• Environmental Engineering Research
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• 제25권3호
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• pp.316-323
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• 2020

The degradation of aqueous oxytetracycline (OTC) from an aqueous solution antibiotic using H₂O₂/Fe²⁺ process was studied in one 1 L batch chemical reactor. The extent of OTC degradation (20 mg/L) was investigated from a known initial pH solution, temperature and the type of catalyst (Fe²⁺, Fe³⁺) and for various initial concentrations of OTC, H₂O₂ and Fe²⁺. The degradation efficiency achieved was found to be very important (90.82% and 90.63%) at initial pH solution of 3 and 4, respectively. However, the type of catalyst and the reaction temperature had a slight impact on the final degradation of OTC. The results showed that the OTC removal increased with increasing initial H₂O₂ concentration in the range of 70 to 150 mg/L and initial Fe²⁺ concentrations in the range of 2 to 5 mg/L. The highest degradation efficiency obtained at ambient temperature was 90.95% with initial concentration of OTC of 10 mg/L, H₂O₂ = 150 mg/L and Fe²⁺ = 5 mg/L. Moreover, biodegradability improved from 0.04 to 0.36 and chemical oxygen demand degradation was 78.35% after 60 min of treatment. This study proved that Fenton process can be used for pretreatment of wastewater contaminated by OTC before a biological treatment.

• 공업화학
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• 제34권6호
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• pp.649-659
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• 2023

This study was initiated to evaluate the phosphorus (P) removal and diesel oil degradation by bacteria isolated from industrial wastewater. The bacteria isolated were identified as Bacillus sp. The P removal efficiencies by Bacillus sp. were 99% at the initial 20 mg/L P concentration. The diesel degradation efficiencies by Bacillus sp. were 86.4% at an initial 1% diesel concentration. Lipophilicity by bacteria was the highest in the log phase, whereas it was the lowest in the death phase. As the diesel was used as a carbon source, P removal efficiencies by Bacillus sp. were 68%. When glucose, acetate, and a mixture of glucose and acetate as second carbon sources were added, the diesel degradation efficiencies were 69.22%, 65.46%, and 51.46%, respectively. The diesel degradation efficiency was higher in the individual additions of glucose or acetate than in the mixture of glucose and acetate. When P concentration increased from 20 mg/L to 30 mg/L, the diesel degradation efficiency was increased by 7% from 65% to 72%, whereas when P concentration was increased from 30 mg/L to 40 mg/L, there was no increase in diesel degradation. One of the five proteins identified by proteome analysis in the 0.5% diesel-treated samples may be involved in alkane degradation and is known as the cytochrome P450 system. Also, two of the sixteen proteins identified in the 1.5% diesel-treated samples may be implicated in the fatty acid transport system and alcohol dehydrogenation.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권4호
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• pp.356-363
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• 2016

Purpose: The purpose of this study is to propose efficiency of equipment testing the luminance degradation of OLED. Methods: The degradation model of Exponential model and Stretched exponential model is analyzed by goodness of fit test using calculated R-square. The degradation model having the higher R-square is finally selected. Scale parameter and Shape parameter using the selected degradation model is estimated. The activation energy and current density n using peck model among the accelerated model is estimated. the estimated parameters are analyzed by t-test. Results: The results of t-test show that the estimated parameters on chamber and hotplate are equal statistically. we can know the similarity of the luminance degradation rate and degradation pattern on chamber and hotplate. Conclusion: The result of the degradation test on chamber and hotplate is similar. when the accelerated degradation test on the panel of the OLED TV is performed, hotplate is requiring less samples, time and cost than chamber. so the accelerated degradation test on the panel of the OLED TV using the hoplate is efficient of time and cost.

• 대한환경공학회지
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• 제37권12호
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• pp.705-711
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• 2015

습식산화법으로 합성한 Ferrate(VI)를 적용하여 2,6-Dichlorophenol의 분해 연구를 하였다. 최적의 분해 조건을 찾기 위해 영향인자로 pH(산성, 염기성, 중성), DCP의 초기 농도, ferrate 주입 농도, 수용액의 온도를 두어 실험하였다. Ferrate(VI)는 강력한 산화력과 선택성이 있으며, 무해한 최종산물인 Fe(III)을 만들어 유용한 성질을 가지고 있다. Ferrate 이온은 산성과 중성 조건에서 재빠르게 Fe(III)으로 환원한다. 본 실험 결과로 DCP의 분해율은 산성과 염기성 조건보다 중성 조건에서 좋은 것으로 나타났다. ferrate 주입 농도와 DCP의 초기 농도에 따라 영향을 강하게 받는다. ferrate의 주입 농도가 증가할수록 또한 DCP의 초기 농도가 감소할수록 DCP의 분해율이 좋게 나타났다. 수용액의 온도는 10, 25, 35, $50^{\circ}C$에서 실험을 진행하였다. 최적의 조건은 $25^{\circ}C$로 나타났으며, $25^{\circ}C$에서 $50^{\circ}C$까지의 범위에서는 증가할수록 효율이 감소하는 것으로 나타났다. DCP의 중간생성물 연구는 GC/MS를 통해 실험하였다.

