• Title/Summary/Keyword: $O_3$ Generation

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A study on reactive chlorine species generation enhanced by heterojunction structures on surface of IrO2-based anodes for water treatment (IrO2 기반 수처리용 산화 전극의 표면 이종 접합 구성에 따른 활성 염소종 발생 증진 특성 연구)

  • Hong, Sukhwa;Cho, Kangwoo
    • Journal of Korean Society of Water and Wastewater
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    • v.32 no.4
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    • pp.349-355
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    • 2018
  • This study interrogated multi-layer heterojunction anodes were interrogated for potential applications to water treatment. The multi-layer anodes with outer layers of $SnO_2/Bi_2O_3$ and/or $TiO_2/Bi_2O_3$ onto $IrO_2/Ta_2O_5$ electrodes were prepared by thermal decomposition and characterized in terms of reactive chlorine species (RCS) generation in 50 mM NaCl solutions. The $IrO_2/Ta_2O_5$ layer on Ti substrate (Anode 1) primarily served as an electron shuttle. The current efficiency (CE) and energy efficiency (EE) for RCS generation were significantly enhanced by the further coating of $SnO_2/Bi_2O_3$ (Anode 2) and $TiO_2/Bi_2O_3$ (Anode 3) layers onto the Anode 1, despite moderate losses in electrical conductivity and active surface area. The CE of the Anode 3 was found to show the highest RCS generation rate, whereas the multi-junction architecture (Anode 4, sequential coating of $IrO_2/Ta_2O_5$, $SnO_2/Bi_2O_3$, and $TiO_2/Bi_2O_3$) showed marginal improvement. The microscopic observations indicated that the outer $TiO_2/Bi_2O_3$ could form a crack-free layer by an incorporation of anatase $TiO_2$ particles, potentially increasing the service life of the anode. The results of this study are expected to broaden the usage of dimensionally stable anodes in water treatment with an enhanced RCS generation and lifetime.

Study on the Generation of Chemically Active Species using Air-plasma Discharging System (공기-플라즈마 방전 시스템에서 화학적 활성종의 생성에 대한 연구)

  • Kim, DongSeog;Park, YoungSeek
    • Journal of Korean Society on Water Environment
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    • v.28 no.3
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    • pp.401-408
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    • 2012
  • High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and air flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the increased of the 2nd voltage (4 kV to 15 kV), RNO degradation, $H_2O_2$ and $O_3$ generation were increased. The conductivity of the solution was not influencing the RNO degradation and $H_2O_2$ and $O_3$ generation. The effects pH was not high on RNO degradation. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

Efficient Second Harmonic Generation of Pulsed Nd-YAG Laser Radiation with Noncritically Phase-Matchable $LiNbO_3$ in Room-Temperature

  • Jong-Soo Lee;Bong-Hoon Kang;Bum Ku Rhee;Chong-Don Kim;Gi-Tae Joo
    • The Korean Journal of Ceramics
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    • v.6 no.3
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    • pp.206-208
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    • 2000
  • 0.65 mol% MgO-doped LiNbO$_3$single crystals were grown by CZ method. The obtained single crystals were colorless and transparent. Noncritically phase-matched second harmonic generation (SHG) of 532-nm radiation from 1064-nm in MgO-doped LiNbO$_3$has been investigated by using pulsed Nd:YAG laser. The phase-matching temperature was room temperature. SHG conversion efficiencies were typically achieved higher than 50% at the phase-matching temperature with no photorefractive damage in the region of fundamental power density which was used in this experiment. The thermo-birefringence coefficient and the electro-birefringence coefficient of SHG were calculated from the temperature phase-matching profile with the electric field.

