Complexation Reaction Of The Rare Earth Spectral Probe The Role Of Micellar Catalysis Field

In the present work, we applied the microphase adsorption - spectral correction technique (MPASC) to study the reactions between three ligands (L) and rare earths (REs) in the presence of the cationic surfactant, cetyltrimethylammonium bromide (CTAB).Three dyes, picramine CA (PCA), naphthochrome green G (NCG) and 1,5-bis (2-hydroxyl-5-chlorphenyl)-3-cyanoformazan (HCPCF) were used as spectral probe ligands. The binary and ternary reactions were not only characterized also the synergistic mechanism of CTAB was analyzed. The formation constants of the binary and ternary complexes such as binding constants (K), the composition ratio (N) were determined by MPASC. Results have shown that N to L to CTAB is 1 or 2 and that of to L to RE is between 1 and 5 and Ks of the L-RE complexes are between 1.0 X 105 and 2.3 X 107. We observed that the aggregation of L on CTAB all obeyed the Langmuir isothermal adsorption. By investigating the variation of N with temperature and ionic strength, Not L to CTAB always decreased with increase of temperature and enhancement of ionic strength. These are attributed to the fact that an increase of temperature will accelerate the desorption of L binding on CTAB and the electrostatic surface of CTAB will be occupied competitively by plenty of CI". Besides, the spectral shifts between L and the L-CTAB complex is lessthan 50 nm. Therefore, the binding between L and CTAB is always weak. Thus, we thought that the interaction of L with CTAB is attributed to the electrostatic attraction not the covalent bond.By investigating the L-RE complexations in CTAB micelle medium, the results have shown that the CTAB micelle provided a catalysis field so as to sensitize the complexation between RE and L. Because the L enriching on CTAB micelle is much higher than that in aqueous phase, the RE - L complexation becomes sensitive and rapid.The present work provided complex chemistry and separation technology with a simple and useful study approach in the presence of surfactant. It will still helpful for us to further investigate trace analysis and industrial application of surfactant.