Solvent Extraction Of Silver Research Articles

Cyanex 301에 의한 은(Ag) 용매추출

Cyanex 301에 의한 은(Ag) 용매추출

Solvent Extraction of Silver from Nitric Acid Solution with a Mixture of LIX84I and PC88A

Solvent Extraction of Silver from Nitric Acid Solution with a Mixture of LIX84I and PC88A

Solvent Extraction of Silver from Nitric Acid Solution with 5,8-Diethyl-7-hydroxy-dodecan-6-oxime

Solvent Extraction of Silver from Nitric Acid Solution with 5,8-Diethyl-7-hydroxy-dodecan-6-oxime

Selective Solvent Extraction of Silver(I) by Tris-Pyridyl Tripodal Ligands and X-Ray Structure of a Silver(I) Coordination Polymer Incorporating One Such Ligand

Two tripodal ligands, each derived from 1,1,1-tris(hydroxymethyl)ethane and terminated respectively by 4-pyridyl (L1) and 2-pyridyl groups (L2), have been synthesised. Competitive seven-metal extraction studies (H2O/CHCl3) incorporating equal concentrations of cobalt(ii), nickel(ii), copper(ii), zinc(ii), silver(i), cadmium(ii), and lead(ii) in the aqueous phase and L1 or L2 in the organic phase showed selective extraction of silver(i) in each case. A parallel solvent extraction experiment involving a related tripodal tris-pyridyl ligand (L3) based on a 1,3,5-substituted aryl ring scaffold and incorporating thioether sulfurs in each tripod arm also showed extraction selectivity for silver(i); extraction efficiencies towards this metal ion fall in the order L3 > L1 > L2. Physical data are in accord with L1 forming a capsule-like complex of type [Ag3L12]3+ in which silver ions link pairs of pyridyl groups from different ligands. In contrast, L2 yields a complex of type [Ag2L2(NO)3]n whose X-ray structure showed it to be a two-dimensional coordination polymer in which the three pyridyl donors of each L2 coordinate to three silver(i) centres, two of which are crystallographically distinct, with the centres also bonded to bidentate and/or bridging bidentate nitrato groups.

Solvent Extraction of Silver and Gold From Alkaline Cyanide Solution with LIX 7950

The cyanidation process is still the dominant technique for gold ore treatment. In this study, the potential use of the guanidine extractant LIX 7950 for recovering silver and gold from alkaline cyanide solution was investigated. The results indicate that LIX 7950 can effectively and efficiently extract silver and gold from their cyanide solution. The extraction of silver and gold with the extractant is favorable at low pH. High cyanide to silver ratio tends to suppress silver loading while cyanide concentration exhibits insignificant effect on gold extraction. The extraction of the mixture solution of metal cyanide complexes with the extractant indicated an extraction sequence of Au >A g > Zn > Ni > Cu > Fe. The loaded silver and gold can be stripped off efficiently with moderate strong NaOH solutions at the presence of small amount of NaCN. The important findings in the research suggest that the extractant can be potentially used to recover silver and gold from alkaline cyanide leachate and the barren cyanide solution from the SX circuit can be recycled to the cyanidation process.

Thiosubstituted Organophosphorus Acids as Selective Extractants for Ag(I) from Acidic Thiourea Solutions

This paper deals with the solvent extraction of silver from thiourea leaching Ag ore liquors as an alternative to the traditional process involving cyanide. The investigation of the extraction mechanism of silver from acidic thiourea solution had not been clearly established to date. The extraction behavior of silver using di(2‐ethylhexyl)dithiophosphoric acid (D2EHDTPA) and di(2,4,4‐trimethylpentyl) thiophosphinic acid (CYANEX 302) was studied. The effect of various parameters such as concentrations of metal, mineral acid, thiourea, and extractant has been investigated. The extracted complexes have been identified through a slope method analysis as AgX(HX)5 for CYANEX 302 and AgX for D2EHDTPA, where HX denotes the extractant. Moreover, complete stripping was ensured with a mixture of NH4SCN and H2SO4. In addition we showed that a first step of extraction with D2EHPA or CYANEX 272 results in the preferential separation of Fe(III) from the Ag(I) leach solution.

