• Economic and Environmental Geology
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• v.38 no.1
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• pp.23-31
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• 2005

This study was performed to investigate the effect of humic acid on the adsorption of arsenic onto hematite and its binding mechanism through the chemical speciation modeling in the binary system and the adsorption modeling in the ternary system. The complexation modeling of arsenic and humic acid was suitable for the binding model with the basis of the electrostatic repulsion and the effect of bridging metal. In comparison with the experimental adsorption data in the ternary system, the competitive adsorption model from the binary intrinsic equilibrium constants was consistent with the amount of arsenic adsorption. However, the additive rule showed the deviation of model in the opposite way of cationic heavy metals, because the reduced organic complexation of arsenic and the enhanced oxyanionic competition diminished the adsorption of arsenic. In terms of the reaction mechanism, the organic complex of arsenic, neutral As(III) and oxyanionic As(V) species were transported and adsorbed competitively to the hematite surface forming the inner-sphere complex in the presence of humic acid.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.369-378
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• 2003

The statistical modeling was introduced to satisfy various experimental conditions on the sorption of heavy metals (Pb, Cu, Cd, and Zn) by clay minerals, i.e. kaolinite, illite and chlorite. The Box-Behnken model designed statistically was applied to determine a relative impact among three variables such as pH, HCO3(or K) concentration and initial concentration of heavy metals. The SAS program was used to obtain the statistical solution by surface response analysis. The results of a statistical sorption modelling indicated that pH is a strong impact of the variables influencing the sorption of heavy metals. A relative effect between an initial concentration of heavy metals and bicarbonate(or K) concentration is dependent on solution condition. The sorption edge of heavy metals as function of pH shows sigmoidal curve, and a great increase in the range of pH 6～8. The sorption sequence among heavy metals is Cu>Pb>>Zn>Cd. The solution chemistry exerts greater influence on the sorption of heavy metals rather than the crystal chemistry of clay minerals. The potassium exerts some effect into a sorption competition with heavy metals. The research suggests that the statistical modeling is an effective method to demonstrate sorption results in three dimension and to reduce the effort of batch sorption experiment.

• Journal of the Korean Geosynthetics Society
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• v.11 no.1
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• pp.1-9
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• 2012

This paper describes the batch test results for application of CFW(Carbonized Foods Waste), which was produced by the process of recycling waste, in PRB system. It analyzed characteristics for individual adsorption and competitive adsorption of Cu and Zn in heavy metals. In individual adsorption, the Langmuir and Freundlich models are used to predict adsorption equilibrium. The adsorption equilibrium corresponded to the Langmuir's and the maximum adsorption amount of Cu was greater than Zn's. The removal of heavy metal is predicted that Zn was faster than Cu. The reaction rate of Zn based on Pseudo-first-order and Pseudo-second-order was faster than Cu's, and the result of competitive adsorption test confirmed that the adsorption amount of Zn is reduced under similar condition for competitive adsorption rate of Cu and Zn. When Zn solution is mixed in Cu, Cu is adsorbed 86% on CFW. However, the adsorption of Zn is 19% on the contrary condition. Therefore, the removal characteristics of separate heavy metal should be considered for efficient treatment of contaminated ground based on complex heavy metal.

• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.24-31
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• 2016

BACKGROUND: Heavy metal adsorption not only depends on rapid cooling slag(RCS) characteristics but also on the nature of the metals involved and on their competitive behavior for RCS adsorption sites. The goal of this study was to investigate the competitive absorption characteristics of Cu, Cd and Zn in single- and multi-metal forms by RCS.METHODS AND RESULTS: Both single- and multi-metal adsorption experiments were conducted to determine the adsorption characteristics of RCS for the heavy metals. Adsorption behaviors of the heavy metals by RCS were evaluated using both the Freundlich and Langmuir adsorption isotherm equations. The maximum adsorption capacities of metals by RCS were in the order of Cu(16.6 mg/g) > Cd(8.1 mg/g) > Zn(6.2 mg/g) in the single-metal adsorption isotherm and Cu(14.5 mg/g) >> Zn(1.3 mg/g) > Cd(0.6 mg/g) in the multi-metal adsorption isotherm. Based on data obtained from Freundlich and Langmuir adsorption models and three-dimensional simulation, multi-metal adsorption behaviors differed from single- metal adsorption due to competition. Cadmium and Zn were easily exchanged and substituted by Cu during multi-metal adsorption.CONCLUSION: Results from adsorption experiments indicate that competitive adsorption among metals increases the mobility of these metals.

