抄録
Cadmium(II) ions uptake by some chemically different surface activated carbons (ACs) were investigated to find out parameters to optimize the adsorption operation in aqueous solutions. The activated carbons were coal based ACs de-ashed by sequential treatments of HCl and H2F2, the de-ashed AC treated with nitric acid to introduce acidic functional groups on the surface, and contrarily out-gassed at 1000°C in helium flow to eliminate these groups. The pH alternation before and after adsorption revealed that the ion exchange between the Cd2+ species and the surface carboxylic acid was taken place for the oxidized AC, whereas the electrostatic interaction between cadmium(II) ions and Cπ electrons on the graphene layer was valid for AC possessing a little or no C-O complexes. Based on the changes in the shapes of adsorption isotherms for some pH ranges, Cd(OH)+ rather than Cd2+ is considered to be preferable adsorption species onto the acidic oxygen free out-gassed AC surfaces.
