| Summary: | The influences of Pb(II) and Cd(II) ions with variation of concentration
and pH on the photoreduction of Hg(II) ion photocatalyzed by TiO2 have been
studied. The photoreduction process was carried out by irradiating a mixture of
Hg(II) ion solution and TiO2 photocatalyst powder with or without Pb(II) and
Cd(II) ions in a closed reactor equipped with UV lamp and under continous
stirring. The effectiveness of the photoreduced Hg(II) ion in the solution was
calculated by substracting the initial Hg(II) concentration by the unreduced
concentration after the photoreduction process. The unreduced Hg(II) ion
concentration was determined by Cold Vapor Atomic Absorption
Spectrophotometric method (CV-AAS).
The results of the research showed the effectiveness of Hg(II) ion
photoreduction catalyzed by TiO2 improves with the increasing Pb(II) ion because
of sinergy effect in the solution. On the other hand, the effectiveness of Hg(II) ion
photoreduction decreases by increasing amount of Cd(II) ion because of
competition in adsorption. Increasing pH 1 to 4 in the presence of Pb(II) ion can
improve Hg(II) ion photoreduction, meanwhile the addition of Cd(II) ion causes
the decrease in the Hg(II) ion photoreduction. When the pH was further increased
from 4 to 9, the addition of both metal ions, causes the decrease of Hg(II) ion
photoreduction. The presence of both metal ions give no effect on Hg(II) ion
photoreduction for solution with pH higher than 9. The crystallinity of TiO2
decreased after it is used as photocatalyst in Hg(II) ion photoreduction in the
presence of Pb(II) or Cd(II) ions.
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