• Title, Summary, Keyword: Adsorption

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Adsorption Isotherm Patterns According to the Interactions Between Adsorbed Particles (흡착입자간 상호작용에 따른 흡착등온선 패턴)

  • Kim, Cheol Ho
    • Korean Journal of Materials Research
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    • v.23 no.8
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    • pp.462-468
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    • 2013
  • We study and describe-from the point of view of the interactions of the adsorbed particles-three types of the adsorption isotherms, namely, Langmuir type adsorption isotherms, phase transition type adsorption isotherms, and adsorption limited type adsorption isotherms, which are observed by experiments. By introducing and using a one dimensional statistical occupancy model, we derived analytical adsorption isotherms for the no force, the attractive force, and the repulsive force exerted on the other adsorbed particles. Our derived adsorption isotherms qualitatively pretty well agree with the experimental results of the adsorption isotherms. To specify each adsorption type, Langmuir type adsorption is a phenomenon that occurs with no forces between the adsorbed particles, phase transition type adsorption is a phenomenon that occurs with the strong attractive forces between the adsorbed particles, and adsorption limited type adsorption is a phenomenon that occurs with the repulsive forces between the adsorbed particles. The theoretical analysis-only using fundamental thermodynamics and occupancy statistics though-qualitatively quite well explains the experimental results.

Excellent toluene removal via adsorption by honeycomb adsorbents under high temperature and humidity conditions

  • Cho, Min-Whee;Kim, Jongjin;Jeong, Jeong Min;Yim, Bongbeen;Lee, Hyun-Jae;Yoo, Yoonjong
    • Environmental Engineering Research
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    • v.25 no.2
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    • pp.171-177
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    • 2020
  • Removal through adsorption is the most widely used and effective treatment method for volatile organic compounds (VOCs) in exhaust gases. However, at high temperatures and humidity, adsorption is competitive due to the presence of moisture and unsmooth physical adsorption thereby deteriorating adsorption performance. Therefore, water adsorption honeycomb (WAH) and VOCs adsorption honeycomb (VAH) were prepared to improve VOCs adsorption at high temperatures and humidity. Adsorbed toluene amounts on single honeycomb (SH), containing only VAH, and combined honeycomb (CH), containing WAH and VAH, were determined. Further, the toluene adsorption rates of honeycomb adsorbents mounted on rotary systems, VAH-single rotor (SR) and WAH/VAH-dual rotor (DR) were determined. Toluene adsorption by WAH/VAH-CH (inlet temperature: 40-50℃; absolute humidity: 28-83 gH2O/kg-dry air) was 1.6 times that by VAH-SH, and the water adsorption efficiency of WAH/VAH-CH was 1.7 times that of VAH-SH. The adsorption/removal efficiency of the WAH/VAH-DR (inlet temperature: 45℃; absolute humidity: 37.5 gH2O/kg-dry air) was 3% higher than that of VAH-SR. This indicates that the WAH at the rotor inlet selectively removed water, thereby improving the adsorption efficiency of the VAH at the outlet.

Reduction of Phosphate Adsorption by Ion Competition with Silicate in Soil

  • Lee, Yong-Bok;Kim, Pil-Joo
    • Korean Journal of Environmental Agriculture
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    • v.26 no.4
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    • pp.286-296
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    • 2007
  • To increase phosphate (P) availability in soils, the efficiency of silicate (Si) in reducing P adsorption was investigated by competitive adsorption tests under changing conditions of pH, ion concentrations, and order of anion addition along with single adsorption properties of each ion at $20^{\circ}C$. In the single ion adsorption study, P and Si ions showed the opposite reaction patterns: phosphate adsorption decreased with increasing pH and attained adsorption maximum however, silicate adsorption increased with increasing pH without attaining adsorption maximum. Phosphorus and Si adsorption were influenced by pH in the range of 5.0 - 9.0 and the type and amount of P and Si concentration. Silicate added to soil before P or in a mixture with P significantly reduced P adsorption above pH 7.0; however, there was no significant Si-induced decreased in P adsorption at pH 5.0 when anions were added as mixture. The efficiency of Si in reducing P adsorption increased with increasing Si concentration and pH. The effect of P on Si adsorption was relatively small at pH 5.0 and no effect of P on silicate adsorption was observed at pH 9.0. The presence of Si strongly depressed P adsorption when Si was added before P compared to P and Si added as a mixture. These results suggest that application of Si may decrease P adsorption and increase the availability of P in soils. Furthermore, a Si source would be better to add before P application to enhance the availability of P in soils.

