Solvent extraction of metals using LIX26 extractant

Solvent extraction of some selected metals from an aqueous buffered solution by LIX26 extractant has been studied. The pH_1/2 values (at which 50% of metal ion is extracted) for extracting different metals by 1 v/v% LIX26 extractant in methyl isobutyl ketone have been obtained. The order of extraction of metals by LIX26 extractant as a function of pH_1/2 value is Pd(II)<Cu(II)<Sb(III)<Fe(II)<Co(II)<Zn(II)<Ni(II) <Pb(II)<Mn(II)<Cd(II).     

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.     

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.     

Solvent extraction of Ni(II) from sulfate solutions with LIX 84I: flow-sheet for the separation of Cu(II), Ni(II) and Zn(II).

This paper reports on solvent-extraction studies of Ni(II) from sulfate solutions with LIX 84I (2-hydroxy-5-nonylacetophenoneoxime) as the extractant. The extraction of metal depends on the equilibrium pH of the aqueous phase and the extractant concentration. The transfer of metal follows a cation exchange-type mechanism: Ni2+ + 2HA --> NiA2 + 2H+. Extraction varies with the nature of the diluents. Temperature has no effect on the extraction of metal. The extraction behavior of associated metals clearly demonstrates the application of LIX 84I as the extractant for the separation of Cu(II), Ni(II) and Zn(II). Based on the results, a flow sheet of the process was developed.     

Extraction mechanism for palladium(II) from hydrochloric acid solution with 2-dodecylthiomethylpyridine using a stirred transfer cell.

2-Dodecylthiomethylpyridine (DTP) was newly synthesized to study its extraction properties for precious metals. DTP was a selective extractant for palladium(II) and gold(III) over base metals. The loading test for palladium(II) showed that one palladium ion reacted with one molecule of DTP. The extraction rate of palladium with DTP was measured using a Lewis-type transfer cell at 303 K. The extraction reaction of palladium with DTP has been found to be a first order reaction with respect to palladium ion, DTP, and hydrogen ion concentrations. This reaction is inversely proportional to chloride ion concentration. The rate-determining step was the parallel reactions of DTP with PdCl3(-) and PdCl4(2-) in the aqueous phase.     

Solvent extraction of metals with commercial oxime extractant (LIX 622)

The extraction characteristics of some selected metals from an aqueous buffered solution by LIX 622, a commercial oxime extractant have been studied. The pH_1/2 values for extracting different metals with 5 v/v% LIX 622 extractant in methyl isobutyl ketone (MIBK) have been obtained. The order of extraction of metals with LIX 622 extractant as a function of pH_1/2 value is determined and results agree well with the order obtained using salicylaldoxime as chelating ligand for the extraction of these metals.     

Extraction and separation of mercury(II) using triisobutyl phosphine sulfide (TIBPS/Cyanex) as an extractant and its application to industrial effluent

Studies have been carried out on the extraction of Hg(II) along with Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Ag(I), from mineral acid media using TIBPS. The effect of different variables influencing extraction of Hg(II), such as, mineral acid used, nature of diluent, concentration of metal ion and extractant has been investigated. Based on the partition data some binary separations from Hg(II) have been achieved. The potential of the extractant for decontaminating Hg from paper industry effluent has been assessed.     

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.     

Temperature-swing solid-phase extraction of heavy metals on a poly(N-isopropylacrylamide) hydrogel

The feasibility of temperature-swing adsorption of heavy metals on a thermosensitive N-isopropylacrylamide (NIPA) hydrogel was examined. We have proposed a novel temperature-swing solid-phase extraction (TS-SPE) technique. First, a metal ion in an aqueous solution is complexed with an extractant. Subsequently, the metal-extractant complexes (or micelles) are adsorbed onto the NIPA hydrogel through a hydrophobic interaction above the lower critical solution temperature (LCST). Finally, the metal-extractant complexes are desorbed from the NIPA hydrogel after it is cooled below the LCST. In a model system consisting of Cu(II) ions, sodium n-dodecylbenzenesulfonate (SDBS), and NIPA hydrogel, the proposed TS-SPE technique has been successfully conducted. The following observations can be made: the amount of adsorbed Cu(II) ions increases with the increase in temperature, the maximum adsorption is attained at a temperature above the LCST, and the hydrogel adsorbs and desorbs Cu(II) ions reversibly due to the temperature-swing between 10 and 40 degrees C. The LCSTs of poly(NIPA) in aqueous SDBS solutions with/without CuCl2 and the surface tensions of their solutions suggest that the hydrophobicity of the complex Cu(DBS)2 is greater than the hydrophobicities of SDBS and DBS. In addition to the separation of heavy metals, TS-SPE is potentially applicable to cases such as the separation of biological molecules by means of metal-ion affinity.     

