In the present work, immobilization of humic acid on bentonite and its application as an adsorbent of Cs137 (Cesium) and Am241 (Americium) is performed. The parameters studied are rate constant, adsorption capacity, and adsorption energy. This research started with the immobilization of humic acid on a bentonite surface followed by a stability test for immobilization of humic acid at various acidities. Adsorption of Cs 137 and AM 241 ions was conducted by first examining the optimum pH giving

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... nimum complexed ions by the soluble fraction of humic acid and maximum adsorbed ions on the adsorbent. While adsorption energy and capacity were determined by the Langmuir isotherm adsorption model. The result shows that the amount of immobilization of humic acid on bentonite is 39.75 % (w/w) at optimum conditions. Immobilization of humic acid was stable up to pH 12.0. For both ions, optimum adsorption occurred at pH 5. At this optimum condition, the adsorption energies of 21.481 kJ.mol-1 and 22.276 kJ.mol-1 for Cs173 and Am241 are obtained, respectively. The result also shows that adsorption capacity and energy for Am241 were higher than that for Cs137 which indicates the affinity of Am241 for both adsorbents was higher than that of Cs137.