• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.585-590
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• 2001

Physicochemical phenomena in soils are dependent upon pH when using electrokinetic extraction for the contaminants removal especially for heavy metals. pH variation in soils is affected on H$\^$+/ and OH￣ ions produced by electrolysis reaction and buffer capacity of soil. High amount of heavy metals are retained in the soils if the soil buffer capacity remains high enough to resist a change in pH. Therefore, accurate pH estimation of soil is important in the application of electrokinetic mechanism for decontamination and understanding of subsurface physicochemical characteristics is also required as well as considering buffer capacity for the enhanced methods application. For these, buffer capacity and pH distribution were measured for the four soils, and also compared with modeling results. The results of buffer modeling were good agreement with experimental data. It is showed that four soils were effected by buffer capacity

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.306-309
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• 2003

Surfactant-enhanced electrokinetic (EK) remediation is an emerging technology that can effectively remove hydrocarbons from low-permeability soils. In this study, the electrokinetic remediation using Calfax 16L-35 was conducted for the removal of phenanthrene from kaolinite. An anionic surfactant Calfax 16L-35 was used at concentrations of 5, 15, and 30g/L to enhance the solubility of phenanthrene. When the surfactant solution was applied to EK system, low electrical potential gradient was maintained because of its ions. Even when the surfactant concentration was high, the removal efficiency of phenanthrene was low After the operation, most of surfactants were remained in soil and there were few in effluent. This phenomena was observed because the migration of Calfax 16L-35 from cathode to anode was predominant over electroosmotic flow which moved in opposite direction. Therefore, the anionic surfactant Calfax 16L-35 is considered to be improper in surfactant - enhanced electrokinetic remediation.

• 한국지반공학회논문집
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• 제18권1호
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• pp.49-57
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• 2002

오염지반 정화를 위한 Electrokinetic 처리 과정에서 지반에 전류를 적용하면 흙물 시스템 내에서 발생하는 유체의 이동 현상과 계면의 특성 변화가 발생하여 Electrokinetic 반응에 영향을 미친다. 본 논문에서는 지반 내에서 발생하는 전기적, 화학적 변수와 그 변화 특성을 규명하고자 실내실험을 수행하여, 시료의 전압, 전류, 제타포텐셜, pH등의 전기 화학적 현상을 연구하였으며 이러한 인자들의 특성변화를 모델링하는 기법을 제시하였다. 그 결과 정화 도중 전압, 전류 변화를 각 농도에서 시간에 따른 지수함수로 표현할 수 있었으며 제타포텐셜의 변화를 pH와 오염농도에 따라 모델링 할 수 있었다.

• 대한기계학회논문집B
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• 제31권4호
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• pp.320-329
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• 2007

Electrokinesis and dielectrophoresis are important transport phenomena produced by external electric field applied to a microchannel containing a conductive fluid. We developed a CFD code to predict electrokinetic and dielectrophoretic flows in a microchannel with a uniform circular post array. Using the code, we calculated particle velocities driven by electrokinesis and dielectrophoresis, and conducted Monte Carlo simulations to visualize the particle motions. The code was validated by comparing the results with those from previous studies in literature. At a low electric field, electrokinesis and diffusion is the dominant transport mechanism. At a moderate electric field, dielectrophoresis is balanced with electrokinesis and diffusion, resulting in flowing filaments of particles in the microchannels. However, dielectrophoresis overwhelms the flow at a high electric field and traps particles locally. These results provide useful insight for optimizing design parameters of a microfluidic chip for biochemical analysis, especially for development of on-chip sample pretreatment techniques using electrokinetic and dielectrophoretic effects.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.91-96
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• 2001

Restoration of contaminated soils to an environmentally acceptable condition is important. One of the newer techniques in soil remediation is a method based on electrokinetic phenomena in soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils. An important advantage of electrokinetic soil remediation over other in-situ processes such as soil flushing is the capability of control over the movement of the contaminants. Because the migration of the contaminants is confined by the electric field, there is little dispersion outside the treatment zone. Furthermore, the process is effective for soils with low and variable permeability. In the present study, the distributions of cadmium in the electrokinetic processing of kaolinite under the condition of constant applied voltage are investigated. Cadmium accumulates near the cathode without reducing the diffusion of hydroxide ion into the soil. In keeping the catholyte pH at neutrality, cadmium migrates toward the cathode without any accumulation of cadmium near the cathode and is successfully removed at the cathode reservoir. It was also found that the progress of electrokinetic processing of cadmium could be gasped to a certain extent by monitoring the local voltage and the current density.

