Adsorption and photophysical properties of fluorescent dyes over montmorillonite and saponite modified by surfactant

- Na-Mt and Na-Sap were prepared and exchange with cationic surfactant CTAB.
- The adsorption of Rhodamine, kiton red and sulforhodamine on these materials was studied.
- Whatever the material the fluorescent dyes are not located inside interlamellar space.
- The dyes are released in water as monomer even for the kiton red.

In the present study, the adsorption capacities of two intercalated smectites, CTAB-saponite and CTAB-montmorillonite with a cationic surfactant, were investigated with three fluorescent dyes namely Rhodamine 640 perchlorate rhodamine (Rho), sulforhodamine B (SR) and Kiton red 620 (KR). The adsorption isotherms fit well with the non-linear Langmuir isotherm model and the maximum adsorption capacities of all the composites are determined. The photophysical properties such as anisotropy and fluorescence lifetime of all the fluorescent dyes over the clay materials are determined. The set of experimental data based on X-Ray diffraction (XRD), transmission electron microscopy (TEM), Thermal analysis (TG-DTA) and fluorescence measurements allow highlighting the presence or the absence of interactions between the dyes and the modified clay minerals.