Solvent extraction of silver from nitric acid solutions by calix[4]arene amide derivatives

Solvent extraction experiments were carried out to recover silver from nitric acid solutions using as the extractants calix[4]arene tetramide (LBC) and its thio-analogue (THIO) dissolved in dichloromethane. The stoichiometry of the formation of the silver-calixarene complex differs depending on the used extractant. It was shown that one silver ion reacts with a single molecule of LBC, while two silver ions are extracted with a single THIO molecule. Very high percent extractions (>90% with LBC and >99% with THIO) were achieved with both extractants by just adding surplus extractant (THIO: 0.6 mol/mol Ag + and LBC: 1.4–1.5 mol/mol Ag +). Based on equilibrium data, the extraction isotherm relationship and the extraction constant K ex for each extractant were derived. The extraction results show that THIO is an efficient extractant extracting silver either from acid or from neutral solutions with the same efficiency. Nitric acid, in the concentration range from 0 to 0.1 mol dm −3, strongly affects the extraction capability of LBC in less acidic solutions, reducing the percent extraction down to 40%. LBC extracts both silver and sodium collectively and with the same efficiency. The selectivity coefficient has a value close to unity ( β ≈ 1). THIO has demonstrated extremely high selectivity for silver over sodium in a mixture. Stripping of silver was performed by two-phase electrowinning from the loaded organic phase, thereby achieving a high stripping degree (50–90%) and reasonably high current efficiency (60–90%). The calixarenes did not change their extraction features during the electrowinning process and can be reused for extraction many times.

Solvent extraction of silver by LIX® 79: experimental equilibrium study

The extraction of silver(I) from argentocyanide aqueous cyanide solutions using LIX® 79 has been studied. Different variables that could affect the extraction system were evaluated: equilibration time, aqueous pH, metal and extractant concentrations, and organic phase diluent. The extraction of the Ag(CN)2− complex with respect to other metal-cyano complexes has also been studied on both synthetic and real leach solutions. Experimental data relating to silver have been analysed numerically to determine the stoichiometry of the extracted species and its equilibrium constant. It was found that silver(I) was extracted into the organic phase by the formation of the species RHAg(CN)2 (LIX 79 = R). Copyright © 2004 Society of Chemical Industry

Solvent extraction of silver(I) from nitrate media using thiourea derivatives

Liquid–liquid extraction of Ag(I) from nitrate solutions using N-(N′,N′-diethyl thiocarbamoyl)-N″-phenylbenzamidine (TCBA) and 1-6,-diethylcarbamoyl imino-1,6-diphenyl-2,5 dithiahexane (TCTH) dissolved in cumene has been studied. The extraction of Ag(I) from 1 mol dm−3 NO3− solutions by TCTH and TCBA was investigated as a function of several variables: equilibration time, organic phase diluent, pH of aqueous phase, Ag(I) and NO3− concentration in aqueous phase as well as TCBA and TCTH concentrations. Experimental equilibrium data were analysed numerically using the programs LETAGROP-DISTR and LETAPL and the results showed that Ag(I) extraction could be explained assuming the formation of AgL and AgNO3HL with TCBA (HL) and AgNO3S with TCTH (S). The metal extraction was not influenced significantly by the structures of the thiourea derivatives used as extractants. The back extraction of Ag(I) from loaded organic phase was performed using different strippants and 0.5 mol dm−3 NaSCN was found to be efficient for this purpose. © 2000 Society of Chemical Industry

Solvent Extraction of Silver(I) over Lead(II) by Oxygen–Sulfur Mixed Donor Podands

A quinoline-bearing podand with five oxygen donors, 1,13-bis(8-quinoly)-1,4,7,10,13-pentaoxatridecane (L1), showed high extractability for both Ag(I) and Pb(II) due to the excellent coordination ability of the quinolyl nitrogen. The introduction of sulfur donor atoms and the exclusion of nitrogen from the ligand structure based on the skeleton of L1 clearly offered not only high extraction efficiency but also excellent selectivity in the separation of Ag(I) over Pb(II). 1H NMR was used to evaluate the binding properties of the podands, and the spectral changes obtained on complexation indicate Ag(I)-specific binding to sulfur donor or pseudocyclization encased Ag(I) which seems to be reflected in the enhanced extractability.

