• 한국환경과학회지
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• 제27권3호
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• pp.167-177
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• 2018

The removal characteristics of As and Se ions from aqueous solution by hexadecyl trimethyl ammonium bromide (HTMAB) modified anthracite (HTMAB-AT) were investigated under various conditions of contact time, pH and temperature. When the pH is 6, the zeta potential value of anthracite (AT) is -24 mV and on the other hand, the zeta potential value of the HTMAB-AT is +44 mV. It can be seen that the overall increase of about 60 mV. Increasing the (+) potential value indicates that the surface of the adsorbent had a stronger positive charge, so adsorption for the anion metal was increased. The isotherm data was well described by Langmuir and Temkin isotherm model. The maximum adsorption capacity was found to be 7.81 and 6.89 mg/g for As and Se ions from the Langmuir isotherm model at 298 K, respectively. The kinetic data was tested using pseudo first and pseudo second order models. The results indicated that adsorption fitted well with the pseudo second order kinetic model. The mechanism of the adsorption process showed that adsorption was dependent on intra particle diffusion model according to two step diffusion. The thermodynamic parameters(${\Delta}G^{\circ}$, ${\Delta}H^{\circ}$, and ${\Delta}S^{\circ}$) were also determined using the equilibrium constant value obtained at different temperatures. The thermodynamic parameters indicated that the adsorption process was physisorption, and also an endothermic and spontaneous process.

• 한국환경과학회지
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• 제26권5호
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• pp.609-619
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• 2017

The removal characteristics of 2,4-dinitrophenol (2,4-DNP) from an aqueous solution by commercial Wood-based Activated Carbon (WAC) have been studied. The effects of various experimental parameters were investigated using a batch adsorption technique. The adsorption capacity of 2,4-DNP by WAC increased with a decrease in the dosage and particle size of WAC, temperature and the initial pH of the solution, and increased with an increase in the initial concentration of the solution. The adsorption equilibrium data were best described by the Redlich-Peterson isotherm model. The maximum adsorption capacities of 2,4-DNP by WAC were 573.07 mg/g at 293 K, 500.00 mg/g at 313 K, and 476.19 mg/g at 333 K, decreasing with increasing temperature. The kinetic data were well fitted to the pseudo-second-order model, and the results of the intra-particle diffusion model suggested that the adsorption process was mainly controlled by particle diffusion. The thermodynamic analysis indicated that the adsorption of 2,4-DNP by WAC was an endothermic and spontaneous process.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.798-806
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• 2017

제주의 농업폐기물인 감귤박으로 제조한 활성탄(WCAC)을 수용액 중의항생제 dimetridazole (DMZ)를 제거하기 위해 사용하였다. WCAC에의한 DMZ의 흡착을 접촉시간, WCAC의 투여량, WCAC의 입자크기, 온도, pH 및 DMZ 농도와 같은 다양한 조건하에서 연구하였다. DMZ의 흡착량은 온도가 증가하고 입자크기가 감소함에 따라 증가하였다. 또한, pH 4 이상에서는 DMZ의 흡착량이 거의 일정하게 유지되었지만, pH 4 이하에서는 감소하는 경향을 보였다. 흡착등온 결과를 Langmuir, Freundlich, Redlich-Peterson 및 Duinin-Radushkevich (D-R) 등온 모델식에 적용하여 검토한 결과 Redlich-Peterson 등온 모델식에 의해 가장 잘 설명되었다. 흡착속도는 유사 2차 속도 모델에 잘 적용될 수 있었으며, 입자 내 확산 모델의 결과로부터 흡착 과정 동안 막 확산과 입자 내 확산이 동시에 일어나는 것을 알 수 있었다. 열역학적 파라미터는 WCAC에 대한 DMZ의 흡착반응은 흡열반응이고 자발적인 과정으로 진행된다는 것을 나타내었다. 실험결과는 WCAC가 항생제 DMZ를 제거하는데 있어서 값싸고 유용한 흡착제가 될 수 있다는 것을 보여주었다.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3391-3398
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• 2013

The carboxylated multiwall carbon nanotubes (MWCNT-COOH) and functionalized with isatin derivative (MWCNT-isatin) have been used as efficient adsorbents for the removal of lead (Pb) from aqueous solutions. The influence of variables including pH, concentration of the lead, amount of adsorbents and contact time was investigated by the batch method. The adsorption of the lead ions from aqueous solution by modified MWCNTs was studied kinetically using different kinetic models. The kinetic data were fitted with pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The sorption process with MWCNT-COOH and MWCNT-isatin was well described by pseudo-second-order and pseudo-first-order kinetics, respectively which it was agreed well with the experimental data. Also, it involved the particle-diffusion mechanism. The values of regression coefficient of various adsorption isotherm models like Langmuir, Freundlich and Tempkin to obtain the characteristic parameters of each model have been carried out. The Langmuir isotherm was found to best represent the measured sorption data for both adsorbent.

