본 연구에서는 예혼합 평면 화염 에어로졸 반응기를 이용하여 응집체의 형상전개에 관한 실험적 연구가 수행되었다. SiCl4 및 TiCl4를 주어진 화염온도에서 각 물질의 화학반응속도 차이를 이용하여 확산제한적인 경우와 반응제한적인 경우에 대해 SiO2 및 TiO2 입자의 형상전개과정을 이해하는 것이 본 연구의 목적이다. 입자형상 관찰 및 측정을 위해 열영동채취법을 이용한 전자현미경 관찰 및 광산란 측정법이 사용되었다. 주어진 반응기 내 온도에서 반응초기 이외는 반응속도 상수가 매우 낮은 SiCl4의 경우, 전자현미경을 이용해 반응기내 위치에 따라 SiO2 응집체 형성과정을 관찰함으로써 확산응집이 응집체 형성의 주요 기작으로 작용됨을 확인했다. 반면 반응후기까지 반응속도 상수가 높게 유지되는 TiCl4의 경우 TiO2 응집체 형성에 있어서 반응제한적 입자성장에 해당됨을 확인했다. 광산란 실험결과 SiO2 및 TiO2 응집체의 프랙탈 차원은 1.23-1.84, 2.81-2.94로 각각 측정되었는데 이는 현미경 사진 결과와 일치한다. 본 연구에서 제조된 TiO2 입자의 광촉매로서의 활용가능성을 조사하기 위해 XRD분석을 수행한 결과, 광화학적 활성이 높은 anatase 성분이 주성분임이 측정되었다.

Using a premixed flat flame aerosol reactor, the experimental study on the morphological evolution of the aggregates was done. With the objectives to understand the morphological process of SiO2 and TiO2 particle that matches to the cases of the reaction-limited aggregation process and the diffusion-limited aggregation process respectively, the difference in chemical reaction rate of SiCl4 and TiCl4 was utilized under given flame temperatures. To evaluate the morphological evolution of the aggregates, the light scattering measurement and electron microscopy coupled with thermophoretic sampling method were used. In the case of SiCl4 oxidation that produces SiO2 particles, the microscopic observation obtained with respect to the axial position in the reactor showed that the diffusion-limited aggregation was the dominant mechanism in the aggregation process because that the very low reaction rates was maintained excepted the earlier reaction stage in the given reactor temperature profile. In the case of TiCl4 that maintains the higher reaction rate during the later reaction stage, it was observed that the reaction-limited aggregation process is the main mechanism on the aggregation. According to the results of the light scattering measurements, the fractal dimension of SiO2 and TiO2 aggregates was 1.23-1.84 and 2.81-2.94 respectively, and those results are corresponds with the photometric measurement. To observe applicability of TiO2 particles as photocatalyst, XRD analysis was conducted. TiO2 particles were generated in our study consisted of anatase mainly that has high photochemical activity.

Morphology Aggregation Light Scattering Chemical Reaction Rate Diffusion-limited Reaction-limited

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