• 자원리싸이클링
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• 제8권1호
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• pp.37-43
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• 1999

본 연구는 망간단괴와 그로부터 유가금속을 침출한 잔사를 카드뮴 폐수의 흡착제로 이용하는 기초실험으로 초기 카드뮴 농도에 따른 흡착성을 살펴보았다. 또한 이를 Freundlich, Langmuir, Temkin 등온흡착식에 적용하여 각 흡착계를 설명하였다. 카드뮴 이온의 초기농도가 증가함에 따라 흡착량은 증가하였으나 흡착성은 점차로 감소하는 경향을 보였다. 이를 Freundlich, Langmuir 식에 적용한 결과, 선형성을 나타내었다. 그리고 Freundlich 식에서 흡착제의 흡착능력을 평가하는 k값은 망간단괴가 11.72로 제일 컸다. 망간단괴의 경우는 Langmuirtlr의 단분자층을 형성하여 흡착되는 흡착질의 최대흡착량인 $X_m$값또한 0.16으로 침출잔사, 잔사-생단괴 혼합, 활성탄에 비해 큼을 알 수 있었다.

• Membrane and Water Treatment
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• 제6권6호
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• pp.439-449
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• 2015

Carbolic Acid which is called phenol is one of the important starting and/or intermediate materials in various industrial processes. However, its excessive release into environment poses a threat to living organisms, as it is a highly carcinogens and hazardous pollutant even at the very low concentration. Thus removal of phenol from polluted environments is very crucial for sustainable remediation process. We developed a low cost adsorption method for separating phenol from a model aqueous solution. The phenol adsorption was studied using two adsorbents i.e., Amber lite XAD-16 and Amber lite XAD-7 HP with a constant amount of resin 0.1 g at varying aqueous phenol concentrations ($50-200mgL^{-1}$) at room temperature. We compared the efficacy of two phenol adsorbents for removing higher phenol concentrations from the media. We investigated equilibrium and kinetics studies of phenol adsorption employing Freundlich, Temkin and Langmuir isotherms. Amberlite XAD-16 performed better than Amberlite XAD-7 HP in terms of phenol removal efficiency that amounted to 95.52%. Pseudo second order model was highly fitted for both of the adsorption systems. The coefficient of determination ($R^2$) with Langmuir isotherm was found to be 0.98 for Amberlite XAD-7 HP. However, Freundlich isotherm showed $R^2$ value of 0.95 for Amberlite XAD-16, indicating that both isotherms could be described for the isotherms on XAD-7 HP and Amberlite XAD-16, respectively.

• 한국수소및신에너지학회논문집
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• 제16권4호
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• pp.307-314
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• 2005

In this work, a static volumetric method was experimentally implemented to measure the adsorption isotherm of hydrogen and methane by the activated carbon. The equilibrium data of stationary phase and mobile phase were correlated into the Langmuir, Freundlich, Langmuir-Freundlich, and Toth isotherms, respectively. In addition, the comparison between prediction and experimental data was made. By a nonlinear regression analysis, the experimental parameters in the equilibrium isotherms were estimated and compared. Then, the linear and quadratic equations for pressure and temperature to adsorption amounts were expressed. The adsorption amounts were increased with the pressure increase and the temperature decrease.

• 한국산업보건학회지
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• 제9권2호
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• pp.19-31
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• 1999

Most breakthrough tests are conducted at higher concentration levels compared to those in the field of air-purifying respirator applications. For example, typical challenge concentrations for breakthrough tests agains tcarbon tetrachloride are ranged between 250-1000 ppm although applicable concentrations range for air-purifying cartridge is 5-50 ppm for carbon tetrachloride. However, no guarantee has been made that isotherms derived from the experiment at high challenge concentrations could estimate adsorption capacity at the lower concentration range where workers wear usually air-purifying respirators. Three models of adsorption isotherms (Freundlich, Langmuir and Dubinin/Radushkevich(D/R) isotherms) that have been commonly applied for respirator cartridge testing were evaluated. Adsorption capacity at each challenge concentration was calculated from the Reaction Kinetic equation fitted for the breakthrough data. These data were used for derivation of three isotherms. In general, the D/R isotherm has given the best agreement between estimated adsorption capacities and experimentally measured. If the challenge concentration of 100 ppm is included for derivation of models, Freundlich and D/R models could succes sfully produced good estimations for adsorption capacities at 50 ppm level. Estimated adsorption capacities by both models ranged in 94 - 109 % of the experimentally measured. However, Langmuir model gives underes timation in all cases.

