Selective Photocatalytic Oxidation of Ammonia to Nitrogen on Metal/TiO2 in Water
Date Issued
2007
Date
2007
Author(s)
Yang, Chun-Chi
DOI
zh-TW
Abstract
This research is about treating ammonia in water by photocatalysis under UV illumination (λ= 365 nm), and the catalysts used are titanium nanotube and titanium dioxide (TiO2). In order to enhance ammonia oxidation rate and nitrogen yields, some metals such as Pd, Pt, Au, Cu was coated on TiO2 by photodeposition method. Effects of pH value were also tested for the optimal reaction conditions.
The results showed that direct photodegradation of ammonia did not occurr under UV illumination (λ= 365 nm). The amount of ammonia volatilization was 15.9 % and 9.3 % at pH value of 10.5 and 9.5, respectively. The diameter of titanium nanotube varied from 20 to 100 nm, its length was about 276 nm, and thickness was about 10 nm. Through photocatalyzing by titanium nanotube after 24 hours, only 20% of ammonia degraded. However, 95% of ammonia degraded within 14 hours while the catalyst was titanium dioxide. Metal loaded on TiO2, especially Pd, improved effectively the ammonia oxidation rate; more than 99% of ammonia was degraded into nitrate during 7 hours. With the pH value decreasing, the ammonia oxidation rate decreased. Furthermore, the ammonia degradation rate using Au/TiO2 was not affected by the pH. For Cu/TiO2, nitrogen yields raised from 3.3 % to 43.1 %, with the pH value decreased from 10.5 to 8.
Subjects
氨氮
光催化氧化
二氧化鈦
奈米鈦管
披覆型二氧化鈦
ammonia
photocatalysis
titanium nanotube
titanium dioxide
Type
thesis
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