Charcoal Sorption Studies. II The Sorption of Water by Hydrogen Treated Charcoals

McDermot, H. L.; Arnell, J. C.

doi:10.1021/j150516a011

Cited by 26 publications

(15 citation statements)

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“…Almost all of the benzene is sorbed over a very narrow range of pressure, and for equal amounts of sorption a higher pressure is required with Type A polystyrene than with Type B. This behavior is associated with adsorption in rather narrow sizedistributions of pores (9). In fact, the present heat and isotherm data are best correlated by assuming that porous adsorption occurs.…”

Section: Results Akd Discussionmentioning

confidence: 69%

Physical Adsorption in the Benzene–polystyrene System

Barton¹,

Mason²

1958

Can. J. Chem.

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Although the sorptioil of solvent vapors by solid polymers is usually considered as a solution process, McLaren and Cutler ( I ) found that when the water sorption isotherm of a water-soluble fraction of polyvinyl acetate was analyzed from the point of view of the Flory-Hugginsequation, values of p much larger than p,,,,. are required in the low pressure region. This phenomenon, indicating phase separation, was attributed to surface adsorption preceding solution formation a t loxv relative pressures. On the other hand, Baughan (2) found that the sorption isotherm of benzene or polystyrene sheets fitted the Flory-Huggins equation over a benzene volume fraction of 0.07 t o 0.57 with an interaction constant p = 0.45. I t would appear in this case that the sorbed bellzene formed a homogeneous solution with the polystyrene.When the sorbate is not a solvent for the sorbent, the "adsorption" characteristics of the reaction can be more pronounced. The presence of strongly adsorbing sites in a polymer matrix which are saturated by initial quantities of sorbing (non-solvent) gases and vapors have been deduced by several workers (3, 4, 5 ) .As long as the concentration of solveilt sorbate is not so high that the sorbate-sorbent complex loses its rigidity, then a certain amount of adsorption on active sites call be expected t o occur in any solvent-polymer system a t low relative pressures. I n the investigatio~~ described in this note, heats of sorption of small amounts of benzene on two samples of polystyrene were measured. The heats evolved were sufficiently high to be considered heats of physical adsorption, and have been taken as evidence that surface adsorption precedes solutioil ill the benzene-polystyrene system. E X P E R I M E N T A LA coilventional all-glass adsorptioii apparatus with mercury valves instead of stopcocks was used. Benzene vapor was measured into a calibrated volume from a reservoir containing thoroughly outgassed reagent grade benzene. The measured dose was then exposed t o a fairly large (ca. 5 g.) sample of outgassed polystyrene, mouilted in the reactioil well of a large diphenyl ether isothermal calorimeter, operating a t 26.9' C. (6, 7). Pressures were measured by conventioilal mercury manometers read to the nearest 0.5 mm.The take-up of benzene as indicated by the falling pressure was initially rapid, but after 10-15 minutes became very slow. The slow take-up, when allowed to proceed, was observed t o continue for many days. In each determination, the contribution from the slow take-up was made as small a s possible by isolatiilg the large calibrated volume from the polystyrene sample as soon as possible after the initial rapid sorptioil had taken place. Slow sorptioil could then oilly continue a t the expense of the relatively small amount of benzene vapor in the dead space.Heat was evolved during the iilitial rapid sorption, and shortly after the benzene pressure had become nearly constant, the rate of movement of the mercury thread in the

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Section: Results Akd Discussionmentioning

confidence: 69%

Physical Adsorption in the Benzene–polystyrene System

Barton¹,

Mason²

1958

Can. J. Chem.

