Investigation of solution chemistry effects on sorption behavior of radionuclide 64Cu(II) on illite

In this work, a series of batch experiments were carried out to investigate the effect of various environmental factors such as contact time, pH, ionic strength, coexisting electrolyte ions, humic substances and temperature on the sorption behavior of illite towards Cu-64(II). The results indicated that Cu-64(II) sorption on illite achieved equilibrium quickly. The pH- and ionic strength-dependent sorption suggested that Cu-64(II) sorption on illite was dominated by ion exchange or outer-sphere surface complexation at pH < 7, whereas the pH-dependent and ionic strength-independent sorption indicated that the sorption process was mainly attributed to inner-sphere surface complexation at pH > 7. A positive effect of humic substances on Cu-64(II) sorption was found at pH < 6.5, whereas a negative effect was observed at pH > 6.5. The Langmuir and Freundlich models were used to simulate the sorption isotherms of Cu-64(II) at three different temperatures of 293, 313, and 333 K. The thermodynamic parameters (Delta H (0), Delta S (0), and Delta G (0)) of Cu-64(II) sorption on illite were calculated from the temperature dependent sorption isotherms, and the results indicated that the sorption of Cu-64(II) on illite was endothermic and spontaneous. From the experimental results, it is possible to conclude that illite has good potentialities for cost-effective treatments of Cu-64(II)-contaminated wastewaters.