Applicability of Composite Beads, Spent Coffee Grounds/Chitosan, for the Adsorptive Removal of Pb(II) from Aqueous Solutions

  • Choi, Hee-Jeong
    • Applied Chemistry for Engineering
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    • v.30 no.5
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    • pp.536-545
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    • 2019
  • An experiment was conducted to evaluate the adsorptive removal of Pb(II) from an aqueous solution using a mixture of spent coffee grounds and chitosan on beads (CC-beads). Various parameters affecting the adsorption process of Pb(II) using CC-beads were investigated. Based on the experimental data, the adsorption kinetics and adsorption isotherms were analyzed for their adsorption rate, maximum adsorption capacity, adsorption energy and adsorption strength. Moreover, the entropy, enthalpy and free energy were also calculated by thermodynamic analysis. According to the FT-IR analysis, a CC-bead has a very suitable structure for easy heavy metal adsorption. The process of adsorbing Pb(II) using CC-beads was suitable for pseudo-second order kinetic and Langmuir model, with a maximum adsorption capacity of 163.51 (mg/g). The adsorption of Pb(II) using CC-beads was closer to chemical adsorption than physical adsorption. In addition, the adsorption of Pb(II) on CC-beads was exothermic and spontaneous in nature. CC-beads are economical because they are inexpensive and also the waste can be recycled, which is very significant in terms of the continuous circulation of resources. Thus, CC-beads can compete with other adsorbents.

Understanding the Mechanism of Hydrogen Adsorption into Metal Organic Frameworks (Metal-Organic Framework의 수소 흡착 메커니즘의 이해)

  • Lee, Tae-Bum;Kim, Dae-Jin;Yoon, Ji-Hye;Choi, Sang-Beom;Kim, Ja-Heon;Choi, Seung-Hoon
    • 한국신재생에너지학회:학술대회논문집
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    • pp.634-637
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    • 2005
  • Hydrogen adsorption mechanism onto the porous metal-organic frameworks (MOFs) has been studied by density functional theory calculation. The selected functionals for the predict ion of interact ion energies between hydrogen and potential adsorption sites of MOF was utilized after the evaluation with the various functionals for interaction energy of $H_2C_6H_6$ model system the adsorption energy of hydrogen molecule into MOF was investigated with the consideration of the favorable adsorption sites and the orientations. We also calculated the second favorable adsorption sites by geometry optimization using every combination of two first absorbed hydrogen molecules. Based on the calculation of first and second adsorption sites and energies, the hydrogen adsorption into MOF follows a cooperative mechanism in which the initial metal sites initiate the propagation of the hydrogen adsorption on the whole frameworks. In addition, it was found that the interaction strength between the simple benzene ring with hydrogen is significantly reinforced when the benzene ring has been incorporated into the framework of MOFs.

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Adsorption Studies of Nickel(II) Ions onto Amorphous Alumina (무정형 알루미나에서의 니켈(II) 이온의 흡착에 관한 연구)

  • Park, Yeong Jae;Suh, Moo Yul;Park, Kyoung Kyun;Choi, Kwang Soon;Jee, Kwang Yong;Kim, Won Ho
    • Analytical Science and Technology
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    • v.13 no.4
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    • pp.433-439
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    • 2000
  • Adsorption behaviors of Ni(II) ions were investigated using amorphous alumina as adsorbent. In the adsorption kinetic study, it was observed that Ni(II) ions were bound to the alumina surface in two adsorption stages, the rapid and slow adsorption stages. The rapid adsorption proceeded within 1 hr, thereafter the slow adsorption occurred. The results of adsorption isotherm experiments showed that the Ni(II) adsorption obeyed the Langmuir-Freundlich isotherm, and that the adsorption enhanced with increasing pH. The change in ionic strength did not exhibit a conspicuous trend in Ni(II) adsorption, thereby suggesting that the adsorption occurs through surface complexation rather than electrostatic interactions. The amounts of adsorption were measured with varying pH at three different Ni(II) concentrations under the condition of constant ionic strength, showing that with increasing Ni(II) concentration, the percentage of adsorption decreased and the adsorption edge was shifted to a higher pH value.

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Effect of Temperature on Cu Adsorption and Competitive Adsorption of Zn and Cu onto Natural Clays using Combined Adsorption-sequential Extraction Analysis(II) (혼합 흡착-연속추출법을 이용한 점토 차수재의 구리(Cu) 흡착 및 아연과 구리 경쟁 흡착 시 온도 영향에 관한 연구(II))

  • 도남영;이승래
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.157-170
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    • 2000
  • In this study, we conducted a combined adsorption-sequential extraction analysis(CASA) to investigate temperature effects of single and competitive adsorption of zinc and copper on natural clays. As a result, it was found out that in a single adsorption of zinc, the adsorption was mostly in the exchangeable phase, with increase n temperature. In a competitive adsorption of zinc, this trend was so strong that the exchangeable phase adsorption increase up to 80~90%. On the other hand, about 50% of copper was adsorbed in the carbonate occluded phase in single and competitive adsorptions. In the single adsorption the adsorption of carbonate occluded phase increased by 5% with the temperature increase and in the competitive adsorption the increase rate is about twice. The adsorption of zinc and copper on natural clays is an endothermic reaction with the exception of exchangeable phase adsorption.

