Isotherms and thermodynamics for the adsorption of n-butane on pitch based activated carbon

Saha, Bidyut Baran; Chakraborty, Anutosh; Koyama, Shigeru; Yoon, Seong Ho; Mochida, Isao; Kumja, M.; Yap, C. T.; Ng, Kim Choon

doi:10.1016/j.ijheatmasstransfer.2007.07.031

Cited by 83 publications

(28 citation statements)

References 27 publications

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“…The adsorption based systems ensures zero ODP and GWP, and can be operated on thermal heat source which gives opportunity to utilize low grade waste heat or solar thermal energy. Many adsorbent/refrigerant pairs have been experienced to establish an efficient and economic adsorption heat pump system which includes: (i) activated carbons with ethanol , methanol (ElSharkawy et al 2009), ammonia (Tamainot-Telto and Critoph 1997), HCF410A (Askalany et al 2014), HFO1234ze(E) (Jribi et al 2013), R134a (Saha et al 2012) and n-butane (Saha et al 2008); (ii) activated carbon fiber with ethanol (Saha et al 2007); (iii) metal organic frameworks (MOFs) with water (Rezk et al 2012), and ethanol (Rezk 2013); (iv) silica-gel with water (Saha et al 1997), and ammonia (Sward 1999); (v) zeolite with CO 2 (Sward 1999), and water (Demir 2013); and many more. Polymers are widely used in industries such as lubricant, rubber, membrane, hydrophobic adsorbent and medicine (Gun'ko et al 2014), and therefore adsorption characteristics of polymers have been studied widely.…”

Section: Introductionmentioning

confidence: 99%

Insights of water vapor sorption onto polymer based sorbents

et al. 2015

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Two polymer based sorbents PS-I and PS-II are analyzed for water sorption applications. Adsorption/desorption isotherms of water vapor onto PS-I and PS-II have been experimentally measured using a magnetic suspension adsorption measurement unit for adsorber temperature ranges 20-80°C and evaporator temperature ranges 2-73°C. The equilibrium adsorption uptake of water vapors corresponding to saturation condition at 30°C by PS-I and PS-II was found nearly 2 and 2.5 times higher than the conventional silica-gel, respectively. Adsorption data has been analyzed for various adsorption models which include Brunauer-Emmett-Teller (BET); Freundlich; DubininAstakhov (D-A); Oswin; and Guggenheim-Anderson-de Boer (GAB) model. The GAB and BET model give the good fit for relative pressure range of 0.10-0.90 and 0.05-0.35, respectively. At all adsorption temperatures of both sorbents, the monolayer uptake by the GAB model is found higher than the BET model. Effect of adsorption potential on adsorption uptake is highlighted in relation with water vapor adsorption mechanism. The isosteric heat of water vapor adsorption is determined for both sorbents using Clausius-Clapeyron equation.

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Section: Introductionmentioning

confidence: 99%

Insights of water vapor sorption onto polymer based sorbents

et al. 2015

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“…As the three methods of predicting the heat of adsorption in this paper are dependent on obtaining a good isotherm fit and getting the correct fitting constants out of that isotherm fit, we follow Saha et al 25 in lumping the adsorbed phase volume v s together with the fitting constant W 0 , to form a new fitting constant n* and writing the D−A equation as…”

Section: ■ Introductionmentioning

confidence: 99%

Predicting the Integral Heat of Adsorption for Gas Physisorption on Microporous and Mesoporous Adsorbents

Whittaker

Wang

Zimmermann³

et al. 2014

J. Phys. Chem. C

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We have developed two predictive methods for the heats of adsorption that stem from isotherm models and benchmarked them against the Clausius−Clapeyron equation. These are the Toth potential function model and the modified Clapeyron equation. Three adsorbate/adsorbent working pairs are used as examples: n-butane/BAX 1500 activated carbon, isobutane/BAX 1500 activated carbon, and ammonia/Fuji Davison type RD silica gel, all of which are examples of gas physisorption on adsorbents with both micro-and mesopores. Isotherms and corresponding integral heats of adsorption were measured in the range 298−348 K. For n-butane and isobutane, the pressures were up to 235 kPa, and for ammonia, the pressures were up to 835 kPa. Our two predictive methods consistently offer significant improvements over the Clausius−Clapeyron equation. Between the two predictive methods, the Toth model is more robust across all three working pairs studied with predictions generally falling within 10−15% of the values of the measured heats. ■ INTRODUCTIONMost gas adsorption data in the literature are presented as experimentally obtained isotherm measurements without measured heats of adsorption. This is presumably because adsorption experiments that incorporate calorimetry are more expensive and more complicated to both set up and operate than experiments based upon volumetric or gravimetric measurements alone. 1,2 However knowledge of the heat of adsorption can lend insight into surface phenomena. 3 Additionally thermal management is an integral part of the design and operation of systems which make use of adsorption phenomena such as adsorption chillers, 4,5 adsorbed gas storage tanks, 6 and adsorption separation units, 7 all of which require knowledge of the heat of adsorption.Conventionally experimentalists circumvent the dearth of calorimetric data by invoking the Clausius−Clapeyron equation, either through measuring many closely spaced isotherms and applying the equation directly to the data (to wit, the isostere method) 8,9 or by fitting the isotherm data with an isotherm model and then applying the Clausius−Clapeyron equation to the model. 10,11 The isostere method can lead to ambiguous results 1,2,12 particularly if the number of isotherms obtained is low, if the isotherms are widely spaced, or where the uncertainty in the isotherm measurement is high. Moreover even at moderate pressure (p < 1 MPa) the ideal gas assumption inherent in Clausius−Clapeyron can lead to large errors in predicting the heat of adsorption. 13 Theoretical models (e.g., refs 14−17) have been developed for this problem by using numerous isotherm models consistent with statistical mechanics and specific to various different adsorbate/adsorbent modes of interaction. However it remains a challenge to know which model to apply to get a correct prediction of the surface interactions and heat of adsorption without significant prior knowledge of the behavior of the adsorbate/adsorbent system. Savara et al. 18 developed a rigorous method for selecting between a number of 2...

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“…It should be noticed from the work of [31] that, ethanol is flammable and has bad effects on nervous system in case of high concentration leakage. Saha et al [32] studied experimentally the thermodynamics and isotherms for the adsorption of n-butane on pitchbased activated carbon (type Maxsorb III), at different equilibrium pressures between 20 and 300 kPa and at temperatures ranging from 298 to 328 K. Their apparatus is shown in Fig. 13.…”

Section: Experimental Workmentioning

confidence: 99%

“…Their results showed that the maximum adsorption capacity of Maxsorb III/n-butane pair was measured to be 0.8 kg/kg at 298.15 K and 232.34 kPa. From the work of [32] it should be noticed that, n-butane is a highly combustible gas. Zhong et al [33] investigated the equilibrium concentration characteristics of ammonia with a composite adsorbent material (BaCl 2 impregnated into a vermiculite matrix).…”

Section: Experimental Workmentioning

confidence: 99%

“…It should be noticed from the work of [31] that, ethanol is flammable and has bad effects on nervous system in case of high concentration leakage. From the work of [32] it could be remarked that n-butane is a highly combustible gas. From the work of [36] it should be noticed that, to prevent water icing, the adsorption system needed to operate with very low vacuum.…”

Section: Experimental Workmentioning

confidence: 99%

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