Seocho, South Korea
Seocho, South Korea

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Kim W.-S.,Kumoh National Institute of Technology | Park G.-Y.,Kumoh National Institute of Technology | Kim D.-H.,Kumoh National Institute of Technology | Jung H.-B.,Ecophile Co. | And 2 more authors.
Electrochimica Acta | Year: 2012

We evaluated the influence of electrode configuration on in situ electrokinetic remediation of As-, Cu-, and Pb-contaminated soil in a pilot-scale field application. Dense electrode configurations resulted in high current under a constant voltage gradient, the high current raised soil temperature, and it caused unnecessary electrical energy consumption. Additionally, temperature increase in soil transported pore water from bottom to top layer, which accumulated contaminants in the top soil layer because the mobilized contaminants was co-transported by the water flow. On the other hand, the groundwater flow, gravitational force, and electro-osmotic flow were combined together and affected complexly the transport of mobilized contaminants. Sequential extraction showed that electrokinetic treatment increased the residual fraction of As, the fraction of Cu bound to organic matter, and the fraction of Pb bound to organic matter and residual portion. This result implies that the groundwater flow and soil temperature should be monitored during the remediation and the configuration should be considered to minimized unnecessary transport of contaminants. © 2012 Elsevier Ltd. All rights reserved.

Kim D.-H.,Korea Army Academy at Yeong Cheon | Jo S.-U.,Eco Phile Co. | Yoo J.-C.,Chonbuk National University | Baek K.,Chonbuk National University
Separation and Purification Technology | Year: 2013

This study was conducted to investigate electrokinetic removal of salts from saline soil with reduced electrical energy consumption using pulsed current that periodically repeats on/off using a direct current (DC) power supply in a pilot scale system (15 min on and off periodically). Each experiment was operated with a constant voltage gradient of 1 V/cm in a reactor (1 × 1 × 0.18 m) using real saline soil during 9 weeks. The removal efficiency of anions in the conventional DC system was slightly higher than that of the pulse system. However, there was less of a difference in removal efficiency between the conventional DC and pulse systems, except with NO3-. The removal efficiency of cations in the conventional DC system was higher than that of the pulse system, which is beneficial for cultivation because cations such as Na +, Mg2+ and K+ are essential elements for crop growth. Even though the pulsed current removed slightly fewer salts and less electrical conductivity than conventional power, the system lowered the electrical energy consumption to 64% and effectively prevented pH changes and electrode corrosion compared with conventional power. Therefore, pulsed current could be an effective technique for electrokinetic restoration of saline soil. © 2013 Elsevier B.V. All rights reserved.

Jeon E.-K.,Chonbuk National University | Jung J.-M.,Chonbuk National University | Kim W.-S.,Korea Environment Corporation | Ko S.-H.,Ecophile Co. | Baek K.,Chonbuk National University
Environmental Science and Pollution Research | Year: 2014

We investigated the in situ applicability of the electrokinetic process with a hexagonal electrode configuration in order to remediate arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated paddy rice field soil at a field scale (width 17 m, length 12.2 m, and depth 1.6 m). An iron electrode was used in order to prevent the severe acidification of the soil near the anode. We selected ethylenediaminetetraacetic acid (EDTA) as a pursing electrolyte to enhance the extraction of Cu and Pb. The system removed 44.4 % of the As, 40.3 % of the Cu, and 46.6 % of the Pb after 24 weeks of operation. Fractionation analysis showed that the As bound to amorphous ion (Fe) and aluminum (Al) oxyhydroxides was changed into a form of As specifically bound. In the case of Cu and Pb, the fraction bound to Fe-Mn oxyhydroxide primarily decreased. The EDTA formed negatively charged complexes with Cu and Pb, and those complexes were transported toward the anode. The energy consumption was very low compared to that on a small scale because there was less energy consumption due to Joule heating. These results show that the in situ electrokinetic process could be applied in order to remediate paddy rice fields contaminated with multiple metals. © 2014 Springer-Verlag Berlin Heidelberg.