Selective extraction of silver(I) over palladium(II) with ketonic derivatives of calixarenes from highly concentrated nitric acid

Solvent extraction of silver(I) and palladium(II) ions with 37,38,39,40,41,42-hexakis(acetomethoxy)-5,11,17,23,29,35-hexakis (1,1,3,3-tetramethylbutyl)calix[6]-arene,25,26,27,28-tetrakis(acetomethoxy)-5,11,17,23-tetrakis(1,1,3,3-tetramethyl-butyl) calix[4]arene, and p-(1,1,3,3-tetramethylbutyl)phenoxyacetone as a monomeric analog, from highly concentrated HCl or HNO 3 into chloroform was investigated. For comparison, the corresponding carboxylate derivatives and the unmodified calixarenes were also examined. Since both silver and palladium ions strongly form complexes with chloride anions, the extraction of both metals was found to be suppressed in highly acidic media. Among the compound employed in the present work, tetrameric ketone was found to be capable of selectively extracting silver over palladium at about 1 mol dm −3 HNO 3 and was suitable for removing traces of silver from a large excess of palladium. It was suggested from the observation of the chemical shift of proton nuclear magnetic resonance that the ketonic derivative of calix[4]arene forms a complex with silver ion surrounded by phenoxy oxygen and carbonyl groups.

Solvent extraction of silver from chloride media with some commercial sulfur-containing extractants

Different kinds of commercial sulfur-containing extractants (SFI-6R, MSP-8, Cyanex 302 and Cyanex 301 in EXXSOL D-80) were examined to extract silver from chloride media. The aggregation of MSP-8 was analyzed quantitatively by means of vapor-pressure osmometry and it was found that this extractant exists as a dimeric species in aliphatic organic diluents. Extractants containing P = S and P(S)SH functional groups strongly extract silver in the whole concentration range of hydrochloric acid except for the very high concentration region, while SFI-6R only weakly extracts silver in the low concentration region and no extraction was observed in the high concentration region. Extraction equilibrium of silver with SFI-6R was measured by the slope analysis method, while for MSP-8, Cyanex 302 and Cyanex 301 the complex stoichiometries were inferred using Job's method. It was elucidated that silver is extracted as 1:2 metal:reagent complex with extractants containing one donor atom of sulfur, while the ratio becomes to 1:1 for an extractant having two sulfur donor atoms.

Solvent Extraction of Silver(I) as Anionic Metal Complexes with 2-Thenoyltrifluoroacetone and 4-Isopropyltropolone into Chloroform in the Presence of Tetrabutylammonium Ions.

The solvent extraction of silver(I) in aqueous 0.1 mol dm-3 sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) and 4-isopropyltropolone (β-isopropyltropolone, Hipt) into chloroform was studied in the absence and presence of tetrabutylammonium ions (tba+), and the results were compared. Although extraction with Htta was poor, it was very much enhanced and nearly quantitative extraction was achieved by the addition of tba+. This was assumed to be due to the fact that the complex, Ag(tta), was hydrophilic due to its hydration, but tba+Ag(tta)2-, which was extracted in the presence of tba+, was very weakly hydrated and bulkier. Both Ag(ipt) and Ag(ipt)(Hipt) were extracted; extraction with Hipt was not very effective in the absence of tba+ By the addition of tba+, the anionic complex, tba+Ag(ipt)2, was also extracted, and nearly quantitative extraction was also achieved. Since the formation of this anionic complex is made by an exchange of ipt- with Hipt of the Ag(ipt)(Hipt) species, the enhancement of extraction was impaired by the dissociation of Hipt from the self-adduct.

Solvent Extraction of Silver Using Bis(O-butylxanthato)alkane Derivatives

New xanthic acid derivatives containing the bisbutyl polymethylene group were used for silver extraction in 0.1M NaClO4. Solvent extraction results showed that silver extraction was established through 1:2 (silver:ligand) complexes. The stabilities of the extractable complexes were determined based the length of the polymethylene chain between the donor atoms and the presence of a neighboring functional group within the structure of the ligands, as revealed by the Kex values. The probable extraction mechanism (extraction and back-extraction) and interferences are also discussed.

