Activated Carbon Adsorption of Copper

Effect of pH and Surface Oxygen Groups on the Adsorption of Cu(ll) Ions 

Source Adapted from Biniak, S., Pakula, M., Syzmanski, G., and Swiatkowski, A., Langmuir, 15, 6117, 1999. With permission. 

The oxidized activated carbon sample showed a jump in adsorption in the pH range 1 to 3, which indicated that the point of zero charge of the oxidized carbon sample lies between pH 1 and 3, which was in agreement with the smdies of Radovic and coworkers.It appears that at low pH values there is electrostatic repulsion between Cu(II) ions and the positively charged surface of oxidized carbon. As the pH increases, the hydrogen ions from the carbon surface are replaced by cations and the Cu(II) ion adsorption increases rapidly. The adsorption of Cu ions is, therefore, influenced principally by the presence of surface functional groups. In order to determine the state of the adsorbed copper species, XPS studies of some carbon species were carried out before and after adsorption of copper ions. On the 

In the case of oxidized activated carbon samples (D-O sample), the carbon-oxygen surface function groups play a dominant role. These functional groups undergo surface ionization and ion-exchange reactions between the H+ on the carbon surface and Cu + ions in the solution. 

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