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.     

Extraction of mercury(II) from aqueous thiocyanate solutions with 5-(4-pyridyl)nonane in benzene, and its subsequent atomic-absorption spectrometric determination

Tracer ( approximately 10(-8)M) mercury(II) can be quantitatively extracted with 5-(4-pyridyl)nonane in benzene from aqueous thiocyanate solutions that are up to 6M in HCl, 1M in H(2)SO(4) or 0.25M in HNO(3), in a single extraction. Optimal conditions for the extraction are given, based on a critical study of the relevant factors such as the effects of the acids, thiocyanate, salting-out and complexing agents and the reagent concentration. The mechanism underlying these extractions is discussed on the basis of the results obtained from partition and slope-analysis data. The extraction of the metal as Hg(PyN)(2)(SCN)(2) is indicated. The extracted mercury can be stripped from the non-aqueous layer with various aqueous solutions, including nitric acid (2M), sodium citrate ( 1M) and sodium thiosulphate (0.1 M). Common salts do not depress the extraction. Distribution coefficients and separation factors of several elements relative to mercury(II) are reported for media that contain the optimal concentrations of the mineral acids and are in 0.2M in potassium thiocyanate. The data have been applied for the determination of mercury in soil and water samples by atomic-absorption spectrometry.     

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.     

Ureasulfonamide Polymeric Sorbent for Selective Mercury Extraction

A new polymeric resin with sulfonamide pendant functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfonamide urea resin with a 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 1.60 mmol/g under non-buffered conditions. The experiments performed under identical conditions with some metal ions reveal that Cd(II), Pb(II), Zn(II), and Fe(III) ions are also extractable in low quantity (0.05–0.1 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups.     

Ureasulfonamide Polymeric Sorbent for Selective Mercury Extraction

Summary. A new polymeric resin with sulfonamide pendant functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfonamide urea resin with a 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 1.60 mmol/g under non-buffered conditions. The experiments performed under identical conditions with some metal ions reveal that Cd(II), Pb(II), Zn(II), and Fe(III) ions are also extractable in low quantity (0.05–0.1 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups.     

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.     

Extraction-separation of mercury with 1-nephthylthiocarbamide

The extraction of mercury(II) has been studied from mineral acid solution using 1-nephthylthiocarbamide (ANTU) in chloroform-acetone mixture (9:1). The variables such as the concentration of acid and extractant have been optimized. The extractability of some other elements at the optimum conditions for mercury is also studied in order to establish the separation procedure. The probable composition of the extracted species has been deduced from log data. Effect of a number of foreign metal ions and anions has also been studied.     

Extraction of group VIII elements with 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5

The extraction of group VIII elements with 1-phenyl-3-methyl-4-trifluoracetyl-pyrazolone-5 from aqueous solutions in chloroform has been studied as a function of pH. Fe(III), Ni(II), Pd(II) and Rh(III) show partial extraction whereas Co(II) is extracted quantitatively. The effect of citrate, cyanide, fluoride, iodide, thiosulphate and thiourea on the extraction of metal ions has been investigated. Back-extraction studies were carried out to strip metal ions from organic phase into appropriate aqueous solutions. Based on these findings some useful analytical separations have been proposed and a few of their possible applications have been discussed.     

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.     

Sensitive detection and semiquantitative determination of mercury(II) and lead(II) in aqueous media using polyurethane foam immobilized 1,5-di-(2-fluorophenyl)-3-mercaptoformazan

1,5-Di-(2-fluorophenyl)-3-mercaptoformazan (F(2)H(2)Dz) immobilized and plasticized with tri-n-butylphosphate (TBP) polyurethane foam (PUF) were found suitable for the detection of mercury(II) and lead(II) in extremely dilute aqueous solutions. In batch mode of extraction with immobilized F(2)H(2)Dz-foam as low as 0.05 and 0.15 mug ml(-1) of mercury(II) and lead(II), respectively were detected and the colored chelates were found more stable over 72 h. Lower concentrations of these metal ions (相似文献   

