Extraction of perrhenate anion from aqueous sulphuric acid medium and its thermodynamics

Aqueous solution was simulated by ammonium perrhenate and sodium sulfate in sulphuric acid system according to waste water from metallurgy process of copper and molybdenum. Molalities of perrhenate after extraction were measured at ionic strength from 0.2 to 2.0 mol kg−1 at temperature range 278.15 K to 303.15 K, using tri-n-octylamine as extractant. Optimization condition of extraction was determined in this sulphuric acid medium. The standard extraction constants K0 at various temperatures were obtained by method of polynomial approximation. Thermodynamic quantities for the extraction process were calculated.