Abstract
Photocatalytic treatment process using titanium dioxide for waste water generated by chelatometric titration for determination of water hardness has been studied. Zinc-ethylenediaminetetraacetic acid (EDTA), magnesium-EDTA, and calcium-EDTA complexes in the waste water could be readily degraded with irradiation of high-pressure mercury lamp, black light, and the sunlight, accompanying a decrease of the concentrations of total organic carbon (TOC) and total zinc. As degradation products, iminodiacetate, oxalate, nitrite, and nitrate ions and inorganic carbon were detected. In this process, the separation of the titanium dioxide particles used for the treatment was easy, because the particles sedimented almost completely by standing for a few days after the irradiation. This method proposed here is simple and does not require any special equipments.
