http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Carbon nanotubes radially anchored on carbon fibers formed by polyacrylonitrile
Hwang, Sookhyun,Kim, Sangwoo,Cho, Gyu-bong,Choi, Hyonkwang Elsevier 2018 Materials research bulletin Vol.97 No.-
<P><B>Abstract</B></P> <P>We investigated a hybrid nanostructure comprised of carbon nanotubes (CNTs) directly grown on polyacrylonitrile-based carbon fibers (PAN-CFs) for three-dimensional energy materials. The optimum growth conditions, such as catalyst loading time in electroless deposition and growth temperature in chemical vapor deposition were identified. The thorn bush-like structures of the multi-walled CNTs on CFs were evaluated by field emission transmission electron microscope and field emission scanning electron microscope. Raman spectra and attenuated total reflectance Fourier transform infrared spectroscopy were used to analyze the crystal and chemical structures of CNTs on CFs. Base on the results from four-point probe measurement, the sheet resistance dropped from 40Ω/sq for PAN-CFs to less than 10Ω/sq for CNTs-grown PAN-CFs. The obtained CNTs/PAN-CFs revealed the specific surface area of 64.4m<SUP>2</SUP>/g with a pore volume of 0.18cm<SUP>3</SUP>/g. Moreover, a sulfur electrode with the CNTs/PAN-CFs current collector exhibited higher electrochemical performance than that of the electrode with planar aluminum current collector.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Vertically aligned carbon nanotubes on carbon fibers were grown by using electroless plating and CVD method. </LI> <LI> The optimized CNTs/CFs revealing a surface area of 64.4cm<SUP>2</SUP>/g and a sheet resistance of 10Ω/sq was achieved. </LI> <LI> For the practical electrochemical application, a CNTs/CFs electrode was used as a current collector of lithium/sulfur cell. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
자외선/H<sub>2</sub>O<sub>2</sub> 처리시 남조류 기인 유기물 특성이 수산화 라디칼 반응성 및 운전조건에 미치는 영향
남숙현 ( Sookhyun Nam ),이주원 ( Juwon Lee ),김은주 ( Eunju Kim ),황태문 ( Tae-mun Hwang ) 한국수처리학회(구 한국수처리기술연구회) 2020 한국수처리학회지 Vol.28 No.4
This study interrogates the influence of algal organic matter on hydroxyl radial (ㆍOH) scavenging factors. The ㆍOH scavenging factor represents the rate at which ㆍOH is scavenged by background substances in aqueous solutions, which is key to the design and operation of UV/H<sub>2</sub>O<sub>2</sub> processes for water treatment. Extracellular organic matter (EOM) and intracellular organic matter (IOM) were extracted from cyanobacteria acquired from lake water. Synthetic water was manufactured by using either EOM or IOM, and the resulting hydroxyl radical scavenging factors were measured and compared. The organic properties of the EOM and IOM were analyzed by using liquid chromatography organic carbon detection (LC-OCD) and fluorescence excitation-emission matrices (F-FEM). Analyses revealed that EOM samples exhibited strong peaks associated with tryptophan-like, fulvic-like, and humic-like (excitation/emission 250-260/380-480) substances. By comparison, the tryptophan-like peak was dominant in IOM samples. Six components were observed in LC-OCD chromatograms, with neutrals being the highest component of both of EOM and IOM, yet EOM also had high humics and LMW acids. This study proposes a predictive model that estimates the optimal UV and H2O2 doses necessary to maximize the removal of target compounds. Removal of 90% of the target compound (D90) required 6.8 mg/L of hydrogen peroxide at 1200 mJ/㎠. When comparing theoretical prediction with experimental values, the difference in the elimination rate was less than 10%.