• 대한환경공학회지
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• 제37권8호
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• pp.450-457
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• 2015

본 연구에서는 제올라이트를 PVA에 고정화시켜 새로운 흡착제인 PVA-Zeolite 비드를 제조하고, XRD 및 SEM 분석을 통해 제조한 PVA-Zeolite 비드는 내부에 제올라이트가 잘 고정화된 다공성 구조를 가지고 있는 것을 확인할 수 있었다. 제조한 흡착제에 의한 Cs 이온과 Sr 이온에 대한 흡착특성을 살펴보기 위하여 pH의 영향, 흡착속도, 흡착등온을 검토하였다. Sr 및 Cs 이온에 대한 평형흡착시간은 약 540 min으로 나타났으며, 흡착속도는 유사 1차 속도식 보다는 유사 2차 속도식에 더 잘 부합하였다. 흡착평형 실험결과는 Langmuir 등온식에 잘 적용되었으며, Langmuir 등온식으로부터 구한 Sr 이온과 Cs 이온의 최대 흡착량은 각각 52.08 mg/g와 58.14 mg/g이었다. PVA-Zeolite 비드에 의한 Sr 이온과 Cs 이온의 흡착공정은 외부물질전달단계는 매우 빠르게 이루어지며, 내부입자확산에 의한 흡착반응은 느리게 진행되어 내부입자확산 단계가 흡착속도 결정단계인 것으로 판단된다.

• Membrane and Water Treatment
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• 제8권1호
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• pp.73-88
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• 2017

Adsorption kinetics of aqueous ferric ion ($Fe^{3+}$) onto bio-natural rice grains (BRG) have been studied in a batch system. The influence of contact time (0-180 minutes), the dosage of BRG adsorbent (10, 20, 40, and $60gL^{-1}$), and ambient temperature (27, 37, 47, and $57^{\circ}C$) for the adsorption system have been reported. The equilibrium time achieved after 20 minutes of adsorption contact time. The maximum removal of ferric ion is 99% by using $60gL^{-1}$ of BRG, $T=37^{\circ}C$, and $50mgL^{-1}$ ferric ion solution. Adsorption kinetic and diffusion models, such as pseudo-first order, pseudo-second order, and Weber-Morris intra-particle diffusion model, have been used to describe the adsorption rate and mechanism of the ferric ion onto BRG surface. The sorption data results are fitted by Lagergren pseudo-second order model ($R^2=1.0$). The kinetic parameters, rate constant, and sorption capacities have been calculated. The new information in this study suggests that BRG could adsorb ferric ion from water physiosorption during the first 5 minutes. Afterward, the electrostatic interaction between ferric ion and BGR-surface could take place as a very weak chemisorptions process. Thus, there is no significant change could be noticed in the FTIR spectra after adsorption. I recommend producing BGR as a bio-natural filtering material for removing the ferric ion from water.

• Korean Chemical Engineering Research
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• 제54권4호
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• pp.487-493
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• 2016

양이온교환 고성능액체크로마토그래피에서 라이소자임을 분석하고, 실험결과인 크로마토그램을 통해 모멘트 분석을 수행하였다. 용리 인산완충용액은 1.0, 0.75, 0.5 M의 소금을 포함하였다. 실험변수는 유량, 용리 완충용액중 소금 농도, 시료의 농도로 하였다. General rate (GR) model을 도입하여 1차와 2차 모멘트를 해석하였다. 1차 모멘트 해석에서 평형상수 K를 구할 수 있으며, 이는 $L/u_0$ vs. $({\mu}_1-t_0)/(1-{\varepsilon}_e)(1-{\varepsilon}_i)$]를 도식화했을 때의 기울기이다. 2차 모멘트 해석에서 입자내 확산계수는 이론단수 실험자료에서 계산하였다. 모멘트 분석결과를 통해 여러 물질전달 현상이 이론단 상당높이(HETP)에 주는 영향을 알아보기 위해 van Deemter plot을 작성하고, 총괄 이론단 상당높이($H_{total}$)에 기여하는 $H_{ax}$, $H_f$, 그리고 $H_d$를 조사하였다. 그 중 입자내 확산계수를 나타내는 $H_d$가 가장 지배적이었고, 외부 물질전달 계수를 나타내는 $H_f$의 영향이 가장 미미했다.

