• Advances in environmental research
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• 제12권1호
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• pp.17-40
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• 2023

This article presents studies of the adsorption process in a continuous system of fluoride solutions at a concentration of 30 mg/L using a bone char packed in fixed-bed columns, as well as regeneration studies in the same system using HNO₃, HCl and NaOH at 0.01, 0.1 and 1 M. The Thomas Model, Artificial Neural Networks (ANNs), Numerical Integration and Mass Transfer Zone were used for the modeling of asyemmetrical breakthrough curves obtained from the fluoride adsorption on bone char. The maximum adsorption capacity of the breakthrough curves was estimated, and various design parameters of the columns were obtained for the different operating conditions. Results showed that an improvement in the modeling capabilities of the Thomas model can be obtained using ANNs. Moreover, ANNs are useful for determining reasonable and accurate design parameters of packed-bed adsorption columns. This modeling approach can be useful for the process system engineering of dynamic adsorption systems involved in the field of water treatment and purification. It is important to highlight that the obtained results indicate that, when using HCl or HNO₃ at a concentration of 0.1 M, a large number of adsorption-desorption cycles are obtained and, therefore, the highest values of adsorption capacity, which leads to a reduction in operation costs.

• Membrane and Water Treatment
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• 제7권5호
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• pp.403-416
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• 2016

The possibility of using carica papaya leaf powder for removal of copper from wastewater as a low cost adsorbent was explored. Different parameters that affect the adsorption process like initial concentration of metal ion, time of contact, adsorbent quantity and pH were evaluated and the outcome of the study was tested using adsorption isotherm models. A maximum of 90%-94.1% copper removal was possible from wastewater having low concentration of the metal using papaya leaf powder under optimum conditions by conducting experimental studies. The biosorption of copper ion was influenced by pH and outcome of experimental results indicate the optimum pH as 7.0 for maximum copper removal. Copper distribution between the solid and liquid phases in batch studies was described by isotherms like Langmuir adsorption and Freundlich models. The adsorption process was better represented by the Freundlich isotherm model. The maximum adsorption capacity of copper was measured to be 24.51 mg/g through the Langmuir model. Pseudo-second order rate equation was better suited for the adsorption process. A dynamic mode study was also conducted to analyse the ability of papaya leaf powder to remove copper (II) ions from aqueous solution and the breakthrough curve was described by an S profile. Present study revealed that papaya leaf powder can be used for the removal of copper from the wastewater and low cost water treatment techniques can be developed using this adsorbent.

• Environmental Analysis Health and Toxicology
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• 제28권
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• pp.6.1-6.7
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• 2013

Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

• 한국산업보건학회지
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• 제24권2호
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• pp.193-200
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• 2014

Objectives: To develop domestic charcoal tubes with good adsorption capacity, breakthrough experiments were performed on four types of activated charcoal. Materials: The adsorption capacity and the adsorption rate were determined using a modified Wheeler equation after the breakthrough experiment. For four types of charcoal (J, K, S and SKC Inc. 226-01), 100 mg were used in the breakthrough experiment. The test was done on benzene, toluene, n-hexane, and acetone in a dynamic chamber. Results: K charcoal had the greatest surface area and the highest micropore volume. J charcoal had a similar surface area and micropore volume to SKC charcoal. S charcoal had the lowest surface area and micropore volume. J charcoal had the highest adsorption capacity at 101, 252 and 609 ppm of benzene. The gap in benzene adsorption capacity among the types of charcoal was the least at 609 ppm and the greatest at 101 ppm. J charcoal showed the highest adsorption capacity at 54, 106, 228 and 508 ppm of toluene. J charcoal and SKC charcoal had a similar adsorption capacity for acetone. J charcoal had the highest adsorption capacity for n-hexane. In the experiment featuring 10% breakthrough volume, 10% breakthrough occurred at 18 liters at $2065.9mg/m^3$ for J charcoal and at 20 liters at $1771.2mg/m^3$ for K charcoal. It was difficult to judge adsorption capacity by surface area and micropore volume of charcoal. J charcoal, which was similar to SKC charcoal in surface area and micropore volume, showed good adsorption capacity at common workplace concentrations. Conclusions: The adsorption capacity of J and K charcoal was superior compared with SKC charcoal. J and K charcoal can be considered appropriate for use as sampling media based on this result.

• 한국환경과학회지
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• 제15권7호
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• pp.695-699
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• 2006

This study is to investigate the relationship between pore structures of activated carbons and adsorption characteristics of toluene vapor using dynamic adsorption method. The surface areas of below $10{\AA}$ in the pore diameter of activated carbons used in this experiment were in the range of 72 -93 % of total cumulative surface area and the toluene vapor equilibrium adsorption capacities were in the range of 350 - 390mg/g. Activated carbons having larger toluene adsorption capacity than the compared activated carbons had relatively pores in the pore diameter range of $7-10{\AA}$. Linear relationship between equilibrium adsorption capacity and cumulative sur- face area was in the diameter range of over $7{\AA}$. It was thought that toluene vapor was relatively well adsorbed on surfaces of pores of over $7{\AA}$.