Kim Y.-H.,Kumoh National Institute of Technology | Kim Y.-H.,Eco Phile Co. | Kim D.-H.,Kumoh National Institute of Technology | Jung H.-B.,Eco Phile Co. | And 3 more authors.
Separation Science and Technology (Philadelphia) | Year: 2012

In this study, the effectiveness of ex situ electrokinetic remediation (EKR) in treating actual As-contaminated soil was evaluated at a pilot scale (1 m [W] × 1 m [L] × 1.5 m [H]). Ethylenediamine tetraacetic acid (EDTA) and sodium hydroxide as the catholyte and anolyte, respectively, were circulated to enhance the desorption of As. Two types of soil were collected from a real contaminated agricultural area: silty loam from a rice paddy and sandy clay loam from dry land. An average of 78% of the As was removed from the two types of soil after 8 weeks, and the residual As concentration met the level set by Korean legal regulations. The average removal rates were 1.06 and 1.55 mg/kg/day, respectively, for the paddy and dry field soil samples. In addition, fractionation analysis showed that most other fractions and even a large portion of the residual fraction were removed after EKR. The ex situ application provided electrolyte more uniformly to the entire soil sample; therefore, there was no significant variation in As removal depending on the depth of the soil. These results indicated that ex situ EKR is an effective technique for the remediation of As-contaminated sites. © 2012 Copyright Taylor and Francis Group, LLC.

Kim K.-J.,Kumoh National Institute of Technology | Cho J.-M.,Kumoh National Institute of Technology | Baek K.,Kumoh National Institute of Technology | Yang J.-S.,Korea Institute of Science and Technology | Ko S.-H.,EcoPhile Co.
Journal of Applied Electrochemistry | Year: 2010

A laboratory-scale investigation was carried out to study the characteristics of electrokinetic (EK) movement for separation of salts from tideland. The salinity of tideland material, including the sodium and chloride contents, was investigated as a function of operation time under a constant voltage gradient of 1 V/cm. As the operation period increased, the salinity of tideland material decreased gradually. However, the rate of decrease gradually diminished with an increase in the operation period. The electrical current increased gradually with the operation time. Ten days of electrokinetic operation decreased the electrical conductivity of the tideland material to 65.5% of the initial value. Sodium was removed completely, but the removal efficiency of chloride was 58.5% after 10 days. The lower removal of chloride was due to the formation of complexes with magnesium and calcium. High concentrations of chloride formed chlorine gas in the anolyte, and aqueous chlorine oxidized the circulation tube. The pH distribution after electrokinetic treatment showed a typical shape, and the change in water content was negligible. The results demonstrate that the electrokinetic process is a suitable means to remove salinity from tidelands. © Springer Science+Business Media B.V. 2010.

Kim B.-K.,Korea Railroad Research Institute | Park G.-Y.,Dasan Building | Jeon E.-K.,Chonbuk National University | Jung J.-M.,Chonbuk National University | And 3 more authors.
Water, Air, and Soil Pollution | Year: 2013

An electrokinetic technique was used to remediate As-, Cu-, and Pb-contaminated paddy soil in a real field on a pilot scale. A hexagonal electrode placement with one anode at the center and six cathodes at the vertices of the hexagon was installed in the field. After operation for 4 weeks, the average removal of Pb was 64.9 % in the top layer (0-0.4 m), 81.2 % in the middle layer (0.4-0.8 m), and 66.9 % in the bottom layer (0.8-1.2 m). The removal of As was 28.2 % in the top layer, 43.2 % in the middle layer, and 24.5 % in the bottom layer. The removal of Cu was 17.7 % in the middle layer and was not observed in the other layers. The relatively high removal of Pb might come from the more labile fraction of Pb in soil compared to As and Cu. However, the circulation of anolyte using an alkaline solution to enhance removal of As failed because the electrolyte leaked between the anode and surrounding soil. Effective circulation might enhance the performance of the electrokinetic process. © 2013 Springer Science+Business Media Dordrecht.