• Journal of the Mineralogical Society of Korea
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• v.7 no.2
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• pp.91-96
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• 1994

중.저준위 방사성 폐기물의 대표적인 핵종인 137Cs, 90Sr에 대한 캐올리나이트의 흡착특성을 수용액의 이온강도와 pH의 영양하에서 알아보았다. 흡착실험은 회분식으로 하였고, 사용한 수용액은 NaCl, CaCl2, MgSO4, KCL 각각을 10-1, 10-2, 10-3, 10-4 mole/$\ell$로 하였다. 수용액광물 평형상태의 pH를 4.5, 7.0, 10.5로 조절하였다. 실험결과 캐올리나이트의 Cs, Sr 흡착은 이온강도와 pH에 상당한 영향을 받으며, Sr 흡차에 양이온들의 경쟁은 Ca2+ Mg2+>K+>Na+ 순을 보이고, Cs의 경우에는 K+>Ca2+ Mg2+>Na+의 순을 보인다. 이는 수용액상에서 이온들의 수호에너지와 관련되며, 광물입자와 이온들의 물구조변환특성에 의해 설명된다. Cs과 Sr 사이에 흡착우선성은 산성 내지 약알카리에서는 Cs이 Sr보다 흡착이 잘 되나, 강알칼리성 환경에서는 Sr이 Cs보다 흡착이 잘 되는 pH 의존성을 보였다. 수용액의 pH가 증가함에 따라 핵종의 흡착량이 증가하는데, 이는 캐올리나이트의 흡착자리인 실라놀과 알루미놀에 의한 제타전위가 pH에 의존함과 잘 일치한다.

• Journal of the Mineralogical Society of Korea
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• v.29 no.2
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• pp.59-71
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• 2016

To investigate the sorption characteristics of Cs, which is one of the major isotopes of nuclear waste, on natural zeolite chabazite, XRD, EPMA, EC, pH, and ICP analysis were performed to obtain the informations on chemical composition, cation exchange capacity, sorption kinetics and isotherm of chabazite as well as competitive adsorption with other cations ($Li^+$, $Na^+$, $K^+$, $Rb^+$, $Sr^{2+}$). The chabazite used in this experiment has chemical composition of $Ca_{1.15}Na_{0.99}K_{1.20}Mg_{0.01}Ba_{0.16}Al_{4.79}Si_{7.21}O_{24}$ and its Si/Al ratio and cation exchange capacity (CEC) were 1.50 and 238.1 meq/100 g, respectively. Using the adsorption data at different times and concentrations, pseudo-second order and Freundlich isotherm equation were the most adequate ones for kinetic and isotherm models, indicating that there are multi sorption layers with more than two layers, and the sorption capacity was estimated by the derived constant from those equations. We also observed that equivalent molar fractions of Cs exchanged in chabazite were different depending on the ionic species from competitive ion exchange experiment. The selectivity sequence of Cs in chabazite with other cations in solution was in the order of $Na^+$, $Li^+$, $Sr^{2+}$, $K^+$ and $Rb^+$ which seems to be related to the hydrated diameters of those caions. When the exchange equilibrium relationship of Cs with other cations were plotted by Kielland plot, $Sr^{2+}$ showed the highest selectivity followed by $Na^+$, $Li^+$, $K^+$, $Rb^+$ and Cs showed positive values with all cations. Equilibrium constants from Kielland plot, which can explain thermodynamics and reaction kinetics for ionic exchange condition, suggest that chabazite has a higher preference for Cs in pores when it exists with $Sr^{2+}$ in solution, which is supposed to be due to the different hydration diameters of cations. Our rsults show that the high selectivity of Cs on chabazite can be used for the selective exchange of Cs in the water contaminated by radioactive nuclei.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.110-114
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• 2010

