Pd/TiO2 광촉매를 이용한 폐수중의 NO3- 제거

최경희; 김서경; 전민수; 신형식; 양오봉; Kyoung Hee Choi; Seo-Kyung Kim; Min-Seo Cheon; Hyung-Sik Shin; O-Bong Yang

Journal of the Korean Industrial and Engineering Chemistry, Vol.14, No.6, 714-720, October, 2003

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Pd/TiO₂ 광촉매를 이용한 폐수중의 NO₃^- 제거

Removal of NO₃^- in the Waste by Pd/TiO₂ Photocatalyst

최경희, 김서경, 전민수, 신형식 , 양오봉 ^†

전북대학교 환경및화학공학부/첨단방사선응용연구센터, 전북 561-756

Kyoung Hee Choi, Seo-Kyung Kim, Min-Seo Cheon, Hyung-Sik Shin , and O-Bong Yang^†

School of Environmental and Chemical Engineering/Center fro Advanced Radiation Technology, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea

E-mail:

초록

졸-겔법에 의하여 제조된 TiO₂와 Pd가 담지된 Pd/TiO₂ 광촉매를 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 Pd를 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.

The removal of NO₃^- from waste water was studied in a batch system under ultra-violet (UV) irradiation, using TiO₂ and Pd/TiO₂ 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 (FT-IR) and specific surface area measurement (BET). The TiO₂ photocatalyst calcined at 750 ℃, which had mainly rutile structure and less amount of OH group, has shown a superior NO₃^- removal efficiency. Also, the photocatalytic decomposition of NO₃^- was enhanced significantly using Pd/TiO₂ which was prepared by impregnating Pd as the reducing metal. These results would suggest that the removal of NO₃^-, 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 NO₃^- was improved significantly with addition of an additive, in the following decreasing order: methanol > ethanol > phenol > propanol. The optimal reaction conditions for the removal of NO₃^- were as following: the ratio of methanol to NO₃^- was 2.0, 3 g catalyst per liter of waste water, and 0.5 wt% Pd loading on TiO₂. 75% of NO₃^- was reduced completely to N₂ gas over Pd/TiO₂, indicating the superior reducing power of Pd/TiO₂ in comparison with naked TiO₂ that showed only 35% of NO₃^- reduced to N₂ gas.

Keywords:NO₃^-;photocatalyst;Pd/TiO₂;nitrogen compound;TiO₂

[References]

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Fanning JC, Coordination Chem. Rev., 199, 159 (2000)
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Kutty TR, Ahuja S, Mater. Res. Bull., 30(2), 233 (1995)
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Beydoun D, Tse H, J. Mol. Catal. A-Chem., 177, 265 (2002)
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김복현, 오양환, 수질환경오염시험법, 동화출판사 (2001)
Fujii H, Ohtaki M, J. Mol. Catal. A-Chem., 129, 61 (1998)
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Ranjit KT, Viswanathan B, J. Photochem. Photobiol. A-Chem., 108, 79 (1997)
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Hermann JM, Guillqard C, Pichat P, Catal. Today, 17, 7 (1993)
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Sanchez E, Lopez T, Mater. Lett., 25, 271 (1995)
Lee BM, Shin DY, J. Korean Ceram. Soc., 37, 308 (2000)

[Related Articles]

[1] Mori T, Suzuki J, Fujimoto K, Watanabe M, Hasegawa Y, Appl. Catal. B: Environ., 23(4), 283 (1999)

[2] Fanning JC, Coordination Chem. Rev., 199, 159 (2000)

[3] Chen J, Ollis FD, Water Res., 33, 5 (1999)

[4] Kutty TR, Ahuja S, Mater. Res. Bull., 30(2), 233 (1995)

[5] Tang Z, Huang CP, Chemosphere, 30, 7 (1995)

[6] Navio JA, Colon G, Trillas M, Peral J, Domenech X, Testa JJ, Padron J, Rodriguez D, Litter MI, Appl. Catal. B: Environ., 16(2), 187 (1998)

[7] Navio JA, Colon G, Macias M, Real C, Litter MI, Appl. Catal. A: Gen., 177(1), 111 (1999)

[8] Beydoun D, Tse H, J. Mol. Catal. A-Chem., 177, 265 (2002)

[9] Arana J, Diaz OG, Saracho MM, Rodriguez JMD, Melian JAH, Pena JP, Appl. Catal. B: Environ., 36(2), 113 (2002)

[10] 김복현, 오양환, 수질환경오염시험법, 동화출판사 (2001)

[11] Fujii H, Ohtaki M, J. Mol. Catal. A-Chem., 129, 61 (1998)

[12] Suresh C, Biju V, Polyhedron, 17, 3131 (1998)

[13] Lee HI, J. Korean Chem. Soc., 41, 12 (1997)

[14] Ranjit KT, Varadarajan TK, J. Photochem. Photobiol. A-Chem., 107, 215 (1997)

[15] Ranjit KT, Viswanathan B, J. Photochem. Photobiol. A-Chem., 108, 73 (1997)

[16] Ranjit KT, Viswanathan B, J. Photochem. Photobiol. A-Chem., 108, 79 (1997)

[17] Gesenhues U, J. Photochem. Photobiol. A-Chem., 139, 243 (2001)

[18] Hermann JM, Guillqard C, Pichat P, Catal. Today, 17, 7 (1993)

[19] Turch CS, Ollis DF, J. Catal., 122, 178 (1990)

[20] Sanchez E, Lopez T, Mater. Lett., 25, 271 (1995)

[21] Lee BM, Shin DY, J. Korean Ceram. Soc., 37, 308 (2000)