Kim B.-K.,KAIST | Baek K.,Kumoh National Institute of Technology | Ko S.-H.,Ecophile Co. | Yang J.-W.,KAIST
Separation and Purification Technology | Year: 2011

As public concerns regarding soil contamination and the related market size have grown in Korea, various soil remediation technologies have been developed. Electrokinetic (EK) remediation has emerged as a promising and effective technology that can be used to remove both organic and inorganic pollutants from soil. Since 1996, when the first EK remediation experiment was conducted in Korea for soil contaminated with heavy metals, many researchers have investigated different EK system configurations or have modified EK remediation methods to suit particular types of soils to achieve enhanced performance. This paper provides an overview accomplishments and the current status of EK remediation technologies in Korea. It discusses current lab-scale experiments, pilot-scale experiments, field applications, and other ongoing research and development projects. Moreover, prospective topics for future research in EK remediation are also suggested. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

Yang J.-S.,Korea Institute of Science and Technology | Kim Y.-S.,Ecophile Co. | Park S.-M.,Chonbuk National University | Baek K.,Chonbuk National University
Environmental Science and Pollution Research | Year: 2014

To test the feasibility of the reuse of iron-rich sludge (IRS) produced from a coal mine drainage treatment plant for removing As(III) and As(V) from aqueous solutions, we investigated various parameters, such as contact time, pH, initial As concentration, and competing ions, based on the IRS characterization. The IRS consisted of goethite and calcite, and had large surface area and small particles. According to energy dispersive X-ray spectroscopy mapping results, As was mainly removed by adsorption onto iron oxides. The adsorption kinetic studies showed that nearly 70 % adsorption of As was achieved within 1 h, and the pseudo-second-order model well explained As sorption on the IRS. The adsorption isotherm results agreed with the Freundlich isotherm model, and the maximum adsorption capacities for As(III) and As(V) were 66.9 and 21.5 mg/g, respectively, at 293 K. In addition, the adsorption showed the endothermic character. At high pH or in the presence of phosphate, the adsorption of As was decreased. When the desorption experiment was conducted to reuse the IRS, 85 % As was desorbed with 1.0 N NaOH. In the column experiment, adsorbed As in real acid mine drainage was 43 % of the maximum adsorbed amount of As in the batch test. These results suggested that the IRS is an effective adsorbent for As and can be effectively applied for the removal of As in water and wastewater. © 2014, Springer-Verlag Berlin Heidelberg.

Jo S.,Ecophile Co. | Shin Y.-J.,Chonbuk National University | Yang J.-S.,Korea Institute of Science and Technology | Moon D.H.,Chosun University | And 2 more authors.
Water, Air, and Soil Pollution | Year: 2015

The electrokinetic transport of sulfate was investigated as a means of treating and restoring a sulfate-accumulating saline soil. The electrokinetic treatment decreased the electrical conductivity of the soil, an indicator of soil salinity, to 58.6, 73.1, and 83.5 % for 7, 14, and 21 days, respectively. More than 96 % of the chloride and nitrate were removed within 7 days. However, the removal of sulfate was highly influenced by the anode material. An iron anode removed sulfate effectively, whereas sulfate was hyper-accumulated in the anodic region when an inert anode was used. The iron anode was oxidized in a sacrificial anodic reaction, which competed with the electrolysis reaction of water at the anode, and finally, the reaction prevented the severe acidification of the soil in the anodic region. However, the competing reactions produced hydrogen ions at the anode and the ions were transported toward the cathode, which, in turn, acidified the soil, especially in the anodic region. The acidification switched the surface charge of the soil from negative to positive, increasing the interaction between the soil surface and sulfate and thus inhibiting the transport of sulfate under the electric field. The zeta potential analysis of the soil provided an explanation. The results indicate that preventing severe acidification is an important factor which influences the transport of anions and iron anode for the enhanced removal of anionic pollutants by electrokinetic remediation. © 2015 Springer International Publishing Switzerland.

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