Macroscopic and microscopic investigation on adsorption of Sr(II) on sericite

Effect of water chemistry on adsorption of Sr(II) on sericite was investigated by batch techniques. The batch experiments showed that adsorption of Sr(II) on sericite significantly increased with increasing pH from 2.0 to 7.0, and then the high-level adsorption was observed at pH > 7.0. The Sr(II) adsorption remarkably decreased with increasing ionic strength, indicating that outer-sphere surface complexation dominated the Sr(II) adsorption on sericite. The adsorption kinetics and isotherms of Sr(II) on sericite can be satisfactorily fitted by pseudo-second-order and Langmuir model, respectively. As surface complexation modeling analysis, the adsorption mechanism of Sr(II) on sericite was cation exchange and outer-sphere surface complexation at pH < 4.0 and pH > 5.0, respectively. These findings are crucial for the estimation of radionuclides on clay minerals at sub-environments.