Decontaminating liquid-containing Cs-137 by natural Pumice stone

Radionuclides, emanating as consequential by-products of nuclear operations, are recognized as a potent source of environmentally deleterious contamination. In light of these concerns, the present investigation has employed unmodified natural pumice within a batch process to effectuate the removal of Cs-137 radionuclides from real liquid radioactive wastes (RLRWs). The discernment of optimal adsorption parameters encompassed a pH level of 5, a pumice dosage of 3.33 g/L, a mixing duration of 5 min, a mixing speed of 100 revolutions per minute, all maintained at room temperature. The attainment of a peak removal efficiency of 91.75% for Cs-137 substantiates the efficacy of the chosen conditions. Moreover, the determination of regression coefficients (R²) arising from the application of Freundlich and Langmuir isotherm analyses yielded values of 0.91 and 0.96, respectively, thus validating the appropriateness of both models in depicting the adsorption mechanism. Evidently, the pseudo-second-order kinetic model exhibited a high correlation coefficient of 0.99, attesting to its aptitude in characterizing the adsorption dynamics. A thermodynamic appraisal of the process indicated an endothermic nature, offering insights into the fundamental energetics governing the interaction. Consequently, the adsorption phenomenon unfolded predominantly on monolayer, heterogeneous surfaces, with chemical interactions taking precedence on the active pumice sites.