Biphasic Water Systems Based on Alkylbenzyldimethylammonium Chloride and Inorganic Salting-out Agents

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)(2)SO4), 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)(2)HPO4 and HNO 3 . 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 mu g) 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 similar to 8.