• 공업화학
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• 제16권1호
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• pp.131-138
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• 2005

활성탄과 제올라이트 13X에 대한 벤젠의 정적흡착실험으로부터 Freundlich isotherm과 Toth isotherm을 구하였으며 똑같은 흡착제로 충진된 흡착탑을 이용하여 벤젠의 파과곡선을 측정하였다. 파과시간과 벤젠 분압의 관계를 해석하여 Freundlich isotherm의 파라미터를 결정하였다. 파과실험 결과의 해석으로부터 예측되는 벤젠의 흡착량이 정적 실험 결과로부터 예측되는 것과 비교적 잘 일치하였다. 활성탄에 대한 동적 실험 결과에서 좀 더 대칭형태에 가까운 파과곡선이 얻어져서 제올라이트 13X에 비해 더 적은 오차가 나타났다.

• 청정기술
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• 제9권4호
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• pp.153-161
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• 2003

벤젠과 톨루엔을 활성탄에 흡착하는 공정을 개발하기 위한 기초 실험을 수행하였다. 정적흡착실험은 온도와 압력의 변화에 따른 벤젠과 톨루엔의 흡착특성을 연구하였다. 흡착제로는 활성탄 12~20mesh와 20~40mesh를 사용하였으며 흡착질로는 벤젠, 톨루엔, 질소를 사용하였다. 실험결과는 Langmuir isotherm으로 fittimg하였고, 온도의존성을 계산하였고, 흡착열과 흡착상수를 얻었다. 이성분 정적흡착실험에서는 Langmuir isotherm parameter들이 Extended Langmuir isotherm에 일반적으로 적용할 수 있는 지를 확인하였다. 이때 사용한 실험기법은 기존의 방법에서처럼 흡착 전후의 기상의 몰분율을 측정하여 실험하는 방법이 아닌 압력변화반을 측정하는 정용적법에 기초한 방법을 사용하였다. 동적흡착실험올 수행하여 실험결과를 전사모사로부터 얻어진 결과와 비교하였다. 본 연구에서는 공정에서 흡착조건을 결정할 수 있는 기본 데이터를 획득할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1312-1316
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• 2014

Metal-carbon nanoreactors (MCNRs) were prepared from a pristine carbon cage (CC) using a simple and efficient template method with nano silica ball (NSB), pyrolysis fuel oil (PFO) and transition metals, such as palladium and gold. Metal nanoparticles were embedded in approximately 25 and 170 nm sized, highly ordered carbon cages. The newly developed Pd, Au and Au-Pd doped carbon nanoreactors were characterized by microanalysis, $N_2$ adsorption-desorption isotherm, powder X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), transmission electron microscopy and inductively coupled plasma (ICP) analysis. The ordered MCNRs have exhibited dynamic hydrogen adsorption capability compared to the carbon cage.

• Carbon letters
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• 제6권3호
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• pp.141-147
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• 2005

The carbon sample "O", phosphoric acid-activated carbon "OP", zinc chloride-activated carbon "OZ", and two steam activated carbons "OS" and "OS2" with different burn-off of 25% and 58% respectively, were prepared from olive stones. The textural properties were determined from the results of nitrogen adsorption at 77 K and by analyzing these results through the application of different adsorption models. The chemistry of the carbon surfaces was determined from the base neutralization capacities, acid neutralization capacity and surface pH. The sorption of $Pb^{2+}$ ions on to the carbons prepared was followed under dynamic and equilibrium conditions. The differences between the values of the textural parameters were attributed to the inapplicability of some adsorption models and to the heterogeneity of the microporous carbons. The sorption of $Pb^{2+}$ ions is favored on carbon and activated carbons. However, chemically activated carbons are more effective compared with steam-activated ones. The sorption of $Pb^{2+}$ ions were related to the chemistry of the surface rather than to the textural properties.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.155-161
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• 2012

바이오필터에서 폐가스에 포함된 유기오염물을 제거하는 효율에 대한 미디움 흡착능력의 영향을 포괄하는 강인한 동적 바이오필터 모델링을 수행하였다. 특히 비정상상태의 운전 조건 하에서도 바이오필터에 의해 처리된 폐가스 내의 유기오염물 농도를 구하기 위한 바이오막, 가스상, 수착(sorption) 부피 및 흡착상의 네가지 모델요소로 구성된 독창적인 모델인 개선된 프로세스럼핑 모델을 제시하였다. 이전의 프로세스럼핑모델에서는 담체에 대한 VOC의 평형 흡착량이 담체의 수착부피 내의 용존 VOC 농도에 선형적으로 비례한다는 가정 하에서 식을 유도하였으므로, 폐가스 처리에 적용이 제한적이었다. 따라서 실제 적용을 위해서 Freundlich 식과 같은 흡착관계식을 프로세스럼핑 모델에 접합하여 모든 농도의 VOC의 경우에 유효한 강인한 프로세스럼핑 모델을 구축하였다. 프로세스럼핑 모델 파라미터 중에서 바이오필터 미디움의 흡착과 관련한 파라미터 값들을 선행논문의 동적 흡착칼럼실험 및 문헌을 통하여 구하였다. 또한 에탄올을 포함한 폐가스처리를 위한 비정상상태의 바이오필터실험을 수행하였고, 그 실험결과와 여러 가지 Thiele modulus(${\phi}$) 값을 가지는 동적 바이오필터모델링 예측 값과 비교하였다. 이때에 구하여진 Thiele modulus(${\phi}$) 값은 0.03에 근접하였다.