• Membrane and Water Treatment
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• 제12권1호
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• pp.23-35
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• 2021

A POM-membrane was fabricated by immobilizing a keggin type polyoxometalate (POM) H5PV2Mo10O40 onto the surface of microporous flat-sheet polymeric polyvinylidene fluoride (PVFD) membrane using a chemical deposition method. The POM-membrane was characterized by FT-IR, SEM and EDX to confirm existing of the POM onto the membrane surface. The POM-membrane was used to remove an anionic textile dye (Reactive Black 5 named as an RB5) from aqueous phases with a cross-flow membrane filtration and a batch adsorption system. The dye removal efficiency of the POM-membrane using the cross-flow membrane filtration system and the batch adsorption system was about 88% and 98%, respectively. The influence factors such as contact time, adsorbent dosage, pH, and initial dye concentration were investigated to understand the adsorption mechanism of the RB5 dye onto the POM-membrane. To find the best fitting isotherm model, Langmuir, Freundlich, BET and Harkins-Jura isotherm models were used to analyze the experimental data. The isotherm analysis showed that the Langmuir isotherm model was found to the best fit for the adsorption data (R2 = 0.9982, qmax = 24.87 mg/g). Also, adsorption kinetic models showed the pseudo second order kinetic model was found the best model to fit the experimental data (R2 = 0.9989, q = 8.29 mg/g, C0 = 15 ppm). Moreover, after four times regeneration with HNO3 acid, the POM-membrane showed high regenerability without losing dye adsorption capacity.

• 청정기술
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• 제27권3호
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• pp.261-268
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• 2021

석탄계 입상 활성탄(CGAC)에 의한 acid black 1 (AB1) 염료의 평형, 동력학 및 열역학적 특성을 초기농도, 접촉 시간, 온도 및 pH 를 흡착변수로 하여 조사하였다. 활성탄에 의한 AB1의 흡착반응은 산성에서는 활성탄의 표면(H⁺)과 AB1이 가지고 있는 sulfite ion (SO₃^-), nitrite ion (NO₂^-) 사이의 정전기적 인력에 의해 일어났고, 최고 흡착률은 pH 3에서 97.7%였다. AB1의 등온 데이터는 Freundlich 등온식에 가장 잘 맞았으며, 계산된 분리계수(1/n) 값으로부터 활성탄에 의한 AB1의 흡착이 효과적인 처리과정이 될 수 있음을 알았다. Temkin 식의 흡착열 관련상수의 값은 물리 흡착 공정(< 20 J mol^-1)임을 나타냈다. 동역학 실험에서는 유사 2차 모델이 유사 1차 모델보다 더 일관성이 있었으며 추정된 평형 흡착량은 오차 백분율의 9.73% 이내에서 잘 일치하였다. 입자내 확산이 흡착 과정에서 속도 조절 단계였다. 활성화 에너지와 엔탈피 변화값으로부터 흡착반응이 물리흡착으로 진행되는 흡열반응임을 확인하였다. 엔트로피 변화는 활성탄 표면에서 AB1의 흡착이 일어나는 동안 고-액 계면에서 활발한 반응에 의해 엔트로피가 증가하는 것으로 나타났다. 자유에너지 변화는 온도증가와 함께 흡착반응의 자발성이 더 커지는 것을 나타냈다.

• Korean Chemical Engineering Research
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• 제53권1호
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• pp.64-70
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• 2015

본 연구는 활성탄에 의한 congo red의 흡착 거동에 대해 회분식 실험을 통해 알아보았다. 흡착변수로 흡착제의 양, pH, 초기농도와 접촉시간과 온도를 사용하였다. 흡착평형자료는 Langmuir, Freundlich, Temkin 및 Dubin-Radushkevich 식에 적용하여 보았다. 평가된 Freundlich 분리계수(1/n)로부터 활성탄에 의한 congo red의 흡착공정이 적절한 처리방법이 될 수 있음을 알았고, Temkin 상수(B)와 Dubinin-Radushkevich 상수(E)로부터 물리흡착공정임을 알았다. 동력학적 실험을 통해 흡착공정이 유사이차반응속도식에 잘 일치함을 알았다. 입상활성탄에 대한 congo red의 흡착공정은 발열반응(${\Delta}H$=42.036 kJ/mol)이었고, Gibbs 자유에너지값(${\Delta}G$=-2.414~-4.596 kJ/mol)은 온도가 증가할수록 감소하였다.

