Physical adsorption of gases on porous solids. I. Comparison of loose powders and porous plugs

1951 ◽  
Vol 209 (1096) ◽  
pp. 59-69 ◽  
Keyword(s):  
Pore Volume ◽  
Capillary Condensation ◽  
Physical Adsorption ◽  
Particle Surface ◽  
Total Pore Volume ◽  
Internal Surface ◽  
Porous Solids ◽  
Porous Plug ◽  
Surface Areas ◽  
Total Particle

For the first time, comparison has been made of adsorption on a given surface both as a free surface and as the internal surface of a porous plug. In this way it has been possible to provide direct evidence both for capillary condensation and for blockage of capillaries with adsorbed layers in porous solids. Blockage produced well-marked effects only where the surface was of the order of 1000 m. 2 /g. and the porosity was less than 0·6. Where it was observed, it was to be noted that (i) molecules tended to be attracted into blocked capillaries, producing swelling, (ii) monolayer capacities and hence surface areas determined by the B. E. T. method were values which corresponded only to the unblocked surface area when the monolayer is nearly complete. At the low-pressure end of adsorption isotherms, plug and powder gave identical results within the limits of experimental error, i. e. better than 1%, so that, until blockage or capillary condensation was manifested, the total particle surface was accessible to adsorption. In agreement with this, the total pore volume was also accessible, since the volume adsorbed at saturation was not less than the pore volume.

Physical adsorption of gases on porous solids - II. Calculation of pore-size distributions

1951 ◽  
Vol 209 (1096) ◽  
pp. 69-81 ◽  
Keyword(s):  
Pore Size ◽  
Capillary Condensation ◽  
Physical Adsorption ◽  
Large Fraction ◽  
Particle Surface ◽  
Porous Solids ◽  
Size Distributions ◽  
Pore Size Distributions ◽  
Total Particle ◽  
Accessible Surface

When capillary condensation takes place, it is accompanied by multilayer adsorption in empty capillaries. To apply the Kelvin equation to pore-size distributions, it is necessary to make allowance for multilayers, and a method of carrying this out is presented. Any such calculation requires either an estimated or experimental adsorption isotherm for the same surface when capillary condensation is absent. In this paper, it was possible to apply it to the data of part I, in which adsorption isotherms were compared for loose powders and for the same powders compressed into porous plugs. Modification of the calculation when capillaries fill by blockage instead of condensation is discussed. Blockage can prevail over capillary condensation only in pores with radii < 8 to 10 Å, and even then only if heats of adsorption are high, so that a large fraction of the surface is covered at low relative pressures. Owing to presence of adsorbed layers, the Kelvin radius is less than the true pore radius, but it is difficult to decide upon the proper correction, and much uncertainty results for radii < 30 Å. Pore-size distribution curves were derived and compared for plugs of varying porosity. They provided strong evidence of tightly packed aggregates of particles, and of an increasing uniformity of pore size as porosity is decreased. In Carbolac 1 plugs of low porosity, a few pores with radii only a little larger than the radius of a CF 2 CI 2 molecule were encountered, but no pores were smaller. This agrees with the observa­tion that the total particle surface was initially accessible to CF 2 CI 2 molecules, but that a rapid decrease of accessible surface took place before even a complete monolayer had been adsorbed.

THE PORE STRUCTURE AND ADSORPTIVE PROPERTIES OF SOME ACTIVATED CHARCOALS: I. THE ADSORPTION OF WATER VAPOUR AND ITS DEPENDENCE ON PORE SIZE

1946 ◽  
Vol 24b (4) ◽  
pp. 109-123 ◽  
Author(s):  
M. N. Fineman ◽  
R. M. Guest ◽  
R. McIntosh
Keyword(s):  
Adsorption Isotherm ◽  
Water Vapour ◽  
Pore Volume ◽  
Water Adsorption ◽  
Capillary Condensation ◽  
Total Pore Volume ◽  
Relative Pressure ◽  
Surface Areas ◽  
Adsorption Of Water ◽  
Adsorptive Properties