The equilibrium of adsorption of basics dyes RB 5 and BG 4 from a single dyes in the mixtures on the sodium-exchanged clay of the Maghnia (Algeria) was studied. The maximum adsorption capacities of BR5 and BG4 in single dyes were 465.13 and 469.90 mg/g respectively. In the simultaneous adsorption of BR5 and BG4 from mixture solutions, three different initials concentrations ratios R (R=$C_{(BR5)}/C_{(BG4)}$) were tested: 2.5/1, 1/1 and 1/2.5 using ADMI method. The isotherms adsorptions of dyes from the mixtures are characteristics of competition phenomenon. A very strong interaction between BR5 and BG4 for the active sites of adsorption of surface of clay is obtained for R = 1/1. The ratio R' (R'=$Qe_{(mixture)}/Qe_{(single)}$) of the adsorption capacity of BR5 and BG4 in the mixture were reduced by factor of 0.86, 0.74 and 0.84 for the initials concentrations ratios R (R=$C_{(BR5)}/C_{(BG4)}$) of 2.5/1, 1/1 and 1/2.5 respectively. The variation of the ratio of the adsorption capacity R‘ of BR5 and BG4 in the mixture solutions with initial concentration ratios R indicates that BR5 dye is slightly favourable in the competition adsorption than BG4. Langmuir and Freundlich models fit very well with adsorption behaviour of single dyes as well as the dyes in mixture solutions.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.358-365
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• 2016

Removing hazardous materials from water resources is very important for efficient utilization of the resources, and adsorptive removal is regarded as a competitive technology when good adsorbents with high capacity/selectivity are available. Metal-organic framework (MOF), composed of both organic and inorganic (metallic) species, have been tried for various adsorptions because of huge surface area/pore volume, well-defined pore structure, and facile functionalization. In this review, we summarized technologies on adsorptive removal of hazardous organics from water mainly using MOFs as adsorbents. Instead of reporting high adsorption capacity or rate, we summarized mechanisms of interaction between adsorbates (organics) and adsorbents (MOFs) and methods to modify or functionalize MOFs for effective adsorptions. We expect for readers of this review to understand needed characteristics of adsorbents for the adsorptive removal, functionalization of MOFs for effective adsorption and so on. Moreover, they might have an idea on storage and delivery of organics via understanding of the mechanism of adsorption and interaction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.279-285
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• 1993

It is important to understand the interrelationship between adsorption, equilibrium and mass transport in efficient design and operation of the granular activated carbon(GAC) adsorption systems. In this study, the micro-diameter-depth adsorption system(MIDDAS) technique was developed to estimate equilibrium and mass transport parameters, which were utilized to simulate adsorption and mass transport phenomena dynamically and mathematically. The homogeneous surface diffusion model(HSDM) utilizing the estimated equilibrium and mass transport parameters including the film transfer coefficients and surface diffusivities from the MIDDAS technique, successfully predicted competitive adsorption, desorption and chromatographic displacement effects. In the binary solute system of p-chlorophenol(PCP) and p-nitrophenol(PNP), PCP was displaced by PNP and the HSDM could predict successfully. While the HSDM described the desorption breakthrough curves for PCP, PNP and PTS well when complete reversible adsorption was assumed, the desorption breakthrough curves for DBS could be predicted after subsequent incorporation of the degree of irreversibility into the model simulations.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.64-68
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• 1998

본 연구는 오염토양/지하수의 정화를 위하여 사용되는 계면활성제 교정기술의 보다 현실적인 평가를 위하여 토양에 흡착된 계면활성제에 대한 소수성 유기오염물인 Naphthalene과 Phenanthrene의 흡수현상에 대한 연구결과를 나타내었다. 음이온 계면활성제인 Sodium Dodecyl Sulfate (SDS)와 중성 계면활성제인 Tween 80의 흡착곡선은 소수성 꼬리 (hydrophobic tails)간의 상호작용에 의하여 S-형 모양을 보이며 이들 흡착된 계면활성제는 Micelle로 존재하는 계면활성제에 비하여 유기오염물에 대한 보다 강한 흡수능력을 나타내었다. 결과에 나타난 흡수능력의 차이는 계면활성제가 흡착되어있거나 Micelle상태로 존재할 경우 다른 구조를 형성하기 때문이라 사료된다. 흡수된 계면활성제와 Micelle의 상호경쟁에 의하여 유기오염물의 부동성(immobility)을 나타내는 분배계수(distribution coefficient)는 계면활성제의 농도에 반비례하였다. 결론적으로 토양/지하수의 오염물 정화를 위하여 계면활성제 교정기술의 적용 시 고정상 (solid phase)에 있는 흡착 계면활성제에 의한 유기오염물의 지체현상 (retardation)을 고려하여야 한다.