Liquid extraction of rhenium(VII) and molybdenum(VI) with trialkylphosphine oxide from acidic solutions

The liquid extraction of rhenium(VII) and molybdenum(VI) ions from sulfuric, hydrochloric, and nitric acid media is studied in the temperature range from 20 to 40°C using trialkylphosphine oxide in kerosene as an extracting agent. The maximum separation of these metals is attained when they are extracted from solutions of 1.0–2.0 M H₂SO₄ (the duration of intense phase mixing was 3–5 min). The enthalpy of the studied process is estimated to be ΔH = ?32.32 kJ/mol for molybdenum and ?51.52 kJ/mol for rhenium. The chemical aspects of the extraction process studied are discussed.