The removal of NO? from waste water was studied in a batch system under ultra-violet (UV) irradiation, using TiO_(2) and Pd/TiO_(2) photocatalysts that were prepared by sol-gel method. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FR-IR) and specific surface area measurement (BET). The TiO_(2) photocatalyst calcined at 750 ℃, which had mainly rutile structure and less amount of OH group, has shown a superior NO_(3)^(-) removal efficiency. Also, the photocatalytic decomposition of NO_(3)^(-) was enhanced significantly using Pd/TiO_(2), which was prepared by impregnating Pd as the reducing metal. These results would suggest that the removal of NO_(1), which is reduction reaction, may be improved by increasing the amount of Pd as the reducing metal and by decreasing the amount of anatase phase and OH group as the oxidizing agents. The removal efficiency of NO_(3)^(-) was improved significantly with addition of an additive, in the following decreasing order: methanol > ethanol > phenol. The optimal reaction conditions for the removal of NO_(3)^(-) were as following: the ratio of methanol to NO_(3)^(-) was 2.0, 3 g catalyst per liter of waste water, and 0.5 wt% Pd loading on TiO_(3) 75% of NO_(3) was reduced completely to N_(2) gas over Pd/TiO_(2) indicating the superior reducing power of Pd/TiO_(2) in comparison with naked TiO_(2) that showed only 35% of NO_(3) reduced to N_(2) gas.

졸-겔법에 의하여 제조된 TiO₂와 Pd가 담지된 Pd/TiO₂광촉매를 이용한 폐수중의 NO₃^(-)제거에 관한 연구로 UV 조사 하에 회분식 반응장치에서 진행하였다. 제조된 촉매들은 X-선회절기(X-ray diffraction, XRD), 적외선분광기(Fourier transform infrared spectroscopy, FT-IR), 전자현미경(scanning electron microscopy, SEM)과 비표면적(BET)으로 특성화하였다. 루타일 구조를 가지고 표면에 OH group의 양이 적은 750℃에서 소성시킨 TiO₂가 NO₃^(-)제거율이 우수하였다. 또한 TiO₂에 Pd를 담지한 Pd/TiO₂ 경우 NO₃^(-)제거율이 크게 향상되었다. 이것은 NO₃^(-)제거가 환원 반응이기 때문에 환원성금속인 Pd을 도입하고 아나타제와 OH group이 적을수록 환원 반응에 유리하기 때문으로 설명할 수 있다. 반응에 희생시약을 첨가하면 NO₃^(-) 제거능이 크게 향상되었으며, 메탄올 > 에탄올 > 페놀 > 프로판올의 순서로 NO₃^(-)의 제거율을 향상시켰다. 최적의 NO₃^(-) 제거율을 보이는 실험조건은 메탄올 : NO₃^(-)의 비가 2:1일 때, 폐수 리터당 촉매 3 g을 사용하였을 때, Pd의 담지량이 0.5 wt%일 때이었다. Pd/TiO₂는 NO₃^(-)의 75% 이상이 N₂로 완전 환원되는데 비하여 TiO₂는 35%만이 N₂로 완전환원되는 생성물 분포를 보여 Pd/TiO₂의 우수한 환원성을 확인할 수 있었다.