Sorption of Am（III） on Na-bentonite： Effect of pH, ionic strength, temperature and humic acid

Sorption of Am（III） on Na-bentonite as a function of contact time, pH, ionic strength, humic acid （HA） and temperature was investigated under ambient conditions. The results showed that the sorption was strongly dependent on pH and ionic strength. Am（III） sorption Can be described well by pseudo-second-order model. The presence of HA takes a positive effect at low pH; but a negative influence under high pH range. Enthalpy, entropy and Gibbs free energy （i.e., △H0, △S0 and △G0） calculated from sorption isotherms suggested that sorption process of Am（III） was spontaneous and endothermic.