the distribution ratio D was found to vary as [extractant]^2.7 and [H⁺]⁻³, where the concentrations refer to the organic and aqueous phases, respectively. It therefore appears that a mixture of complex species is extracted, and the possible structures of these species and a mechanism for the extraction are discussed.     

Extractive separation of Cu<Superscript>2+</Superscript>–Co<Superscript>2+</Superscript> and Ni<Superscript>2+</Superscript>–Co<Superscript>2+</Superscript> mixtures using <Emphasis Type="Italic">N</Emphasis>-salicylideneaniline

A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures.     

An XPS investigation of silver bromide-coated ion-selective electrodes

XPS data of AgBr-coated ion-selective electrodes exposed to high concentrations of Ag⁺, Cl⁻, Br⁻, I⁻, and NH₃ revealed a change in the surface properties of the original electrode. A 40 min to one week exposure of the silver bromide ion-selective electrode surface to solutions containing high concentrations of chloride ions leads to the formation of a mixed halide layer, as the chloride ions are incorporated in the surface. Exposure to high concentrations of iodide-containing solutions results in a new silver iodide layer on top of the original silver bromide laver. Silver ions diffuse to the newly formed layers. NH₃ results in the rapid degradation of the AgBr surface as the diamine complex, Ag(NH₃)⁺₂, is formed.