Selective Extraction Of Pd Research Articles

Recovery of Pure Pd(II) from Spent Electroplating Solutions by Solvent Extraction with Ionic Liquids from Sulfuric Acid Leaching Solution of Cemented Pd

Palladium (Pd) electroplating is widely practiced in the manufacture of advanced electronic devices. The Pd(II) present in spent electroplating solutions is treated by cementation with zinc (Zn) metal powder. In order to recover pure Pd from the cemented Pd, a process that consisted of leaching followed by solvent extraction was investigated. For this purpose, solvent extraction experiments using synthesized ionic liquids (ILs) with organic and inorganic anions were performed to find separation conditions at which selective extraction of Pd(II) over Zn(II) from synthetic H2SO4 leaching solutions is possible. The concentration of sulfuric acid was varied from 0.5 to 9 M. The complete separation of Pd(II) over Zn(II) by ILs such as ALi–CY301 (N-methyl-N,N,N-trioctylammonium bis(2,4,4-trimethylpentyl) dithiophosphinic), ALi–SCN (N-methyl-N,N,N-trioctylammonium thiocyanate), ALi–I (N-methyl-N,N,N-trioctylammonium iodide) and ALi–Br (N-methyl-N,N,N-trioctylammonium bromide) depends on H2SO4 concentration, while ALi–LIX63 (N-methyl-N,N,N-trioctylammonium 5,8-diethyl-7-hydroxydodecane-6-oxime) and ALi–LIX84 (N-methyl-N,N,N-trioctylammonium 2-hydroxy-5-nonylacetophenone oxime) can completely separate Pd(II) irrespective of H2SO4 concentration. Additionally, the mixture of HCl and thiourea, aqua regia solution, NH3 solution and the mixture of NH4Cl and NH3 are powerful stripping agents for Pd(II) from the loaded ALi–LIX63/ALi–LIX84, ALi–CY301, ALi–Br/ALi–I and ALi–SCN, respectively. However, application of the separation conditions to the real 5 M sulfuric acid leaching solutions of cemented Pd indicated that it was difficult to separate the two ions by extraction with ALi–LIX63 and ALi–LIX84. Use of NaClO as an oxidizing agent during the sulfuric acid leaching of real cemented Pd resulted in an enhancement of Zn(II) extraction by ALi–LIX63 and ALi–LIX84. Therefore, removal of chloride ions from the sulfuric acid leaching solutions is necessary to apply the separation conditions obtained from synthetic sulfuric acid leaching solutions.

Recovery of Pd(II) from leach solutions of automotive catalysts by solvent extraction with new thiophosphate extractants

Thiophosphate- and phosphate- based extractants, 1,3-bis(diethoxythiophosphinoyloxy)benzene (Ext 1) and 1,3-bis(diethoxyphosphinoyloxy)benzene (Ext 2), respectively, were synthesized and studied for their ability to extract Pd(II) from HCl and HNO3 media. Ext 1 (0.1 M) in 1-octanol selectively extracted 90–99.9% of Pd(II) in HCl (0.1–8.0 M) and 99.8% of Pd(II) in HNO3 (0.1–8.0 M) single-metal solutions, whereas Ext 2 demonstrated negligible Pd(II) extraction in either solution. The Pd(II) extraction rate, acid durability, optimal organic/aqueous (O/A) phase ratio, and Pd(II) loading capacity of Ext 1 were evaluated. Ext 1 was very stable in HCl and HCl/HNO3 solutions. Selective extraction of Pd(II) by Ext 1 (E% = 99%) was achieved from a solution containing Pd, Pt, Rh, rare metals, base metal ions, and leach liquors from automotive catalysts. Back-extraction of Pd(II) was performed using a solution of 0.1 M thiourea and 1.0 M HCl, allowing Ext 1 to be reused for 5 cycles. Ext 1 achieved rapid and selective extraction of Pd(II) from automotive catalyst solutions from platinum group metal refineries.

