• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.133-138
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• 2006

Chemical wastes containing small amounts of uranium can not be disposed of them after treatment as an industrial waste, because the uranium concentration in the final dry cake exceeds the exemption level. Especially for the removal of uranium in this study, the method for immobilizing Diphosil powder within alginate beads is adopted to make a bead form from a powdered resin. Sodium alginate bead itself showed a capability to uptake uranium to above 60%, but the value was decreased to below 30% after equilibrium. The adsorption rate of uranium increased with the increasing content of Diphosil in the sodium alginate bead. Diphosil resin itself showed very fast uptake of uranium from early stages, and then the rates were leveled off. Diphosil bead showed an improved capability to uptake uranium considering the pure Diphosil content in the composite bead, and provide a considerable potential for further applications of a continuous process by using Diphosil as a bead form.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.603-618
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• 2023

This study focused on evaluating the suitability of the WRK (waste repository Korea) bentonite as a buffer material in the SNF (spent nuclear fuel) repository. The U (uranium) adsorption/desorption characteristics and the adsorption mechanisms of the WRK bentonite were presented through various analyses, adsorption/desorption experiments, and kinetic adsorption modeling at various pH conditions. Mineralogical and structural analyses supported that the major mineral of the WRK bentonite is the Ca-montmorillonite having the great possibility for the U adsorption. From results of the U adsorption/desorption experiments (intial U concentration: 1 mg/L) for the WRK bentonite, despite the low ratio of the WRK bentonite/U (2 g/L), high U adsorption efficiency (>74%) and low U desorption rate (<14%) were acquired at pH 5, 6, 10, and 11 in solution, supporting that the WRK bentonite can be used as the buffer material preventing the U migration in the SNF repository. Relatively low U adsorption efficiency (<45%) for the WRK bentonite was acquired at pH 3 and 7 because the U exists as various species in solution depending on pH and thus its U adsorption mechanisms are different due to the U speciation. Based on experimental results and previous studies, the main U adsorption mechanisms of the WRK bentonite were understood in viewpoint of the chemical adsorption. At the acid conditions (＜pH 3), the U is apt to adsorb as forms of UO₂²⁺, mainly due to the ionic bond with Si-O or Al-O(OH) present on the WRK bentonite rather than the ion exchange with Ca²⁺ among layers of the WRK bentonite, showing the relatively low U adsorption efficiency. At the alkaline conditions (>pH 7), the U could be adsorbed in the form of anionic U-hydroxy complexes (UO₂(OH)₃^-, UO₂(OH)₄^2-, (UO₂)₃(OH)₇^-, etc.), mainly by bonding with oxygen (O^-) from Si-O or Al-O(OH) on the WRK bentonite or by co-precipitation in the form of hydroxide, showing the high U adsorption. At pH 7, the relatively low U adsorption efficiency (42%) was acquired in this study and it was due to the existence of the U-carbonates in solution, having relatively high solubility than other U species. The U adsorption efficiency of the WRK bentonite can be increased by maintaining a neutral or highly alkaline condition because of the formation of U-hydroxyl complexes rather than the uranyl ion (UO₂²⁺) in solution,and by restraining the formation of U-carbonate complexes in solution.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.704-712
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• 2006

This research was designed to investigate the removal of heavy metals, such as $Al^{3+}$, $Cu^{2+}$, $Mn^{2+}$, $Pb^{2+}$ and $Zn^{2+}$, by adsorption on clay minerals. Bentonite(Raw-Bentonite), $Ca^{2+}$ and $Na^+$ ion exchanged bentonite(Ca- and Na-Bentonite) and montmorillonite, such as KSF and K10 from Sigma Aldrich, were used as adsorbents. The component of five inorganic adsorbents was analyzed by XRF, and the concentration of metal ions was measured by ICP. The cation exchange capacity(CEC) and the particle charge of adsorbents were measured. The initial concentration range of metal ions was $10{\sim}100$ mg/L. From the experimental results, it was shown that the adsorption equilibrium was attained after $1{\sim}2$ hours. The maximum percentage removal of $Al^{3+}$, $Cu^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ on Na-Bentonite were more than 98% and that of $Mn^{2+}$ was 66%. $Al^{3+}$ was leached out from KSF with the higher concentration of hydrogen ion. Percentage removals of $Pb^{2+}$ and $Zn^{2+}$ on KSF were 88% and 59%, respectively. In general, the percentage removal of metal ions was decreased with the higher initial concentration of metal ions. The adsorption capacity of metal ions on Na-Bentonite was $1.3{\sim}19$ mg/g. Freundlich equation was used to fit the acquired experimental data. As the results, the adsorption capacity of metal ions was in the order of Na-Bentonite$\gg$Raw-Bentonite$\cong$K10>Ca-Bentonite>KSF. Freundlich constant, K of Na-Bentonite was the largest for metal ions. The order K of Na-Bentonite was Al>Cu>Pb>Zn>Mn, and the adsorption intensity(1/n) was determined to be $0.2{\sim}0.39$.