An examination of the influence of the structure of charcoal adsorbents on the form of the water adsorption isotherm has been attempted by determinations of (1) surface areas of a series of charcoals of varying degrees of activation using nitrogen and butane as adsorbates; (2) total pore volume of each adsorbent sample by density measurements in helium and in mercury; (3) density of adsorbents when immersed in water; (4) adsorption isotherms for water vapour; and (5) surface areas of charcoals partly saturated with water vapour.The evidence appears to suggest that certain very small and certain very large voids in charcoal are not occupied by water vapour at any value of the relative pressure. The former, 10% by volume, are important in terms of surface area; the latter, 30% by volume, influence pore volume calculations. An explanation of the shape of the water adsorption isotherm is attempted in the light of these facts. Estimates of the submicro, micro, and macro pore sizes show fair agreement when these are based upon either the capillary condensation theory or measurements of the total area and volume of the charcoal pores.

scholarly journals Microporous Materials Based on Norbornadiene-Based Cross-Linked Polymers

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1382 ◽  
Author(s):  
Dmitry Alentiev ◽  
Dariya Dzhaparidze ◽  
Natalia Gavrilova ◽  
Victor Shantarovich ◽  
Elena Kiseleva ◽  
...  
Keyword(s):  
Pore Volume ◽  
Total Pore Volume ◽  
Amorphous Polymers ◽  
Co2 Uptake ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Pd Catalysts ◽  
X Ray ◽  
Positron Annihilation Lifetime ◽  
Surface Areas

New microporous homopolymers were readily prepared from norbornadiene-2,5, its dimer and trimer by addition (vinyl) polymerization of the corresponding monomers with 60–98% yields. As a catalyst Pd-N-heterocyclic carbene complex or Ni(II) 2-ethylhexanoate activated with Na+[B(3,5-(CF3)2C6H3)4]− or methylaluminoxane was used. The synthesized polynorbornenes are cross-linked and insoluble. They are glassy and amorphous polymers. Depending on the nature of the catalyst applied, BET surface areas were in the range of 420–970 m2/g. The polymers with the highest surface area were obtained in the presence of Pd-catalysts from the trimer of norbornadiene-2,5. The total pore volume of the polymers varies from 0.39 to 0.79 cm3/g, while the true volume of micropores was 0.14–0.16 cm3/g according to t-plot. These polymers gave CO2 uptake from 1.2 to 1.9 mmol/g at 273 K and 1 atm. The porous structure of new polymers was also studied by means of wide-angle X-ray diffraction and positron annihilation lifetime spectroscopy.

scholarly journals Some Surface Properties of Activated Carbons Prepared by Gasification with Different Gases

1997 ◽  
Vol 15 (9) ◽  
pp. 707-715 ◽  
Author(s):  
Amina A. Attia
Keyword(s):  
Carbon Dioxide ◽  
Surface Area ◽  
Water Vapour ◽  
Pore Volume ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Surface Areas ◽  
Adsorption Of Nitrogen ◽  
Adsorption Of Water ◽  
Different Gases

A non-activated carbon ‘D’ was obtained by carbonizing date pits at 773 K in a limited supply of air. Activated carbons were obtained by gasifying portions of ‘D’ with air at 773 K, carbon dioxide at 1123 K, or steam at 1173 K, all to different burn-offs between 15% and 60%. The adsorption of nitrogen at 77 K and of carbon dioxide at 298 K was investigated using a volumetric adsorption apparatus of a conventional type. The adsorption of water vapour at 298 K and the chemisorption of pyridine at 423 K was followed by means of quartz spring balances. Gasification with oxidizing gases increased the surface area and total pore volume, as measured by nitrogen or carbon dioxide adsorption. In most cases, comparable surface areas were measured by nitrogen and carbon dioxide. The adsorption of water vapour depended on the percentage burn-off and the gasification conditions. Chemisorption of pyridine at 423 K was found to be related to the chemistry of the surface rather than to the surface area or total pore volume.

