EXTRACTION BY PHASE SEPARATION WITH MIXED IONIC SOLVENTS - DESCRIPTIVE CHEMISTRY

The extraction of inorganic salts from aqueous solution by organic salts dissolved in toluene has been studied. A typical system is shown by the reaction: [formula omitted] where the barred species are in the organic phase. Using 0.5M alkylammonium carboxylates in toluene, the effectiveness of different amine types as extractants is in the order: quaternary > primary > secondary > tertiary. The effectiveness of organic acids is in the order: carboxylic > alkylphosphoric > arylsulfonic. The order of extraction of inorganic salts by carboxylic acid systems is: Ca2+ > Mg2- > Na+ > K+, and NO3- > Br > Cl- > SO-. Because the equilibrium is readily reversible, the extracted species are stripped from the organic phase simply by contact with water. Since no chemical energy is used, the system functions generally as a separation, rather than a concentration system. In certain cases, however, where a common ion exists in the feed solution, or where a two-temperature cycle is used, a substantial concentration of the extracted species may also be achieved. © 1969, American Chemical Society. All rights reserved.