Hiromichi Yamada

Solvent effects on extraction of copper with capric acid

Abstract Extracation of copper(II) with capric acid in several inert solvents was carried out at 25°C and at aqueous ionic strength of 0.1 M(NaClO4). Organic solvents used are n-hexane, cyclohexane, carbon tetrachloride, toluene, benzene, chlorobenzene, 1,2-dichloroethane. In these solvents dimeric copper caprate being responsible for the extraction, the extraction equilbrium is written as: 2 Cu 2 + 3( HR ) 2,0 ⇌ ( CuR 2 HR ) 2,0 + 4H + . The following extraction constants were obtained: logKex = −11.88±0.03 for n-hexane, −11.67±0.03 for cyclohexane, −11.61±0.03 for carbon tetrachloride, −11.57±0.03 for toluene, −11.36±0.03 for benzene, −11.30±0.03 for chlorobenzene and −11.10±0.03 for 1,2-dichloroethane. The extraction constant has been related with the solubility parameter of the solvents.

Solvent Extraction of Metal Carboxylates

Publisher Summary This chapter presents a study on solvent extraction of metal carboxylates. Carboxylic acids are conveniently utilized in the extraction of a number of metal ions. In the early 1950s, there were several procedures proposed, involving carboxylic acids for separation of metals such as copper and beryllium. The carboxylate extraction system has been recognized as more advantageous than the chelate extraction system because one can deal with more concentrated metal solutions in the former than in the latter. Thus, the application of the carboxylate extraction to hydrometallurgy has been attempted, and in this connection extensive studies have been carried out in the Soviet Union and the United Kingdom. The polymerization of metal carboxylates is characterized either by the liberation of free carboxylic acid or by the formation of hydroxo or oxo bridges. Recently, attention has been drawn to the extraction of heteropolynuclear metal carboxylates. The solvent effect on the extraction and dimerization of copper(II) decanoate has been interpreted according to regular solution theory.

Extraction of Cu(II) with decanoic acid into 1-octanol

Abstract Extraction of Cu(II) with decanoic acid in 1-octanol was carried out at 25°C and aqueous ionic strength of 0.1 mol dm−3 (NaClO4). Monomeric and dimeric copper decanoates are responsible for the extraction at a total copper concentration of 5×10−3 mol dm−3 and decanoic acid concentration of 0.5–2.0 mol dm−3. Species involved in the organic phase are CuA2, CuA2HA, Cu2A4 and Cu2A4(HA)2. Adduct formation and dimerization of copper decanoates in the 1-octanol phase can be formulated as: CuA 2 +HA ⇌ K ad, monomer CuA 2 HA CuA 2 +2HA ⇌ β ad, dimer CuA 4 (HA) 2 2 CuA 2 ⇌ K dim−t CuA 4 2 CuA 2 HA ⇌ K dim−2 CuA 4 (HA) 2 with log KPrmad, monomer=−0.24±0.04, logβad, dimer=−0.41±0.04, logKdim-1=3.46±0.06 and Kdim-2=3.53±0.06, respectively.

Extraction of scandium with capric acid

Abstract Partition of indium was carried out at 25°C between water and benzene containing capric acid, the total concentration of indium and that of capric acid being 5 × 10−3 M and 0·25–1·25 M respectively. Monomeric, trimeric and hexameric indium caprates are responsible for the extraction. The compositions of these species are InR33HR, (InR3HR)3 and (InR2(OH))6 and the corresponding extraction equilibria are written as: In 3+ + 3(HR) 2,0 ⇌ K ex(monomer) InR 3 3HR 0 + 3H + 3In 3+ + 6(HR) 2,0 ⇌ K ex(monomer) InR 3 3HR 3,0 + 9H + 6In 3+ + 6(HR) 2,0 ⇌ K ex(monomer) InR 2 ( OH ) 6,0 + 18H + where the subscript o refers to the organic phase. The following extraction constants were obtained: log Kex(monomer) = −7·34±0·05, log Kex(trimer) = −18·6 ± 0·2 and log Kex(hexamer) = −36·1±0·2. Trimerization and hexamerization in the organic phase can be formulated as: 3In R 3+ 3(HR) ⇌ K trim (InR 3 HR) 3 + 3(HR) 2 6In R 3+ 3(HR)+6 H 2 O ⇌ K hexam (InR 2 ))OH 6 + 12(HR) 2 with the equilibrium constants of log Ktrim = 3·4 ± 0·4 and log Khexam = 7·9 ± 0·5 respectively.

Properties of α-bromovaleric acid as extracting agent for copper(II)

Abstract Copper(II) was extracted with α-bromovaleric acid in benzene from 0.1 mol dm −3 (Na, H)ClO 4 aqueous solution at 25°C. The acid dissociation constant of the extracting agent was determined to be K a = 10 −2.79 in aqueous solution at 25°C. The partition constant of the acid (HA) between the aqueous phase and benzene, and the dimerization constant of the acid in benzene were evaluated to be 2.6 and 56 in molarity, respectively. The dimeric copper(II) α-bromovalerate is responsible for the extraction: 2Cu 2+ +3(HA) 2, o ⇌ K ex Cu 2 A 4 (HA) 2, o +4H 3 O + , (subscript o = organic phase) with log K ex = −7.87. The complex formation of cupric ion with the acid anion observed in the aqueous phase was taken into consideration for calculation of the extraction constant. It was proved that the formation of dimeric copper(II) species is not prevented by the bromine at the α-position in the valeric acid.