Reliable estimation of adsorption isotherm parameters using adequate pore size distribution

Danial Husseinzadeh,Akbar Shahsavand 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.5

The equilibrium adsorption isotherm has a crucial effect on various characteristics of the solid adsorbent (e.g., pore volume, bulk density, surface area, pore geometry). A historical paradox exists in conventional estimation of adsorption isotherm parameters. Traditionally, the total amount of adsorb material (total adsorption isotherm) has been considered equivalent to the local adsorption isotherm. This assumption is only valid when the corresponding pore size or energy distribution (PSD or ED) of the porous adsorbent can be successfully represented with the Dirac delta function. In practice, the actual PSD (or ED) is far from such assumption, and the traditional method for prediction of local adsorption isotherm parameters leads to serious errors. Up to now, the powerful combination of inverse theory and linear regularization technique has drastically failed when used for extraction of PSD from real adsorption data. For this reason, all previous researches used synthetic data because they were not able to extract proper PSD from the measured total adsorption isotherm with unrealistic parameters of local adsorption isotherm. We propose a novel approach that can successfully provide the correct values of local adsorption isotherm parameters without any a priori and unrealistic assumptions. Two distinct methods are suggested and several illustrative (synthetic and real experimental) examples are presented to clearly demonstrate the effectiveness of the newly proposed methods on computing the correct values of local adsorption isotherm parameters. The so-called Iterative and Optima methods’ impressive performances on extraction of correct PSD are validated using several experimental data sets.

상용 흡착제의 수증기 흡착등온선 모델에 관한 실험 및 이론적 연구

김준식(Jun-Sik Kim),우성용(Seong-Yong Woo),김경훈(Kyung-Hun Kim),김영득(Young-Deuk Kim) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

Adsorbent-adsorbate pairs are a key parameter in the performance of adsorptive systems (e.g., chiller, heat pump, and desalination plant). Modeling the adsorption isotherm is essential for the design and performance prediction of the adsorptive system because the performance is only influenced by the adsorption isotherm. In this study, the two isotherm models (the hybrid Langmuir-Sips and the Do-Do isotherm models) were proposed to the best fit with the measured isotherms of commercial adsorbents (i.e., silica gel, zeolite, and metal organic framework). First, the equilibrium adsorption isotherms of nitrogen, argon, and water vapor on the adsorbents were investigated to determine the applicability of adsorbents for the adsorptive systems. The equilibrium adsorption isotherm of water vapor on the adsorbents was then evaluated by the proposed isotherm models. Here, the coefficient of determination (R-squared) was used to assess the fitting degree of adsorption isotherm models with the measured isotherms.

Ag^(+)/aluminosilica 흡착제에 대한 에탄과 에틸렌의 흡착특성 연구

손의락,한상섭,박종호,김종남,조순행,이태종 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.6

고농도의 에틸렌을 생산하기 위해서 π-complexation을 유도할 수 있는 질산은을 알루미노실리카에 함침시킨 흡착제를 제조하였다. 순수 성분 흡착량 측정을 위해 Cahn balance를 사용하였고, 이성분 흡착량을 측정하기 위해 부피법을 이용하였다. 순수 성분은 온도 298.15 K, 323.15 K, 353.15 K 그리고 압력 0-5.100 mmHg 범위에서 측정하였으며, 이성분은 온도 298.15 K, 323.15 K 그리고 평형 압력 900 mmHg에서 측정하였다. 에탄의 순수성분 흡착량은 Langmuir식으로도 잘 나타낼 수 있었고, 에틸렌의 순수성분 흡착량은 Toth식과 물리흡착면과 화학흡착면을 고려한 Langmuir+Unilan, Langmuir-Freundlich모델이 잘 나타내었다. 표면 덮임 정도가 증가함에 따라 에탄 및 에틸렌의 흡착열이 감소함을 알 수 있었다. 흡착열, 이성분계 흡착등온선을 계산하기 위하여 (Langmuir-Freundlich, Toth식 및 IAS 모델을 사용하였다. To produce high concentration of ethylene, new adsorbents were synthesized by incipient wetness method of AgNO₃ on aluminosilica. Cahn balance was used to measure pure isotherms of C₂H₄ and C₂H₄ and volumetric apparatus was used to measure C2H4-C2H6 binary isotherms. Adsorption isotherms of pure gases were measured at 298.15 K, 323.15 K and 353.15 K, pressure ranges are from 0 mmHg to 5,100 mmHg. Pure ethane isotherm showed good agreement with Langmuir isotherm and pure ethylene isotherm showed good agreement with Langmuir-Freundlich and Langmuir+Unilan isotherms which were derived from considering physical site and chemical site. The decrease in heat of adsorption of ethylene with increasing the coverage was observed and the same result in case of ethane. Langmuir-Freundlich isotherm, Toth isotherm and ideal adsorbed solution(IAS) model were used to calculate isosteric heats of adsorption, and also used to predict binary isotherms.

