Research On Phase Regins And Extraction Of Aqueous Two Phase System In Mixtures Of Anionic And Cationic Surfactants

Effect of addictives on phase behaviors is invested in mixtures of cationic and anionic surfactants system, the system is consists of CetylTrimethyl Ammonium Bromide(CTAB)and Sodium Dodecyl Sulphate(SDS). Some results can help us understand the origin of phase separation in Aqueous Two-Phase System (ATPS). The pseudo ternary phase diagram of the mixtures expresses two narrow phase regions, which represents two kinds of different ATPS systems formed when cationic and anionic surfactants are in excess, respectively (called ASTPc and ASTPa). In the present work, some negative characteristics are always appeared in ATPSa, such as narrow phase region, unstable phase behaviors, influenced easily by temperature. With the help of the study on cationic two-phase region, we look for a way to enlarge the cationic two-phase region.In this paper several addictives are applied to enlarge phase region of ATPSa, such as Na2SO4, sodium salicylate, Glucosamine Hydrochloride,2-Aminopyridine, Chitosan, Cationic Starch, Tetraphenylphosphonium,8-Hydroxyquinoline sulfate. But the phase region of ATPSa was not enlarged by those addictives in mixtures of cationic and anionic surfactants system.From the effect of addictives on ATPSa we learnt that some characters which addictives owned can favorable to form larger aqueous two-phase region. The addictive should have large space volumemany which is caused by many atoms, enormous polarizability and good water solubility. Self-assembled process of addictive is also in favour of formation of ATPSa. Thiamine Hydrochloride meets the above requirements, which enlarge the region of ATPSa effectively. The anionic aqueous two-phase region is widened successfully with stable and durothermic features. When the value of RCTAB closes to 1, the region of ATPSa is the largest in the system of SDS/CTAB/Thiamine Hydrochloride/H2O. Aqueous two-phase system is also easily formed when SDS and Thiamine Hydrochloride mixed properly.Extraction effect by the ATPS is also invested in this paper. some materials are extracted in this system, such as metallic ion(Cu2+, Fe3+), metal complex(Cu-DDTC, [HgBr3]-)and biomacromolecule(BSA). The results show that distribution coefficient of metal complex and biomacromolecule is larger but metallic ion is lower in ATPS. Distribution coefficient is controled by electric property and hydrophobicity of addictives. Distribution coefficient is higher when addictives have hydrophobic nature regardless of positive charge or negative charge which owned. Distribution coefficient show two sides when addictives without hydrophobic characteristics. If the electric property of addictives as the same of aggregates, the distribution coefficient would larger; inverse, the distribution coefficient would lower. There are different extraction powers between ATPSc and ATPSa respectively. The study of extraction is focused on the extraction of Hg2+, extraction power of aqueous two phase systems shows that this system has potential application prospects.