대한환경공학회지 (Journal of Korean Society of Environmental Engineers)

  • 제31권10호
  • /
  • Pages.927-932
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  • 2009
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  • 1225-5025(pISSN)
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  • 2383-7810(eISSN)
대한환경공학회 (Korean Society of Environmental Engineers)
권호 표지

나노-$TiO_2$ 입자로 코팅된 다공성 담체의 광촉매 반응에 관한 동력학

Kinetics of Photocatalytic Reactions with Porous Carriers Coated with Nano-$TiO_2$ Particles

  • Park, Seong-Jun (Center for Environmental Biotechnology in Biodesign institute at Arizona State University) ;
  • Rittmann, Bruce E. (Center for Environmental Biotechnology in Biodesign institute at Arizona State University) ;
  • Bae, Woo-Keun (Department of Civil and Environmental Engineering, Hanyang University)
  • 투고 : 2009.08.31
  • 심사 : 2009.09.28
  • 발행 : 2009.10.31
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초록

난분해성 및 독성 폐수 처리는 고급산화 기술과 생물학적 처리가 친화결합(intimate coupling) 을 이룰 때 최적의 효과를 거둘 수 있다. 본 연구에서는 광촉매 산화와 생물학적 처리를 친화결합하도록 고안된 다공성 $TiO_2$ 코팅 담체를 제조하여 광촉매 반응에 관한 동력학 연구를 수행하였다. 저온 sol-gel 코팅법으로 제조된 PVA 재질의 다공성 $TiO_2$ 담체는 UV 조사하에서 methylene blue (MB)를 효율적으로 분해하였다. 시험 농도(최대 100 ${\mu}M$)에서 MB의 흡착속도는 1차반응 (first-order reaction)의 성질을 보였으며, 흡착과 산화를 포함한 총반응속도는 유사 Langmuir 모델로 예측 가능하였다. 이러한 원인은 담체 표면에 MB가 흡착됨에 따라 UV 조사에 의하여 광촉매 반응이 일어날 표면이 줄어들었기 때문인 것으로 판단된다. 다공성 $TiO_2$ 담체의 단위 $TiO_2$ 량당 최대 MB 제거속도는 슬러리 $TiO_2$ 반응기에서 얻은 MB 제거속도보다 4배 더 빨랐다. 본 연구로 인하여 저온 sol-gel 코팅법으로 제조한 PVA 재질 다공성 $TiO_2$ 담체가 성공적인 광분해 반응을 나타내는 것이 확인되었으며, 동 담체에 대한 광촉매 반응의 동력학적 성질이 구명되어, 향후 생물처리를 친화결합 시킬 수 있는 연구 바탕을 확보하였다.

Toxic and recalcitrant organic pollutants in wastewaters can be effectively treated when advanced oxidation and biodegradation are combined, ideally with intimate coupling, in which both processes occur simultaneously in the same system. One means to achieve intimate coupling is to coat nanoscale $TiO_2$ on the outside of macroporous biofilm carriers. This study investigated the kinetics of photocatalysis with $TiO_2$-coated porous carriers. The carriers were made of polyvinyl alcohol (PVA) and coated with $TiO_2$ using a low-temperature sol-gel process. The $TiO_2$-coated carriers catalyzed the oxidation of methylene blue (MB) effectively under irradiation of UV light. The overall reaction rate with adsorption and photolysis saturated at high MB concentration, and approached the adsorption rate, which was first order for all MB concent rations. This result indicates that adsorbed MB may have slowed photocatalysis by blocking active sites for photocatalysis. The overall kinetics could be described by a quasi-Langmuir model. The estimated maximum specific (per unit mass of $TiO_2$) transformation rate of MB by the $TiO_2$-coated carriers was four times larger than that obtained from slurry-$TiO_2$ reactors. This observation demonstrated that the $TiO_2$ present as a coating on the carriers maintained high efficiency for transforming recalcitrant organic matter via photocatalysis. These findings serve as a foundation for advancement of an intimate coupling of photocatalysis to biodegradation.

키워드

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