海湾河口表层沉积物中重金属形态连续萃取方法的优化研究

采用单一萃取程序对建立的重金属形态连续萃取方法的萃取条件进行优化.分别以Ca和Mg、Fe、有机质(OM)和酸可挥发性硫(AVS)作为萃取剂释放酸溶态、还原态、有机质结合态和硫化物结合态等重金属目标形态的表征参量,考察萃取剂对相应目标形态的萃取能力和选择性.分别根据表征参量和重金属在萃取溶液中的含量变化确定最优萃取时间和萃取样液比.结果表明,优化萃取条件后,萃取剂对目标形态重金属均有很强的释放能力.酸溶态萃取剂对其它非残留态影响很小;还原态萃取剂除对酸溶态有少量提取外,对其它形态影响较小;有机质结合态萃取剂对硫化物结合态有少量萃取,对其它形态影响较小.硫化物结合态在酸溶态、还原态和有机质结合态之后萃取,避免了对这三种形态的影响.优化后的连续萃取方法对重金属形态有较好的选择性,可对海湾和河口表层沉积物中重金属的目标形态进行较为合理地分离和评价.     

Extraction of nonferrous metals by bisacylated diethylenetriamine

Bisacylated diethylenetriamine (BAD) with an α,α′ branched substituent has been synthesized. Conditions for the extraction of copper(II), cobalt(II), nickel(II), zinc(II), and iron(III) chlorides from hydrochloric, chloride, and ammoniac solutions have been studied. The protonation constants of the extractant and the concentration constants of metal extraction have been calculated. The extraction in the pH range of 2–10 has a coordination mechanism; at hither acidities, the extraction occurs via ion exchange.     

1-(2-pyridylazo)-2-naphthol (PAN) as extractant in solid-liquid extraction of some trivalent rare earth elements

In the present paper, solid-liquid extraction behaviour of RE(III) (RE La, Ce, Pr, Nd, Sm, Gd, Dy and Yb) by the use of 1-(2-pyridylazo)-2-naphthol (PAN, HL) as an extractant in paraffin (m.p. 48 approximately 50 degrees) has been investigated at 80 +/- 0.07 degrees. The effect of equilibrium time, pH of aqueous phase, concentration of extractant in paraffin and solid diluent as well as buffer solution used on the extraction efficiency of RE(III) have been discussed. The extraction reaction is RE(3+) + 2HL(o) + Cl(-) <==> REL(2)Cl(o) + 2H(+).     

Liquid—liquid extraction of transition metals with acylthioacetamides

The extraction behaviour of acylthioacetamides, R¹—CO—CH₂—CS—NR²R³, was studied for a series of transition metals. The highest distribution ratios were obtained with benzoylthioacetanilide. Complexes with acylthioacetamides which were completely substituted on the amide group were extracted slowly. The ranking of the extraction characteristics is related to the different pK_a values of the compounds used. Polymerization and solvation reactions can be excluded at metal concentrations of ? 10^-3 mol dm^-3 and extractant concentrations of ?10^-1 mol dm^-3, respectively. Decreasing extractability, Cu(II) > Zn(II) > Ni(II) > Co(II) > Cd(II), corresponds to the stability constants of the extracted metal chelates. Iron(III) cannot be extracted at pH ?3; Hg(II), Pd(II), and Au(III) are extracted readily over a reasonably wide pH range. The different extraction constants for zinc(II) and cadmium(II) permit an effective separation of these ions with benzoylthioacetanilide.     

Extraction of thorium from aqueous nitric acid solution by bis-2-(butoxyethyl ether) (DBC)

The solvent extraction of thorium(IV) (4.3·10^–4M) from nitric acid solution by bis-2-(butoxyethyl ether) (butex or DBC) has been studied. It has been investigated as a function of nitric acid, extractant and metal ion concentration. The effect of equilibration time, diverse ions and salting-out agent on the extraction has also been examined. Among anions, fluoride, phosphate, oxalate and perchlorate have reduced the extraction. Cations such as Na(I), K(I), Ca(II), Zn(II), Al(III), Ti(IV), Zr(IV) except Sr(II) and Pb(II) do not interfere in the extraction. The extraction is enhanced upto 97% in three stages at 6M HNO₃ having 2.94M NaNO₃ as salting-out agent. The extraction is found to be independent of thorium concentration in the range studied (4.3·10^–4–4.3·10^–2M). The temperature (18–45°C) has an adverse effect on the extraction. A 1% solution of ammonium bifluoride is found to be a good stripping solution and recovery of thorium is >98%.     

A highly efficient solvent system containing functionalized diglycolamides and an ionic liquid for americium recovery from radioactive wastes