Synthesis of pincer-type extractants for selective extraction of palladium from PGMs: An improved liquid-liquid extraction approach to current refining processes

SCS pincer ligands 1–4 were synthesised, and their ability to extract Pd(II) from HCl and HNO3 media was studied. The Pd(II) extraction properties of 1–4 were compared with those of commercial extractants (DOS and LIX®84-I) in kerosene. 1 and 2 showed superior Pd(II) extractability (E% = 99.9) relative to DOS and LIX®84-I from 0.1–8.0 M HCl and to DOS from 0.1–8.0 M HNO3 and mixed HCl + HNO3 media. The Pd(II) extraction rate, acid durability, the most suitable organic/aqueous (O/A) phase ratio, and Pd(II) loading capacity of extractants 1, 2, and DOS were evaluated. 1 and 2 exhibited a greater Pd(II) extraction rate and Pd(II) loading capacity than DOS. 1 was very stable in acid media (HCl and HCl + HNO3), whereas 2 and DOS deteriorated in HCl + HNO3. Selective extraction of Pd(II) by 1 and 2 was achieved from a mixed solution containing Pd, Pt, Rh, rare metals, and base metal ions that simulated the leach liquors of automotive catalysts. The back extraction of Pd(II) and reusability of extractants 1 and 2 were studied. The Pd(II) extraction mechanism of 1–4 was investigated using FT-IR, UV-visible, and NMR spectroscopy.

Highly selective extraction of Pd(II) with 5-octyloxymethyl-7-bromo-8-quinolinol from acidic solution

A novel extractant, 5-octyloxymethyl-7-bromo-8-quinolinol (HBrO8Q), was employed to extract Pd(II) from low-acidity aqueous solution. The extraction behaviors indicated that HBrO8Q had high extraction efficiency and selectivity for Pd(II) under the experimental conditions, and the stoichiometry of Pd(II) with HBrO8Q was found to be 1:1 by means of mole ratio method and Job’s method. The thermodynamic study indicated that the extraction process was endothermic and spontaneous. Additionally, complete back extraction of palladium could be achieved by using acidic thiourea solution.

Rapid and selective extraction of Pd(ii) ions using the SCS type pincer ligand 1,3-bis(dimethylthiocarbamoyloxy)benzene, and its Pd(ii) extraction mechanism

Extractant1extracts Pd(ii) ionsviapincer type S–C–S tridentate ligands, with the formation of fused six-membered chelate rings. Rapid and selective extraction by1of >99% Pd(ii) ions from an automotive catalyst leach liquor was observed.

Feasibility Studies on Palladium Extraction from Leach Liquors of Automotive Catalysts Using p-Diethylphosphonomethylthiacalix[6]arene

Feasibility studies for the recovery of Pd(II) from leach liquors of automotive catalysts using p-diethylphosphonomethylthiacalix[6]arene (1) and p-tert-butylthiacalix[6]arene (2) were conducted. Compound 1 was found to be a more efficient extractant than 2 for Pd(II) ions, indicating selective extraction of Pd(II) ions [E% = 98.4%] from the leach liquors. The majority of other metal ions present in the leached solution were not extracted except Zr(IV) ions [E% = 22%]. Stripping of the Pd(II) ions from the extractants was performed using acidic thiourea, thereby enabling the recycling of the extractants.

A highly efficient and magnetically retrievable functionalized nano-adsorbent for ultrasonication assisted rapid and selective extraction of Pd2+ ions from water samples

A novel and highly efficient magnetic core shell based nanoadsorbent has been fabricated and applied for the extraction of Pd2+ ions.

Selective extraction of Pd(II) ions from automotive catalyst residue in Cl− media by O-thiocarbamoyl-functionalized thiacalix[n]arenes

The extraction of Pd(II) ions from automotive catalyst residue solutions in Cl− media was studied using 5,11,17,23,29,35-tert-butyl-37,38,39,40,41,42-(dimethylthiocarbamoyl)oxy thiacalix[6]arene (1) and 5,11,17,23-tert-butyl-25,26,27,28-(dimethylthiocarbamoyl)oxy thiacalix[4]arene (2). Compounds 1 and 2 were found to have higher Pd(II)-ion extraction abilities than p-tert-butylthiacalix[6]arene (3) and p-tert-butylthiacalix[4]arene (4) in Cl− media. The prepared compounds selectively extracted Pd(II) ions from the single-metal, simulated mixed-metal, and automotive catalyst leached solutions. Compound 1 extracts 99.5–82% of Pd(II) from 0.1–2.0M HCl media and 75–55% from 4.0–8.0M HCl media. Compounds 1 and 2 have very high Pd(II)-loading capacities, which depend on the number of dimethylthiocarbamoyl moieties in 1 and 2. Pd(II) extraction efficiency of 1 and 2 was dependent on the Cl− concentration and independent of the H+ concentration. The acid durability test of the extractants was carried out with 2.0M HCl–1.0M HNO3 solutions. The FT-IR results showed that compounds 1 and 2 are more durable than compounds 3 and 4 in acidic media and are suitable for metal extraction in highly acidic media. In addition, compounds 1 and 2 selectively extracted 99% of Pd(II) ions from an automotive catalyst residue leached solution composed of Rh, Pd, Pt, Zr, Ce, Ba, Al, La, and Y in 1.0M Cl− media. Thus, 1 and 2 can be used as effective extractants for Pd(II) separation from secondary resources.