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Effect of Disinfection Process Combination on E. coli Deactivation and Oxidants Generation (E. coli 불활성화와 산화제 생성에 미치는 소독 공정 결합의 영향)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.20 no.7
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    • pp.891-898
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    • 2011
  • The aim of this research was to evaluate the effect of combination of disinfection process (electrolysis, UV process) on Escherichia coli (E. coli) disinfection and oxidants (OH radical, $ClO_2$, HOCl, $H_2O_2$ and $O_3$) generation. The effect of electrolyte type (NaCl, KCl and $Na_2SO_4$) on the E. coli disinfection and oxidants generation were evaluated. The experimental results showed that performance of E. coli disinfection of electrolysis and UV single process was similar. Combination of electrolysis and UV process enhanced the E. coli disinfection and 4-carboxybenzaldehyde (4-CBA, indicator of the generation of OH radical) degradation. It is clearly showed synergy effect on disinfection and OH radical formation. However chlorine ($ClO_2$, HOCl) and oxygen type ($H_2O_2$, $O_3$) oxidants were decreased with the combination of two process. In electrolysis + UV complex process, electro-generated $H_2O_2$ and $O_3$ were reacted with UV light of UV-C lamp and increased 4-CBA degradation(increase OH radical). Disinfection of electrolyte of chlorine type was higher than that of the sulfate type electrolyte due to the higher generation of OH radical and oxidants.

A Study for Oxidants Generation on Oxygen-plasma Discharging Process Discharging System (산소-플라즈마 공정에서 산화제의 생성에 대한 연구)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.22 no.12
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    • pp.1561-1569
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    • 2013
  • This study carried out a laboratory scale plasma reactor about the characteristics of chemically oxidative species (${\cdot}OH$, $H_2O_2$ and $O_3$) produced in dielectric barrier discharge plasma. It was studied the influence of various parameters such as gas type, $1^{st}$ voltage, oxygen flow rate, electric conductivity and pH of solution for the generation of the oxidant. $H_2O_2$ and $O_3$.) $H_2O_2$ and $O_3$ was measured by direct assay using absorption spectrophotometry. OH radical was measured indirectly by measuring the degradation of the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical). The experimental results showed that the effect of influent gases on RNO degradation was ranked in the following order: oxygen > air >> argon. The optimum $1^{st}$ voltage for RNO degradation were 90 V. As the increased of $1^{st}$ voltage, generated $H_2O_2$ and $O_3$ concentration were increased. The intensity of the UV light emitted from oxygen-plasma discharge was lower than that of the sun light. The generated hydrogen peroxide concentration and ozone concentration was not high. Therefore it is suggested that the main mechanism of oxidation of the oxygen-plasma process is OH radical. The conductivity of the solution did not affected the generation of oxidative species. The higher pH, the lower $H_2O_2$ and $O_3$ generation were observed. However, RNO degradation was not varied with the change of the solution pH.

High Power Characteristics of $Pb(Y_{2/3}W_{1/3})O_3-Pb(Zr,Ti)O_3$Ceramics ($Pb(Y_{2/3}W_{1/3})O_3-Pb(Zr,Ti)O_3$계 세라믹스의 고출력 특성)

  • ;Kenji Uchino
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.5
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    • pp.394-399
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    • 1998
  • High power characteristics with vibration velocity were studied in $Pb(Y_{2/3}W_{1/3})O_3-Pb(Zr,Ti)O_3$(PYW-PZT) ceramics by using the constant current method. Young s modulus $Y_0^E$ and mechanical quality factor $Q_m$ are a function of the square of effective vibration velocity \upsilon_0$. The nonlinear proportional constants of the above functions indicate the degree of stability under the vibration level change. The stability of PYW-PZT ceramics estimated by these constants coincides with the results obtained through the heat generation. It was found that $Q_m$ was markedly decreased with increasing the vibration velocity, accompanying a lot of heat generation. The vibration hysteresis and dielectric loss according to the vibration velocity was reduced by doping $Fe_2O_3$to the ceramics. On the contrary, these losses was increased by doping $Nb_2O_5$.

