• 한국산학기술학회논문지
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• 제3권2호
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• pp.146-155
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• 2002

Surface complexation models employ mass law equations to describe the reaction of surface functional groups with ions in the solution and also Gouy-Chapman theory to consider the electrostatic effects in the surface reactions. In current surface complexation models, however, the coulombic factors used are not wholly consistent with the Gouy-Chapman model of the surface. This study was to provide the derivation of the coulombic term usually employed and then a revised coulombic term completely consistent with Gouy-Chapman Theory. The electrical potential energy. zF${\psi}$, in current surface complexation models is not consistent with the Gouy-Chapman theory with the potential gradient close to the charged surface but with the Donnan model with the uniform potential. Even though the new coulombic factor yielded lower surface potential, it provided worse fits for acid-base titration data of the goethite suspensions.

• Environmental Engineering Research
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• 제8권2호
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• pp.91-97
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• 2003

• 한국환경과학회지
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• 제8권2호
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• pp.211-219
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• 1999

Surface complexation models(SCMs) have been performed to predict metal ion adsorption behavior onto the mineral surface. Application of SCMs, however, requires a self-consistent approach to determine model parameter values. In this paper, in order to determine the metal ion adsorption parameters for the triple layer model(TLM) version of the SCM, we used the zeta potential data for Zeolite and Kaolinite, and the metal ion adsorption data for Pb(II) and Cd(II). Fitting parameters determined for the modeling were as follows ; total site concentration, site density, specific surface area, surface acidity constants, etc. Zeta potential as a new approach other than the acidic-alkalimetric titration method was adopted for simulation of adsorption phenomena. Some fitting parameters were determined by the trial and error method. Modeling approach was successful in quantitatively simulating adsorption behavior under various geochemical conditions.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.196-201
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• 2000

The influence of adsorption on cadmium toxicity to soil microorganisms in smectite-rich soils and sediments was quantified as a function of solution and sorbent characteristics. Adsorption and surface complexation experiments were conducted to infer Cd sorption mechanisms to a reference smectite and three fractions of a Veritsol soil, and to elucidate the effects of the surface complexation on Cd bioavailability and toxicity in soils and sediments. Cadmium adsorption isotherms conformed to the Langmuir adsorption model, with adsorptive capacities of the different samples dependent on their characteristics. Equilibrium geochemical modeling (MINTEQA2) was used to predict the speciation of Cd in the soil suspensions using Langmuir and Triple Layer surface complexation models. The influence of adsorption and surface complexation on cadmium toxicity to soil microorganisms was assessed indirectly through the relative change in microbial hydrolysis of fluorescein diacetate (FDA) as a function of total Cd concentration and sorbent characteristics. Adsorption decreased the toxicity of Cd to soil microorganisms. Inner-sphere complexation is more effective than outer-sphere complexation in reducing the bioavailability and toxicity of heavy metals in soils and sediments.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.296-300
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• 2003

다성분 양이온 교환을 위한 평형과 동역학 데이터는 질량 작용 법칙과 표면 착화 모델을 이용하여 수행 및 평가하였다. 양이온 흡착의 평형과 칼럼 실험은 양이온 교환 합성 수지 IRN 77로 H/sup +/, Li/sup +/, Na/sup +/, NH₄/sup +/, Mg²/sup +/ 이용하여 2, 3, 4, 5 성분 양이온 교환을 수행하였다. 질량 작용 법칙과 표면 착화 모델은 이온 선택도와 경쟁적 양이온 교환을 조사하기 위하여 데이터에 대해 시험하였다. 표면 착화 모델은 질량 작용 모델보다 평형과 동역학 실험 데이터를 정확히 예측하였다.

