36kHz 초음파 반응기에서의 원주파수 및 파생주파수의 음압 분포 분석

손영규,Son, Younggyu 한국지하수토양환경학회 2016 지하수토양환경 Vol.21 No.6

Acoustic emission spectra was analyzed to investigate the distribution of sound pressure in a 36 kHz sonoreactor. The sound pressure of fundamental frequency (f: 36 kHz), harmonics (2f: 72 kHz, 3f: 108 kHz, 4f: 144 kHz, 5f: 180 kHz, 6f: 216 kHz), and subharmonics (1.5f: 54 kHz, 2.5f: 90 kHz, 3.5f: 126 kHz, 4.5f: 162 kHz, 5.5f: 198 kHz, 6.5f; 234 kHz) was measured at every 5 cm from the ultrasonic transducer using a hydrophone and a spectrum analyzer. It was revealed that the input power of ultrasound, the application of mechanical mixing, and the concentration of SDS affected the sound pressure distributions of the fundamental frequency and total detected frequencies frequencies significantly. Moreover a linear relationship was found between the average total sound pressure and the degree of sonochemical oxidation while there was no significant linear relationship between the average sound pressure of fundamental frequency and the degree of sonochemical oxidation.

74 kHz 초음파 반응기에서 수위 변화에 따른 초음파 화학 반응의 변화

손영규,Son, Younggyu 한국지하수토양환경학회 2016 지하수토양환경 Vol.21 No.1

Acoustic cavitation can induce various sonochemical effects including pyrolysis and radical reactions and sonophysical effects including microjets and shockwave. In environmental engineering field, ultrasound technology using sonochemical effects can be useful for the removal and mineralization of recalcitrant trace pollutants in aqueous phase as one of emerging advanced oxidation processes (AOPs). In this study, the effect of liquid height, the distance from the transducer to the water surface, on sonochemical oxidation reactions was investigated using KI dosimetry. As the liquid height/volume increased (40~400 mm), the cavitation yield steadily increased even though the power density drastically decreased. It was found that the enhancement at higher liquid height conditions was due to the formation of standing wave field, where cavitation events could stably occur and a large amount of oxidizing radicals such as OH radicals could be continuously provided.

다양한 액상 수위/부피 조건에서의 300kHz 초음파 캐비테이션 산화반응 분석 연구

이성은,손영규,Lee, Seongeun,Son, Younggyu 한국물환경학회 2022 한국물환경학회지 Vol.38 No.5

In this study, the effect of liquid height/volume on sonochemical oxidation reactions was investigated in 300 kHz sonoreactors. The gas mixture of Ar/O₂ (50:50) was applied in two modes including saturation and sparging, and zero-order reaction (KI dosimetry) and first-order reaction (Bisphenol A (BPA) degradation) were used to quantitatively analyze sonochemical oxidation reactions. For the zero-order reaction, the highest sonochemical oxidation activity was obtained for the liquid height of 5𝛌, and the lowest height for both the gas saturation and sparging conditions. In addition, the sparging did not enhance the sonochemical oxidation activity for all height conditions except for 50𝛌, where very low activity was obtained. It was found that in sonochemiluminescence (SCL) images the sonochemical active zone was formed adjacent to the liquid surface for the gas sparging condition due to the formation of the standing wave field while the active zone was formed adjacent to the transducer at the bottom due to the blockage of ultrasound. For the first-order reaction, the highest activity was also obtained at 5𝛌 and the comparison based on the reactant mass was not appropriate because the concentration of the reactant (BPA) decreased significantly as the reaction time elapsed. Consequently, it was revealed that the determination of optimal liquid height (ultrasound irradiation distance) based on the wavelength of the applied ultrasound frequency was very important for the optimal design of sonoreactors in terms of reaction efficiency and reactor size.

이중 반응기 조건 및 비균일계 조건에서의 초음파 에너지 및 화학적 효과 평가

이현재,손영규,Lee, Hyeon Jae,Son, Younggyu 한국지하수토양환경학회 2017 지하수토양환경 Vol.22 No.5

The effects of ultrasound in heterogeneous system were investigated in three kinds of ultrasonic systems including a bath-type system (System #1), a double-bath-type system (System #2), and a double-bath-type system partly filled with glass beads (System #3). The ultrasound energy and its attenuation were quantified using calorimetry and the sound pressure measurement method. The sonochemical effects mainly involved in radical oxidation reactions were quantified using KI dosimetry. It was found that ultrasound energy was significantly attenuated in System #2 and #3 due to the presence of solid materials such as a submerged stainless steel reactor and glass beads. However, in spite of low ultrasound energy status, sonochemical oxidation reactions occurred more violently due to the presence of glass beads in System #3. In addition, calorimetry was more adequate to estimate the total energy status of ultrasound in sonoreactors compared to the sound pressure measurement method.