SOLVENT EXTRACTION OF SILVER BY CYANEX 272, CYANEX 302 AND CYANEX 30

ABSTRACT The solvent extraction of silver from nitrate media by the extractants Cyanex 272 (bis)2,4,4-trimethylpentyl)phosphinic acid), Cyanex 302 ( bis(2,4,4-trimethylpentyl)thiophosphinic acid) and Cyanex 301 ( bis( 2,4,4-trimethyl-pentyl)dithiophosphinic acid) is characterized. Extraction shifts to lower pH with increasing sulfur substitution in the phosphinic acid, in accordance with the increased extractant acidity imparted by the soft nature of the sulfur donor atoms. The effects of extractant concentration, aqueous-phase ionic strength and organic-phase diluent on the extraction behavior are examined. The stoichiometry of the extraction reactions and the geometry of the extracted complexes are postulated based on slope analysis and spectroscopic measurements. All three extractants behave as bidentate ligands and combine in a 1:1 stoichiometric ratio with silver. The sulfur-containing ligands form multi-nuclear oligomeric complexes in which the ligands bridge between metal centers.

Solvent Extraction and Related Studies on Silver Recovery from Aqueous Solutions

Abstract The main research in the solvent extraction of silver is exhaustively reviewed, together with relevant data on the metal ion complexation properties in one phase. Such features as the transport of competitive cations through liquid membranes and selectivity in silver extraction are also reviewed. The behavior of organic ligands interacting with silver is analyzed on the basis of the atom type or types directly responsible for extraction/complexation processes.

Solvent extraction of silver(I) with amberlite-LA-2 using110mAg as tracer

The use of Amberlite-LA-2, a high molecular weight secondary amine, for the radiochemical solvent extraction of Ag(I) present as anionic thiosulfato complex at pH 3 is described. The effects of different parameters on the extraction and preconcentration have been studied in detail. The method was successfully applied in the determination of silver in several synthetic mixutres and also in a few medicinal samples.

Spectrophotometric Determination of Sulfide at the 10−6 mol 1−1 Level by Solvent Extraction of Silver(I) with Methylene Blue

Excess silver(I) from its reaction with sulfide was extracted into 1, 2-dichloroethane using Methylene Blue; the extract was measured spectrophotometrically at 657nm for the determination of sulfide. Hydrogen sulfide, separated from sample matrices, was introduced into a solution in which the hydrogen sulfide was completely converted into silver sulfide. A linear calibration graph with a negative slope was obtained over the range 8.0×10-8-4.5×10-6M (M=mol dm-3) sulfide (0.026-1.44μg of S2- in 10ml(ml=cm3)) and the relative standard deviation was 0.93% at the 2.5 ×10-6M sulfide level when applied to hot-spring water samples. The effective molar desorptivity for sulfide is -1.99×105l mol-1 cm-1.Good recoveries of sulfide from hot-spring waters were achieved using the proposed method.

Application of the sulphide podand 1,12-Di-2-thienyl-2,5,8,11-tetrathiadodecane to the determination of silver in ores and tailings by solvent extraction-atomic absorption spectrometry

A method has been developed for the determination of silver in copper ores and tailings by AAS based on the solvent extraction of silver with 1,12-di-2-thienyl-2,5,8,11-tetrathiadodecane, an acyclic neutral ligand with six sulphur donor atoms (sulphide podand), in IBMK. The separation was carried out on samples dissolved in 2 M nitric acid in the presence of boric acid. The accuracy of the method was examined using standard reference materials [a copper-zinc ore and a copper (pyrite) ore]. An r.s.d. of 2.8–4.9% for 10–4–10–3% silver in ores was obtained.

The Solvent Extraction of Silver and Thallium(I) Picrates by Crown Ethers

Abstract Extraction constants of silver and thallium(I) picrates and those of 12-crown-4 (12C4) and benzo-15-crown-5(B15C5) with silver and thallium(I) picrates have been determined between benzene and water at 25 °C. Ionpair complex-formation constants (KMLA,o) of 12C4 and B15C5 with silver and thallium picrates in the benzene solution have been calculated and compared with those of 15-crown-5 (15C5), 18-crown-6 (18C6), dibenzo-18-crown-6 (DB18C6), and dibenzo-24-crown-8 (DB24C8). The KMLA,o sequences of the crown ethers with Ag+ and Tl+ are 15C5, 18C6>DB18C6>B15C5>DB24C8>>12C4 and 18C6>>DB18C6>DB24C8>15C5>B15C5>>12C4, respectively. For both Ag+ and Tl+ systems, the relative sizes of the cation and the crown ether cavity, the number of donor oxygen atoms in the crown ether ring, the basicity of donor oxygen atom, and the flexibility of the crown ether are important factors in determining stabilities of the complexes with these crown ethers in the benzene solution.