Adsorption characteristics of sericite for cesium ions from an aqueous solution

• Recently, the concern on sequestering of radioactive elements has been increased.
• Sericite was used as a novel adsorbent to remove cesium ions.
• The maximum adsorption capacity of sericite for cesium ions was 6.68 mg/g.
• The adsorption mechanism was ion exchange between cesium ion and hydroxyl groups.
• The adsorption of cesium ions using sericite follows well the pseudo-second-order kinetics.

To efficiently remove cesium ions from aqueous solution, sericite was used as a novel adsorbent. The silanol (SiO2) and aluminol (Al2O3) groups in sericite are likely to play an important role in adsorption process. The maximum adsorption capacity (qm) and adsorption constant (KL) for cesium ions obtained from the Langmuir isotherm model were 6.68 mg/g and 0.227 L/mg, respectively and regression curve fit well with the experimental data as the 0.965 of correlation coefficients (r2). However, when the Freundlich isotherm model was used correlation coefficient (r2) was 0.973. Therefore, it was concluded that Freundlich model fits equilibrium data better than Langmuir model. When the 6.0 g/L of sericie concentration was added to aqueous solution, cesium ions were removed by about 80% and the increase was not happened above 6.0 g/L of sericite concentration any more. The process was determined as exothermic reaction because the removal efficiency of cesium ions decreased as temperature increased. Furthermore, all adsorption was completed in 120 min and comparing the pseudo first and second-order kinetic models indicates that the adsorption of cesium ions using sericite follows well the pseudo-second-order kinetics.