Study On The Adsorption Of Cobalt (Ⅱ), Nickel (Ⅱ) And Copper (Ⅱ) On GMZ Bentonite

It is a basic characteristic of radioactive waste that many radionuclides (or elements) coexist. The adsorption of single adsorbate, coexisting two and three adsorbates on the Na-bentonite was studied as a function of pH, adsorbate concentration, ionic strength and the presence of citrate by a batch adsorption method. The present thesis deals with the competition adsorption of cobalt(Ⅱ), nickel(Ⅱ) and copper(Ⅱ) on a bentonite from Gaomiaozi, inner-Mongolia, China (GZM bentonite).It was found that pH significantly affected the adsorption of cobalt(Ⅱ), nickel(Ⅱ) and copper(Ⅱ) on the Na-bentonite, The adsorption percentage increased with increasing pH up to 100%; The adsorption decreased with increasing ionic strength in the low pH range, whereas the adsorption was not obviously affected in the high pH range; A negative effect of CA on the adsorption of cobalt(Ⅱ), nickel(Ⅱ) and copper(Ⅱ) on the Na-bentonite was observed; The adsorption of nickel(Ⅱ) and cobalt(Ⅱ) were strongly influenced by the competition of the other two metal cations in the multiple adsorbates systems at pH 6.5±0.1, whereas the adsorption of copper(Ⅱ) was not affected by nickel(Ⅱ) and cobalt(Ⅱ) at pH 6.5±0.1; The adsorption affinity of the Na-bentonite for the three cations followed the order of copper(Ⅱ)>nickel(ll)>cobalt(Ⅱ); The main adsorption mechanisms for cobalt(Ⅱ), nickel(Ⅱ) and copper(Ⅱ) on the Na-bentonite were cation exchange and surface complexation.