• 유기물자원화
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• 제25권3호
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• pp.5-12
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• 2017

촉매오존화에 의한 메틸렌 블루(MB) 제거특성과 그에 미치는 운전변수의 영향을 관찰하기 위해 회분식 실험을 수행하였다. 촉매오존화에서 오존 분해반응의 촉매로 작용하는 활성탄의 투입량이 증가함에 따라 MB 및 TOC 제거속도가 증가하는 것으로 나타났다. 반응기로 공급되는 가스상 오존의 농도가 증가함에 따라 물질전달이 크게 일어나므로 MB 제거속도를 증가시키는 것으로 나타났다. 촉매오존화에서 오존의 분해에 의해 생성된 $OH{\cdot}$에 의해 MB의 분해가 일어나므로 오존화에 비해 MB의 제거속도가 빠를 뿐 아니라 훨씬 높은 TOC 제거율을 기대할 수 있는 것으로 나타났다. 촉매오존화에서 오염물질 처리는 pH의 변화에 큰 영향을 받지 않는 것으로 나타나 현장 적용시에 있을 수 있는 유입수의 변동에 대한 적용성이 높은 것으로 나타났다. 이러한 결과는 촉매오존화가 섬유산업에서 발생하는 난분해성 폐수를 처리하기 위한 효과적인 대안이 될 수 있음을 보여준다.

• Journal of Applied Biological Chemistry
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• 제49권4호
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• pp.157-161
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• 2006

The performance of abiotic degradation of oxadiazon was investigated by applying zerovalent iron(ZVI), potassium permanganate($KMnO_4$) and titanium dioxide($TiO_2$) in the contaminated water. Experimental conditions allowed the disappearance of oxadiazon in the abiotic system. The degradation of this herbicide was monitored in buffer solutions having pH 3, 5 and 7 in the presence of iron powder in which the maximum degradation rate was achieved at acidic condition(pH 3) by 2% of ZVI treatment. The oxidative degradation of oxadiazon was observed in aqueous solution by $KMnO_4$ at pH 3, 7 and 10 in which the highest disappearance rate was found at neutral pH when treated with 2% of $KMnO_4$. The catalytic degradation of oxadiazon in $TiO_2$ suspension was obtained under dark and UV irradiation conditions. UV irradiation enhanced the degradation of oxadiazon in aquatic system in the presence of $TiO_2$. Conclusively, the remediation strategy using these abiotic reagents could be applied to remove oxadiazon from the contaminated water.

• 약학회지
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• 제30권5호
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• pp.228-231
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• 1986

The effect of temperature and pH on the degrdation of minoxidil in the aqueous solution was investigated and the stability of pharmaceutical preparation for solution was also studied. The degradation of minoxidil in the aqueous solution was first order type reaction and the rate constant at $20^{\circ}C$ in pH 7.0 phosphate buffer solution was 9.464${\times]10^{-3} day^{-1}$ and calculated activation energy was 11.7 kcal/mol. The degradation of minoxidil was acid-base catalytic reaction and the most stable range of pH was about 5.0. The liquid pharmaceutical preparation was very stable in 3 months.

• 산업기술연구
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• 제29권A호
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• pp.89-94
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• 2009

The efficiency of heterogeneous catalysts has been investigated in ozonation process for organic removal. Heterogeneous catalytic ozonation was conducted for the degradation of humic acid in the presence of Granular Activated Carbon or Zeolite as a solid catalyst. And the results were compared to those of ozonation alone and adsorption alone without ozonation. The degradation characteristics of humic acid in each process were examined with the values of pH, TOC, $UV_{254}$ and $COD_{Cr}$.

• 한국세라믹학회지
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• 제52권6호
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• pp.502-507
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• 2015

We examined the photo catalytic activity and catalytic recyclability of CdSe/graphene nanocomposites fabricated via modified hydrothermal technique. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Raman spectroscopic analysis, and X-ray photoelectron spectroscopy (XPS). The photocatalytic behavior was investigated through decomposition of RBB as a standard dye under visible light radiation. Our results indicate that there is significant potential for graphene based semiconductor hybrids materials to be used as photocatalysts under visible light irradiation for the degradation of organic dyes from industry effluents.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권6호
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• pp.422-430
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• 2000

Mechanism of lignin biodegradation caused by basidiomycetes and the history of lignin biodegradation studies were briefly reviewed. The important roles of fungal extracellular ligninolytic enzymes such as lignin and manganese peroxidases (LiP and MnP) were also summarized. These enzymes were unique in their catalytic mechanisms and substrate specificities. Either LiP or MnP system is capable of oxidizing a variety of aromatic substrates via a one-electron oxidation. Extracellular fungal system for aromatic degradation is non-specific, which recently attracts many people working a bioremediation field. On the other hand, an intracellular degradation system for aromatic compounds is rather specific in the fungal cell. Structurally similar compounds were prepared and metabolized, indicating that an intracellular degradation strategy consisted of the cellular systems for substrate recognition and metabolic response. It was assumed that lignin-degrading fungi might be needed to develop multiple metabolic pathways for a variety of aromatic compounds caused by the action of non-specific ligninolytic enzymes on lignin. Our recent results on chemical stress responsible factors analyzed using mRNA differential display techniques were also mentioned.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1214-1218
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• 2005