• Carbon letters
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• 제10권1호
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• pp.23-32
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• 2009

The adsorption of phenolic compound resorcinol on activated carbons prepared from Moringa oleifera (Drumstick bark) has been investigated. Activated carbon was prepared by impregnating Moringa oleifera with 50% phosphoric acid in the ratio of 1:1 and 1:2(w/w), designated as MOAC1 and MOAC2. Equilibrium and isotherm studies were carried out. The influences of variables such as contact time, initial concentration of resorcinol, carbon dosage in the solution on percentage adsorption and adsorption capacity of the bark have been analysed. The equilibration time was found to be 4 h. Kinetics of resorcinol onto activated carbons was checked for pseudo first order and pseudo second order model. It was found that the adsorption of resorcinol follows pseudo second order kinetics for both MOAC1 and MOAC2. The isotherm data were correlated with isotherm models, namely Langmuir and Freundlich. Adsorption isotherms were satisfactorily fitted by both the Langmuir and Freundlich model for MOAC1 and MOAC2.

• Environmental Engineering Research
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• 제10권2호
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• pp.45-53
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• 2005

Metal oxide particles with mole ratio of aluminum: titanium of 1:1 were synthesized by a sol-gel method. Langmuir (a) and Freundlich (b) adsorption isotherms of dissolved lead [Pb(Ⅱ)] ion on the metal oxide particles containing aluminum and titanium were determined as follows, respectively,(a) , (b) at pH 6where, correlation coefficients (R2) of Langmuir and Freundlich adsorption isotherms were 0.95 and 0.96, respectively.The overall adsorption rate of Pb(Ⅱ) on the metal oxide particles containing aluminum and titanium was determined by a differential bed reactor. The overall adsorption rate at pH 6 was as a following equation.at pH 6

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.380-383
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• 2004

Heavy metal release from wastewater is a serious environmental problem, and therefore, various wastewater treatment techniques have been developed. Among the techniques, sorption technique is most attractive. Considerable researches have been recently focused on finding out inexpensive sorbents, especially from various natural materials. In order to evaluate the applicability of the scoria taken from the Jeju Island, Korea to remove heavy metals (Pb, Cu, Zn, Cd) from aqueous solutions, equilibrium sorption experiments were conducted in this study. In equilibrium tests, powdered activated carbon (PAC), one of the most commonly used sorbents, was also tested to compare the effectiveness of the Jeju scoria with that of PAC. The Jeju scoria had larger adsorption capacity and affinity for metal ions (Pb(II), Cu(II), Zn(II), Cd(II)) than PAC. The sorption parameters of the two sorbents were evaluated by using both the Langmuir and Freundlich isotherms, and the sorption data were better fitted to the Freundlich isotherm. In addition, the sorption behavior of metal ions (Pb(II), Cu(II), Zn(II), Cd(II)) onto the scoria displayed a typical characteristic of the cation sorption. The removal of metal ions decreased at a lower pH condition due to competition with hydrogen ions for the sorption sites of Jeju scoria, while the removal increased at a high pH condition due to hydroxide precipitation.