자외선/염소 및 자외선/과산화수소 기술에 의한 Microcystin-LR 처리 특성 비교
남숙현 ( Sookhyun Nam ),이주원 ( Joowun Lee ),김은주 ( Eunju Kim ),구재욱 ( Jaewuk Koo ),황태문 ( Tae-mun Hwang ) 한국수처리학회 2022 한국수처리학회지 Vol.30 No.5
Microcystin-LR (MC-LR), the most widely known toxin produced in cyanobacteria, is problematic because of its toxicity. This study was carried out to evaluate the capability of ultraviolet photolysis of chlorine(UV/Cl<sub>2</sub>) and ultraviolet photolysis of hydrogen peroxide(UV/H<sub>2</sub>O<sub>2</sub>). Results showed that direct photolysis with 254 nm UV irradiation achieved substantial toxin removal. In particular, in UV/Cl<sub>2</sub> oxidation treatment, the removal rate of MC-LR was improved through various radical reactions that were similar to UV/H<sub>2</sub>O<sub>2</sub>. In the UV/chlorine process at the pH of 7.0, UV irradiation amount of100 mJ/cm<sup>2</sup> and chlorine concentration of 0.3 mg/L, the MC-LR removal rate was 52.0%, indicating that the removal rate was increased by 24% compared to the UV only treatment. In the UV/chlorine and UV/H<sub>2</sub>O<sub>2</sub> process at pH 7.0, the first-order degradation rate constants of MC-LR were 3.1×10<sup>-3</sup>~3.6×10<sup>-3</sup> s<sup>-1</sup> and 2.9×10<sup>-3</sup>~3.7×10<sup>-3</sup> s<sup>-1</sup>, respectively. It was shown that the degradation rate constant of MC-LR was lowered by 19.4% at pH 9.0 compared to that of pH 7.0, where the analysis found that the change in pH affected oxidation ability. UV/H<sub>2</sub>O<sub>2</sub> was not affected by pH. This result affects the energy consumption needed to meet the required 90% elimination of MC-LR.
먹는물의 미생물 실시간 감시를 위한 온라인 ATP 측정법의 적용
남숙현 ( Sookhyun Nam ),황태문 ( Tae-mun Hwang ),김은주 ( Eunju Kim ),안주석 ( Jooseok An ),구재욱 ( Jae-wuk Koo ),이주원 ( Joowun Lee ) 한국수처리학회 2021 한국수처리학회지 Vol.29 No.5
The evaluation of microbial contamination in drinking water is a major concern worldwide. Adenosine triphosphate (ATP) monitoring can serve as a complement to the HPC method currently used for water quality tests because it offers rapid measurement, ease of use, and activity against microorganisms. In this study, we proposed an alternative to in situ rapid microbial monitoring methods. The ATP levels in tap water and surface-treated water were monitored using an online ATP analyzer. The ATP level of the surface-treated water was three times higher than that of the tap water. Furthermore, the correlation between E. coli and ATP confirmed that if the number of microorganisms in water is small, the ATP data must be obtained according to the target water characteristics to enable the monitoring for microbial viability in drinking water. For effective E. coli monitoring, online ATP data was stored in its own server database and an internet-of-things (IoT)-based microbial monitoring system was established and successfully applied. Recent advances in the ATP technology and IoT technology have enabled the quick and accurate online monitoring of the ATP level in water. This helps in maintaining the microbial stability of drinking water by detecting the signs of its microbial contamination early and to process it as quickly as possible.
정수공정에서 유기물 모니터링을 위한 Fluorescence EEM의 적용
남숙현 ( Sookhyun Nam ),이주원 ( Juwon Lee ),김은주 ( Eunju Kim ),구재욱 ( Jaewuk Koo ),황태문 ( Tae-mun Hwang ) 한국수처리학회(구 한국수처리기술연구회) 2020 한국수처리학회지 Vol.28 No.3
Natural organic matter (NOM) is a substance that affects performance in the water treatment process that is crucial to understand. NOM can have different composition according to environmental changes. In this study, we applied the fluorescence excitation emission matrices-parallel factor analysis (FEEM-PARAFAC) method for characterizing dissolved organic matter (DOM). This method provides valuable insight into the chemical composition of DOM and the effects of various treatment processes in engineered systems. This study was conducted on raw water, coagulation/sedimentation, sand filtration, and activated carbon in N water treatment. The correlation between the component and the process was derived by PARAFAC with 100 fluorescence spectra. Using this method, components correlated with the DOM removal for water process were derived. It was determined, C1 (E<sub>x</sub>/E<sub>m</sub> = 250(350)/450) is the main component to monitor the removal rates of DOM in the flocculation/sedimentation process, the C1/C2 fraction (E<sub>x</sub>/E<sub>m</sub> = 250(325)/400) is the main component in the sand filter process, and C2 (E<sub>x</sub>/E<sub>m</sub> = 250(325)/400) is the main component in the activated carbon process. It has been found to be a suitable tool to track the change of organic matter quantity and quality in water treatment processes.