Equilibria and kinetics of natural gas adsorption on multi-walled carbon nanotube material

Delavar, Maedeh; Ghoreyshi, Ali Asghar; Jahanshahi, Mohsen; Khalili, Soodabeh; Nabian, Nima

doi:10.1039/c2ra01095j

Cited by 51 publications

(46 citation statements)

References 36 publications

(30 reference statements)

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“…Due to the physisorption nature of methane adsorption in CNTs, 19 the fundamental interacting energy between methane and the CNT is caused by van der Waals interactions. Thus, methane atoms and carbon atoms were modeled as Lennard-Jones (LJ) particles.…”

Section: Model and Methodsmentioning

confidence: 99%

“…However, the adsorbed methane in CNT was actually in grand canonical (μVT) ensemble because the chemical potential and temperature of methane in CNT are equal to those of the bulk phase in equilibrium. Five CNTs [ (7,7), (9,9), (11,11), (15,15), (19,19), (23,23)] with diameters varying from 9 to 32 Å were chosen to explore the effect of the pore size on the adsorption behavior. The adsorption processes were modeled at temperatures of 300, 340, and 380 K, and pressures in the range of 20−300 bar.…”

Section: Model and Methodsmentioning

confidence: 99%

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Atomic Mechanisms and Equation of State of Methane Adsorption in Carbon Nanopores

Zhu

Zhao

2014

J. Phys. Chem. C

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Adsorption is an important issue both in the estimation of natural gas reserves and efficient storage of methane. In this study, we focus on the mechanisms of methane adsorption in carbon nanopores and endeavor to establish the equation of state for the adsorbed phase through molecular dynamics simulations and theoretical analyses. Here, the nanopores were modeled by carbon nanotubes (CNTs). The higher storage capacity of the CNT compared to the bulk phase was attributed to the additional pressure exerted by the CNT wall on the adsorbed phase, considering which, the equation of state for the adsorbed phase was established. As the CNT diameter increases, the adsorption structure transforms from a single-file chain to two adsorption layers. Moreover, it was found that there exists an optimal CNT diameter that maximizes the adsorption, which is due to the competition between the curvature effect and the size effect. In the explanation of this phenomenon, the nanostructure of the CNT wall plays an important role, without considering which, the adsorption density would monotonically decrease as the CNT diameter rises. Our findings and related analyses may help reveal the underlying mechanisms behind the adsorption phenomena, which is not only of theoretical importance, but may also help estimate the natural gas reserves and design nanoporous materials with higher storage capacity.

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Section: Model and Methodsmentioning

confidence: 99%

Section: Model and Methodsmentioning

confidence: 99%

Atomic Mechanisms and Equation of State of Methane Adsorption in Carbon Nanopores

Zhu

Zhao

2014

J. Phys. Chem. C

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“…From the plot, the correlation coefficient R 2 ‐values were calculated and found to be >0.9 indicating the acceptability of the kinetic equation and the second order nature of the adsorption process of gas molecules on TiO 2 NPs. The possibility of intraparticle diffusion was examined using the intraparticle diffusion model which is expressed in Equation as:

q_{normalt} = k_{normalp} t^{0.5}

where k p is the rate constant (mmol/g min −0.5 ) and t is the time (min). The intraparticle diffusion mechanism has been used to determine the adsorption process on a porous material .…”

Section: Resultsmentioning

confidence: 99%

Development of a Two‐Tier Fibrous Membrane by Sequential Electrospinning for Effective Air Filtration

Ramachandran

Rajiv

2018

CLEAN Soil Air Water

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In the current work, a strategy to fabricate two‐tier structured poly l‐lactide/TiO2 nanoparticles (NPs) incorporated polyvinylpyrrolidone (PLLA/PVP‐TiO2 NPs) fibrous membrane for air filtration via sequential electrospinning technique are reported. Anatase TiO2 NPs ranging from 90 to 105 nm in size were synthesized by the sol–gel method. The diameter of PLLA and PVP‐TiO2 NPs fibers was in the range of 1.15–1.45 and 1.8–2.2 μm, respectively. This two‐tier membrane possessed thermal stability with decomposition temperatures at 364.2 and 447.5 °C for PLLA and PVP‐TiO2, respectively. Gas molecules such as CO, CO2, O2, hydrocarbon (HC) and particulate matter (PM) were adsorbed on the surface of TiO2 nanoparticles as confirmed by IR spectroscopy. The gas adsorption results revealed that 89% of CO2, 80% of CO, 64% of O2, 92% of HC, and 79% of PM were adsorbed after filtration. The pressure drop across the membrane increased from 265 to 341 Pa after filtration. The dust‐loading capacity was quantified by weighing the membrane at regular intervals after exposing it to the exhaust. Adsorption of gases followed the pseudo‐second order kinetic model and intraparticle diffusion mechanism. This two‐tier membrane may be an efficient air filter for domestic and industrial purposes.

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“…The Sips isotherm is used for evaluation of isosteric heat of gas adsorption [39,46]. This equation is sometimes called the Langmuir-Freundlich isotherm because it has the combined form of Langmuir and Freundlich isotherms [39].…”

Section: Sips Isotherm (Langmuir-freundlich)mentioning

confidence: 99%

A New Approach for Analysis of Adsorption from Liquid Phase: A Critical Review

Abdollahi¹

2015

J Pollut Eff Cont

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At first, the KASRA model and KASRA equation are discussed [1][2][3]. KASRA is an abbreviation for "Kinetics of Adsorption Study in the Regions with Constant Adsorption Acceleration". The KASRA model was presented by Samiey [1] in 2013 and is based on the following assumptions: (1) each time range with constant adsorption acceleration, is named a "region", (2) there are two regions before attaining plateau region, (3) the boundaries between the first and second regions and the second and third (plateau) regions are named "starting second region" (abbreviated as ssr) and "kinetics of adsorption termination" (abbreviated as kat) points, respectively and are determined by the KASRA equation, (Figures 1-4). Due to different features of the first and second regions, parameters obtained from a kinetic equation (such as the pore-diffusion, Avrami and Elovich equations, etc.) for these two regions are different from each other and the related equations for these regions come different pathways to the point q t =0 at t=0 (or q 01 according to the KASRA model). It is good to say that KASRA is a Persian word meaning king. AbstractIn different concentration ranges of adsorbed species, various interactions occur between them and surface adsorption sites and there are different regions in an adsorption isotherm. In the common method for study of adsorption process, all of these regions are considered as one region and thus there are concerns regarding using adsorption equations. In this work, based on the KASRA and ARIAN regional models, a new method is presented for analysis of adsorption kinetic and thermodynamic data, respectively. The KASRA and ARIAN models are three-and four-region models, respectively and adsorption equations are used on the basis assumptions used in these models. According to the ARIAN model, adsorption binding constant of each region of an adsorption isotherm is different from the other regions. On the other hand, based on the kinetic KASRA model and ideal-second-order (ISO) equation, during the adsorption in each initial adsorbate concentration, different interactions occur between adsorbate species and adsorbent surface sites and thus the observed adsorption binding constant is an average value of these binding constants.

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Equilibria and kinetics of natural gas adsorption on multi-walled carbon nanotube material

Cited by 51 publications

References 36 publications

Atomic Mechanisms and Equation of State of Methane Adsorption in Carbon Nanopores

Atomic Mechanisms and Equation of State of Methane Adsorption in Carbon Nanopores

Development of a Two‐Tier Fibrous Membrane by Sequential Electrospinning for Effective Air Filtration

A New Approach for Analysis of Adsorption from Liquid Phase: A Critical Review

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