• Environmental Engineering Research
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• 제24권3호
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• pp.456-462
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• 2019

Hydrocarbon contamination is among the most challenging problems in soil remediation. Electrokinetic method can be a promising method to remediate hydrocarbon-contaminated soils. Electrokinetic method consists of different transport phenomena including electro-migration, electrophoresis, and electroosmotic flow. Electroosmotic flow is the main transport phenomenon for hydrocarbon removal in soil porous media. However, the main component of hydrocarbons is the hydrophobic organic which indicates low water solubility; therefore, it makes the electroosmotic flow less effective. The objective of the present study is to enhance electrokinetic remediation of diesel-contaminated silty sand by increasing the solubility of the hydrocarbons in the soil and then increase the efficiency. For this purpose, sodium dodecyl sulfate (SDS) was used as a catholyte. In this content, SDS 0.05 M was used as catholyte and $Na_2SO_4$ 0.1 M was used as an anolyte. Low (1 V/cm) and high (2 V/cm) voltage gradients were used in periodic and continuous forms. The best removal efficiency was observed for high voltage gradient (2 V/cm) in a periodic form, which was 63.86. This result showed that a combination of periodic voltage application in addition to the employment of SDS is an effective method for hydrocarbon removal from low permeable sand.

• 센서학회지
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• 제16권2호
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• pp.115-119
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• 2007

We report electrokinetic streaming potential detection in a microchannel. Streaming potential, one of the representative electrokinetic phenomena, becomes noticeable either when the channel size reduces or when the concentration of electrolyte reduces. We suggest a triangular-shaped microchannel to enhance streaming potential. The triangular-shaped microchannel shows better performance than the straight one in terms of streaming potential. Couple of possible methods to enhance streaming potential is also discussed. Moreover, this type of channel and phenomenon can be applied to biological sensor application and energy transduction.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.191-194
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• 2004

The concentration of hydrogen peroxide in soil and effluent was measured to understand the relationship between the profile of hydrogen peroxide and the removal efficiency of phenanthrene in an Electrokinetic-Fenton process. Electrokinetic phenomena were observed in two different conditions for 1, 2, 4, and 7 days; 3.5% and 10% hydrogen peroxide. The concentration of hydrogen peroxide in soil was high near the anode and decreased towards the cathode due to the direction of electroosmosis. The hydrogen peroxide concentration in effluent increased with time, but the value was lower than the initial. The removal efficiency of phenanthrene at 10% hydrogen peroxide was higher than the case at 3.5%. The removal efficiency after 7 days was high(> 97%) in both cases.

• 자원환경지질
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• 제32권1호
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• pp.43-51
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• 1999

In order to remediate hazardous waste site, a process of electrokinetically purging chemicals from saturated soil is examined by laboratory experiments. Electrokinetic soil remediation is one of the most promising soil decontamination processes that habe igh removal efficiency and time-effectiveness in low-permeability soils such as clay. Being combined with several mechanisms-electromigration, elec troosmosis, diffusion and electrolysis of water, electrokinetic soil processing can remove non-polar organics as well as ionic contaminants. The objectives of this study are; 1) the exploration of the feasibility of electrokinetic soil processing on the removal of heavy metals, 2) the investigation of applicability to the tailing-soils in aban doned mining area, 3) the examination of effects of soil pH and conductivity on the transport phenomena of elements in soils, and 4) the investigation of the applicability of the ionexchange membrance to the efficient collection of heavy metals removed from contaminated soils. With the result of this study, it is suggested that the removal efficiency is significantly influenced by applied voltage & current, type of purging solutions, soil pH, permeability and zeta potentials of soil. Although further study should be needed, it is possible to collect removed heavy metals with ion-exchange membrance in cathode compartment.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.181-185
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• 2004

Electrokinetic bioremediation was conducted on phenanthrene-contaminated soil to study the effects of soil temperature and pH on microbial population and removal efficiency at different current densities from 0.63 to 3.13 mA cm$^{-2}$ . Microorganism used in the biodegradation of phenanthrene was Sphingomonas sp. 3Y, which was isolated from a diesel-contaminated site. The microorganism was successfully penetrated into the contaminated soil by electrokinetic phenomena and the highest microbial population was observed in the middle region of soil specimen where soil pH was near neutral. Therefore, phenanthrene removal occurred mainly at anode and middle parts of soil specimen due to a relatively high microbial population. Also, the highest removal efficiency of 68.8% was obtained at 1.88 mA cm$^{-2}$ while low degradation was detected at 3.13 mA cm$^{-2}$ . It was presumably because the soil temperature at 1.88 mAcm$^{-2}$ was close to the appropriate temperature of about 30'c while the temperature increase to above 45$^{\circ}C$ at 3.13 mA cm$^{-2}$ inhibited the microbial activity severely.