Sintered Carbon Nanomaterials: Structural Change and Adsorption Properties

2016 ◽  
Vol 230 (12) ◽  
Author(s):  
Natalia Strokova ◽  
Serguei Savilov ◽  
Hui Xia ◽  
Serguei Aldoshin ◽  
Valery Lunin
Keyword(s):  
Structural Change ◽  
Pore Volume ◽  
Density Functional ◽  
Carbon Nanomaterials ◽  
Physical Adsorption ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Diameter Distribution ◽  
Sem Images ◽  
Plasma Sintering

AbstractPorous powdered carbon nanomaterials [carbon nanotubes (CNT) and carbon nanoshells (CNS)] were compacted using spark plasma sintering (SPS) technique. High resolution transmission electron microscopy (HRTEM) and SEM images demonstrate the structural change: the increase of density and thickness of nanoshells stack, formation of interparticle bonds between nanotubes. Surface properties of original and sintered materials were studied by liquid nitrogen sorption and compared to the characteristics for real vapors sorption. The data collected for water, ethanol, acetonitrile and benzene show both physical adsorption and chemisorption. The mean pore diameter distribution calculated from nitrogen adsorption by density functional theory (DFT) approach shows the reduction of total pore volume in CNS pellet while for CNT pellet total pore volume does not differ dramatically from those for non-compacted samples. The isosteric heats of sorption for all chosed vapors were calculated.

Porous Solids of Boron Phosphate, Aluminum Phosphate, and Silicon Phosphate

1994 ◽  
Vol 371 ◽  
Author(s):  
K. B. Babb ◽  
D. A. Lindquist ◽  
S. S. Rooke ◽  
W. E. Young ◽  
M. G. Kleve
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Total Pore Volume ◽  
Aluminum Phosphate ◽  
Porous Solids ◽  
Gel Point ◽  
Average Pore ◽  
Average Pore Radius ◽  
Surface Areas

AbstractAnhydrous sol-gel condensation of triethyl phosphate [(CH3CH2O)3PO] with boron trichioride (BCl3), triethyl aluminum [(CH3CH2)3Al] or silicon tetrachloride [SiCI4] in organic solvents led to rigid gels. The pore fluid of the gels was removed under supercritical conditions in a pressurized vessel to form porous solids. The condensation chemistry prior to the gel point was monitored by solution 1H, 13C, 31P, and 11B NMR. The materials were then calcined at progressively higher temperatures to produce high surface area phosphates. Nitrogen gasphysisorption was used to determine the surface areas, total pore volume, and average pore radius of the products. FT-IR was used to determine functional groups in the materials. The microstructure was also examined by scanning electron microscopy.

Functionalization of Porous Clay Heterostructures with Silane Coupling Agents

2017 ◽  
Vol 54 (2) ◽  
pp. 341-344
Author(s):  
Anda Ionelia Mihai (Voicu) ◽  
Sorina Alexandra Garea ◽  
Eugeniu Vasile ◽  
Cristina Lavinia Nistor ◽  
Horia Iovu
Keyword(s):  
Pore Volume ◽  
Total Pore Volume ◽  
Coupling Agents ◽  
Silane Coupling Agents ◽  
Porous Clay Heterostructures ◽  
Bet Analysis ◽  
Silane Coupling ◽  
Ftir Spectrometry ◽  
Textural Parameters ◽  
Epoxy Groups

The goal of this paper was to study the modification of porous clay heterostructures (PCHs) with various silane coupling agents. Two commercial coupling agents (3-aminopropyl-triethoxysilane (APTES) and 3-glycidoxypropyl-trimethoxysilane (GPTMS)) with different functional groups (amine and epoxy groups) were used as modifying agents for the PCHs functionalization. The functionalization of PCH with APTES and GPTMS was evaluated by Fourier transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA), X-Ray Diffractions (XRD) and BET Analysis. FTIR spectra of modified PCHs confirmed the presence of characteristic peaks of silane coupling agents. TGA results highlighted an increase of weight loss for the modified PCHs that was assigned to the degradation of silane coupling agents (APTES and GPTMS) attached to the PCHs. The XRD results showed that the structure of modified PCHs was influenced by the type of the silane coupling agent. The functionalization of PCHs with silane coupling agents was also confirmed by BET analysis. Textural parameters (specific surface area (SBET), total pore volume (Vt )) suggested that the modified PCHs exhibit lower values of SBET and a significant decrease of total pore volume than unmodified PCHs.

