Adsorption Of Cs(Ⅰ) And Eu(Ⅲ) On Illite And TiO₂

The adsorption of Cs(â… ) and Eu(â…¢) on illite and anatase was studied by a batch experimental method.The objectives were(1) to collect Cs(â… ),Eu(â…¢) adsorption data on K- and Na-illite and anatase,respectively,over wide experimental conditions,(2) to set up a proper surface complexation model which was capable of quatitative description of the adsorption data and(3) to compare the adsorption of Cs(â… ) on dispersed and compacted K-illite.The anantase was characterized in details by analytical techniques such as X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),partical size analysis and specific surface area analysis.It was found that the TiO₂ specimen was a mixture of anatase(97%) and rutile(3%).The specific surface area of anatase was found to be 10 m²/g.The results by continuous potentiometric titrations at three ionic strengths(0.001,0.01 and 0.1 mol/L NaCl) at 25℃indicated that the point of zero charge(PZC) of the anatase specimen is around pH 6.The titration curves are independent of ionic strength.The results can be modeled by constant capacity model.The adsorption of Eu(â…¢) on the anatase was investigated as functions of pH,Eu(â…¢) concentration,ionic strength and CO₂ partial pressure.It was found that Eu(â…¢) adsorption is significantly affected by both pH and Eu(â…¢) concentration,but independent of ionic strength.A constant capacity model with inner-sphere surface complexes≡SOEu²⁺,≡SOEu(OH)⁺ and≡SOEu(OH)₃^- was used to quantitatively interpret the sorption data.Moreover,the effect of CO₂ on Eu(â…¢) ??rption onto anatase is not obvious.Cs(â… ) adsorption on dispersed and compacted K-illite were investigated as functions of Cs(â… ) concentration,pH and ionic strength by a batch capillary method. It was found that the K_d values were almost same at different pH value.In the dispersed and compacted states,K_d values discrease with increasing ionic strength. There is a desorption hysteresis in dispersed state in comparison with Cs(â… ) adsorption in compacted state.At the same conditions,K_d of Cs(â… ) on Na-illite is higher than that on K-illite.