• Korean Journal of Environmental Agriculture
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• v.16 no.1
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• pp.72-79
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• 1997

Adsorption, leaching, and retention of the Flupyrazofos(KH-502), a new active ingredient for insecticide, in the soils under laborarory and field conditions were investigated to provide the basic data for the safety use and to assess a secondary impact of this insecticide on soil and water environments. A significant power function relation was found between the adsorbed KH-502 and time, representing that 45% of the added KH-502 was adsorbed within 30 min. but a quasiequilibrium was reached after 6 to 12 hr with a slower adsorption. Adsorption phenomena followed th first-order kinetics and time required for 50% adsorption was 5.8 hr. The equilibrium adsorption isotherm was explained by the Freundlich equation and was classified as S-type. The amounts of KH-502 leached through the soil column (C) as compared to initial conc. ($C_0$) were very low and these relative concentrations ($C/C_0$) were 0.073 and 0.017 in SL and CL soils, respectively. The residual conc. of KH-502 in the surface soil was comparatively low and decreased with time. Half-lives of KH-502 in the surface soil was comparatively low and decreased with time. Half-lives of KH-502 under the field conditions were estimated to be 20 and 18 days in the SL and CL soils, respectively. The KH-502 cone, transported to the subsurface soils was extremely low. These results demonstrate that KH-502 has a low pollution risk potential to the surrounding environment as far as it is used following the recommended guideline.

• Korean Journal of Environmental Agriculture
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• v.5 no.2
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• pp.101-105
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• 1986

An adsorption and desorption experiment was conducted to utilize natural zeolite as cadmium adsorbent in wastewater. Adsorption of cadmium by natural zeolite was conformed to Freundlich's adsorption equation and natural zeolite was found to be effective adsorbent. The higher the cadmium concentration of solution, the more the adsorption amount of cadmium was and the adsorption was in the order of $Ca-<Nontreated-<H-{\leqq}Al-<Nazeolite$. Ion selectivity of natural zeolite in mixed solution increased in the order of Cd$NaCl<CaCl_2<AlCl_3<HCl$.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.623-629
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• 2011

The adsorption characteristics of tricyclazole by granular activated carbon were experimently investigated in the batch adsorption. Kinetic studies of adsorption of tricyclazole were carried out at 298, 308 and 318 K, using aqueous solutions with 250, 500 and 1,000 mg/L initial concentration of tricyclazole. It was established that the adsorption equilibrium of tricyclazole on granular activated carbon was successfully fitted by Freundlich isotherm equation at 298 K. The pseudo first order and pseudo second order models were used to evaluate the kinetic data and the pseudo second order kinetic model was the best with good correlation. Values of the rate constant ($k_2$) have been calculated as 0.1076, 0.0531, and 0.0309 g/mg h at 250, 500 and 1,000 mg/L initial concentration of tricyclazole, respectively. Thermodynamic parameter such as activation energy, standard enthalpy, standard entropy and standard free energy were evaluated. The positive value for enthalpy, -66.43 kJ/mol indicated that adsorption interaction of tricyclazole on activated carbon was an exothermic process. The estimated values for standard free energy were -5.08~-8.10 kJ/mol over activated carbon at 200 mg/L, indicated toward a exothermic process.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.663-672
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• 2009

In this studies, the adsorption test using Chlorella pyrenoidosa was conducted to examine the effect of Pb adsorption according to various immobilized methods such as Ca-alginate, K-carrageenan, and Polyacrylamide. From the results, the duration to need to reach adsorption equilibrium was delayed according to the immobilization. And, the higher adsorption capacity of immobilized Chlorella pyrenoidosa was represented in the higher concentration of Pb, the smaller amount of immobilizing agent, and the higher pH of solution. The maximum adsorption capacity of Pb was shown in the adsorption test using Chlorella pyrenoidosa immobilized with Ca-alginate even though it was sensitive pH. The adsorption results properly represented with Freundlich isotherm equations. And, pseudo second-order chemisorption kinetic rate equation was applicable to all the biosorption data over the entire time range. The FT-IR analysis showed that the mechanism involved in biosorption of Pb by Chlorella pyrenoidosa was mainly attributed to Pb binding of carbo-acid and amide group. Adsorbed Pb on immobilized Chlorella prenoidosa was easily desorbed in the higher concentration of desorbents(NTA, HCl, EDTA, $H_2SO_4,\;Na_2CO_3$). Among the several desorbents, NTA showed the maximum desoption capacities of Pb from Chlorella pyrenoidosa immobilized with Ca-alginate and K-carrageenan and EDTA was the most effective in Chlorella pyrenoidosa immobilized with polyacrylamide. The desoprtion efficiency in the optimum condition was 90.0, 83.0, and 80.0%, respectively.

• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.459-463
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• 2012

In the present study, experiments have been performed to investigate the effects of the type of adsorbent, pH, and ionic strength on the adsorption of nutrients (nitrate and phosphate in artificial solution) onto the dredged sediment from a coastal fishery. In addition, this study aims to evaluate the possibility of removing the nutrients from the water using the dredged sediment. In the adsorption experiments of the nutrients, the reactions were completed within 10 minutes using ${NO_3}^-$-N($100{\mu}M$, 10mM) and ${PO_4}^{3-}$-P($100{\mu}M$, 10mM). In the steady state, 61% and 77% of the initial amounts were removed respectively for $100{\mu}M$ ${NO_3}^-$-N and $100{\mu}M$ ${PO_4}^{3-}$-P. The thermal treatment of the dredged sediment at $900^{\circ}C$ was not helpful to increase the removal efficiencies of the nutrients. Additives such as CaO and MgO dropped the removal efficiency of ${NO_3}^-$ to 0%, but increased that of ${PO_4}^{3-}$ up to 98%. Adsorption isotherms of ${NO_3}^-$ and ${PO_4}^{3-}$ could be explained by the Freundlich equation ($R^2$>0.99). The adsorption reaction was little influenced by the pH and ionic strength. Based on the results showing short reaction time and considerably high removal efficiencies of the nutrients, it is proposed to apply the dredged sediment from a coastal fishery to removing nutrients such as nitrate and phosphate in the water.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.325-332
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• 1998

This study was carried out to investigate the adsorption and the movement of herbicide fenoxaprop-P-ethyl in the silty clay soil(SiC) and the sandy loam soil(SL). Fifteen percent of the added herbicide was adsorbed within 30 min after shaking, and a quasi-equilibrium was reached after 8 to 14 h. The time required for 50% adsorption was 15.8 h in the SiC and 19.3 h in the SL. The equilibrium adsorption isotherm was followed by the Freundlich equation and the Kd was 3.86 in the SiC and 2.32 in the SL. The herbicide in the soil columns flooded with 3 cm water depth and eluted at 0.8 cm/day was leached to 6 cm and 8 cm depth at 7 and 21 days after the treatment, respectively. However, the movement was widened with increased amount of leaching water. The herbicide in the field soils was moved up to 6 cm and 8 cm depth at 14 and 56 days after the treatment, respectively. However, the large amount of the applied herbicide was distributed in 0~2 cm profile in all of the soils examined. Half-life of the chemical in soils was shorter than 7 days and the time to 90% degradation was about 4 weeks. The results indicate that the herbicide has relatively small mobility and short persistence.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.327-332
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• 1987

Soil samples were collected from the paddy soils growing two crops of rice and garlic in Kyung-pook province. To obtain the basic information on the application of S-fertilizer in the garlic field, the adsorption and release amount of $SO_4{^{-2}}$ in subsoil samples were determined. The ranges of $SO_4{^{-2}}$ contents in surface and sub-soil were 59-117 and 34-102 ppm, respectively. The amount of $SO_4{^{-2}}$ adsorbed by soil samples was found to be more at lower pH and higher concentration of $SO_4{^{-2}}$. The $SO_4{^{-2}}$ adsorption constants in Freundlich equation tended to be higher at lower pH. It is apparent that most of $SO_4{^{-2}}$ was released in the first extraction. However, the lower the pH of extracted solution, the more the $SO_4{^{-2}}$ contents was released by distilled water.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.526-531
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• 2020

