This study investigates the extraction of rhenium using trialkylbenzyl ammonium chloride (TABAC) as an alternative to trialkylamine (TAA) for recovering rhenium from highly diluted solutions. Rhenium, present as ReO₄⁻ over a wide acidity range, was extracted via an anion exchange mechanism in single-stage experiments monitored by inductively coupled plasma mass spectrometry (ICP-MS). Key variables, including pH, acid concentration, and the concentrations of extractant and metal, were examined. The results demonstrated a high extraction efficiency exceeding 99% within a pH range of 2 to 7 and from solutions containing sulfuric or hydrochloric acid at concentrations of 0.1 to 3.0 M (mol/L). However, extraction from nitric acid solutions was less efficient, with less than 30% recovery. Performance for both TAA-kerosene and TABAC-kerosene followed the order H₂SO₄ > HCl > HNO₃. The optimal TABAC concentration was 10⁻² M (mol/L) in kerosene. TABAC also showed higher selectivity than TAA, with separation coefficients Re/Mo = 66.8 and Re/W = 55.8 in 0.1–1.0 M (mol/L) sulfuric acid. Based on equilibrium studies, the complexes formed during extraction were identified as [R₃R′NH]ReO₄. This approach may offer environmentally friendly and cost-effective benefits for large-scale industrial applications, enabling efficient recovery of valuable rhenium while reducing waste and environmental impact.

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.

Extraction technology plays a key role in the industrial production of rhenium, accounting for more than 70% of the world's production of this element. In aqueous and alkaline solutions, rhenium is present in the form of the anion ReO4 - , which necessitates the use of anion exchange extractants based on tertiary amines. Despite the widespread application and many years of research on rhenium extraction with amines, the obtained data remain contradictory. The extraction of rhenium from aqueous solutions by an amine extractant occurs through an anion exchange mechanism with the formation of the complex TAAHReO4. To increase the solubility of amine salts in the organic phase, high-molecular-weight aliphatic alcohols, such as decyl alcohol, are added, which act as modifiers of the organic phase without extracting rhenium themselves. The aim of this work is to investigate the extraction of rhenium with trialkylamine from a model solution that simulates the composition of nitrate desorbate obtained from the processing of uranium ores. Specifically, various factors affecting the extraction and reextraction of rhenium are studied to determine the optimal parameters of these processes. The study uses trialkylamine as the extractant and decyl alcohol as the modifying additive. The results of the study show that the optimal parameters for rhenium extraction are: an extractant concentration of TAA:DA:kerosene=40:5:55 (% by volume), an organic to aqueous phase ratio of V_org/aq = 1:5, an extraction time of 5 minutes, and a rhenium extraction rate of up to 75%. Similar results were obtained with an extractant concentration of TAA:DA:kerosene = 30:10:60 and an extraction time of 5 minutes, where the rhenium extraction rate was about 74%. The re-extraction of rhenium is most efficiently carried out using an ammonia solution with a concentration of 114 g/L NH3⋅H2O and a phase contact time of 10 minutes, with a re-extraction rate of 85.5%. Similar results were obtained with the addition of 174 g/L (NH4)2SO4, where the rhenium re-extraction rate was 82%.