Adsorption of uranyl(II) into modified lamellar Na-Kanemite

The Na-Kanemite sample was used for organofunctionalization process with N-propyldiethylenetrimethoxysilane and 3-aminopropyltriethoxysilane, after expanding the interlayer distance with polar organic solvents such as dimethyl sulfoxide (DMSO). The new organofunctionalized matrix was characterized by carbon nuclear magnetic resonance in the solid state SEM and chemical analysis. The resulted material was submitted to the process of adsorption with uranyl(II) at pH 2.0 and 298 ± 1 K. The Langmuir adsorption isotherm model has been to fit the experimental data with regression non-linear; the net thermal effects obtained from calorimetric titration measurements were adjusted to a modified Langmuir equation. The adsorption process was exothermic (ΔH = −7.14 to −5.98 kJ mol−1) accompanied by an increase in entropy (ΔS = 52.28–62.12 J K−1 mol−1) and Gibbs energy (ΔG = −22.62 to −24.44 kJ mol−1). The favorable values corroborate with the uranyl(II)/basic reactive centres interaction at the solid/liquid interface in the spontaneous process for the new nanomaterials.

Graphical abstractThe aim of the present investigation is to explore the performance of a synthetic Na-Kanemite in unmodified and chemically modified form in adsorption process. This matrix was obtained through innovator synthetic process with low temperature; the chemical modification process was developed with organofunctionalization with N-propyldiethylenetrimethoxysilane and 3-aminopropyltriethoxysilane [12]. The resulted matrix was characterized by 13C MAS/NMR, SEM and chemical analysis [13], the anchoring of alkylsilyl group in lamellar structure is proved with the spectrum of modified matrix. The unmodified and chemically modified matrices were used for uranyl cation adsorption process investigated at pH 2.0 and temperature at 298 ± 1 K. The energetic effect caused by uranyl(II)/nitrogen basic centre on Na-Kanemite interaction at the solid/liquid interface was determined through calorimetric titration procedure.Figure optionsDownload full-size imageDownload as PowerPoint slide