Determination of trace levels of mercury in aqueous solutions by inductively coupled plasma atomic emission spectrometry: Elimination of the ‘memory effect’

The measurement of mercury in aqueous solutions by ICP-AES is adversely affected by the memory effect wherein mercury accumulates within the sample introduction system and is slowly released over time to give increasing response signals at the same initial mercury concentration. The memory effect is obviated by the addition of Hg(II) complexants: thiourea and gold(III) chloride are both effective in preventing mercury sorption and vapor buildup with the latter being preferred because the memory effect vanishes more rapidly. Conditions are described wherein it is possible to quantify low levels of mercury(II) in aqueous solutions by ICP-AES under routine operating conditions that can be applied to other metal ions by adding 1 mg of gold(III) chloride per 3 mg of mercury(II) to those solutions.     

On the adsorption of cadmium(II) ions on a HMDE from KF + thiourea aqueous solutions: A chronocoulometric study

The adsorption of cadmium(II) ions from thiourea aqueous solutions has been studied by double potential step chronocoulometry (DPSSC). The adsorption is strong on mercury electrodes and it has been studied as a function of thiourea concentration, cadmium(II) concentration and potential. A discrepancy between the double-layer charge values from either blank solutions or solutions containing reactant obtained by this technique has been found.     

Hierarchically imprinted organic-inorganic hybrid sorbent for selective separation of mercury ion from aqueous solution

A new type of hierarchically organic-inorganic hybrid sorbent was prepared by a double-imprinting approach for the selective separation of Hg(II) from aqueous solution. In the imprinting process, both mercury ions and surfactant micelles (cetyltrimethylammonium bromide, CTAB) were used as templates, N-[3-(trimethoxy-silyl)propyl]ethylenediamine (TPED) as functional monomer, and tetraethoxysilane (TEOS) as cross-linking agent. The mercury ions and surfactant were removed from sorbent via acid leaching and ethanol extraction, respectively. The adsorption property and selective recognition ability of the sorbents were studied by equilibrium-adsorption method. Results showed that in the presence of Cu(II) or Cd(II) the biggest selectivity coefficient of the imprinted sorbents for Hg(II) was over 100, which is much higher than those of non-imprinted sorbents. The largest relative selectivity coefficient (k′) of the ion-imprinted functionalized sorbent between Hg(II) and Cu(II) was over 300, and between Hg(II) and Cd(II) over 200. The uptake capacities and the selectivity coefficients of the hierarchically imprinted sorbent were much higher than those of the sorbent prepared without CTAB template. Furthermore, the new imprinted sorbent possessed a fast kinetics for the removal of Hg(II) from aqueous solution with the saturation time less than 5 min, and could be used repeatedly. This sorbent has been successfully applied to the separation and determination of the trace Hg(II) in real water samples and those spiked with standards. This new sorbent can be used as an effective solid-phase extraction material for the selective preconcentration and separation of Hg(II) in environmental samples.     

Preconcentration and separation of iron, zinc, cadmium and mercury, from waste water using Nile blue a grafted polyurethane foam

The present work describes a novel method for the incorporation of Nile blue A into polyurethane foam matrix. This foam material was found to be very suitable for the extraction of metal ions from aqueous solutions. The characterization of Nile blue A grafted foam and the effect of halide concentration, pH, shaking time, extraction isotherm and capacity have been investigated. This foam material was found to be suitable for the separation and preconcentration of iron (III), zinc (II), cadmium (II) and mercury (II) from waste water. The extraction was accomplished in (15-20) minutes. Iron was separated from acid medium (2-4 M HCl), zinc from (3-5 M HCl), cadmium from (4-6 M HCl) as thiocyanate complexes and mercury was separated from (1-2 M HCl) as chloride.     

