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Enhancement of sonochemical oxidation reactions using air sparging in a 36 kHz sonoreactor
Choi, Jongbok,Khim, Jeehyeong,Neppolian, Bernaurdshaw,Son, Younggyu Elsevier 2019 Ultrasonics sonochemistry Vol.51 No.-
<P><B>Abstract</B></P> <P>The effect of air sparging on sonochemical oxidation reactions was investigated using a relatively large reactor equipped with a 36 kHz transducer module at the bottom. KI dosimetry and luminol techniques were used for quantitative and qualitative analysis of the reactions. The cavitation yield increased and then varied minimally as the liquid height increased from 1λ (42 mm) to 8λ (333 mm) with no air sparging. The flow rate of the air used for sparging and the position of the sparger significantly affected the extent of the sonochemical oxidation reactions. A significant enhancement in the sonochemical oxidation by air sparging was observed for higher liquid height and higher flow rate conditions at a constant input power. This enhancement is attributed to the violent mixing effect and the significant change in the sound field and cavitation-active zone in the liquid. Higher sonochemical activity was obtained when air sparging was applied closer to the transducer module at a higher flow rate. Imaging the motion of the liquid surface and sonochemiluminescence revealed that the instability of the liquid body was directly related to the sonochemical activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of air sparging was investigated in a 36 kHz large sonoreactor. </LI> <LI> The sparging flow rate and the sparger position affected the sonochemical activity. </LI> <LI> The instability of the liquid body was directly related to the sonochemical activity. </LI> </UL> </P>
Sonication Effect on NAPL Extraction from Soils
Kim, Young-Uk,Khim, Jeehyeong,Lee, In-Mo 한국지반공학회 2000 지반 : 한국지반공학회지 Vol.16 No.3
초음파를 이용한 지반 세척의 효율을 높이기 위한 방법이 최근에 개발되었지만 그에 대한 연구는 아직 초기 단계인 실정이다. 본 연구는 초음파가 지반 정화에 미치는 영향에 대하여 실내 실험을 통해 고찰하였으며 특히 초음파 에너지의 강도, 시료의 종류 및 밀도, 그리고 수두의 변화가 지반 세척에 미치는 영향에 대하여 연구를 수행하였다. 상기의 연구 결과 지반 세척시 초음파가 세척 능력을 상당히 향상시키는 것으로 나타났으며 초음파에너지가 강할수록, 흐름 속도가 느릴수록 초음파의 효과가 크게 나타났다.
Son, Younggyu,Lim, Myunghee,Khim, Jeehyeong,Ashokkumar, Muthupandian American Chemical Society 2012 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.51 No.1
<P>The photocatalytic process is considered as one of the advanced oxidation processes (AOPs) for the degradation/mineralization of pollutants, and it is known that ultrasound can significantly enhance these reactions when combined with photocatalytic processes. However little is known about the design parameters of these AOPs for industrial use. In this study, the attenuation of UV light under various conditions including ultrasound irradiation (36 and 935 kHz) and photocatalytic particle concentrations (TiO<SUB>2</SUB>: 0 to 100 mg/L) was investigated in a large-scale reactor. In addition, hydroxyl radical-induced oxidation in each process was compared using KI dosimetry. It was found that UV light was attenuated significantly due to the presence of dispersed particles and ultrasonic waves. The effective irradiation radius of UV light using a commercial module was determined to be with less than 10 cm considering the hydroxyl radical-induced activity in the combined processes. The results from this study may be useful to design large-scale UV-light-based AOPs for the removal of organic contaminants from an aqueous environment.</P>
Lee, Gooyong,Cui, Mingcan,Yoon, Yeomin,Khim, Jeehyeong,Jang, Min Elsevier 2018 JOURNAL OF CLEANER PRODUCTION Vol.186 No.-
