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거의 모든 정수장에서 탁도를 제거하기 위해 응집, 침전공정을 행한다. 정수 처리과정에서 황산알루미늄(Alum)과 폴리염화알루미늄(PAC)과 같은 응집제를 사용하여 잔류알루미늄농도가 증가하는 것으로 알려졌다. 따라서 Jar-test를 사용하여 응집에 영향을 미치는 여러 요인들 중 잔류탁도와 잔류알루미늄농도를 최소화 할 수 있는 최적조건을 찾고자 하였다. 그 결과는 다음과 같다. Alum과 PAC 20∼30㎎/ℓ범위에서 잔류알루미늄농도는 0.128∼0.178㎎/ℓ 검출되어, 처리수의 잔류알루미늄농도 감소를 위해서는 응집제의 최적 주입률 결정이 중요한 것으로 나타났다. Almost the purification plants are accomplished coagulation sedimentation for removing the turbidity. It has been known that the concentration of residual aluminum increases during the purification treatment due to aluminum sulfate and poly aluminum chloride, which are being used as a coagulant. We intended to find the optimal condition to minimize the concentration of residual turbidity and aluminum using jar-test with the various condition affecting the coagulation. The results were as follows. The residual aluminum concentration is detected 0.128㎎/ℓ∼0.178㎎/ℓ at the range of 20∼30㎎/ℓ for Alum and PAC. Thus, it is important that the optimal dosage of coagulant can be decided to decrease the concetration of residual aluminum in purified water.
The hydrocracking and hydroisomerization of n-heptane were studied over Ru/La-Y based catalysts, and as an experimental apparatus a Catatest minipilot licensed by IFP was used in this study. The effect off chlorine adsorption on the catalyst surface was observed by using lwt% methylene chloride, the reactional optimum concentration of additive. The activity of each catalyst was enhanced by more than 50% over its initial activity and the secondary splitting was also greatly increased. The increase of Lewis acidity by chlorine adsorption on the catalyst increased the selectivity of hydrocracking, in addition, the Bro^¨nsted acidity increased the selectivity of isomerization. Through an experiment on the deactivation of catalysts, it was confirmed that coke formation on the catalyst surface and sintering of active sites deactivated the catalysts. In a study of the turnover number of each catalyst used in hydrocracking, it was revealed that all of the reactions were structure-sensitive.
The hydrocracking and hydroisomerization of n-heptane were studied over Ru/La-Y based catalysts, and as an experimental apparatus a Catatest minipilot licensed by IFP was used in this study. Co and Ni were used as promoters and methylene chloride was used as an additive, so the effects of promoters impregnated into the prepared catalyst and of an additive were observed. A kinetic analysis of hydrocracking by the LHHW model indicated that the reaction orders were between 0.8 and 1 with respect to the partical pressure of n-haptane and were between -0.5 and -0.8 with respect to the partial pressure of hydrogen and the activation energies were between 10 and 40 kcal/g-mol. And the heats of adsorption of n-haptane and hydrogen were calculated.
표면적 증가시키고, 보다 작은 입자 크기와 적절한 band gap 에너지를 갖도록 이온교환법과 졸-겔법을 이용하여 TiO_2를 기조로한 광촉매를 제조하였다. 제조된 촉매는 UV-DRS, XRD, XRF, Particle Size analyzer(Laser), B.E.T surface area analyzer 등을 이용하여 band gap energy, structure, 입자크기, 조성등 물성 측정을 하였다. 침전법을 이용하여 sol상의 nano-sized TiO_2 based photocatalyst를 제조할 수 있었으며, 이는 같은 방법으로 제조된 powder 촉매보다 활성이 크게 향상되었으며, 이는 quantum yield가 증가되어 활성이 증가되는 것으로 해석된다. 한편 Bentonite를 기조로 한 이온교환 법에 의하여 제조된 TiO_2/Bentonite 광촉매는 표면적을 5배 이상 증가시킬 수 있었고, 침전법에 의하여 제조된 촉매와 근사한 3.0 eV이내로 band gap 에너지를 낮출 수 있지만, 촉매활성도는 sol 촉매보다 낮게 나타났다. 본 연구에서 제조된 모든 TiO_2촉매는 모두 anatase 구조를 갖고 있었고, 본 실험 조건에서는 다른 구조를 발견할 수 없었다. Photocatalysts based on titania were prepared through a ion-exchange method and sol-gel methods in order to increase their surface area, decrease the particle size and to produce the desired band-gap energy. TiO_2/Bentonite photocatalysts were prepared by ion-exchange method with TiCl_4 solution and sol-gel method were employed to prepare nanometer-sized sol and dried particle catalysts. They were characterized with UV-DRS, XRD, XRF, Particle size analyzer(Laser), B.E.T. Surface area analyzer. The sol-phase nanometer-sized TiO_2 based catalyst has highest external surface area and smallest crystallite size of anatase, and exhibited the highest photocatalytic activity for the decomposition of 2-propanol. And it had the similar band-gap energy of below 3.0eV as the catalyst by the precipitation method. Also all TiO_2 catalysts prepared in this study had no other structure than the anatase structure on the experimental conditions. HTsol-15 had the highest activity in this experiments, constant reaction rate in the reaction conditions and no deactivation.