Solvent Extraction of Lanthanides(III) in the Presence of the Acetate Ion Acting as a Complexing Agent Using Mixtures of Cyanex 272 and Caprylic Acid in Hexane

A new extraction system containing a mixture of Cyanex 272 and caprylic acid is proposed for the extraction and separation of lanthanides(III). It was shown that this system possesses a high level of extraction ability and capacity. The extraction of lanthanides(III) from chloride-acetate and nitrate-acetate media was investigated on an example of La(III). The composition of the extracted species was confirmed, based on the analysis of lanthanum(III) extraction isotherms. In the case of acetic-acetate aqueous solutions, a decrease in lanthanum(III) extraction efficiency was observed, due to the decreasing equilibrium pH of the aqueous phase in accordance with the cation-exchange mechanism. The composition of the synergistic mixture of Cyanex 272-caprylic acid established demonstrates highly efficient separation of rare-earth metal ions.

Solvent Extraction of Didymium by TBP, Aliquat 336 and HDEHP in The Presence of Ca(NO3)2

Three commercially available extractants (tri-butyl-phosphate (TBP), di-(2-ethylhexyl)phosphoric acid (HDEHP) and Aliquat 336 (a mixture of quaternary ammonium bases)) were tested for separation of Pr(III) and Nd(III) in both static and dynamic modes. In the case of HDEHP, phase stability and influence of nitric acid were considered. Extraction isotherms were constructed, and influence of water-soluble complexing agents on the separation factor was investigated for Aliquat 336. In the case of TBP, influence of calcium nitrate in aqueous phase on the extraction efficiency was investigated. Model countercurrent experiments were conducted for TBP and Aliquat 336. It was shown that TBP is the best choice due to its high capacity and cation extraction order (Nd > Pr).

Recovery of Copper, Nickel and Zinc from Sulfate Solutions by Solvent Extraction Using LIX 984N

Recovery of valuable metals such as copper, nickel and zinc from synthetic sulfate solutions using LIX 984N as the extractant dissolved in kerosene was investigated. The metals get extracted at different equilibrium pH of the aqueous phase and thus the pH of the aqueous solutions forms the basis of their separation. Copper was extracted at an equilibrium pH of 3.5, while nickel and zinc get extracted at an equilibrium pH of 7.3 and 8.8 respectively. The extraction isotherms of copper, nickel and zinc were obtained by contacting the respective metal solutions and 0.05 M LIX 984N at different A:O phase ratio at their respective equilibrium pH of maximum extraction. A two-stage counter- current extraction simulation was done to achieve quantitative extraction of the metals. Furthermore, a two-stage counter- current stripping simulation yielded quantitative recovery of the individual metals, from their loaded organic phases. On the basis of the results, a flow sheet of the process has been developed.

Extraction of Tungsten with Trialkylamine - Effect of pH

Extraction equilibrium in the system aqueous solution of sodium tungstate-solution of trialkylamine in a mixed diluent was investigated. A tertiary amine with C7-C9 straight alkyl chains was dissolved in a mixture of tributyl phosphate and kerosene and presaturated with sulfuric acid to give normal trialkylamine sulfate. Extraction isotherms at 25 °C and at several constant values of equilibrium pH were measured in a broad range of aqueous tungstate concentrations. pH 2.0-6.0 was adjusted by addition of sulfuric acid during equilibration. The equilibrium tungstate and sulfate contents in both phases were determined. A typical tungstate isotherm exhibits a steep ascending part in the low concentration range, corresponding to the region of anion exchange, and a flat part in the high concentration range, where the acid content in the organic phase is virtually exhausted. The level of the flat part decreases with growing pH, corresponding to the increasing number of negative charges per tungsten atom in the tungstate polyanions extracted. At pH > 5, also the effect of hydrolysis of amine sulfate could be detected.