Treatment of wastewater containing Cu(II)-EDTA using immobilized TiO₂/solar light

Abstract

The photocatalytic oxidation (PCO) of Cu(II)-ethylene diamine tetra-acetic acid (EDTA), employing immobilized TiO₂, under natural sunlight rather than artificial UV light conditions, was investigated at a latitude 38°. The immobilized TiO₂ film was prepared using a sol gel process, the crystalline structure of which was identified, by X-ray diffraction analysis, as a mixture of the rutile and anatase forms. The PCO of Cu(II)-EDTA was examined in a circulating reactor with 20 L of 10^{− 4} M Cu(II)-EDTA and synthetic and real wastewaters at pH 4 and 6.5, respectively. The removals of both Cu(II) and DOC were initially relatively rapid, but slowed as the reaction proceeded and generally followed first-order kinetics. The rate constants for the removal of Cu(II) and DOC were 1.1 × 10^{− 3} and 1.6 × 10^{− 3} min^{− 1}, respectively. The efficiency of the PCO in the decomplexation of Cu(II)-EDTA increased with increasing H₂O₂ dose using both the synthetic and real wastewaters. Therefore, we suggest the PCO process using the solar/immobilized TiO₂ system, with addition of H₂O₂ as well as filtration for the removal of suspended solids, can be effectively applied to the treatment of Cu(II)-EDTA containing real wastewater.

Keywords:

• Cu(II)-EDTA
• photocatalysis
• solar light
• TiO₂

Acknowledgments

This work was partly supported by grant No. (R-01-2002-000-00305-0) from the Basic Research Program of the Korea Science & Engineering Foundation, and partly supported by the RRC program of Ministry of Commerce, Industry and Energy.