• Environmental Engineering Research
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• 제18권1호
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• pp.45-53
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• 2013

Biocarrier beads with dead biomass, Bacillus drentensis, immobilized in polymer polysulfone were synthesized to remove heavy metals from wastewater. To identify the sorption mechanisms and theoretical nature of underlying processes, a series of batch experiments were carried out to quantify the biosorption of Pb(II) and Cu(II) by the biocarrier beads. The parameters obtained from the thermodynamic analysis revealed that the biosorption of Pb(II) and Cu(II) by biomass immobilized in biocarrier beads was a spontaneous, irreversible, and physically-occurring adsorption phenomenon. Comparing batch experimental data to various adsorption isotherms confirmed that Koble-Corrigan and Langmuir isotherms well represented the biosorption equilibrium and the system likely occurred through monolayer sorption onto a homogeneous surface. The maximum adsorption capacities of the biocarrier beads for Pb(II) and Cu(II) were calculated as 0.3332 and 0.5598 mg/g, respectively. For the entire biosorption process, pseudo-second-order and Ritchie second-order kinetic models were observed to provide better descriptions for the biosorption kinetic data. Application of the intra-particle diffusion model showed that the intraparticle diffusion was not the rate-limiting step for the biosorption phenomena. Overall, the dead biomass immobilized in polysulfone biocarrier beads effectively removed metal ions and could be applied as a biosorbent in wastewater treatment.

• Carbon letters
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• 제22권
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• pp.14-24
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• 2017

Carboxylated multi-wall carbon nanotubes (MWCNTs-COOH) have been used as efficient adsorbents for the removal of picric acid from aqueous solutions under stirring and ultrasound conditions. Batch experiments were conducted to study the influence of the different parameters such as pH, amount of adsorbents, contact time and concentration of picric acid on the adsorption process. The kinetic data were fitted with pseudo-first order, pseudo-second-order, Elovich and intra-particle diffusion models. The kinetic studies were well described by the pseudo-second-order kinetic model for both methods. In addition, the adsorption isotherms of picric acid from aqueous solutions on the MWCNTs were investigated using six two-parameter models (Langmuir, Freundlich, Tempkin, Halsey, Harkins-Jura, Fowler-Guggenheim), four three-parameter models (Redlich-Peterson, Khan, Radke-Prausnitz, and Toth), two four-parameter equations (Fritz-Schlunder and Baudu) and one five-parameter equation (Fritz-Schlunder). Three error analysis methods, correlation coefficient, chi-square test and average relative errors, were applied to determine the best fit isotherm. The error analysis showed that the models with more than two parameters better described the picric acid sorption data compared to the two-parameter models. In particular, the Baudu equation provided the best model for the picric acid sorption data for both methods.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.723-729
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• 2015

고성능액체크로마토그래피(high-performance liquid chromatography, HPLC)에서 C18(octadecyl silica, ODS) 칼럼에서 고리형 아데노신 일인산(cyclic adenosine monophosphate, cAMP)의 크로마토그램을 얻은 후, 모멘트 분석을 수행하였다. 일반속도 모델(general rate model, GR model)을 기반으로 first absolute moment와 second central moment를 계산하였다. 모멘트 분석의 중요한 세 가지 계수인 분자확산계수(molecular diffusivity, $D_m$), 외부물질전달계수(external mass transfer coefficient, $k_f$), 입자내부확산계수(intra-particle diffusivity, $D_e$)는 각각 Wilke-Chang 식, Wilson-Geankoplis 식을 이용하고 이론단수(theoretical plate number) 식과 van Deemter 식을 비교하여 계산하였다. 실험은 각각 세 가지의 이동상 조성, 용질 농도, 유량 조건에서 수행하였다. Van Deemter 그래프를 그려 모멘트 분석결과를 정성적으로 정리했으며, 이론단 상당높이(height equivalent to a theoretical plate, HETP, $H_{total}$)에 $H_{ax}$, $H_f$, $H_d$가 미치는 영향을 알아보기 위해 van Deemter coefficient를 비교했다. HETP에 가장 큰 영향을 주는 요인은 입자내부확산($H_d$)이었으며 외부물질 전달($H_f$)는 그 영향이 매우 작았다.