Complexation and sorption studies of Co(II) with γ-alumina-bound fulvic acid: effect of pH, ionic strength, fulvic acid and alumina concentration

The removal of heavy metal ion Co(II) from aqueous solution is studied using c-Al2O3 by batch technique. The experiments are performed at T = 20 +/- 2 degrees C, in 0.01 M NaNO3 solutions and under aerobic conditions. The effect of pH, ionic strength, fulvic acid (FA) and alumina concentration on the sorption of Co(II) on alumina are also respectively investigated. The pH affects the sorption of Co(II) significantly as compared with the effect of FA and ionic strength. The results indicate that strong chemical bonds are formed between Co(II) and the bare or FA coated alumina surface, and a transition from the adsorption to surface-induced precipitation of Co(II) on alumina surface takes place. The addition sequences of Co/FA on Co(II) sorption is also studied and the results indicate that the sorption of Co(II) in ternary system is independent of addition sequences. The results also suggest that the sorption of metal ions on mineral surface depends on the nature of mineral, nature of organic ligand and nature of metal ion.