합성수지 흡착제에 의한 p-Chlorophenol 및 2,4-Dichlorophenol의 액상흡착평형특성에 관한 연구

류정 ( Lyu Jeong ),김현규 ( Kim Hyeon Gyu ),원성호 ( Won Seong Ho ),황상면 ( Hwang Sang Myeon ),김상민 ( Kim Sang Min ),김남기 ( Kim Nam Gi ),이용철 ( Lee Yong Cheol ) 한국공업화학회 2003 공업화학 Vol.14 No.5

Rohm & Haas사에 의해 제조된 합성수지 흡착제, Amberlite XAD-4, XAD-7 및 XAD-1180을 사용하여 수용액상의 파라클로로페놀(p-chlorophenol) 및 2,4-디클로로페놀(2,4-dichlorophenol)의 흡착평형에 대한 특성들이 연구되었다. 흡착평형에 대한 실험결과들은 8가지 흡착등온식에 대한 비선형 회귀분석을 통해 이론적으로 고찰되었다. 실험 자료에 대한 회기분석 결과, 각 합성수지 흡착제에 대한 파라클로로페놀 및 2,4-디클로로페놀의 흡착거동은 BET 등온식, Four-parameter 등온식, Freundlich 등온식, Redlich-Petersen 등온식 및 Slips 등온식을 통해 4.31%의 오차범위 내에서 성공적으로 재현되었으나 Langmuir 등온식 및 Toth 등온식에 의해서는 최대 8.49%의 오차로서 다른 등온식들에 비하여 비교적 높은 오차분포를 갖는 결과를 보였다. Adsorption equilibrium characteristics of p-chlorophenol and 2,4-dichlorophenol on the polymeric synthetic adsorbents, Amberlite XAD-4, XAI-7 and XAD-1180 manufactured by Kohm & Haas Co.. in the aqueous solution were investigated by experimental tests and theoretical analyses. To evaluate theoretically experimental isotherms, eight adsorption equations and regressional methods were used. From the nonlinear regressional analyses adsorption equilibrium behaviors of p-chlorophenol and 2.3-dichlorophenol with polymeric synthetic adsorbents were successfully reproduced by BET isotherm, Four-parameter isotherm. Freundlich isotherm. Loading ratio correlation isotherm, Redlich-Petersen isotherm and Sips isotherm within the deviation of 4.31 %. But the results were not good for Langmuir isotherm and Toth isotherm with the upper deviation of 8.49 %.

흡착입자간 상호작용에 따른 흡착등온선 패턴

김철호,Kim, Cheol Ho 한국재료학회 2013 한국재료학회지 Vol.23 No.8

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.

Review Paper : An Application of Equilibrium Constant to the Calculation of an Extraction Isotherm for the Synergistic Solvent Extraction of Mn (2)

( Nagaphani Kumar Batchu ),( Jae Woo Ahn ),( Man Seung Lee ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.11

The equilibrium constant is an important parameter in solvent extraction equilibrium and can be used to represent the extractant capability. The paper describes the application of the equilibrium constant in calculating an extraction isotherm. The solvent extraction of Mn(II) from chloride solutions using a mixture of Cyanex 272 + Cyanex 301 and Cyanex 301+ TBP was studied. Extraction isotherms were obtained using both the mixtures and these isotherms were compared with the calculated isotherms. The calculated isotherms were obtained by utilizing the equilibrium constant for the synergistic mixture. A comparison was made between isotherms obtained experimentally and calculated. (Received February 21, 2013)

Isothermal Heat Treatment of AISI 430 Ferritic Stainless Steel after High Temperature Gas Nitriding

( Sang Jun Park ),( Jung Min Kim ),( Hee Jae Kang ),( Chang Yong Kang ),( Yung Hee Kim ),( Jang Hyun Sung ) 한국열처리공학회 2012 熱處理工學會誌 Vol.25 No.3

It has been known that the femtic stainless steel can be changed to martensitic stainless steel when nitrogen is added. However the high hardness of martensitic stainless steel prevents the plastic deformation. In this study, instead of martensite, the surface microstructure was changed into nitrogen pearlite to increase the plastic deformation easily by isothermal heat treatment after high temperature gas nitriding (HTGN) the AISI 430 femtic stainless steel. The isothermal treatment was carried out at 780°C for 4, 6, and 10 hrs, respectively, after HTGN treatment at 1100°C for 10 hrs. The surface layer of isothermal-treated steel appeared nitrogen pearlite composed with fine chromium nitride and ferrite. Hence, the interior region that was not affected by nitrogen permeation exhibited ferrite phase. When quenching the isothermal treated steel at 1100°C, martensitic phase formed at the surface layer. The hardness of surface layer of isothermal-treated steel and quenched steel measured the value of 1 50-240 Hv and 630 Hv, respectively.

