| Title |
TiO2 Reuse and Recovery from the Photocatalytic Oxidation of Cu(2)-EDTA using TiO2/UV-A System |
| Keywords |
Cu(2)-EDTA; Photocatalytic oxidation; PCO; TiO2; Reuse; Recovery |
| Abstract |
TiO₂-catalyst suspensions work efficiently in Photocatalytic oxidation (PCO) for wastewater treatment. Nevertheless, once photocatalysis is completed, separation of the catalyst from solution becomes the main problem. The PCO of Cu(Ⅱ)-EDTA was studied to determine the reusability of the titanium dioxide catalyst. Aqueous solutions of 10^(-4)M Cu(Ⅱ)-EDTA were treated using illuminated TiO₂ particles at pH 6 in a circulating reactor. TiO₂ was reused in PCO system for treatment or Cu(Ⅱ)-EDTA comparing two procedures: reuse of water and TiO₂ and reuse of the entire suspension after PCO of Cu(Ⅱ)-EDTA. The results are as follows; (ⅰ) Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation and filtration, whereas, when TiO₂ is separated from water, the reused TiO₂ is not deactivated. (ⅱ) The TiO₂ mean recovery (%) with reused TiO₂ was 86.4%(1.73g/L). Although the mean initial degradation rate of Cu(Ⅱ)-EDTA and Cu(Ⅱ) was lower than that using fresh TiO₂, there was no significant change in the rate during the course of the three-trial experiment. It is suggested that Cu(Ⅱ)-EDTA could be effectively treated using an recycling procedure of PCO and catalyst recovery. (ⅲ) However, without TiO₂ separation, the loss of efficiency of the PCO in the use of water and TiO₂ due to Cu(Ⅱ), DOC remained from previous degradation and Cu(Ⅱ)-EDTA added to the same suspension was observed after 2 trials, and resulted in the inhibition of the Cu(Ⅱ)-EDTA, Cu(Ⅱ) and DOC destruction. |