title: Liquid-liquid extraction of Cd(II) from pure and Ni/Cd acidic chloride media using Cyanex 921: a selective treatment of hazardous leachate of spent Ni-Cd batteries.
abstract: The present paper is focused on solvent extraction of hazardous Cd(II) from acidic chloride media by Cyanex 921, a new extractant mixed with 10% (v/v) TBP in xylene. The optimum conditions for extraction and stripping of Cd(II) were investigated with an aqueous feed of 0.1 mol/L Cd(II) in 2.0 mol/L HCl. McCabe-Thiele diagram was in good agreement with the simulation studies, showing the quantitative extraction (99.9%) of Cd(II) within two counter-current stages utilizing 0.30 mol/L Cyanex 921 at O/A ratio of 3/2 in 10 min. Stoichiometry of the complexes extracted was determined and confirmed by numerical treatment and graphical method, revealing the formation of HCdCl3 · 2L and HCdCl3 · 4L for Cyanex 921(L) concentration in the range 0.03-0.1 mol/L and 0.1-1.0 mol/L, respectively. The thermodynamic parameters for the extraction of cadmium were also determined. The stripping efficiency of cadmium from the loaded organic with 0.10 mol/L HCl was 99.6% in a three-stage counter-current process at an O/A ratio of 2/3. Cyanex 921 was successfully applied for the separation of Cd(II) from Ni(II) in the simulated leach liquor of spent Ni-Cd batteries. The study demonstrates the applicability of the present hydrometallurgical approach for the treatment of hazardous waste, the spent Ni-Cd batteries.
authors: Chungnam National University (CNU), Environmental Engineering, Daejeon 305-764, Republic of Korea; Korea Institute of Geoscience and Mineral Resources (KIGAM), Mineral Resources Research Division, Daejeon 305-350, Republic of Korea.
authors: Seon-Young
authors: SY
authors: Choi
authors: Korea Institute of Geoscience and Mineral Resources (KIGAM), Mineral Resources Research Division, Daejeon 305-350, Republic of Korea; Korea University of Science and Technology (UST), Resources Recycling, Daejeon 305-350, Republic of Korea. Electronic address: writtingtu@gmail.com.
authors: Viet Tu
authors: VT
authors: Nguyen
authors: Korea Institute of Geoscience and Mineral Resources (KIGAM), Mineral Resources Research Division, Daejeon 305-350, Republic of Korea; Korea University of Science and Technology (UST), Resources Recycling, Daejeon 305-350, Republic of Korea. Electronic address: jclee@kigam.re.kr.
authors: Jae-Chun
authors: JC
authors: Lee
authors: Chungnam National University (CNU), Environmental Engineering, Daejeon 305-764, Republic of Korea.
authors: Ho
authors: H
authors: Kang
authors: CSIR - National Metallurgical Laboratory (NML), Metal Extraction & Forming Division, Jamshedpur 831007, India.
authors: B D
authors: BD
authors: Pandey
mesh_terms: D002104:Cadmium / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D011211:Electric Power Supplies; D006863:Hydrogen-Ion Concentration; D059625:Liquid-Liquid Extraction; D009532:Nickel / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods; D014866:Waste Products
chemical_list: D002712:Chlorides; D009943:Organophosphorus Compounds; D014866:Waste Products; D002104:Cadmium; C044965:trioctyl phosphine oxide; D009532:Nickel
keywords: Cyanex 921; Divalent cadmium; Ni–Cd batteries; Recycling; Solvent extraction