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Analysis of a Fire Case Caused by Heat Generation due to Cu2O Breeding (아산화동증식 발열에 의한 화재 사례의 분석)

  • Park, Jin-Young;Lee, Eui-Pyeong
    • Fire Science and Engineering
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    • v.34 no.2
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    • pp.54-63
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    • 2020
  • Although fires caused by heat generation due to Cu2O breeding in wire connections are well-known among fire investigators, there are few papers on the analysis and introduction of fire cases by heat generation due to Cu2O breeding. This study analyzed fire statistics caused by heat generation in electrical connections and the phenomena and features of heat generation due to Cu2O breeding. Then, a fire which occurred in the wire connection in a university lab by heat generation due to Cu2O breeding was analyzed in more detail. This fire case could reach a conclusion that heat generation due to Cu2O breeding caused a fire in the wire connection through the fire pattern investigation of fire origin, the visual investigation of wire connection, 3D CT, power-on-test, and stereoscopic microscopy, SEM and EDS analysis.

Second harmonic generation of YCOB($YCa_4O(BO_3)_3$) (YCOB($YCa_4O(BO_3)_3$)의 제2조화파 발생)

  • 장원권
    • Korean Journal of Optics and Photonics
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    • v.10 no.4
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    • pp.301-305
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    • 1999
  • The phase matching conditions of the new optical crystal grown by Czochralski pulling method, YCOB($YCa_4O(BO_3)_3$) with wavelength were suggested, and the second harmonic generation efficiency for the fundamental of Nd:YAG laser of 1064 nm was investigated. The variation of nonlinearity with rare earth ion doping was also investigated by measuring the second harmonic generation efficiencies of $Yb^{3+}$ + $Nd^{3+}$and ion doped YCOBs.

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The Relationship between Domain Switching and Acoustic Emission in (Pb,La)$TiO_3$ Ferroelectric Ceramacs ((Pb,La)$TiO_3$ 강유전체 세라믹에서 분역반전과 Acoustic Emission의 관계)

  • 최동구;최시경
    • Journal of the Korean Ceramic Society
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    • v.33 no.6
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    • pp.672-678
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    • 1996
  • The relationship between domain switching and acoustic emission (AE) during poling was investigated using the tetragonal ferroelectric ceramics with composition of (Pb,La)TiO3+0.01MnO2 The amount of AE generation during poling increased with increasing dc electric field and raising temperature. It was confirmed that the change of the amount of AE generation with poling condition resulted from the difference of the amount of 90$^{\circ}$ domain switching and total amount of AE generation for 10 minutes was approximately proportional to the amount of 90$^{\circ}$domain switching. The A generations of two specimens which have different tetragonality rations(c/s rations) 15 at% and 24at% La-doped were also investigated. The sample with c/a ratio of 1.012 where 90$^{\circ}$ domains are dominate had larger amount of AE generation and 90$^{\circ}$ domain switching compared with the sample with c/a ratio of 1.004 where 180$^{\circ}$ domains are dominant.

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Fourth and Fifth Harmonic Generations of an Nd:YAG Laser using Nonlinear Optical $LiB_{3}O_{5}$ and $CsLiB_{6}O_{10}$ Crystals (비선형 단결정 $LiB_{3}O_{5}$$CsLiB_{6}O_{10}$을 이용한 Nd:YAG 레이저의 4차 및 5차 조화파 발생)

  • Jang Jong Hun;Kim Ji Won;Yun Chun Seop
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.02a
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    • pp.234-235
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    • 2003
  • All solid-state UV lasers provide efficient, clean and semipermanent light sources for various applications, such as eye surgery, microchip lithography. $CsLiB_{6}O_{10}$ (CLBO) is one of the most suitable crystals for UV generation because of its small walk-off, large effective nonlinear susceptibility in UV region and high damage threshold. We produced fourth (266 nm) and fifth (213 nm) harmonic generation of an Nd:YAG laser (1064 nm) with $LiB_{3}O_{5}$ as a second harmonic generation medium and CLBO as a fourth harmonic and fifth harmonic mediums. (omitted)

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