Uranyi ion transport through tri-n-octylamine-xylene based supported liquid membranes

Tri-n-octylamine (TOA) dissolved in xylene has been used as carrier, constituting liquid membrane supported in Celgard 2400 polypropylene microporous film for the transport of uranyl ions against their concentration gradient from aqueous acid solutions to an alkaline aqueous phase. Effect of sttrring rate, nitric acid concentration and TOA concentration in the organic membrane phase, on the flux of uranyl ions through the membrane has been studied. Viscosity and density data have been obtained to estimate diffusion coefficients and hence the permeability coefficients to compare the same with experimental values, using distribution coefficient data, measured from solvent extraction experiments and available in the literature. Analysis of the flux data has been performed to study the stoichiometry of the chemical reaction involved in complex formation reaction. The results have been compared with simple liquid-liquid extraction data.     

Extraction of thiocyanate complexes of cobalt(II) by diphenyl-2-pyridylmethane in benzene from mineral acid solutions

Extraction of Co(II) by diphenyl-2-pyridylmethane (DPPM) in benzene form mineral acid solutions containing potassium thiocyanate has been studied at room temperature (23±2°C). Its extraction from mineral acids alone is rather poor. Optimal aqueous phase composition for the quantitative extraction of Co(II) by 0.1M DPPM is 0.1M acid+0.2M KSCN. Stoichiometric studies indicate that an ionic type complex, (DPPM·H)₂·Co(SCN)₄, is responsible for extraction. The metal can be back-extracted from the organic phase by aqueous acetate, citrate or oxalate solutions. Separation factors from other metals determined under optimal conditions reveal that Co(II) can be quantitatively separated from CsI), Sr(II), Cr(III), Ln(III), Zr(IV), Hf(IV), Cr(VI) and Tc(VII), Mo(VI), Zn(II), Au(III), Hg(II) and U(VI) are, however, coextracted and hence should be previously removed by other techniques or reagents.     

Extraction of metals by neutral sulfur-containing extractants: Part I. o-isopropyl-n-ethylthiocarbamate

The formation of neutral mixed complexes of the MX_mS_p type (where M is a metal ion with m⁺ charge, X the inorganic anion, and S the sulfur-containing extractant) allows a selective extraction of various elements. The extraction of many metals from mineral acid solutions or from halide-sulfuric acid mixtures by 0.05 M O-isopropyl-N-ethylthiocarbamate(IPETC) solution in chloroform has been studied. (IPETC) possesses very high selectivity for silver and mercury ions in extractions from HNO₃, H_{2)SO4, HClO4 and HCl solutions. In addition to silver and mercury, Cu, Au, Tl and Se are readily extracted from solutions containing bromide. From iodide solutions, copper, gold and thallium ions may be selectively extracted because silver and mercury cannot be extracted at concentrations of iodide above 0.1 M.(IPETC} extracts metals as mixed complexes, containing the halide and apparently the extractant in the molecular form.     

Extractive separation of trace amounts of mercury, cadmium and zinc

A simple solvent extraction procedure is reported for the sequential separation of mercury(II), cadmium(II) and zinc(II). Mercury is separated first using 1,3-diphenyl-2-thiourea in chloroform at an overall acidity of 0.3M HCl. Then cadmium separated using the same reagent at pH 10 into dichloromethane. The zinc which is remaining in the aqueous phase is then quantitatively extracted into toluene-cyclohexanol mixture using 2-mercaptobenzoxazole. Suitable stripping solutions have been proposed for the re-extraction of these metal ions for their subsequent estimations. The method has been made highly selective by the use of appropriate masking agents and has been applied in conjunction with estimation procedures for the determination of these metal ions in city waste incineration ash (CRM 176), mercuric chloride (A. R. grade) and in magnesium alloy samples.     

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.     

Mutual Binary Separations of Zinc,Cadmium and Mercury by Extraction with Tribenzylamine from Aqueous Bromide and Iodide Solutions

Abstract

The extraction of zinc, cadmium and mercury(II) with a 0. 1 M solution of tribenzylamine in chloroform was studied at varying concentrations of hydrobromic and hydroiodic acid solutions. The extractions of halo complexes of these elements are in accordance with the stability of their tetrahalo complexes in aqueous solution. Using the data mutual binary separations of zinc, cadmium and mercury with high separation coefficients are proposed.