Although photocatalysis in aqueous TiO2 suspension has widely been applied for removal of micro-contaminants, it still has various drawbacks: attenuation of light intensity in aqueous phase, inhibitory effect of coexisting substances, separation of purified water and catalyst, among others. The authors try to develop a novel rotating advanced oxidation contactor (RAOC) with composite TiO2-Zeolite sheet to overcome such disadvantages of conventional photocatalysis. The TiO2 powder (P25) and high-silica zeolite (HSZ-385) were made into a composite as sheet matrix, and the sheets were fixed to both sides of the stainless steel disk. The disk was mounted on a lab-scale submerged RAOC and rotated slowly. Only the disk surface exposed to air was irradiated with a UV lamp, which could overcome the attenuation of light intensity. The HSZ-385 in the sheet matrix selectively adsorbs hydrophobic micro-contaminants in aqueous phase, and thereafter the adsorbed contaminants are decomposed by photocatalysis on the disk surface exposed to air.     In the present study, the authors targeted sulfamethazine (SMT) for removal. Batch experiments demonstrated that ca. 90% of SMT in distilled water (C0=10mg/L) was removed from aqueous phase within 6 hours. Accumulation of SMT onto the sheet reached its peak at 2 hours, and finally ca. 90% of the initial SMT was decomposed by photocatalysis during 24 hours. The structures of six intermediates were estimated through LC/MS/MS analyses. Some intermediates were initially accumulated onto the sheet, and thereafter they decreased by photocatalysis. On the other hand, intermediates in aqueous phase gradually increased, indicating that more hydrophilic intermediates produced by photocatalysis were desorbed from the sheet and remained in aqueous phase. Finally, 35% of the initial SMT was mineralized by the RAOC during 24 hours. These results demonstrate that the novel RAOC can overcome the drawbacks of the conventional photocatalysis.

Rotating advanced oxidation contactor with composite TiO<sub>2</sub>-zeolite sheet: Removal mechanisms of sulfamethazine and its intermediates

248th National Meeting (2014)

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Rotating advanced oxidation contactor with composite TiO2-zeolite sheet: Removal mechanisms of sulfamethazine and its intermediates

Rotating advanced oxidation contactor with composite TiO₂-zeolite sheet: Removal mechanisms of sulfamethazine and its intermediates