Adsorption of Cd, Cu and Zn from aqueous solutions onto ferronickel slag under different potentially toxic metal combination

Park, Jong-Hwan,Kim, Seong-Heon,Kang, Se-Won,Kang, Byung-Hwa,Cho, Ju-Sik,Heo, Jong-Soo,Delaune, Ronald D.,Ok, Yong Sik,Seo, Dong-Cheol IWA Publishing 2016 Water Science & Technology Vol.73 No.5

<P>Adsorption characteristics of potentially toxic metals in single-and multi-metal forms onto ferronickel slag were evaluated. Competitive sorption of metals by ferronickel slag has never been reported previously. The maximum adsorption capacities of toxic metals on ferronickel were in the order of Cd (10.2 mg g(-1)) > Cu (8.4 mg g(-1)) > Zn (4.4 mg g(-1)) in the single-metal adsorption isotherm and Cu (6.1 mg g(-1)) >> Cd (2.3 mg g(-1)) > Zn (0.3 mg g(-1)) in the multi-metal adsorption isotherm. In comparison with single-metal adsorption isotherm, the reduction rates of maximum toxic metal adsorption capacity in the multi-metal adsorption isotherm were in the following order of Zn (93%) > Cd (78%) >> Cu (27%). The Freundlich isotherm provides a slightly better fit than the Langmuir isotherm equation using ferronickel slag for potentially toxic metal adsorption. Multi-metal adsorption behaviors differed from single-metal adsorption due to competition, based on data obtained from Freundlich and Langmuir adsorption models and three-dimensional simulation. Especially, Cd and Zn were easily exchanged and substituted by Cu during multi-metal adsorption. Further competitive adsorption studies are necessary in order to accurately estimate adsorption capacity of ferronickel slag for potentially toxic metals in natural environments.</P>

식물 바이러스병 진단방법에 관한 고찰

이은혜 ( Eun-hye Lee ),윤선희 ( Seon-hee Yun ),( Huin Lee ),주호종 ( Ho-jong Ju ) 전북대학교 농업과학기술연구소 2022 농업생명과학연구 Vol.53 No.1

Although plant viruses are very small compared to other pathogen groups, they cause diseases in plants resulting in great quantitative and qualitative loss It causes losses of more than $30 billion annually worldwide. Since viral pathogens are absolute parasites in cells, direct control using chemicals is very difficult. Especially, once it occurred, it is almost impossible to get rid of viruses from infected plant in the field. Therefore, prevention of the virus spread through diagnosis is the best approach to control viral diseases so far. Here we compared diagnostic methods based on serological methods and molecular biological methods. Serological diagnostic methods include enzyme-linked immunosorbent assay (ELISA), dot blot immunobinding assay (DBIA), and tissue blot immunobinding assay (TBIA). Use of serological diagnostic method is gradually decreasing because It has disadvantages over molecular biological based diagnostic methods in terms of time required for diagnosis, false positives due to cross-reaction, and sensitivity. On the other hand, PCR-based molecular biological diagnostic methods are on the rise. PCR-based methods are divided into two groups. One is the traditional PCR system which need temperature change during amplification. The other is isothermal-based amplification system which is not required for temperature change. Many isothermal amplification methods have been developed, including Nucleic acid sequence-based amplification (NASBA), Loop-mediated isothermal amplification (LAMP), Recombinase polymerase amplification (RPA), etc. Traditional PCR based methods require expensive equipment, but isothermal-based amplification does not require expensive equipment. Isothermal diagnostic methods can be usefully in underdeveloped countries. Among isothermal amplification methods, RPA is most likely to be applied to on-site diagnosis due to its very short diagnosis time and excellent sensitivity. In conclusion, since accurate and fast detection system is an essential to control plant viruses, the development of betted diagnostic methods than the current existing diagnostic method should be continued, and that will greatly contribute to the control of plant viral diseases.

등온 및 동적 흡착 실험을 통한 제강 슬래그의 비소 흡착 특성

오참뜻,이성수,Toshifumi, Igarashi,권호진,이원택,박준범 한국지반공학회 2010 한국지반공학회논문집 Vol.26 No.9

Sorption characteristics of arsenic on furnace slag were investigated to remove arsenic from groundwater using furnace slag, which is industrial waste generated from steel company. Adsorption isotherm experiments and kinetic sorption experiments were performed and the chemical characteristics of supernatants from these experiments were analyzed. Results showed that all supernatants were alkaline (above pH 9) and the highest ion concentration in the solution was found with calcium (30~50 mg/L). Results of adsorption isotherms were more adequately described by the Freundlich model than Langmuir model. From adsorption isotherms experiments, it was noted that the adsorption amount of As(V) was 87% higher than that of As(III). Results of kinetic sorption experiments were more properly fitted by pseudo second order (PSO) model than pseudo first order model. Equilibrium adsorption amount (qe) and relaxation time (tr) calculated from PSO model increased with initial concentration of arsenic. Equilibrium adsorption amount of As(V) was higher than that of As(III) and relaxation time of As(V) was shorter than that of As(III). Adsorption isotherm results could be predicted by kinetic adsorption results, since equilibrium adsorption amount calculated through PSO model generally agreed with equilibrium adsorption amount measured from adsorption isotherm.