Extraction of Palladium(II) from Nitric Acid Solutions with 1‐Benzoyl‐3‐[6‐(3‐benzoyl‐thioureido)‐hexyl]‐thiourea

The extraction of palladium (II) from HNO3 solutions with 1‐Benzoyl‐3‐[6‐(3‐benzoyl‐thioureido)‐hexyl]‐thiourea (Ia) and several monodentate thiourea derivatives in 1,2‐dichloroethane has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant in the organic phase on the Pd(II) extraction is considered. The stoichiometry of the extracted complexes has been determined. The increasing number of thioamide groups in the molecule of Ia increases its extraction efficiency towards Pd(II). The potentialities of a polymeric resin impregnated with compound Ia for selective extraction of Pd(II) from nitric acid solutions are demonstrated.

Recovery palladium, gold and platinum from hydrochloric acid solution using 2-hydroxy-4-sec-octanoyl diphenyl-ketoxime

The selective extraction of Pd(II) over Au(III) and Pt(IV) as well as subsequently selective extraction of Au(III) over Pt(IV) from hydrochloric acid (HCl) solution were achieved by using 2-hydroxy-4-sec-octanoyl diphenyl-ketoxime diluted in kerosene as extractant. The typical composition of solution used for the present study contains Pd: 5.95 g/L, Au: 5.42 g/L and Pt: 10.23 g/L. Pd(II) is extracted into organic phase quantitatively after three-stage counter-current extraction operation with extraction percentage >99.9% at pH 2. At a higher HCl concentration (5 M), Au(III) is effectively extracted into organic phase from the resulting raffinate by four-stage counter-current extraction operation. On the other hand, stripping of Pd(II) from loaded organic phase needs high acid solution while the stripping of Au(III) can be achieved at pH 2. Four-stage stripping with 6 M HCl at O:A = 2:1 yielded >99.9% Pd(II) stripping efficiency and four stages stripping with 0.01 M HCl at O:A phase ratio of 2:1 performed >99.9% Au(III) stripping efficiency. The resulting solutions for each metal, after the corresponding process such as precipitation or reduction, can be used for yielding metal powder with the purity better than 99.99%. A complete process flow sheet for the separation and recovery of Pd(II), Au(III) and Pt(IV) is established based on the present investigation.

BENZYL(2-METHOXY-3-DIPHENYLPHOSPHINO)PROPYL ETHER AS A CARRIER FOR THE SELECTIVE TRANSPORT OF Pd(II) THROUGH A SOLID SUPPORTED LIQUID MEMBRANE

Benzyl(2-methoxy-3-diphenylphosphino)propyl ether (BPOMe), a new chelating reagent, was synthesised for the selective extraction of Pd(II) from aqueous chloride solutions. This reagent was used as a carrier in a solid supported liquid membrane system for the transport of palladium, and chemical conditions where selected using laminar configuration. The best stripping results where obtained with thiourea at an acidic pH, and, among the organic solvents tested as liquid membrane diluents, decaline gave the most stable solid supported liquid membrane (SSLM) and was the most efficient in the transport of Pd(II). The effect of both carrier and initial metal concentration on the permeability value was also studied, and it was observed that BPOMe is more effective at low level metal concentrations. The selectivity of this reagent towards palladium has been evaluated using source solutions in chloride media containing Pd(II), Pt(IV) and Rh(III). The results revealed that palladium was the only metal extracted. Based on these results, a hollow fiber membrane configuration was employed for the selective preconcentration of palladium.

Neutron activation determination of noble metals for the analysis of technological and natural materials

Two previously developed methods of noble metal neutron activation (NA) determination have been applied for the analysis of technological materials. While comparing the data obtained by both methods with those obtained in Central Chemical Laboratory the systematical discreapences have been shown to be absent. A new method of Pd, Au, Pt and Ir NA determination in natural and technological specimens based on the selective extraction of Pd and Au preliminary to irradiation has been developed. Results of the analysis of “Glomar Cellenger”'s deep-water drilling samples are discussed obtained by this method.