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Adsorption of selected endocrine disrupting compounds (EDCs)/pharmaceutical active compounds (PhACs) onto granular activated carbon (GAC) : effect of single and multiple solutes (EDCs/PhACs의 단일,복합 조건에서의 GAC에 대한 흡착 연구)

  • Jung, Chanil;Son, Jooyoung;Yoon, Yeomin;Oh, Jeill
    • Journal of Korean Society of Water and Wastewater
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    • v.28 no.2
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    • pp.235-248
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    • 2014
  • The widespread occurrence of dissolved endocrine disrupting compounds(EDCs) and pharmaceutical active compounds(PhACs) in water sources is of concern due to their adverse effects. To remove these chemicals, adsorption of EDCs/PhACs on granular activated carbon(GAC) was investigated, and bisphenol A, carbamazepine, diclofenac, ibuprofen, and sulfamethoxazole were selected as commonly occurring EDCs/PhACs in the aquatic environment. Various adsorption isotherms were applied to evaluate compatability with each adsorption in the condition of single-solute. Removal difference between individual and competitive adsorption were investigated from the physicochemical properties of each adsorbate. Hydrophobicity interaction was the main adsorption mechanism in the single-solute adsorption with order of maximum adsorption capacity as bisphenol A > carbamazepine > sulfamethoxazole > diclofenac > ibuprofen, while both hydrophobicity and molecular size play significant roles in competitive adsorption. Adsorption kinetic was also controled by hydrophobicity of each adsorbate resulting in higher hydrophobicity allowed faster adsorption on available adsorption site on GAC. EDCs/PhACs adsorption on GAC was determined as an endothermic reaction resulting in better adsorption at higher temperature ($40^{\circ}C$) than lower temperature ($10^{\circ}C$).

Adsorption Characteristics by Synthesized Goethite in the Mixed Solution Systems of Phosphate, Sulfate, and Copper Ions (합성 Goethite에 의한 인산이온, 황산이온 및 구리이온의 혼합용액에서의 흡착특성)

  • 감상규;이동환;이민규
    • Journal of Environmental Science International
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    • v.12 no.10
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    • pp.1055-1060
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    • 2003
  • Adsorption on goethite of individual component from a solution containing phosphate, sulfate, or copper ion was investigated. Competitive adsorption in the binary and ternary solution systems composed of phosphate, sulfate, and copper ions was also investigated. In competitive adsorption systems with phosphate and sulfate ions, the presence of phosphate ion reduced the adsorption of sulfate ion largely. On the other hand, the presence of sulfate ion caused only a small decrease in phosphate adsorption. This result suggests that phosphate ion is a stronger competitor for adsorption on goethite than sulfate ion, which is consistent with the higher affinity of phosphate for the surface compared to sulfate ion. Compared to the results from single-sorbate systems, adsorption of copper ion in the binary system of sulfate ion and copper ion was found to be enhanced in the presence of sulfate ion. Addition of sulfate ion to the binary system of copper ion and phosphate ion resulted in a small enhancement in copper sorption. This result implies that the presence of sulfate ion promotes adsorption of the ternary complex FeOHCuSO$_4$. The adsorption isotherms could be well described by the Langmuir adsorption equation.

Study on Process Parameter of Ethyl Violet by Activated Carbon Adsorption (활성탄 흡착에 의한 Ethyl Violet의 공정 파라미터 연구)

  • Lee, Jong-Jib
    • Journal of Korean Society of Water Science and Technology
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    • v.26 no.6
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    • pp.143-152
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    • 2018
  • The process parameters of ethyl violet from aqueous solution by activated carbon adsorption were carried out as a function of pH, temperature, contact time, initial concentration and temperature. The adsorption equilibrium data can be described well by the Langmuir and Freundlich isotherm models. Base on Langmuir constant ($R_L=0.0343{\sim}0.0523$) and Freundlich constant (1/n=0.1633~0.1974), This process could be employed as effective treatment for adsorption of ethyl violet. The kinetic experimental results showed that the adsorption process can be well described with the pseudo second order model. Based on the positive enthalpy (6.505 kJ/mol), the adsorption of ethyl violet onto granular activated carbon is endothermic. The negative Gibbs free energy (-1.169~-1.681 kJ/mol) obtained indicates that the adsorption process is spontaneous and physisorption.