• 한국환경과학회지
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• 제29권8호
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• pp.827-835
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• 2020

Zeolite material having XRD peaks of Na-A zeolite in the 2θ range of 7.18 to 34.18 can be synthesized from the waste catalyst using a fusion/hydrothermal method. The adsorption rate of Mn ions by a commercial Na-A zeolite and the synthesized zeolitic material increased as the adsorption temperature increased in the range of 10 ~ 40℃. The adsorption of Mn ion were very rapid in the first 30 min and then reached to the equilibrium state after approximately 60 min. The adsorption kinetics of Mn ions by the commercial Na-A zeolite and the zeolitic material were found to be well fitted to the pseudo-2^nd order kinetic model. Equilibrium data by the commercial Na-A zeolite and the zeolitic material fit the Langmuir, Koble-Corrigan, and Redlich-Peterson isotherm models well rather than Freundlich isotherm model. The removal capacity of the Mn ions by the commercial Na-A zeolite and the zeolitic material obtained from the Langmuir model was 135.2 mg/g and 128.9 mg/g at 30℃, respectively. The adsorption capacity of Mn ions by the synthesized zeolitic material was almost similar to that of commercial Na-A zeolite. The synthesized zeolitic material could be applied as an economically feasible commercial adsorbent.

• 청정기술
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• 제20권1호
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• pp.35-41
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• 2014

본 연구에서는 입상 활성탄($8{\times}30mesh$, $1,578m^2/g$)을 사용하여 quinoline yellow 염료를 흡착하는데 필요한 흡착평형과 흡착동역학 및 열역학에 대하여 조사하였다. 등온흡착평형관계를 검토한 결과, 평가된 Langmuir 식의 상수($R_L=0.0730{\sim}0.0854$)와 Freundlich 식의 상수(1/n = 0.2077~0.2268)로부터 입상 활성탄에 의해 quinoline yellow를 적절하게 흡착처리 할 수 있음을 알았고, Temkin 식의 상수(B = 15.759~21.014 J/mol)와 Dubinin-Radushkevich 식의 상수(E = 1.0508~1.1514 kJ/mol)로부터 흡착공정이 물리흡착공정임을 알았다. 흡착공정에 대한 동력학적 해석을 통해 반응속도식의 적용결과는 유사이차반응속도식이 유사일차반응속도식에 비해 일치도가 높은 것으로 나타났으며, 흡착공정은 입자내세공확산과 표면확산의 두단계로 진행됨을 알았다. 유사이차반응속도식을 적용한 열역학적 해석을 통해 평가된 엔탈피 변화값(+35.03 kJ/mol)과 활성화에너지값(+35.137 kJ/mol)으로부터 흡착공정이 흡열반응으로 진행됨을 알았다. 또한 엔트로피 변화값(+134.38 J/mol K)은 흡착공정의 무질서도가 증가한다는 것을 나타내었고, 온도가 올라갈수록 자유에너지값이 감소하는 경향을 보인 것은 활성탄에 대한 quinoline yellow의 흡착반응은 온도가 올라갈수록 자발성이 높아지는 것으로 판단되었다.

• Environmental Engineering Research
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• 제18권4호
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• pp.247-252
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• 2013

In this work, removal of phenol from aqueous solutions by activated red mud was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy was used to observe the morphology and surface components of activated red mud, respectively. The effects of various parameters on the removal efficiency were studied, such as contact time, pH, initial phenol concentration, and adsorbent dosage. The removal percentage of phenol was initially increased, as the solution pH increased from 3 to 7, and then decreased above neutral pH. The removal percentage of phenol was decreased by increasing the initial phenol concentrations. Adsorption results show that equilibrium data follow the Freundlich isotherm, and kinetic data was well described by a pseudo-second-order kinetic model. Experimental results show that the activated red mud can be used to treat aqueous solutions containing phenol, as a low cost adsorbent with high efficiency.

• Carbon letters
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• 제23권
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• pp.30-37
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• 2017

Dyes are widely used in various industries including textile, cosmetic, paper, plastics, rubber, and coating, and their discharge into waterways causes serious environmental and health problems. Four different carbon nanostructures, graphene oxide, oxidized multi-walled carbon nanotubes, activated carbon and multi-walled carbon nanotubes, were used as adsorbents for the removal of Nile Blue A (NBA) dye from aqueous solution. The four carbon nanostructures were characterized by scanning electron microscope and X-ray diffractometer. The effects of various parameters were investigated. Kinetic adsorption data were analyzed using the first-order model and the pseudo-second-order model. The regression results showed that the adsorption kinetics were more accurately represented by the pseudo-second-order model. The equilibrium data for the aqueous solutions were fitted to Langmuir and Freundlich isotherms, and the equilibrium adsorption of NBA was best described by the Langmuir isotherm model. This is the first research on the removal of dye using four carbon nanostructures adsorbents.

