Solution chemistry effects on sorption behavior of radionuclide 63Ni(II) in illite-water suspensions

In this work a naturally occurring like was characterized by using FTIR and XRD to determine its chemical constituents and crystal structure A series of batch experiments were carried out to investigate the effect of various environmental factors such as contact time pH ionic strength foreign ions coexisting humic substances and temperature on the sorption behavior of illite towards radionuclide Ni-63(II) The sorption of Ni-63(II) on illite was strongly dependent on pH and ionic strength A positive effect of HA/FA on Ni-63(II) sorption was found at pH <6 5 whereas a negative effect was observed at pH > 6 5 The Langmuir Freundlich and D-R models were used to simulate the sorption isotherms of Ni-63(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 Ni-63(II) sorption on illite were calculated from the temperature dependent sorption isotherms and the results indicated that the sorption of Ni-63(II) on illite was endothermic and spontaneous At low pH the sorption of Ni-63(II) was dominated by outer-sphere surface complexation and ion exchange with Na+/H+ on Mite surfaces whereas inner-sphere surface complexation was the main sorption mechanism at high pH From the experimental results It is possible to conclude that illite has good potentialities for cost-effective treatments of Ni-63(II)-contaminated wastewaters (C) 2010 Elsevier BV All rights reserved