• 한국환경농학회지
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• 제39권1호
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• pp.58-64
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• 2020

BACKGROUND: Most of the researches on the dye removal using ozonation have been focused on the removal efficiency. However, the research on their removal characteristics and mechanism according to the reaction time has been still insufficient. METHODS AND RESULTS: In this study, the effects of initial pH and dye concentration with reaction time on the degradation characteristics of methyl orange (MO) and methylene blue (MB) by ozonation were evaluated. The degradation efficiency of MB by ozonation increased with increasing pH. On the other hand, the degradation efficiency of MO by ozonation did not show a significant difference with varing pH. The both MO and MB by ozonation were decomposed within 30 min irrespective of the dye concentration, but the decomposition rates of dyes were faster at lower initial dye concentration. The decomposition efficiency of total organic carbon (TOC) in each dye solution by ozonation was low, which was found to be effective for partial decomposition such as decolorization rather than complete degradation of the dye. CONCLUSION: Overall, ozonation was an effective method for removing nondegradable dyes. However, it is necessary to study the optimization of dye degradation under various environmental conditions for ozonation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권1호
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• pp.34-39
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• 2005

Trichloroethylene (TCE) is an environmental contaminant provoking genetic mutation and damages to liver and central nerve system even at low concentrations. A practical scheme is reported using toluene as a primary substrate to revitalize the biofilter column for an extended period of TCE degradation. The rate of trichloroethylene (TCE) degradation by Pseudomonas putida F1 at $25^{\circ}C$ decreased exponentially with time, without toluene feeding to a biofilter column ($11\;cm\;I.D.{\times}95\;cm$ height). The rate of decrease was 2.5 times faster at a TCE concentration of $970\;{\mu}g/L$ compared to a TCE concentration of $110\;{\mu}g/L$. The TCE itself was not toxic to the cells, but the metabolic intermediates of the TCE degradation were apparently responsible for the decrease in the TCE degradation rate. A short-term (2 h) supply of toluene ($2,200\;{\mu}g/L$) at an empty bed residence time (EBRT) of 6.4 min recovered the relative column activity by $43\%$ when the TCE removal efficiency at the time of toluene feeding was $58\%$. The recovery of the TCE removal efficiency increased at higher incoming toluene concentrations and longer toluene supply durations according to the Monod type of kinetic expressions. A longer duration ($1.4{\sim}2.4$ times) of toluene supply increased the recovery of the TCE removal efficiency by $20\%$ for the same toluene load.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1266-1267
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• 2011

We studied the influence of cathode material on the stability of organic phtovoltaics (OPVs). OPVs with LiF/Al and Ag/Ca/Ag cathode were fabricated and the stability were evaluated. The sample with LiF/Al cathode showed efficiency degradation from 2.42% to 2.04% during 50 days. On the other hand, the sample with Ag/Ca/Ag cathode showed more steeper efficiency degradation from 2.38% to 0.80% during 50 days. The different of degradation can be attributed to a larger increase of series resistance ($R_s$) in Ag/Ca/Ag cathode sample.

• 한국세라믹학회지
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• 제54권3호
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• pp.205-210
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• 2017

In this study, we examined the photo-degradation efficiency of $CoSe_2$-Graphene-$TiO_2$ ($CoSe_2-G-TiO_2$) nanocomposites under visible light irradiation using rhodamine B (RhB) as standard dye. $CoSe_2-G-TiO_2$ nanocomposites were synthesized by ultrasonication and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopic analysis and UV-Vis absorbance spectra analysis. Our results show that the $CoSe_2-G-TiO_2$ nanocomposite exhibited significant photo degradation efficiency compared to pure $TiO_2$ and $CoSe_2-G$, approximately 85.2% of the rhodamine (Rh B) degraded after 2.5 h. It is concluded that the $CoSe_2-G-TiO_2$ nanocomposite is a promising candidate for use in dye pollutants.

• ETRI Journal
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• 제30권6호
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• pp.833-843
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• 2008

The effect of forward and reverse electrostatic discharge (ESD) on the electro-optical characteristics of oxide vertical-cavity surface-emitting lasers is investigated using a human body model for the purpose of understanding degradation behavior. Forward ESD-induced degradation is complicated, showing three degradation phases depending on ESD voltage, while reverse ESD-induced degradation is relatively simple, exhibiting two phases of degradation divided by a sudden distinctive change in electro-optical characteristics. We demonstrate that the increase in the threshold current is mainly due to the increase in leakage current, nonradiative recombination current, and optical loss. The decrease in the slope efficiency is mainly due to the increase in optical loss.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.797-802
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• 2001

Two strains of rumen fungi (Piromyces rhizinflata B157, Orpinomyces joyonii SG4) and three strains of rumen cellulolytic bacteria (Ruminococcus albus B199, Ruminococcus flavefaciens FD1 and Fibrobacter succinogenes S85) were used as mono-cultures or combinationally arranged as co- and sequential-cultures to assess the relative contributions and interactions between rumen fungi and cellulolytic bacteria on rice straw degradation. The rates of dry matter degradation of co-cultures were similar to those of corresponding bacterial mono-cultures. Compared to corresponding sequential-cultures, the degradation of rice straw was reduced in all co-cultures (P<0.01). Regardless of the microbial species, the cellulolytic bacteria seemed to inhibit the degradation of rice straw by rumen fungi. The high efficiency of fungal cellulolysis seems to affect bacterial degradation rates.