Batch kinetics of ¹³⁴Cs and ^152+154Eu radionuclides onto poly-condensed feldspar and perlite based sorbents

Sorption of fission products onto polycondensed aluminosilicates (PC-AS_(s)) is a relatively recent and gets out the mechanisms by which the formers are trapped. Here, PC feldspar (PC-FD), perlite (PC-PR) and their blend (PC-FDPR) were synthesized by the alkaline activation using Na-/K-silicates at Si-modulus of 1.35. XRD patterns revealed the semi-crystalline natures of sorbents. Na- and K-feldspars were detected in PC-FD while Na-based carbonate crystals were detected in others. Components of the poly(sialate-disiloxo) structure were detected in FT-IR spectra. Thermographs were deconvoluted and the amounts of the sticking and zeolitic water were estimated. Kinetic batches for sorption of ¹³⁴Cs and ^152+154Eu onto the elaborated yields were constructed. Ranking of sorbed amounts (q_e) was varied from ¹³⁴Cs (PC-FDPR>PC-FD>PC-PR) to ^152+154Eu (PC-PR>PC-FD>PC-FDPR). Maximum q_e was recorded at elevated temperature (323 K) to be 4.28 and 1.45 mg/g for ¹³⁴Cs/PC-FDPR and ^152+154Eu/PC-PR, respectively. Along all batches, chemi-sorption mechanism is common denominator. The effective diffusion coefficients (D_i) were in the order of 10^-14 m²/s. Both PC-FD and PC-FDPR recorded greater D_i values of ¹³⁴Cs than ^152+154Eu. The low values of E_a (kJ/mol) reflected the weak adsorbats-adsorbents interactions. While, the high negative values of ∆S^‡ suggested that the studied radionuclides were sorbed in associative reaction mechanism.