Improvement of monitoring of tertiary filtration with particle counting

2006 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
V. Miska ◽  
J.H.J.M. van der Graaf ◽  
J. de Koning
Keyword(s):  
Particle Surface ◽  
Minor Effect ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Mass Distributions ◽  
Particle Counting ◽  
Total Particle ◽  
Particle Counts ◽  
A Minor ◽  
Sample Dilution

Nowadays filtration processes are still monitored with conventional analyses like turbidity measurements and, in case of flocculation–filtration, with phosphorus analyses. Turbidity measurements have the disadvantage that breakthrough of small flocs cannot be displayed, because of the blindness regarding changes in the mass distributions. Additional particle volume distributions calculated from particle size distributions (PSDs) would provide a better assessment of filtration performance. Lab-scale experiments have been executed on a flocculation–filtration column fed with effluent from WWTP Beverwijk in The Netherlands. Besides particle counting at various sampling points, the effect of sample dilution on the accuracy of PSD measurements has been reflected. It was found that the dilution has a minor effect on PSD of low turbidity samples such as process filtrate. The correlation between total particle counts, total particle volume (TPV) and total particle surface is not high but is at least better for diluted measurements of particles in the range 2–10 μm. Furthermore, possible relations between floc-bound phosphorus and TPV removal had been investigated. A good correlation coefficient is found for TPV removal versus floc-bound phosphorus removal for the experiments with polyaluminiumchloride and the experiments with single denitrifying and blank filtration.

scholarly journals Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 298
Author(s):  
Chenlong Ding ◽  
Jinxian He ◽  
Hongchen Wu ◽  
Xiaoli Zhang
Keyword(s):  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Shale Gas ◽  
Pore Volume ◽  
Ordos Basin ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Taiyuan Formation

Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m2/g and 0.001398–0.008718 cm3/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

Adsorption Characteristics of Superplasticizer with Waste Plexiglas (WPS) onto Cement Particle Surface

2011 ◽  
Vol 328-330 ◽  
pp. 547-550
Author(s):  
Gang Zheng ◽  
Ru Min Wang ◽  
Gao Yang Zhao ◽  
Zhong Yu
Keyword(s):  
Physical Adsorption ◽  
Particle Surface ◽  
Radical Copolymerization ◽  
Cement Particle ◽  
Free Radical Copolymerization ◽  
Ζ Potential ◽  
Adsorption Characteristics ◽  
Adsorbed Quantity ◽  
Uv Visible ◽  
Repulsive Forces

In this study, by using UV-visible adsorption spectrophotometer, ζ-potential analyzer and X-ray photo spectroscopy, the adsorption characteristics and surface electrochemical properties of WPS were studied in comparison with traditional naphthalene sulfonated formaldehyde condensates (FDN) whose dispersion ability mainly depends on electrostatic repulsive forces. WPS was prepared through free radical copolymerization in self-Single screw reactive extruder and synthesized from waste plexiglas and vinyl monomers by way of special extrusion modification. The results show that the adsorption of WPS and FDN on cement particle surface approximately conforms to Langmuir’s adsorption isotherm. The adsorption of WPS belongs to physical adsorption and its saturated adsorbed quantity was 5.38mg/g. When the dosage of WPS was 1 wt.% of cement, the thickness of the adsorption layer on the surface of cement particles was 61.2 nm. The ζ-potential of cement particle with WPS changed from positive (15 mV) to negative (-64.74mV) with its concentration increasing from 0 to 20 g/L and decreased from -65.19 to-39.82 mV (reducing by 38.9%) with its concentration of 10 g/L within 60 h.

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