• Journal of Soil and Groundwater Environment
• /
• v.8 no.1
• /
• pp.1-8
• /
• 2003

Three different surfactants, APG, Brij30, and SDS, were tested to study the characteristics of sorption on soil surfaces, washing ability, biodegradability, and electrokinetic removal. Kaolinite and phenanthrene were selected as a model soil and a representative HOC, respectively. Phenanthrene was sorbed on kaolinite up to 2,200 mg/kg dry soil. The APG, Brij30, and SDS were sorbed on soil to 40, 7, and 4g/kg soil, respectively. The washing ability of phenanthrene was in order of Brij30＆gt;SDS＆gt;APG. The biodegradability tested with sludge was in order of APG＆gt;Brij30＆gt;SDS. In the electrokinetic test, the highest removal efficiency was obtained with APG that exhibited the highest electroosmotic flow. To increase the removal efficiency of HOC in the electrokinetic remediation, the most important factor was the selection of surfactant which maximized the electroosmotic flow.

• Journal of Soil and Groundwater Environment
• /
• v.6 no.1
• /
• pp.13-21
• /
• 2001

The characteristics of $Co^{2+}$ removal in the kaolinite column were analyzed by electrokinetic remediation. Ethanoic buffer was injected in the kaolinite column and $CH_3$COOH was continuously added to the cathode reservoir to restrain the pH increase. The pH of the cathode of the kaolinite column was 4.0 at first. Since it was controlled to be under 6.5 after 43.6 hours due to ethanoic buffer, precipitation of ${Co(OH)}_2$ was not formed in the column. Effluent rate increased with time and $Co^{2+}$ removal in the column at initial time was mainly controlled by ion migration. 13.1% of total $Co^{2+}$ in the column was removed after 10 hours, the 46.8% of total $Co^{2+}$ after 20.8 hours, and the 71.7% of total $Co^{2+}$ after 30.1 hours, the 94.6% of total $Co^{2+}$ after 43.6 hours, Meanwhile, the residual concentrations in the column calculated by the developed model were similar to experiment results.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.2 no.2
• /
• pp.145-153
• /
• 2004

H$_2$SO$_4$ and citric acid were used as additives for the electrokinetic remediation experiment to increase removal efficiency of $^{137}$ Cs and $^{60}$ Co from the radioactive soil waste stored for more than 10 years. The average effluent velocity discharged from the elctrokinectic remediation experimental column was 2.0${\times}$10$^{-2}$ cm/min and the discharged soil wastewater volume for 10 days is 3.6 pore volume of the column. 97% of $^{60}$ Co in the column was decontaminated for 10 days of operation, while only 54% of $^{137}$ Cs was decontaminated. These results are considered that the absorption equilibrium coefficient of $^{137}$ Cs is higher than that of $^{60}$ Co. The predicted values of the residual concentration by the proposed mathematical model were well coincided with the experimental results within the experimental error range

• Journal of Environmental Impact Assessment
• /
• v.24 no.4
• /
• pp.344-351
• /
• 2015

In this study, bio-electrokinetics was used to increase migration of arsenic by activating endemic microorganisms in the soil. In this technology, bio-electrokinetics which the cultured soil microorganisms and nutrients injected combines with biological technology. This technology using electrical movement of microorganisms could overcome the weakness of late degradation speed and low removal efficiency. And, various soil microorganisms reduce ferreous, manganese, etc., using organic matter by as an electron donor by injecting mixture of soil microorganisms and nutrients instead of using electrolyte of the electrode. Accordingly, surrounding metal oxide microorganisms convert arsenic (III) to arsenic (V) to increase migration of arsenic (III), in consequence, migration of arsenic increased in 60 to 70% compared to about 30% of conventional electrokinetics.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.11
• /
• pp.2007-2016
• /
• 2000

After kaolin clay was compulsorily contaminated with $Sr^{2+}$ ion. the remediation characteristics by electrokinetic method were analyzed. In the first experiment. NaCl solution was used as an electrolyte to raise the electric field strength. After remediation for 0.8 days. the pH of the cathode side of the soil column was elevated from 4.0 to 11.7. and thereby precipitation $Sr(OH)_2$, started to be formed in the side. Therefore. efficiency of soil remediation was reduced significantly and the 32% of total $Sr^{2+}$ ion in the column was decontaminated in 6.7 days. In the second experiment. ethanoic buffer was injected in the soil column and $CH_3COOH$ was continuously inputted in cathode reservoir to restrain the pH elevation. The pH of the cathode side of the soil column was only ascended from 4.0 to 6.0 in 3.8 days and $Sr(OH)_2$ was not formed. The 21% of total $Sr^{2+}$ in the soil column was decontaminated in 0.6 days. and the 33% of total $Sr^{2+}$ in 0.9 days. and the 84% of total $Sr^{2+}$ in 1.6 days. and the 92% of total $Sr^{2+}$ in 2.5 days. and the 97% of total $Sr^{2+}$ in 3.8 days. Meanwhile. the residual concentrations in the column calculated by the developed model were similar to those by experiment.

• Journal of Soil and Groundwater Environment
• /
• v.7 no.3
• /
• pp.85-94
• /
• 2002

Overall objective of this study was to evaluate the electrochemical characteristics of fine soils during the electrokinetic(EK) remediation. Zeta potential of kaolinite as a function of solution pH and surfactant concentration was investigated to make a relationship with electroosmotic flow direction and rate. During the EK experiments, pH of pore solution, electroosmotic permeability($k_e$), electric conductivity($\delta_e$) and voltage distribution was measured, respectively, The point of zero charge(PZC) of kaolinite was estimated to be about 4.2 and the zeta potential of kaolinite above PZC was more negative as solution pH increased. Sorption of surfactants on the kaolinite altered the zeta potential of kaolinite. resulting from the variation of electrochemical characteristics of kaolinite surface. hs the EK experiment progressed, low pH was predominant over most of the kaolinite specimen and thus resulted in very low mass and charge flow. The $k_e$ and $\delta_e$ was also affected by the variation of voltage drop across the EK column with time. Results from this study implied that zeta potential of kaolinite affected by the pH variation of pore solution and voltage distribution in soil column played important role in the determination of mass and charge flow during EK process. It was also suggested that pH adjustment or addition of suitable sorbates could alter the electrochemical characteristics of soil surface and thus maintain high mass and charge flow rate with time.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.696-700
• /
• 2003

$H_2SO_4$ and citric acid had higher extraction efficiency of $^{137}Cs$ from soil than the other chemicals. Thus, $H_2SO_4$and citric acid were used as additives on remediation experiment by electrokinetic method to increase removal efficiency of $^{137}Cs$ from the radioactive soil being stored during a long time. An average velocity of effluent discharged from experimental column $2.0{\times}10^{-2}$/cm/min and a volume of the discharged soil wastewater for 10 days is 3.6 Pore Volume. The 54% of a total of $^{137}Cs$ in the column was decontaminated for 10 days. Furthermore, the predicted values of residual concentration by the developed model were quite similar to those obtained from experiments.