Three room temperature ionic liquids (RTILs), viz. C(4)mim(+)·PF(6)(-), C(6)mim(+)·PF(6)(-) and C(8)mim(+)·PF(6)(-), were evaluated as diluents for the extraction of Am(III) by N,N,N',N'-tetraoctyl diglycolamide (TODGA). At 3 M HNO(3), the D(Am)-values by 0.01 M TODGA were found to be 102, 34 and 74 for C(4)mim(+)·PF(6)(-), C(6)mim(+)·PF(6)(-) and C(8)mim(+)·PF(6)(-), respectively. The extraction of Am(III) decreased with increasing feed acidity for all three diluents, indicating an ion exchange mechanism for the extraction. The stoichiometry of the extracted species suggested that two TODGA molecules were associated with Am(III) during the extraction for all three RTILs and the conditional extraction constants have been determined. The D(M)-values for different metal ions followed the order: 75 (Am(III)) > 30.7 (Pu(IV)) > 3.9 (Np(IV)) > 1.19 (Pu(VI)) > 0.52 (U(VI)) > 0.12 (Cs(I)) > 0.024 (Sr(II)). The distribution behaviour of Am(III) was also studied with a recently synthesized calix[4]arene-4DGA (C4DGA) extractant dissolved in C(8)mim(+)·PF(6)(-). Using this extractant diluent combination, the D(Am)-value was 194 at 3 M HNO(3) using 5 × 10(-5) M C4DGA, suggesting a very high distribution coefficient at very low extractant concentrations. The stoichiometry of the extracted species containing Am was found to be 1:2 (M:L) in C(8)mim(+)·PF(6)(-). The thermodynamics of the extraction was also studied for both extractants in C(8)mim(+)·PF(6)(-). The use of RTILs gives rise to significantly improved extraction properties than the commonly used n-dodecane and an unusual increase in separation factor values was seen for the first time which can lead to selective separation of Am from wastes containing a mixture of U, Pu and Am.     

Functionalized HMS mesoporous silica as solid phase extractant for Pb(II) prior to its determination by flame atomic absorption spectrometry

In this work, a mesoporous silica has been chemically modified with 5-mercapto-1-methyl-1-H-tetrazol using the homogeneous route (MTTZ-HMS). This synthetic route involved the reaction of 5-mercapto-1-methyl-1-H-tetrazol with 3-chloropropyltriethoxysilane, prior to immobilization on the support. The resulting material has been characterized and employed as solid phase extractant for Pb(II). The effect of several variables (stirring time, pH, temperature, metal concentration, presence of other metals) has been studied using batch and column techniques. In batch experiments, 15 min stirring time, 55 degrees C and pH 8 were the optimal conditions for Pb(II) adsorption. In column experiments, sorption was quantitative for 1000 mL of 2.41 x 10(-4 )mM of Pb(II) solution and adsorbed ions were eluted out by 5 mL of 1 M HCl (preconcentration factor of 200). Spiked tap water was used for the preconcentration and determination of Pb(II) by flame atomic absorption spectrometry, and a 100% recovery was obtained. The LOD and LOQ values of the proposed method were found to be 3.52 x 10(-3) and 4.20 x 10(-3 )mM, respectively. The RSD for three preconcentration experiments was found to be 相似文献   

Simultaneous extraction of several persistent organic pollutants in sediment using focused ultrasonic solid-liquid extraction

Focused ultrasonic solid-liquid extraction (FUSLE) has been optimised for simultaneous analysis of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalate esters (PEs), and nonylphenols (NPs) in sediment samples. Optimisation was performed using naturally polluted freeze-dried sediment samples. The variables studied during the optimisation process were: percentage of maximum power (10-60%), extraction time (10-300 s), number of cycles (1-9), composition of the extraction solvent (acetone-n-hexane, 10:90-90:10), and sample mass (0.1-1 g). The volume of the extractant was constant (10 mL) and the extraction was performed at 0 degrees C in an ice-bath during the optimisation process. All these variables were studied using an experimental design approach by means of The Unscrambler software. The extraction time and the operational variables (number of cycles and power) had no statistically significant effect in the extraction and they were held at 2 min, 20% power, and seven cycles, respectively. The mass and the addition of non-polar solvent (n-hexane) had a negative effect in the extraction yield and, thus, the mass was held at 0.5 g and pure acetone was used as extraction solvent. After those variables were optimised, the effect of the extraction temperature (0 degrees C or room temperature) was also studied. The validation of the extraction method was performed using NIST-1944 reference material in the case of PAHs and PCBs. Because no certified reference sediment is available for PEs and NPs, the results obtained for FUSLE were compared with those obtained for microwave-assisted extraction (MAE) under conditions optimised elsewhere. In all the cases the analysis were performed by gas chromatography-mass spectrometry (GC-MS). Good accuracy were achieved in all cases. The limits of detection (LODs) obtained were between 0.10 and 1.70 ng g(-1) for PAHs (except for naphthalene 5.33 ng g(-1)), 0.02 and 0.16 ng g(-1) for PCBs, 46 and 188 ng g(-1) for PEs, and 0.6 and 12.4 microg g(-1) for NPs. The precision was around 5-10% for most of the PAHs and PCBs and around 2-10% for most of the PEs and NPs.     

Acetothioacetanilide as a gravimetric reagent for palladium, platinum and rhodium

Acetothioacetanilide, CH(3)CO . CH(2) . CS . NH . C(6)H(5) is found to be a very suitable gravimetric reagent for Pd(II), Pt(II) and Rh(III). The complexes [composition, M(C(10)H(10)NOS)(2); for M = Pd(II) and Pt(II), and M(C(10)H(10)NOS)(3)] are stable and can be weighed after drying at 105-110 degrees . Separation from base metals has been studied, and a structural interpretation made from DTA, TG and infrared data.