• 한국산학기술학회논문지
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• 제21권7호
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• pp.667-674
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• 2020

활성탄에 의한 reactive orange 16 (RO 16) 염료의 흡착은 흡착제의 양, pH, 초기 농도, 접촉시간과 온도를 흡착변수로 사용하여 실험하였으며, 분리계수, 속도상수, 율속단계, 활성화 에너지, 엔탈피, 엔트로피, 자유에너지와 같은 공정 파라미터에 대해 조사하였다. RO 16의 흡착은 활성탄 표면의 양이온 (H⁺)과 RO 16이 가지고 있는 설포네이트 이온 및 수산 이온사이의 정전기적 인력으로 인해 pH 3에서 흡착율이 가장 높았다. 등온자료는 Langmuir, Freundlich 및 Temkin 등온식을 적용하였다. Freundlich 상수(1/n=0.398~0.441)와 Langmuir 분리계수(R_L=0.459~0.491)에 의해 활성탄에 의한 RO 16의 흡착조작은 적절한 제거방법임을 확인하였다. Temkin 식의 흡착에너지 (B_T=0.293~0.576 kJ/mol) 값으로부터 이 흡착공정이 물리흡착공정이라는 것을 알았다. 흡착 동력학 실험은 RO 16의 흡착이 유사이차반응속도식에 잘 맞는 것으로 나타났다. 흡착공정의 율속단계는 입자 내 확산 단계인 것이 확인되었다. 양수값의 엔탈피 변화는 물리흡착임을 나타냈다. 음수값의 깁스 자유에너지 변화는 온도가 올라갈수록 -3.16<-11.60<-14.01 kJ/mol 순으로 작아졌다. 따라서 RO 16의 흡착공정의 자발성이 온도가 증가할수록 높아진다는 것을 보여주었다.

• 한국환경과학회지
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• 제28권1호
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• pp.55-64
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• 2019

The adsorption properties of $Cs^+$ and $Cu^{2+}$ ions were evaluated by using a polysulfone scoria zeolite (PSf-SZ) composite with synthetic zeolite synthesized from Jeju volcanic rocks (scoria). In order to investigate the adsorption properties, various parameters, such as pH, contact time, reaction rate, concentration, and temperature in aqueous solutions, were evaluated by tests carried out in batch experiments. The adsorption capacities of $Cs^+$ and $Cu^{2+}$ ions increased between pH 2 but achieved equilibrium at pH 4 and above. The adsorption rate increased rapidly up to the initial 24 h, after which it plateaued ; the adsorption rate then sustained at equilibrium from 48 h. The adsorption kinetics of $Cs^+$ and $Cu^{2+}$ ions were described better by the pseudo-second-order kinetic model than the pseudo-first-order kinetic model. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model. The maximum adsorption capacities of $Cs^+$ and $Cu^{2+}$ ions obtained from the Langmuir model were 53.8 mg/g and 84.7 mg/g, respectively. The calculated thermodynamic parameters showed that the adsorption of $Cs^+$ and $Cu^{2+}$ ions on PSf-SZ was feasible, spontaneous and endothermic reaction.

• 한국환경과학회지
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• 제21권7호
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• pp.805-813
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• 2012

The removal property of Cu and Zn ions by chemical precipitation and adsorption using zeolite(Z-C1) prepared from coal fly ash(CFA) were evaluated in this study. Adsorption kinetic and equilibrium mechanisms described to analyze parameters and correlation factors with Lagergen $1^{st}$ and $2^{nd}$ order model and Langmuir and Freundlich model. Analysis of adsorption kinetics data revealed that the pseudo $2^{nd}$ order kinetics mechanism was predominant. The equilibrium data in pH 3 - 5 were able to be fitted well to a Langmuir model, by which the maximum adsorption capacities($q_{max}$) were determined at 124.9 - 140.1 mg $Cu^{2+}/g$ and 153.2 - 166.9 mg $Zn^{2+}/g$, respectively. We found that Z-C1 has a potential application as absorbents in metal ion recovery with low pH.