• Journal of Soil and Groundwater Environment
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• v.13 no.2
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• pp.1-11
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• 2008

Phenanthrene uptake by surfactant sorbed on activated carbon was investigated to recycle of surfactant in washed solution for contaminated soil. The partitioning of phenanthrene to the activated carbon coating with Triton X-100 as a surfactant was also evaluated by a mathematical model. Phenanthrene-contaminated soil (200 mg/kg) was washed in 10 g/L of surfactant solution. Washed phenanthrene in solution was separated by various particle loadings of granular activated carbon through a mode of selective adsorption. Removal of phenanthrene was 99.3%, and surfactant recovery was 88.9% by 2.5 g/L of granular activated carbon, respectively. Phenanthrene uptake by activated carbon was greater than that of phenanthrene calculated by a standard model for a system with one partitioning component. This is accounted for enhanced surface solubilization by hemi-micelles adsorbed onto granular activated carbon. The effectiveness factor is greater than 1 and molar ratio of solubilization to sorbed surfactant is higher than that of liquid surfactant. Results suggest that separation of contaminants and surfactants by activated carbon through washing process in soil is much effective than that of calculated in a theoretical model.

• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.8-15
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• 2013

Little research has been conducted to explore the heavy metal removal potential of biochar. The adsorption characteristics of heavy metals by sesame waste biochar (pyrolysis at $600^{\circ}C$ for 1 hour) as heavy metal absorbent were investigated. The sesame waste biochar was characterized by SEM-EDS and FT-IR, and heavy metal removal was studied using Freundlich and Langmuir equations. The removal rates of heavy metals were higher in the order of Pb>Cu>Cd>Zn, showing that the adsorption efficiency of Pb was higher than those of any other heavy metals. Freundlich and Langmuir adsorption isotherms were used to model the equilibrium adsorption data obtained for adsorption of heavy metals on biochar produced from sesame waste. Pb, Cu, Cd and Zn equilibrium adsorption data were fitted well to the two models, but Pb gave a better fit to Langmuir model. Heavy metals were observed on the biochar surface after adsorption by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Main functional groups were aromatic C=O ring (at $1160cm^{-1}$, $1384cm^{-1}$ and $1621cm^{-1}$) by FT-IR analysis. Thus, biochar produced from sesame waste could be useful adsorbent for treating heavy metal wastewaters.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.576-583
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• 2023

This study investigated the possibility of new adsorbent materials made from pig bone-based biomass. To this end, the properties of pig bone-based activated carbon (PAC) prepared from animal biomass were investigated, and its carbon dioxide adsorption performance was examined. KOH was used as the activation agent, and the specific surface area increased with increasing activation temperature, and the adsorption efficiency of carbon dioxide also increased. The sample activated at 800 ℃ exhibited the largest specific surface area of 1208.7 m²/g and the highest CO₂ adsorption efficiency of 3.33 mmol/g at 273 K, 1 bar. However, the specific surface area and the CO₂ adsorption efficiency decreased at activation temperatures above 900 ℃ due to crystallinity changes and overactivation. On the other hand, when the selectivity was calculated using the ideal adsorption solution theory, PAC-900 samples at 273 K and below 0.8 bar showed the best selectivity. These results suggest that the high selectivity of carbon dioxide/nitrogen adsorption at 273 K is due to the carbon dioxide adsorption capacity of hydroxyapatite formed by the decomposition of carbonate when pig bone is activated at 900 ℃ and its crystallinity.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.141-143
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• 2006

Carboxylic phthalocyanine합성물을 분석한 결과 Copc의 Co가 3.06Wt.(%)에서 Cooapc가 0.28Wt.(%)로 나타난 것으로 보아 carboxylic group이 증가한 것을 알 수 있었으머, Fepc도 같은 결과로 나타났다. 휘발성유기화합물의 제거효율을 분석한 결과 극성이 높은 물질은 쉽게 흡착 되었으며 일부 제거가 되지 않은 물질은 Fig.3, Fig.4에서 보는바와 같이 Feoapc보다는 Cooapc가 제거효율이 높은 것으로 나타났다.

• Nuclear Engineering and Technology
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• v.16 no.3
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• pp.161-168
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• 1984

The adsorption model to predict the time dependent removal efficiency of methyl iodide by triethylenediamine (TEDA) impregnated charcoal bed under humid condition is proposed. Under humid conditions, the reduction of equilibrium adsorption capacity and effective pore diffusivity is considered. The predicted values are compared with the experimental results.

• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.700-705
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• 2012

The present study is to explore the possibility of utilizing loess and fly ash as well as activated carbon for the adsorptive removal of T-N and T-P in water. Here, we investigated adsorption efficiency and Freundlich constants k and 1/n of each adsorbent. It was found that fly ash has not adsorptive capability for both T-N and T-P in water. Adsorption of T-N from water by loess has not occurred, but showed that adsorption efficiency for T-P reached approximately 57.5% at equilibrium time of 24 hr and room temperature. Activated carbon was shown to be an effective adsorbent for adsorption of T-N from water. Freundlich constant 1/n value of activated carbon represented that adsorptive capability of activated carbon is almost equivalent to loess.