Removal Of Toxic Metals In Wastewater By Photocatalytic Method

Endang Tri Wahyuni(*), Nurul Hidayat Aprilita, Husnul Hatimah, Afifah Maya Wulandari, and Mudasir

Chemistry Department, Faculty of Mathematic and Natural Sciences, GadjahMadaUniversity
Sekip Utara POB Bls 21 Yogyakarta Indonesia
(*) e-mail : endtriw@yahoo.com

Abstract

The removal of toxic metal ions including Cu(II), Cd(II), Cr(VI), and Pb(II) from the solution has been systematically studied by using photocatalytic method with TiO2photocatalyst. In this study, the influence of Cr(VI), Cd(II), and Pb(II) on the photoreduction of Cu(II) in the solution was evaluated. The research results indicate that the removal of Cu(II) and Cr(VI), Cd(II), and Pb(II) in the single solution can be successfully achieved by photocatalytic reduction, adsorption on TiO2 photocatalyst, as well as photocatalytic oxidation, respectively. It is interesting to note that TiO2 can act simultaneously as photocatalyst both for photoreduction, i.e. by releasing electrons and for photooxidation by providing positip radicals as OHradicals, as well as behaves as an adsorbent by utilizing its active sites. The removal of the metal ions was controlled by solution pH, and the most effective removal for all metal ions was reached at pH 5. It is also found that the presence of Cr(VI) with various concentration and pH leads to a decrease in the Cu(II) photocatalytic reduction due to the competition in the reduction between Cr(VI) and Cu(II). Meanwhile, the improvement of the Cu(II) photoreduction was observed when Pb(II) is present in the solution, because Pb(II) can be oxidized to Pb(IV) so that it gives synergic effect on the Cu(II) photoreduction. Moreover, the presence of Cd(II) can slightly decrease the effectiveness of the Cu(II) photoreduction due to adsorption competition in the surface of TiO2.

Keywords : Toxic metals, photocatalytic, TiO2, reduction

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