Separation and Purification Technology 62 (2008) 596–601 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur Solvent extraction of Cu(I) from waste etch chloride solution using tri-butyl phosphate (TBP) diluted in 1-octanol J.-c. Lee a,∗ , T. Zhu b , M.K. Jha a , S.-k. Kim a , K.-k. Yoo a , J. Jeong a a Minerals & Materials Processing Division, Korea Institute of Geoscience & Mineral Resources (KIGAM), 30 Gajeong-dong, Yuseong-gu, Daejeon 305-350, South Korea b Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China article info Article history: Received 31 October 2007 Received in revised form 3 February 2008 Accepted 12 March 2008 Keywords: Solvent extraction Cuprous Tri-butyl phosphate 1-Octanol Etch waste abstract Cuprous ion has wide applications in various industries due to its properties to form stable coordination compound of high solubility with different ligands. Compared to extensive R&D work on solvent extraction of cupric ion, the limited work is reported on cuprous ion extraction using organic extractant. Therefore, in the present work, solvent extraction studies have been carried out for the extraction of cuprous ion Cu(I) from chloride solution using extractant tri-butyl phosphate (TBP) diluted in 1-octanol, for application to recover Cu(I) from the etch waste of printed circuit boards (PCBs). Initially, the studies were carried out for the selection of suitable diluent to be used for Cu(I) extraction from chloride solution. The organic 1-octanol was found effective diluent for TBP. The behavior and reaction mechanism of TBP diluted in 1-octanol was also studied for the extraction of Cu(I) from chloride solution. Various process parameters viz. contact time, concentration of chloride ion, hydrochloric acid and extractant, temperature, etc., were also studied. The extractant TBP diluted in 1-octanol was found suitable for the extraction of Cu(I) from the waste chloride solution (containing both Cu(I) and Cu(II)) generated from the plant of PCBs manufacturing. The extraction isotherm plot indicates the requirement of two stages for the complete extraction of Cu(I). The studies revealed the formation of complex [CuCl 2 - ·H + ·TBP] in the organic phase. The extraction and stripping studies showed the suitability of the TBP diluted in 1-octanol for the recovery of cuprous ion from the waste chloride etch solution of PCBs. © 2008 Elsevier B.V. All rights reserved. 1. Introduction In electronics industries, copper is extensively used as engineer- ing material for the fabrication of micro-electronic components, micro-engineered structures and precision parts. Copper etching is considerably important process for getting smooth surface, par- ticularly in the fabrication of printed circuit boards (PCBs). Due to high etching capacity and easy regeneration properties, the cupric chloride is an acceptable etchant in these industries. In PCBs man- ufacturing industries, solution composed of cupric chloride and hydrochloric acid is used as an etchant to oxidize and dissolve metallic copper, which results in the generation of a large amount of waste solution containing cupric and cuprous ions. The concen- trations of etch solution depends on the etching medium and the material to be leached. Etch waste effluent generally contains high copper contents (40–60 g/L Cu) in comparison to the etch wash liquor (2–10g/L Cu). In addition to etching, the waste solutions containing copper are also being generated through pickling and ∗ Corresponding author. Tel.: +82 42 868 3613; fax: +82 42 868 3705. E-mail address: jclee@kigam.re.kr (J.-c. Lee). electroplating processes. The acidic effluents thus generated are normally treated with lime to neutralize, but it consumes acid and produces sludge of mixed metal hydroxides. Cementation or electrolytic recovery of copper from etch waste is not advisable in respect to purity of copper recovered [1]. There- fore, the separation of copper by solvent extraction is attractive. Many researchers worked for the solvent extraction of Cu(II) from different solutions. Fletcher et al. [2] used pyridine dicarboxylate esters instead of amines to create a copper-selective extraction system. The chelating component of the extractant mixture was LIX 860. This extractant was selective for copper under condi- tions of medium acidity (H + < 1 M), where the solvation mechanism operates. Mishonov and Kyuchoukov [3] used a mixed extractant, comprising of Alamine 336 and LIX 54, to separate copper and zinc from hydrochloric acid. They reported that the metal ions were extracted from hydrochloric acid medium; the extract was scrubbed in two steps, whereas zinc passed from Alamine 336 to LIX 54, in order to remove copper and chloride ions. In the CUPREX process Dalton et al. [4] suggested to oxidize copper to Cu(II) in the leached solution and then to extract with DS5443. Zhou et al. [5] studied the co-extraction of Cu 2+ and Fe 2+ with quaternary ammo- nium chloride. The redox reaction occurred between Cu 2+ and Fe 2+ 1383-5866/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2008.03.007