80
4 Investigation into the Adsorption of Cadmium and Lead …
4.8.2 Outcome of pH Investigation
It can be seen from Fig. 4.1, that the percentage of metal ion loss rises with increment
in pH to a limit of pH 6 for Cd(II) and pH 5 for Pb(II) and subsequently decreases
with more pH increase. At lower pH levels, hydrogen ions will penetrate the GXCS
surface allowing decreased adsorption sites with metal ions to deal with. Raising the
pH of the solutions contributes to a reduction in the rivalry of hydrogen ions with
metal ions for adsorption sites, thereby allowing the elimination of higher proportion
Fig. 4.1 a Influence of pH on cadmium and lead elimination (conditions: 2.5 g/L GXCS; contact
time: 120 min; temperature: 25 °C), b influence of point of zero charge
4 Investigation into the Adsorption of Cadmium and Lead …
4.8.2 Outcome of pH Investigation
It can be seen from Fig. 4.1, that the percentage of metal ion loss rises with increment
in pH to a limit of pH 6 for Cd(II) and pH 5 for Pb(II) and subsequently decreases
with more pH increase. At lower pH levels, hydrogen ions will penetrate the GXCS
surface allowing decreased adsorption sites with metal ions to deal with. Raising the
pH of the solutions contributes to a reduction in the rivalry of hydrogen ions with
metal ions for adsorption sites, thereby allowing the elimination of higher proportion
Fig. 4.1 a Influence of pH on cadmium and lead elimination (conditions: 2.5 g/L GXCS; contact
time: 120 min; temperature: 25 °C), b influence of point of zero charge