Polymer inclusion membrane containing a tripodal diglycolamide (T-DGA): Characterization and sorption isotherm studies

Polymer inclusion membranes (PIMs) of the composition, 25.6% T-DGA (tripodal diglycolamide), 53.9% NPOE (2-nitrophenyloctyl ether), and 20.5% CTA (cellulose triacetate) were prepared and characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission infrared mapping microscopy (TIMM) using Fourier transform infrared (FT-IR) spectroscopy. Uptake of Am³⁺ was found to be higher than that of Eu³⁺ and >82% uptake of Am³⁺ was seen with the PIM of the composition mentioned above. The batch sorption study of Eu³⁺ (used as a surrogate of Am³⁺) by this PIM was investigated in 1 M HNO₃ and the data were fitted with different conventional kinetic and isotherm model equations. The sorption followed pseudo-second order (H_o) kinetic model suggesting a two-step uptake process, a fast chemical reaction followed by a slow diffusion process. The experimental data were best fitted with a three-parameter model, i.e., the Redlich-Peterson isotherm model. A comparison is made with results obtained with T2EHDGA-based PIMs reported earlier.