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Electroplating of palladium (Pd) is practiced in the manufacture of electronic materials. The increasing demand for Pd metal necessitates the recovery of Pd(II) from the spent electroplating solutions. In this work, the recovery of Pd compound was studied from the cemented Pd by zinc (Zn) metal from spent electroplating solutions. Initially, the selective extraction ability of ionic liquids synthesized from commercial extractants for Pd(II) over Zn(II) from the synthetic HCl solution was investigated. Pd(II) was selectively extracted over Zn(II) from 9 M HCl solution by ALi-CY301(Nmethyl-N,N,N-trioctylammonium bis(2,4,4-trimethylpentyl) dithiophosphinic) and by ALi-I (N-methyl-N,N,N-trioctylammonium iodide) from weak HCl solution (pH 1). Since 9 M HCl was needed to completely dissolve Pd from the cemented Pd, ALi-CY301 was employed for the separation of Pd(II) and Zn(II) from the real HCl leaching solution of the cemented Pd. Two-stages counter-current extraction of the real HCl solution with ALi-CY301 resulted in selective extraction of Pd(II). Pd(II) was effectively stripped from the loaded ALi-CY301 by a mixture of HCl and NaClO. After oxidizing Pd(II) in the stripping solution to Pd(IV) by adding NaClO, Pd(IV) compound was synthesized by adding NH4Cl as a precipitant. By comparing leaching and extraction efficiency between hydrochloric and sulfuric acid solutions, a hydrometallurgical process consisted of HCl leaching, extraction with ALi-CY301 and precipitation with NH4Cl was recommended for the recovery of pure (NH4)2PdCl6 from the cemented Pd. [ABSTRACT FROM AUTHOR]

Spent lithium-ion batteries (LIBs) are good secondary resources for recycle and reuse. To develop a process for the separation of Cu(II), Co(II), Mn(II), Ni(II) and Li(I) with high purity from spent LIBs and circumvent some drawbacks of the previous work, solvent extraction and ion exchange experiments were done in this work. The synthetic hydrochloric acid leaching solution of 3 M was employed. Compared to Aliquat 336 (N-Methyl-N, N, N-trioctyl ammonium chloride), extraction with Cyanex 301 (bis(2,4,4-trimethylpentyl) dithiophosphinic acid) led to selective extraction of Cu(II) over other metal ions. Employing ion exchange with TEVA-SCN resin can completely separate Co(II) over Mn(II). After adjusting the pH of Co(II) free raffinate to 3, Mn(II) was quantitatively extracted by the mixture of Alamine 336 (mixture of tri-octyl/decyl amine) and PC 88A (2-ethylhexyl hydrogen-2-ethylhexylphosphonate) with two stage cross-current extraction. The synthesized ionic liquid (ALi-CY) was used for complete extraction of Ni(II), whereas Li(I) remained in final raffinate. The metal ions in the loaded organic phase were completely stripped with the proper agents (5% aqua regia for Cu(II), 5% NH3 for Co(II), weak H2SO4 solution for Mn(II) and Ni(II) stripping, respectively). The experimental results revealed that purity of the metal ions in stripping solution was higher than 99.9%. A flowsheet was suggested to separate metal ions from the HCl leaching solutions of spent LIBs. [ABSTRACT FROM AUTHOR]

Spent lithium ion batteries contain valuable critical metals such as cobalt, copper, lithium and nickel. In order to develop a process for the separation of the divalent metal ions from spent lithium ion batteries, solvent extraction experiments were performed by employing synthetic hydrochloric acid leaching solution. The synthetic solution contained Cu(II), Co(II), Mn(II) and Ni(II) and its acidity was 3 M HCl. Extraction with Aliquat 336 led to selective extraction of Cu(II) with a small amount of Co(II). After adding NaCl to the Cu(II) free raffinate to enhance the complex formation of Co(II), Co(II) was selectively extracted into Aliquat 336 together with Mn(II). The small amount of Mn(II) in the loaded Aliquat 336 was scrubbed by pure Co(II) solution. After adjusting the pH of the raffinate to 3, 91,3% of Mn(II) was selectively extracted over Ni(II) by the mixture of D2EHPA and Alamine 336. In this extraction, the mole fraction of D2EHPA in the mixture affected the extraction of Mn(II). McCabe-Thiele diagrams for the extraction of Cu(II) and Co(II) were constructed. Batch simulation experiments for the three stage counter-current extraction verified the selective extraction of the target metal ions in each extraction step. Namely, the total extraction percentage of Cu(II) and Co(II) was 71.6% and 98.8% respectively. Most metals in the loaded organic phase were stripped completely with the appropriate agents (1.0 M H2SO4 for Cu(II), 0.1 M H2SO4 for Co(II) and 0.3 M HCl for Mn(II) stripping). A process was proposed to separate the metal ions by solvent extraction. [ABSTRACT FROM AUTHOR]