In this study, the removal of radionuclide 60Co(II) from wastewater by Ca-rectorite was studied as a function of various environmental parameters such as contact time,
pH, ionic strength, coexisting electrolyte ions, humic substances (HS) and temperature under ambient conditions. The results
indicated that the sorption of Co(II) on Ca-rectorite was strongly dependent on pH and ionic strength. The Langmuir and Freundlich
models were used to simulate the sorption isotherms of Co(II) at three different temperatures of 298.15, 318.15 and 338.15 K.
The thermodynamic parameters (
) calculated from the temperature-dependent sorption isotherms indicated that the sorption process of Co(II) on Ca-rectorite
was spontaneous and endothermic. At low pH, the sorption of Co(II) was dominated by outer-sphere surface complexation and
ion exchange with Ca+/H+ on Ca-rectorite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the
experimental results, it is possible to conclude that Ca-rectorite has good potentialities for cost-effective disposal of
radiocobalt bearing wastewaters.