Aqueous two-phase system of cationic and anionic surfactant mixture and its application to the extraction of porphyrins and metalloporphyrins Original Research Article

Aqueous two-phase system is obtained when a cationic surfactant with bigger alkyl polar head groups such as dodecyltriethylammonium bromide (C12NE) is mixed with an anionic surfactant like sodium dodecyl sulfate (SDS) at certain surfactant concentrations and molar ratios. When C12NE is in excess, the top phase is opalescent and is a surfactant-rich micellar solution, while the bottom phase is transparent and is a dilute micellar solution. Such a new aqueous two-phase separation system is employed in extractive separation practice. Several dyes with different chemical structure like anthraquinone, methyl red and methylene blue partitioned in the two-phase system are investigated. Porphyrin compounds and metalloporphyrins, i.e., hematoporphyrin (hemato), uroporphyrin (uro), Cu-TPPS4 (tetraphenylporphine tetrasulfonic acid), Zn-TPPS4, Cu-T-4(TAP)P (tetrakis(p-trimethylammoniophenyl) porphine), are also extracted with the present two-phase system. It is found that hydrophobic as well as charge interaction between a substance partitioned in the system and the micelles are predominant factors that govern the extraction.