Home – Home – Jornals – Chemistry for Sustainable Development 2021 number 1

The development of new two-phase aqueous systems based on surfactants for extraction requires the identification of patterns of delamination depending on the nature of the surfactant and salting-out agent. The phase equilibria in ternary aqueous delaminating systems containing a cationic surfactant - alkylbenzyldimethylammonium chloride (catamine AB) and an inorganic salting-out agent were studied. Catamine AB forms stratifying systems with chlorides (KCl, NaCl, NH₄Cl, LiCl, CaCl₂), sulphates (K₂SO₄, Na₂SO₄, (NH₄)₂SO₄), nitrates (KNO₃, NH₄NO₃, NaNO₃, Mg(NO₃)₂, LiNO₃, Al(NO₃)₃, Ca(NO₃)₂), as well as with Na₂CO₃, K₂CO₃, KHCO₃, NaBr, KSCN, NH₄F, (NH₄)₂HPO₄ and HNO₃. The influence of the nature of the salting-out agent on the process of system delamination is discussed. The best salting-out agents for catamine AB are nitrates, which have relatively low hydration energy in the series of studied anions. The phase diagram of the water - catamine AB - sodium chloride system was built up. The stratification region exists in a rather wide acidity range up to 2.4 mol/L H₂SO₄ (or HCl), and up to 2.8 mol/L NH₃ (or 4.7 mol/L NaOH). The phases remain transparent at all studied concentrations of inorganic acids and bases. The extraction ability of the water - catamine AB - sodium chloride system was evaluated. Thallium (III) is quantitatively recovered in the range of sulphuric acid concentrations from 0.5 to 2 mol/L. The range of recoverable metals may be expanded by using organic complexing agents. Quantitative extraction of lanthanum (100 μg) is observed in the system containing 2.2 g of surfactant, 2.0 g of the salting-out agent, 1 mL of 0.01 mol/L Arsenazo III solution with a total volume of 15 mL and pH ~8.