adsorption of fluorescein on zr-pillared montmorillonite clays: studied by time-resolved fluorescence spectroscopy

In the present study, the adsorption capacities of two intercalated smectites, na+-pmt and ca2+-pmt with the zr pillar were investigated on fluorescent dye adsorption. the modified clay sample was characterized in detail using x-ray diffraction (xrd), and fourier transform infrared spectroscopy (ft-ir). the values of interlayer spacing are similar about 16 å for all samples. the adsorption isotherms fit well with the non-linear langmuir isotherm model and the maximum adsorption capacities of all materials are determined. for all samples interlayer spacing after interactions between the dye and the modified clay are similar about 18 å as measured by x-ray diffraction. the pillar improves the adoption capacity to wards fluorescein due to its location inside interlayer space. interestingly, the time-resolved fluorescence shows that the dye is not released in solution as is the case for the pristine clay.