Extraction of Rhenium With Trialkylbenzylammonium Chloride

Abstract In rhenium technology, it is extracted along the way from highly diluted solutions, mainly by extraction with tertiary amines. Salts of quaternary ammonium bases (QAB) are potential extractants for rhenium, but there is a lack of information on the extraction of the metal with QAB salts. The aim of this work was to study the patterns of rhenium extraction with trialkylbenzylammonium chloride (TABAC). The experiments were carried out from model solutions in one stage. The content of metals was controlled from the aqueous phase by the ICP-MS method. The extraction of rhenium by TABAC was studied depending on the pH values of solutions, the nature and concentration of mineral acids, as well as the concentrations of the extractant in the organic and metal in the aqueous phases. Rhenium in a wide range of acidity of the aqueous phase is present in the form of the ReO4- anion, therefore is effectively extracted with TABAC by the anion exchange mechanism. Quantitative recovery (> 99%) is achieved in the pH range 2 - 7, as well as by varying the concentrations of sulfuric and hydrochloric acids from 0.1 to 3.0 M. The recovery of rhenium from nitric acid solutions does not exceed 30%. It has been shown that the extraction ability of TABAC in relation to rhenium is higher than that of the industrial extractant trialkylamine. Based on the study of extraction equilibria, it was established that complexes of the composition [R3R'NH]ReO4 are extracted into the organic phase. The possibility of separating rhenium, molybdenum and tungsten with a TABAC solution in kerosene was studied. Separation coefficients were calculated and it was determined that rhenium can be separated from accompanying metals from solutions with a pH greater than 7, as well as when extracted from hydrochloric and sulfuric acid solutions. It has been established that the separation factors of metals in the extraction with TABAC are higher than in the extraction with trialkylamine. Thus, trialkyl-benzylammonium chloride was considered as a selective rhenium extractant.