Ti-HMS samples in which titanium species exist in various forms of isolated tetrahedral state, finely dispersed $TiO_2$ cluster, and some in extra-framework anatase phase were prepared via a direct synthesis route using dodecylamine (DDS) as a structure directing agent by systematically varying the titanium loadings between 2 and 50 mol% Ti/(Ti+Si) in substrate composition. Physicochemical properties of the materials were evaluated using XRD, SEM/TEM, N2 adsorption, UV-vis and XANES spectroscopies. Catalytic properties of Ti-HMS in cyclohexene and 2,6-di-tert-butyl phenol (2,6-DTBP) oxidation using aqueous $H_2O_2$, and vapor phase photocatalytic degradation of acetaldehyde were evaluated. High $H_2O_2$ selectivity was obtained in cyclohexene oxidation, and cyclohexene conversion was found primarily dependent on the amount of tetrahedrally coordinated Ti sites. For bulky 2,6-DTBP oxidation and photocatalytic oxidation of acetaldehyde, on the other hand, conversions were found dependent on the total amount of Ti sites and maintaining an uniform mesoporous structure in the catalysts was not critical for efficient catalysis.

• Environmental Engineering Research
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• 제24권4호
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• pp.711-717
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• 2019

The application of advanced oxidation for the treatment of oil refinery wastewater under UV radiation by using nanoparticles of titanium dioxide was investigated. Synthetic wastewater prepared from phenol crystals; Power Glide SAE40 motor vehicle oil and water was used. Response surface methodology (RSM) based on the Box-Behnken design was employed to design the experimental runs, optimize and study the interaction effects of the operating parameters including catalyst concentration, run time and airflow rate to maximize the degradation of oil (SOG) and phenol. The analysis of variance and the response models developed were used to evaluate the data obtained at a 95% confidence level. The use of the RSM demonstrated the graphical relationship that exists between individual factors and their interactive effects on the response, as compared to the one factor at time approach. The obtained optimum conditions of photocatalytic degradation are the catalyst concentration of 2 g/L, the run time of 30 min and the airflow rate of 1.04 L/min. Under the optimum conditions, a 68% desirability performance was obtained, representing 81% and 66% of SOG and phenol degradability, respectively. Thus, the hydrocarbon oils were readily degradable, while the phenols were more resistant to photocatalytic degradation.

• 한국재료학회지
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• 제24권1호
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• pp.6-12
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• 2014

In the present work, $WO_3$ and $WO_3-TiO_2$ were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of $WO_3-TiO_2$ sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the $WO_3-TiO_2$ composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a $WO_3$ coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing $TiO_2$ response to ultrasonic radiations. In case of the addition of $WO_3$ as new matter, the excited electrons from the $WO_3$ particles are quickly transferred to $TiO_2$ particle, as the conduction band of $WO_3$ is 0.74 eV which is -0.5 eV more than that of $TiO_2$. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of $TiO_2$ nanoparticles was improved by loading $WO_3$.

• Korean Chemical Engineering Research
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• 제61권4호
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• pp.591-597
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• 2023

Pakistan depends heavily on imports for its fuel requirements. In this experiment, catalytic pyrolysis of a blend of feedstock's consisting of date seed, wheat straw, and corn cob was conducted in a fixed bed reactor to produce oil that can be used as an alternative fuel. The main focus was to emphasize the outcome of important variables on the produced oil. The effects of operating conditions on the yield of bio-oil were studied by changing temperature (350-500 ℃), heating rate (10, 15, 20 ℃/min), and particle size (1, 2, 3 mm). Moreover, ZnO was used as a catalyst in the process. First, the thermal degradation of the feedstock was investigated by TGA and DTG analysis at 10 ℃/min of different particle sizes of 1, 2, and 3mm from a temperature range of 0 to 1000 ℃. The optimum temperature was found to be 450 ℃ for maximum degradation, and the oil yield was indicated to be around 37%. It was deduced from the experiment that the maximum production of bio-oil was 32.21% at a temperature of 450 ℃, a particle size of 1mm, and a heating rate of 15 ℃/min. When using the catalyst under the same operating conditions, the bio-oil production increased to 41.05%. The heating value of the produced oil was 22 MJ/kg compared to low-quality biodiesel oil, which could be used as a fuel.