• 방사성폐기물학회지
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• 제21권4호
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• pp.427-438
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• 2023

Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acid-base titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2003년도 춘계학술발표논문집
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• pp.322-324
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• 2003

이온교환은 액체상에 존재하는 이온과 고체상에 존재하는 이온이 당량적으로 치환되는 것으로 정의하며, 치환되는 정도는 일반적으로 전하의 크기와 이온이 수화반경에 따라 달라진다. 지금까지의 이온교환 반응에 대한 모델링 연구는 실험식, 질량작용식, 열역학식, 전기이중층이론, 표면착화모델 등을 이용하여 2 성분에 대하여 다양한 시도를 하였다. 본 연구에서는 2, 3, 4성분에 대해 질량작용법칙과 전기이중층이론을 조합한 표면착화모델과 질량작용법칙을 이용한 모델을 수행하였다. 그 결과 표면착화모델이 질량작용법칙을 이용한 것보다 실험치와 일치함을 알 수 있었다.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.307-311
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• 2003

탈염기 혼합 이온교환 수지탑에서 양 ㆍ 음이온의 최적혼합비율을 결정하기 위해 실험을 수행하였다. 2, 3, 4, 5 성분 양ㆍ음이온 흡착은 많은 양이온 그리고 음이온의 선택도를 얻기 위하여 small-volume batch test로부터 실험 데이터를 얻기 위해 수행되었다. Quantitative run time은 반-실험적 질량 작용과 표면 착화 모델을 이용한 이온 교환 모델에 의해서 추정될 수 있었다. 탈염기 수지층의 음이온 교환수지에 대한 양이온 교환수지의 비율을 증가시킴으로써 더 길게 사용될 수 있다.

• 한국광물학회지
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• 제17권2호
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• pp.157-168
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• 2004

수용액 내 캐올리나이트와 할로이사이트의 표면화학 특성을 전위차 적정 실험과 FITEQL3.2 프로그램을 이용하여 연구하였다. 표면복합반응 모델 중 일정용량 모델을 적용하였으며, 표면을 사면체 자리와 팔면체 자리로 나누어 설정한 2 sites - 3 $pK_{a/s}$ 모델은 캐올리나이트와 할로이사이트의 표면화학 특성을 설명하는데 적합하였다. 두 점토광물 표면은 pH 4 이상에서 음전하를 띄며 pH가 높아질수록 양성자 표면 전하 밀도는 낮아진다. 산성 및 중성 영역에선 Si 사리(≡$SiO^{-}$ )가, 염기성 영역에선 Al 자리(≡$AlO^{-}$)가 양이온을 흡착하는데 중요한 역할을 할 것으로 예상된다. 모델링 결과 캐올리나이트의 경우 $pK_{a2(si)}$ /$^{int}$, p $K_{al(Al) }$ /$^{int}$ /, $pK_{a2}$ $(Al)^{int}$ /는 각각 4.436. 4.564, 및 8.461이며, 할로이사이트의 경우는 각각 7.852, 3.885, 7.084이다. 캐올리나이트의 총 Si 표면자리 농도와 총 Al 표면자리 농도는 0.215와 0.148 mM이며, 할로이사이트의 경우는 0.357과 0.246 mM이다 두 광물 모두 Si 표면자리 밀도 : Al 표면자리 밀도가 1 : 0.69로 비슷하다. 캐올리나이트의 총 표면자리 밀도는 3.774 sites/$nm^2$로 할로이사이트의 2.292 sites/n $m^2$ 값보다 약 1.6배정도 높다.다.

• Environmental Engineering Research
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• 제22권1호
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• pp.95-107
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• 2017

Adsorption equilibrium and kinetic behavior of two toxic heavy metals hexavalent chromium [Cr(VI)] and mercury [Hg(II)] on mustard oil cake (MOC) was studied. Isotherm of total chromium was of concave type (S1 type) suggesting cooperative adsorption. Total chromium adsorption followed BET isotherm model. Isotherm of Hg(II) was of L3 type with monolayer followed by multilayer formation due to blockage of pores of MOC at lower concentration of Hg(II). Combined BET-Langmuir and BET-Freundlich models were appropriate to predict Hg(II) adsorption data on MOC. Boyd's model confirmed that external mass transfer was rate limiting step for both total chromium and Hg(II) adsorptions with average diffusivity of $1.09{\times}10^{-16}$ and $0.97m^2/sec$, respectively. Desorption was more than 60% with Hg(II), but poor with chromium. The optimum pH for adsorptions of total chromium and Hg(II) were 2-3 and 5, respectively. At strong acidic pH, Cr(VI) was adsorbed by ion exchange mechanism and after adsorption reduced to Cr(III) and remained on MOC surface. Hg(II) removal was achieved by complexation of $HgCl_2$ with deprotonated amine ($-NH_2$) and carboxyl (COO-) groups of MOC.