이중 초음파 조사 시스템에서 진동부 사이의 거리가 초음파 화학 반응에 미치는 영향

김은경,손영규,Kim, Eunkyung,Son, Younggyu 한국지하수토양환경학회 2013 지하수토양환경 Vol.18 No.5

Many researchers have studied the effectiveness of ultrasound in chemical and environmental engineering fields including material synthesis, pollutant removal, cleaning, extraction, and disinfection. Acoustic cavitation induced by ultrasound irradiation in aqueous phase can cause various sonophysical and sonochemical reactions without any chemicals. However most of the previous studies focused only on the relationships between ultrasonic conditions and the results of sonochemical reactions in lab-scale sonoreactors. As a results of this, only a few studies have been devoted to design and optimization of industrial scale sonoreactors. In this study, the effect of the distance between two opposite transducer modules on sonochemical reactions was investigated in single and dual irradiation systems (334 kHz) for four distances including 50, 100, 150, and 200 mm using KI dosimetry. It was found that the dual irradiation systems provided higher performance in terms of the zeroth reaction coefficient and the cavitation yield compared to the single irradiation systems. The sonochemiluminescence (SCL) images for the visualization of the cavitation field showed that cavitation active zone was larger and sonochemical reaction intensity was much higher in the dual irradiation system than in the single irradiation system.

자외선 및 초음파 공정에 의한 수용액 상의 PCBs 분해

이덕영,손영규,Lee, Dukyoung,Son, Younggyu 한국지하수토양환경학회 2021 지하수토양환경 Vol.26 No.4

The removal of PCBs (Polychlorinated biphenyls) in aqueous phase was investigated in the ultraviolet (UV) process, ultrasonics (US) process and ultraviolet/ultrasonic (UV/US) process using PCB No.7 and Aroclor 1260. For PCB No.7 relatively high removal efficiency over 90% was obtained during 20 min in the UV process and UV/US process. On the other hand, lower removal efficiency of 50 - 70% was achieved for it consisted of individual congeners of PCBs containing 3~8 of chlorine atom. It was found that the dechlorination reaction (the photolytic cleavage of C-Cl bond) was considered as a main removal mechanism in the UV process while PCBs were removed by cavitation-induced radical reaction in the US process. No significant dechlorination occurred in the US process. Consequently, it was suggested that the UV process or UV/US process was applicable for the removal of PCBs in aqueous phase in terms of the removal efficiency and operation time. In addition, the application of saturating gas such as Ar and Air could be considered to control redox condition and enhance the severity of acoustic cavitation for the removal of PCBs.

다단 혼 형태의 초음파 장비를 이용한 초음파 화학적 효과 연구

최종복,이성은,손영규,Choi, Jongbok,Lee, Seongeun,Son, Younggyu 한국지하수토양환경학회 2020 지하수토양환경 Vol.25 No.4

Since the typical horn-type ultrasonic equipment induces a reaction at the probe tip, the sonochemical reaction has a limitation that it occurs only in a specific area. As one of the ways to overcome this limitation, an ultrasonic device with multi-stepped horn equipped with several oscillators has been developed. The objective of this study was to investigate the sonochemical effects induced by acoustic cavitation system in 20 kHz multi-stepped ultrasonic horn using calorimetry, KI dosimetry and the luminol test. The sonochemical effects of multi-stepped ultrasonic horn were compared with that of the typical horn-type 20 kHz ultrasonic device. The effect of immersion depth and power on the sonochemical reaction was investigated in the ultrasonic system with multi-stepped ultrasonic horn. Higher calorimetric energy was obtained at higher immersion depth and power conditions. Sonochemical effects increased significantly when using the high immersion depth and input power. However, as the input power increased, the cavitation reaction zone concentrated around the ultrasonic horn. Additionally, the experiments to examine the effect of liquid temperature was conducted. The smaller sonochemical reaction was obtained for the higher liquid temperature. The effect on temperature seems to be closely related to liquid conditions such as viscosity and vapor pressure of water.

왕수를 이용한 중금속 오염토양에서의 추출방안 연구

이덕영,정선국,손영규,Lee, Dukyoung,Jung, Sunkook,Son, Younggyu 한국지하수토양환경학회 2018 지하수토양환경 Vol.23 No.2

Aqua regia extraction for the quantification of heavy metals and As in contaminated soils was investigated as one of preliminary steps for on-site monitoring using sensor technology. Soil samples were taken from closed railway depot, closed mines, and closed refinery and various extraction conditions including $30^{\circ}C/15min$, $30^{\circ}C/30min$, $30^{\circ}C/60min$, $30^{\circ}C/120min$, $80^{\circ}C/15min$, $80^{\circ}C/30min$, $80^{\circ}C/60min$, $80^{\circ}C/120min$ were tested. The optimal extraction condition was determined as $80^{\circ}C/60min$ because the extraction efficiencies of Zn were relatively low and did not reach the targeted level (80-100% of original concentrations) for $30^{\circ}C$ conditions. It was found that the fractionation of heavy metals and As using the sequential extraction method was useful to understand the degree of metal extraction. In order to enhance the extraction efficiency within short extraction time, ultrasound technology using a 20 kHz horn-type sonicator was additionally used for $30^{\circ}C/15min$. It was revealed that ultrasound could significantly enhance the extraction efficiency and pulsed irradiation showed higher efficiency than continuous irradiation due to the less formation of bubble clouds. However high temperature condition ($80^{\circ}C$) was required to achieve high extraction efficiency for Zn in spite of the use of ultrasound.

자외선 및 초음파를 이용한 수용액상의 PCBs 분해 연구

이덕영(Dukyoung Lee),손영규(Younggyu Son),최종복(Jongbok Choi) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11

초음파 화학적효과 증진을 위한 용존가스 영향 연구

최종복(Jongbok Choi),손영규(Younggyu Son),이덕영(Dukyoung Lee) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11