• Advances in environmental research
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• 제4권3호
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• pp.197-210
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• 2015

Hexavalent chromium [Cr (VI)] adsorption on lateritic soil and lateritic soil blended with black cotton (BC) soil, marine clay and bentonite clay were studied in the laboratory using batch adsorption techniques. In the present investigation the natural laterite soil was blended with 10%, 20% and 30% BC soil, marine clay and bentonite clay separately. The interactions on test soils have been studied with respect to the linear, Freundlich and Langmuir isotherms. The linear isotherm parameter, Freundlich and Langmuir isotherm parameters were determined from the batch adsorption tests. The adsorption of Cr (VI) on natural laterite soil and blended laterite soil was determined using double beam spectrophotometer. The distribution coefficients obtained were 1.251, 1.359 and 2.622 L/kg for lateritic soil blended with 10%, 20% and 30% BC soil; 5.396, 12.973 and 48.641 L/kg for lateritic soil blended with marine clay and 5.093, 8.148 and 12.179 L/kg for lateritic soil blended with bentonite clay respectively. The experimental data fitted well to the Langmuir model as observed from the higher value of correlation coefficient. Soil pH and iron content in soil(s) has greater influence on Cr (VI) adsorption. From the study it is concluded that laterite soil can be blended with clayey soils for removing Cr (VI) by adsorption.

• Bulletin of the Korean Chemical Society
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• 제29권8호
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• pp.1549-1553
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• 2008

A molecular imprinted polymer (MIP) using (+)catechin ((+)C) as a template and acrylamide (AM) as a functional monomer was prepared. Acetonitrile was used as the porogen with ethylene glycol dimethacrylate (EGDMA) as the crosslinker and 2,2'-azobis(isobutyronitrile) (AIBN) as the initiator. The adsorption isotherms in the MIP were measured and the parameters of the equilibrium isotherms were estimated by linear and nonlinear regression analyses. The linear equation for original concentration and adsorpted concentrations was then expressed, and the adsorption equilibrium data were correlated into Langmuir, Freundlich, quadratic, and Langmuir Extension isotherm models. The mixture compounds of (+)C and epicatechin (EC) show competitive adsorption on specific binding sites of the (+)catechin-MIP. The adsorption concentrations of (+)C, epicatechin (EC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG), on the (+)catechin-molecular imprinted polymer were compared. Through the analysis, the (+)catechin-molecular imprinted polymer showed higher adsorption ability than blank polymer which was synthesized molecular imprinted polymer without (+)catechin. Furthermore, the competitive Langmuir isotherms were applied to the mixture compounds of (+)C and EC.

• 한국지반환경공학회 논문집
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• 제10권7호
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• pp.25-32
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• 2009

본 연구는 팽창질석을 사용하여 수용액 상의 구리이온 흡착 제거능을 평가 하고자 하였다. 질석의 화학적 조성분석은 XRF, 구리이온 농도분석은 UV-VIS를 각각 사용하여 이루어졌다. 수용액 상의 구리이온의 제거양상을 살펴보기 위해 batch kinetic test와 batch sorption test가 실시되었고, 그 결과 구리의 제거속도($K_{obs}$, 1/hr)는 초기pH 3일때 0.73, pH 4일때 1.52, pH 5일때 1.71였고 초기농도가 $1mg\;L^{-1}$ 일때 3.19, 5일때 1.90, 10일때 0.73으로 초기구리농도와 반비례하고 초기 pH와는 비례하여 증가하는 양상을 보였다. 하지만 초기용액의 농도차이보다 초기pH의 영향이 지배적일 것이라는 예상하에 동일한 농도에 pH만 달리하여 실험해본 결과 역시 예상대로 pH에 따라 제거속도가 크게 차이남을 알 수 있었다. 최종적으로 batch sorption test를 통해 얻은 결과를 각각 Freundlich와 Langmuir 등온흡착식에 대입한 결과 두 식 모두 양호한 fitting 결과를 얻을 수 있었으나 Freundlich 식의 결정계수가 0.965로 Langmuir 식의 결정계수 0.936보다 좀 더 높게 나타나 좀 더 정확한 fitting 결과를 보여주었다. Langmuir 모델로부터 얻은 최대흡착용량($Q_{max}$), Freundlich 모델의 분배계수, n 값은 각각 $1,250mg\;kg^{-1}$, $635.1L\;kg^{-1}$, 1.69였다. 이러한 결과는 팽창질석이 다양한 형태의 수용액 상에 존재하는 구리이온을 효과적으로 제거할 수 있음을 보여준다.