Adsorption of copper, cobalt, and manganese ions from aqueous solutions using oxidized multi-walled carbon nanotubes

Adsorption of Cu²⁺, Co²⁺, and Mn²⁺ metal ions on oxidized multi-walled carbon nanotubes (O-MWCNTs) was investigated as a function of contact time, pH, sorbent dosage, and initial metal ion concentration. Multi-walled carbon nanotubes (MWCNTs) were oxidized using HNO₃. All the adsorption experiments were conducted by the batch method. Determination of metal ions was performed by the flame atomic absorption spectrometry. The results showed that the amount of metal ions adsorbed strongly depended on pH. The affinity order of the three adsorbed metal ions by O-MWCNTs was Cu2²⁺> Co²⁺ > Mn²⁺.