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“…In the figure, a steep increase in the weight of S1 occurs at relatively low humidity, and this feature indicates that S1 is more susceptible to moisture than the other activated carbons. In the previous reports of the moisture effect on the adsorption ability or capacity of cartridges of respirators [1][2][3][4][5][6][7][8][9][10][11][12][13][14] , there is little description of the porous structures and the specific surface areas of activated carbon contents of the cartridges. However, from the comparison of the curves in Fig.…”

Section: The Effect Of Moisture Contents Of Activated Carbonmentioning

confidence: 99%

“…3 (a)). In the previous reports [1][2][3][4][5][6][7][8][9][10][11][12][13][14] , the relative humidity of the test gas flow was taken as the index of adsorption capacity in relation to the breakthrough time. However, the weight increase by preliminary moisture adsorption relative to the weight before preconditioning is another simple indicator of the adsorption capacity of the carbon bed, and we have used this indicator for the breakthrough time in the figures.…”

Section: The Effect Of Moisture Contents Of Activated Carbonmentioning

confidence: 99%

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Quantitative Evaluation of the Effect of Moisture Contents of Coconut Shell Activated Carbon Used for Respirators on Adsorption Capacity for Organic Vapors

2010

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Activated carbon is an elemental material used for hygienic applications, particularly as an adsorbent for harmful gases and vapors. In Japanese industrial and occupational hygiene, activated carbon produced from coconut shell is a traditional and popular adsorbent material due to its excellent adsorption ability and cost advantage. In this research, in order to clarify the effect of the preliminary content of moisture on the adsorption capacity in detail, we prepared several coconut shell activated carbons which were preconditioned by equilibration with moisture at different relative humidities. We measured their adsorption capacities as breakthrough times for 6 kinds of organic vapor, and attempted to determine the relationships between the relative weight increase of water adsorption and the decrease of adsorption capacities of the activated carbon specimens for the organic vapors. The procedure of the quantitative evaluation of the effect of moisture and the results are useful for practical applications of activated carbon, particularly those used as adsorbents in workplaces.

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“…Among these influencing factors, moisture content has been the focus of many quantitative researches, and there are many reports [6][7][8][9][10][11][12][13][14][15][16][17][18][19] regarding its effect on gas filters or experimental packed beds of activated carbon at room temperature (approximately at 293-298 K). Further, Wood et al have reported the effective estimation of the breakthrough time of activated carbon beds for organic vapors 20,21) which covers the effect of all levels of relative humidities by extension of the Wheeler-Jonas breakthrough time equation [22][23][24] modified by Yoon et al 25,26) .…”

Section: Introductionmentioning

confidence: 99%

Reduction of Adsorption Capacity of Coconut Shell Activated Carbon for Organic Vapors Due to Moisture Contents

2010

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In occupational hygiene, activated carbon produced from coconut shell is a common adsorbent material for harmful substances including organic vapors due to its outstanding adsorption capacity and cost advantage. However, moisture adsorption of the carbon generally decreases the adsorption capacity for organic vapors. In a previous report, we prepared several coconut shell activated carbons which had been preconditioned by equilibration with moisture at different relative humidities and measured the breakthrough times for 6 kinds of organic vapor, in order to clarify the effect of preliminary moisture content in activated carbon on the adsorption capacity in detail. We found that the relative percent weight increase due to moisture adsorption of the carbon specimen had a quantitative effect, reducing the breakthrough time. In this report, we carried out further measurements of the effect of moisture content on the adsorption of 13 kinds of organic vapor, and investigated the relationship between moisture adsorption and the reduction of the breakthrough time of activated carbon specimens. We also applied the data to the Wood's breakthrough time estimation model which is an extension of the Wheeler-Jonas equation.

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Charcoal Sorption Studies. II The Sorption of Water by Hydrogen Treated Charcoals

Cited by 26 publications

References 0 publications

Physical Adsorption in the Benzene–polystyrene System

Physical Adsorption in the Benzene–polystyrene System

Quantitative Evaluation of the Effect of Moisture Contents of Coconut Shell Activated Carbon Used for Respirators on Adsorption Capacity for Organic Vapors

Reduction of Adsorption Capacity of Coconut Shell Activated Carbon for Organic Vapors Due to Moisture Contents

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