<P><B>Abstract</B></P> <P>A one-step and facile process was used to incorporate coal mine drainage sludge (CMDS) into granular polyurethane (PU), designated as PU<SUB>CMDS</SUB>, to remediate circumneutral mine drainages simultaneously contaminated by arsenic and heavy-metals. PU<SUB>CMDS</SUB> was characterized through physiochemical analyses. Several batch and column tests were carried out. CMDS was homogeneously stuck on the large-sized pore surface of PU. Based on the kinetic modeling, the low-range Biot number (B<SUB>N</SUB>, 0.86–2.63) indicated that external diffusion is a main rate-limiting step. Rapid small-scale column tests (RSSCTs) also showed this phenomenon, in which the empty bed contact time (EBCT) influenced the arsenic removal efficiency more than did the PU<SUB>CMDS</SUB> size. PU<SUB>CMDS</SUB> had 8190–14,330 bed volumes (BVs) of breakthrough (BT, 50 μg L<SUP>−1</SUP>) for As(V), while it did not have BTs for other heavy metals, except for Fe(III). Two pilot-scale columns were conducted to observe their outlets till 7644 and 3800 BVs. As a result, PU<SUB>CMDS</SUB> did not have any BTs for all regulations of As (total) and heavy metals. All results in this study demonstrated not only that PU<SUB>CMDS</SUB> can effectively remove arsenic and other heavy metals in circumneutral mine drainages, but also that it shows an example of sustainable development concept in mine sector.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PU<SUB>CMDS</SUB> was prepared by simple method. </LI> <LI> PU<SUB>CMDS</SUB> was applied to remediate circum-neutral mine drainages. </LI> <LI> RSSCTs showed PU<SUB>CMDS</SUB> had 8190–14,330 BVs of BT (50 μg L<SUP>−1</SUP>) for As(V). </LI> <LI> PU<SUB>CMDS</SUB> did not have BT for other heavy metals, except Fe(III). </LI> <LI> Results of pilot-scale columns denoted that PU<SUB>CMDS</SUB> did not have BTs for all species. </LI> </UL> </P>
Hyam, Rajeshkumar Shankar,Lee, Jongseok,Cho, Eunju,Khim, Jeehyeong,Lee, Haigun American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.12
<P>In the present study, amorphous titanium dioxide (TiO2) nanotubes were synthesized by one-step anodization technique and subsequently annealed in different environments to investigate the effect of annealing atmospheres on the formation of different crystalline phases. X-ray Diffraction (XRD) patterns clearly showed the presence of anatase TiO2 phase with various crystallite sizes. The samples annealed in oxygen and air atmospheres at 500 degrees C showed a dominant anatase phase and a small amount of rutile phase, on the other hand, the samples annealed in nitrogen and argon atmospheres and in a vacuum at 500 degrees C contained the anatase phase only. XPS analysis of the samples showed a broadening in the binding energy curves with respect to variation in annealing atmosphere, confirming the variation in surface defects, which in turn affect photocatalytic degradation. The vacuum-annealed sample showed superior photocatalytic degradation efficiency as it had relatively higher pseudo-first order rate constants (k) of 0.009/min.</P>
Cho, Eunju,Arhonditsis, George B.,Khim, Jeehyeong,Chung, Sewoong,Heo, Tae-Young Elsevier 2016 Environmental modelling & software Vol.80 No.-
<P><B>Abstract</B></P> <P>Sensitivity and uncertainty analysis of contaminant fate and transport modeling have received considerable attention in the literature. In this study, our objective is to elucidate the uncertainty pertaining to micropollutant modeling in the sediment-water column interface. Our sensitivity analysis suggests that not only partitioning coefficients of metals but also critical stress values for cohesive sediment affect greatly the predictions of suspended sediment and metal concentrations. Bayesian Monte Carlo is used to quantify the propagation of parameter uncertainty through the model and obtain the posterior parameter probabilities. The delineation of periods related to different river flow regimes allowed optimizing the characterization of cohesive sediment parameters and effectively reducing the overall model uncertainty. We conclude by offering prescriptive guidelines about how Bayesian inference techniques can be integrated with contaminant modeling and improve the methodological foundation of uncertainty analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sensitivity and uncertainty analysis was performed for sediment-metal modeling. </LI> <LI> Suspended sediment predictions are sensitive to critical erosion stress. </LI> <LI> Sediment bed-water partitioning coefficient is critical for metal predictions. </LI> <LI> River flow dynamics affect contaminant fate and model parameter sensitivity. </LI> <LI> Strategies to improve uncertainty analysis of sediment-metal modeling are discussed. </LI> </UL> </P>