• Korean Chemical Engineering Research
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• 제59권4호
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• pp.565-573
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• 2021

활성탄에 의한 Brilliant Green(BG), Quinoline Yellow(QY) 염료의 흡착에 대한 등온선, 동력학, 열역학적 특성치와 경쟁흡착을 흡착제의 양, pH, 초기농도, 접촉시간 및 온도를 변수로 하여 수행하였다. BG와 QY는 가지고 있는 atomic nitrogen 이온(N⁺)의 영향으로 pH 11에서 92.4%의 최고 흡착율을 나타내었고, QY는 sulfite 이온(SO₃^-)의 영향으로 pH3에서 90.9%의 최고 흡착률을 나타냈다. 등온흡착 데이터로부터, BG의 경우는 Freundlich 등온식에 잘 맞아서 다분자층 흡착이었고, QY는 Langmuir 등온식이 가장 높은 일치도를 나타내어 주로 단분자층흡착이었다. Freundlich 식과 Langmuir 식의 분리계수는 활성탄에 의해 이들 염료를 효과적으로 처리할 수 있는 공정임을 나타냈다. Temkin 등온식에 의해 평가된 흡착 에너지는 활성탄에 의한 BG와 QY의 흡착이 물리 흡착임을 확인시켰다. 동력학적 실험결과는 유사 이차 반응속도식이 유사일차 반응속도식보다 일치도가 높았고 평형흡착량에 대한 오차도 더 작았다. 입자내 확산식을 이용하여 도시한 그래프는 2단계의 직선으로 나타났는데 기울기가 낮은 입자내 확산이 율속단계임을 확인하였다. 흡착공정의 활성화 에너지와 엔탈피 변화는 흡착과정이 비교적 수월하게 일어나며 흡열반응임을 나타냈다. 엔트로피 변화는 활성탄에 대한 BG와 QY 염료의 흡착이 진행됨에 따라 흡착시스템의 무질서도가 증가함을 나타냈고, Gibbs 자유 에너지 변화로 부터 흡착반응이 온도가 높아질수록 자발성이 더 커진다는 것을 알았다. 혼합용액의 경쟁흡착 결과는 상대적으로 흡착률이 높은 QY가 BG에 의해 큰 방해를 받아 흡착률이 크게 감소하는 것으로 나타났다.

• 한국지반공학회논문집
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• 제27권4호
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• pp.43-50
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• 2011

본 연구에서는 국내 해안지역에 존재하는 카드뮴을 산업 폐기물인 제강슬래그를 이용하여 제거하고자, 제강슬래그의 카드뮴 제거 성능을 평가하였다. 이를 위해 회분식 실험으로 등온흡착 실험과 동적흡착 실험을 수행하였다. 등온 흡착 실험을 통해 제강슬래그의 카드뮴 제거는 Langmuir 모델이 Freundlich에 비해 잘 맞음을 확인하였고 최대 흡착량(${\beta}$)을 계산할 수 있었다. 동적흡착 실험결과의 경우, 유사이차 모델을 이용해 해석하였고 카드뮴의 초기농도가 높을수록 평형 흡착량 ($q_e$)은 증가하였고 반응상수 ($k_2$)와 초기반응속도 (h)는 줄어들었다. 모사해수 조건에서 $q_e$는 증류수 조건과 큰 차이가 없었지만 $k_2$와 h는 증류수에 비해 줄어들었다. 또한, 유사이차 모델을 통해 예측된 $q_e$이 등온흡착 실험에서 구한 평형 흡착량 ($C_s$)과 유사해 동적흡착 실험결과로 등온흡착 실험결과를 예측하는 것이 가능함을 확인하였으며 유사이차 모델을 이용해 목표 제거율에 도달하는 반응시간을 계산할 수 있었다.

• 한국환경과학회지
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• 제24권2호
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• pp.151-162
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• 2015

The adsorption characteristics of Sr ions and Cs ions in single and binary solution by zeolite A were investigated in batch experiment. The adsorption rate of Sr ions and Cs ions by zeolite A obeyed pseudo-second-order kinetic model in single and binary solution. The initial adsorption rates (h) and adsorption capacities of both ions obtained from pseudo-second-order kinetic model, and the values were decreased with increasing concentration of the competitive ions (0~1.5 mM). Also, adsorption isotherm data in binary solution were well fitted to the extended Langmuir model, the maximum adsorption capacities of Sr and Cs calculated from the model were 1.78 mmol/g and 1.64 mmol/g, respectively. The adsorption of Sr and Cs ions by zeolite A was carried out in the presence of other cations such as $Na^+$, $K^+$, $Mg^{2+}$ and $Ca^{2+}$. The results showed that the zeolite A can maintain a relatively high adsorption capacity for Sr and Cs ions and exhibits a high selectivity in the presence of competitive cations. The effect of competition had an order of $Ca^{2+}$ > $K^+$ > $Mg^{2+}$ > $Na^+$ for Sr ions and $K^+$ > $Ca^{2+}$ > $Na^+$ > $Mg^{2+}$ for Cs ions at the same cation concentration.