Manganese ions contained in water phase are acting as a toxic substance in the human body and also known to affect the nervous system. In particular, effective treatment technology is required since manganese removal is difficult due to its high solubility in a wide pH range. In this study, Prinus densiflora bark was chemically modified with hydrogen peroxide, and the modified adsorbent was used for removing manganese ions in an aqueous solution. The modified adsorbent showed high removal capacity of 82.1 and 56.2%, respectively, at conditions of 5 and 10 mg/L manganese ions. Also, the adsorption isotherm from the data was applied to the theoretical equation. As a result, the adsorption behavior of manganese ions was better suited to the Langmuir than Freundlich model, and it was also found from kinematics that the pseudo-second order kinetic model was more suitable. In addition, the changes of Gibbs free energy indicated that the adsorption reaction became more spontaneously with increasing temperature. Consequently, these experimental results may be used as a water treatment technology which can efficiently treat manganese ions contained in water.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1045-1053
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• 2000

The adsorption and desorption of herbicides such as napropamide and pendimethalin was studied in three kinds of soil. sandy loam. silty clay and loam. The results of batch tests performed with various shaking time, pH, organic matter content and temperature in soil were summarized as follows. The shaking times reached to the equilibrium of the adsorption and desorption for napropamide and pendimethalin in soil were 12 and 6 hours. respectively. For each soil. the adsorption rates of napropamide were 23.35%. 31.57% and 25.95%, the desorption rates of them were 18.42%, 13.42% and 15.89%, respectively. And the adsorption rates of pendimethalin were 59.61%, 77.26% and 64.02%, and the desorption rates of them were 3.23%, 2.93% and 3.07%, respectively. The adsorption isotherms with the Freundlich equation showed better consistency than those with the Langmuir one. The adsorption was affected by the organic matter content when it exceed 2.0%. But if the organic matter content is below 2.0%, it was affected by the clay content. When the organic matter content is 0.95~7.45%, the adsorption coefficients ($K_{fa}$) of napropamide and pendimethalin were 1.17~2.50 and 4.74~16.08 and the desorption coefficients($K_{fd}$) of them were 5.33~34.06 and 24.25~134.00, respectively. Because of the physical adsorption between herbicide molecules and soil surface, little effect of pH variation of soils was appeared for the adsorption and desorption. Because of the solubility of herbicide is related to the temperature, the adsorption rate was decreased and the desorption rate was increased with the temperature increase, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.936-941
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• 2010

This study was conducted to investigate formaldehyde removals by silver nano-particles attached on the surface of granular activated carbon (Ag-AC) and to compare the results to those obtained with ordinary activated carbon (AC). The BET analysis showed that the overall surface area and the fraction of micropores (less than $20{\AA}$ diameter) of the Ag-AC were significantly decreased because the silver particles blocked the small pores on the surface of the Ag-AC. The formaldehyde removal capacity of the Ag-AC determined using the Freundlich isotherm was higher than that of AC. Despite the decreased BET surface area and micropore volume, the Ag-AC had the increased removal capacity for formaldehyde, presumably due to catalytic oxidation by silver nano-particles. In contrast, the adsorption intensity of the Ag-AC, estimated by 1/n in the Freundlich isotherm equation, was similar to that of the ordinary AC, indicating that the surface modification using silver nano-particles did not affect the adsorption characteristics of AC. In a column experiment, the Ag-AC also showed a longer breakthrough time than that of the AC. Simulation results using the homogeneous surface diffusion model (HSDM) were well fitted to the breakthrough curve of formaldehyde for the ordinary AC, but the predictions showed substantial deviations from the experimental data for the Ag-AC. The discrepancy was due to the catalytic oxidation of silver nano-particles that was not incorporated in the HSDM. Consequently, a new numerical model that takes the catalytic oxidation into accounts needs to be developed to predict the combined oxidation and adsorption process more accurately.