Materials Research Meeting 2019
December 10-14, 2019, Yokohama, Japan

Advanced oxidation process for water purification using deep-ultraviolet
light and TiO2 nano composite electrode*Akihiro Okazaki1, Haruo Kuriyama1, Izumi Serizawa1 ,Aiga Hara2 , Yuiri Hirano2, Yukihiro
Nakabayashi2, Nitish Roy2, Norihiro Suzuki2, Chiaki Terashima2, Kazuya Nakata2, Ken-ichi
Katumata2, Akira Fujishima2.
1

ORC Manufacturing, 4896, Tamagawa, Chino, Nagano, Japan, 2 Tokyo University of Science, 2641, Yamasaki ,Noda,Chiba, Japan.
*a-okazaki@orc.co.jp
Keywords: MRM, SDGs, Innovation, water purification,photocatalyst,boron-doped diamond,deep UV(222 nm)
light,electrochemical.
Introduction
Ozone has a strong oxidizing power (oxidation reduction potential : 2.07 eV). Therefore, it is effective insterilization, disinfection and deodorization. Ozone attracts attention as an eco-friendly water processing
technology. However, the oxidizing power of ozone is insufficient for the decomposition of persistent organicsubstances. Therefore, in this study, we focused on the advanced oxidation process to produce a hydroxy radical(oxidation-reduction potential : 2.85 eV), which has a stronger oxidation power, by decomposing ozone andhydrogen peroxide (oxidation-reduction potential 1.77 eV) effectively. We used boron-doped diamond (BDD) as
an electrode to generate ozone. Also, the titanium oxide was added on the BDD electrode and used as aphotocatalyst. We aim at achieving the high-speed, low-cost and eco-friendly water purification by using the fastoxidation of ozone formed from the BDD electrode and the strong oxidation derived from photocatalyst
simultaneously.
Experiment
We fabricated a mesoporous TiO2 thin film on a boron-doped diamond (BDD) layer by a surfactant-assisted
sol-gel method1), in which self-assembled amphiphilic surfactant micelles were used as an organic template.
Scanning electron microscopy revealed uniform mesopores, approximately 20 nm in diameter, that were
hexagonally packed in the TiO2 thin film. Wide-angle X-ray diffraction and Raman spectroscopy clarified thatthe framework was crystallized in the anatase phase. In addition, Current–voltage (I–V) measurements showedrectification features at the TiO2/BDD hetero junction, confirming that a p–n hetero-interface was formed.
Water purification ability, was evaluated from the decomposition of a residual pharmaceutical products(sulfamethoxazole (SMX)), which adversely affects a real aquatic environment. 1.2 mW/cm2 of 222 nm UV light
was irradiated on the photocatalyst (TiO2/BDD), while applying constant current to BDD electrode. We
examined the SMX concentration over time by high performance liquid chromatography (HPLC) measurement.

Results and Discussions
Figure 1. shows the SMX decomposition byphotocatalytic effect and electrochemical effect (redline). As references, result of photocatalytic effect(purple line), electrochemical effect (blue line) andphotolysis (pink line) are also included. Whenelectrochemical effect and photocatalytic effect wereused in combination, the decomposition of SMX wasenhanced. Also, the decomposition of the by-productgenerated by the decomposition of SMX was also
improved these results clarified the combination ofelectrolytic effect, photocatalyst, and ultraviolet lightpromotes the decomposition of not only SMX but also
by-products.
References1) X. Jiang, X. Suzuki et al., Eur. J. Inorg. Chem., 2013,3286 (2013); (b) N. Suzuki et al., Chem. Lett., 44, 656 (2015)

Fig. 1. SMX decomposition by photocatalytic effect (purpleline), electrochemical effect (blue line), photolysis (pinkline) and both (red line).