• 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.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.629-636
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• 2003

The retardation of heavy metals in a mixture of fly ash and bentonite was studied as a potential barrier material for a landfill. Column tests were conducted using synthetic leachate having 100 mg/L and 50 mg/L of lead (Pb) and cadmium (Cd), respectively. Results indicated that the mixture had obvious retardation ability for heavy metals. To investigate the retardation factor caused by adsorption, batch adsorption tests were conducted at various concentrations. Test results were correlated with both Langmuir and Freundlich isotherms. The adsorption of the lead ion was applicable to the Langmuir isotherm and the adsorption of the cadmium ion was applicable to the Freundlich isotherm. In addition, based on experimental results, the migration characteristics of heavy metals through the bed of fly ash and bentonite mixture were investigated using the PHREEQC, a reactive transport model, under the real conditions of the landfill liner.

• 한국환경과학회지
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• 제4권5호
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• pp.141-141
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• 1995

The waste biomass of Sacchromyces uvarum, used in fermentation industries to produce ethanol, were studied for their ability to absorb various heavy metal ions. Heavy metal ions studied in this research were Cd, Co, Cr, Cu, Ni and Pb. The order of the sorption capacity was Pb>Cu>Co=Cr=Cd>Ni. The living Sacchromyces uvarum exhibited higher metal-uptake capacity than the dead Sacchromyces uvarum. After we compare the uptake capacity of the Sacchromyces uvarum for individual metal ions with for a mixture of them, the following was observed: in the mixed heavy metal solution the uptake capacity was decreased than the one heavy metal solution. The selective uptake was observed when all . the heavy metal ions were dissolved in a mixed solution. The adsorption isotherm modelling was decribed with the Langmuir and Freundlich model. The results were in good agreement with the Langmuir model.

• 한국환경과학회지
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• 제4권5호
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• pp.527-534
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• 1995

The waste biomass of Sacchromyces uvarum, used in fermentation industries to produce ethanol, were studied for their ability to absorb various heavy metal ions. Heavy metal ions studied in this research were Cd, Co, Cr, Cu, Ni and Pb. The order of the sorption capacity was Pb>Cu>Co=Cr=Cd>Ni. The living Sacchromyces uvarum exhibited higher metal-uptake capacity than the dead Sacchromyces uvarum. After we compare the uptake capacity of the Sacchromyces uvarum for individual metal ions with for a mixture of them, the following was observed: in the mixed heavy metal solution the uptake capacity was decreased than the one heavy metal solution. The selective uptake was observed when all . the heavy metal ions were dissolved in a mixed solution. The adsorption isotherm modelling was decribed with the Langmuir and Freundlich model. The results were in good agreement with the Langmuir model.

• 동아시아식생활학회지
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• 제14권5호
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• pp.457-462
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• 2004

Physical properties of soybean curd powder prepared with hot air, vacuum and freeze drying methods were investigated. Adsorption characteristics were studied under various water activities (such as 0.11, 0.33, 0.44, 0.55, 0.66, 0.75, 0.85, and 0.93) at 5℃, and prediction models were developed. Equilibrium moisture and monolayer moisture contents were the highest when freeze dried. due to the porous structure. In this result, Oswin model was the best fit for the isotherm of soybean curd. Sorption enthalpy indicated that high moisture content of powder showed lower sorption than that of low moisture content.

• Advances in environmental research
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• 제5권4호
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• pp.225-235
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• 2016

Synthesized hydroxyapatite (Hyd) and Fe-hydroxyapatite (Fe-Hyd) composite were used for the removal of Methylene Blue (MB) from aqueous solutions in this study. The effect of adsorbent amount, pH and initial MB concentration were carried out to investigate in the aqueous solution. The kinetic study shows that the MB adsorption process with Hyd or Fe-Hyd follow pseudo-second order kinetic model. Experimental results are well fitted to the Langmuir isotherm model. The maximum adsorption capacities of Hyd and Fe-Hyd were obtained as 2.90 mg/g and 5.64 mg/g for MB according to Langmuir Isotherm models, respectively. Fe-Hyd composite increased the adsorption capacity of Hyd by 1.95 times that Hyd. It is concluded that Fe-Hyd composite is promising and economical adsorbent for MB removal in the aqueous solution.

• 한국식품저장유통학회지
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• 제4권1호
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• pp.33-38
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• 1997

In order to provide informations for designing packaging and storage condition of dry jujube (Zizyphus jujuba MILLER), moisture sorption isotherm was determined for temperatures of 20, 30 and 4$0^{\circ}C$, and quality changes were evaluated as function of temperature and water activity. Dry jujube at a given water activity showed higher equilibrium moisture content for lower temperature. Moisture isothem could be fitted by GAB model equation, giving higher C value, lower m0 and relatively constant k value with increase in temperature. Ascorbic acid was lost more highly at higher temperature and water activity, and showed negligible retention for whole range of water activity and temperature studied after 141 days. Browning increased with water activity up to 0.73 at 30 and 4$0^{\circ}C$. Dry jujube of high water activity had high L value in surface color, which represent brightness of surface color. Considering quality retention in the storage, dry jujube is desired to be dried to water activity of 0.42 and be stored at temperature below 3$0^{\circ}C$