Immersion enthalpy of benzene/cyclohexane and toluene/cyclohexane binary mixtures into modified activated carbons

Hernández-Monje, Diana; Giraldo, Liliana; Moreno–Piraján, Juan Carlos

doi:10.1007/s10973-019-08478-0

Cited by 12 publications

(12 citation statements)

References 35 publications

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“…Regarding the physical characterization for OAC (activated carbon prepared from coconut shell by physical activation subjected to an oxidization process at 358 K with 6 M HNO 3 solution), OAC723 (oxidized sample “OAC” subjected at heat treatment up to 723 K under N 2 atmosphere) and OAC1023 (oxidized sample “OAC” subjected at heat treatment up to 1023 K under N 2 atmosphere); the solids do not show noticeable differences, but there is a trend, since the surface area (BET model, C positive) and the micropore volume (Dubinin–Radushkevich model) are: OAC 819 m 2 g −1 , 0.33 cm 3 g −1 < OAC723: 873 m 2 g −1 , 0.35 cm 3 g −1 < OAC1023: 908 m 2 g −1 , 0.37 cm 3 g −1 ; this was also supported with the pore size distribution showed in another work [ 37 ], which demonstrated a pore volume for OAC<OAC723<OAC1023 with highly microporous behavior of the samples, where most of the pores had widths smaller than 20 Å.…”

Section: Resultssupporting

confidence: 82%

“…The fact that OAC was the sample with the smallest surface area and the smallest pore volume was due to modification with nitric acid which generated incorporation of surface groups (mostly acidic) that could decrease the textural parameters of the solid, while samples subjected to heat treatment slightly increase these characteristics, due to the possible transformation of some surface groups to CO and CO 2 . This is due to the modification temperatures 723 and 1023 K, which are also increasing the basicity of samples [ 37 , 45 , 46 , 47 ].…”

Section: Resultsmentioning

confidence: 99%

“…For a closed system of solid–liquid interaction with one solute and one solvent at a determined pressure ( P ) and temperature ( T ), the variation of a thermodynamic parameter can be described by [ 37 ]:

where X can be the immersion enthalpy ( H ), and

where

and

are the partial molar enthalpies for the components q and r ; this process is performed at constant P and T , then the contribution of every component of the system to the enthalpy can be determined.…”

Section: Introductionmentioning

confidence: 99%

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Enthalpic and Liquid-Phase Adsorption Study of Toluene–Cyclohexane and Toluene–Hexane Binary Systems on Modified Activated Carbons

2021

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The liquid-phase adsorption of toluene in cyclohexane and hexane solutions on modified activated carbons was evaluated; the energy involved in the interaction between these solutions and the solids was determined by immersion enthalpies of pure solvents and their mixtures, and the contribution of the system constituents was calculated by differential enthalpies. The thermal treatment generated modifications that favored adsorption and interaction with the evaluated solutions, since it increased the textural parameters and the basic character of the samples. Cyclohexane could create greater competition with the adsorption sites compared to hexane, but it favored the increase in adsorption capacities (0.416 to 1.026 mmol g−1) and the interactions with the solid evaluated through the immersion enthalpies. The immersion enthalpies of pure solvents (−16.36 to −112.7 J g−1) and mixtures (−25.65 to −104.34 J g−1) had exothermic behaviors that were decreasing due to the possible displacement of solvent molecules when increasing the solute concentration in the mixtures. The differential enthalpies for toluene were negative (−18.63 to −2.14 J), mainly due to the π–π interaction with the solid, while those of the solvent–solid component tended to be positive values (−4.25 to 55.97 J) due to the displacement of the solvent molecules by those of toluene.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

where X can be the immersion enthalpy ( H ), and

where

and

Section: Introductionmentioning

confidence: 99%

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Enthalpic and Liquid-Phase Adsorption Study of Toluene–Cyclohexane and Toluene–Hexane Binary Systems on Modified Activated Carbons

2021

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“…The proposed design was shown to be a better alternative to a continuous barrier. Hernandez-Monje et al [19] presented a study in which the energy product from the interaction between three different organic solvents with three activated carbon samples with different physiochemical properties was measured. The highest interaction energy was found with benzene and toluene mixtures with activated carbon, thermally treated at 750 • C.…”

Section: Adsorption Theorymentioning

confidence: 99%

Experimental Measurement of Bulk Thermal Conductivity of Activated Carbon with Adsorbed Natural Gas for ANG Energy Storage Tank Design Application

2020

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The development of adsorptive natural gas storage tanks for vehicles requires the synthesis of many technologies. The design for an effective Adsorbed Natural Gas (ANG) tank requires that the tank be filled isothermally within a five-minute charge time. The heat generated within the activated carbon is on the order of 150 MJ/m 3 of storage volume. The tank can be effectively buffered using Phase Change Material (PCM) to absorb the heat. The effective design of these tanks requires knowledge of the thermal properties of activated carbon with adsorbed methane. This paper discusses experimental measurements of the thermal conductivity of activated carbon with adsorbed methane. It was found that within the tank the thermal conductivity remains almost constant within the temperature and pressure ranges that ANG tanks will operate.

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“…As the enthalpy obtained corresponds to an adsorbent-solution multicomponent type system that depends on the temperature and pressure (P), this variable can be expressed as (the process is carried out at constant pressure and temperature; Hernández-Monje et al, 2019a):…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Toluene and Hexane Adsorption on Activated Carbons From Gas and Liquid Phase. Enthalpy and Isotherms

Hernández-Monje

Giraldo

Moreno–Piraján

2020

Front. Environ. Chem.

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Activated carbons with different chemical and textural properties were used to carry out the adsorption of toluene and hexane from gas phase and from liquid phase for toluene-hexane solutions where toluene was used as a solute and hexane as the solvent, complementing the process with the evaluation of the immersion enthalpy for the pure components and toluene-hexane mixtures at different molar fractions. The adsorption capacities for the gas phase were between 3.40 and 0.05 mmol g −1 , being higher for toluene because of the π-π interaction with the solid; when evaluating the liquid phase, the adsorption capacities were 0.24 and 0.74 mmol g −1 , where the adsorption of toluene decreased compared to the gas phase because of the solute-solute, solvent-solvent, solute-solvent interaction. The immersion enthalpies for the pure solvents were between −40.87 and −126.10 J g −1 being higher also for toluene confirming a greater interaction compared to hexane; for the mixtures, immersion enthalpy was higher than hexane enthalpies, but lower than toluene enthalpies with values between −59.79 and −107.95 J g −1. It was found that there was a greater interaction between the sample with a lower content of acid groups and a greater surface area with toluene due to the high electron density of carbon and London-type as π-π interactions with the aromatic compound. For mixtures, hexane decreased the adsorption capacity and interaction with respect to toluene because there was competition for adsorption sites and subsequent displacement of hexane molecules when the amount of toluene on the surface increased.

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Immersion enthalpy of benzene/cyclohexane and toluene/cyclohexane binary mixtures into modified activated carbons

Cited by 12 publications

References 35 publications

Enthalpic and Liquid-Phase Adsorption Study of Toluene–Cyclohexane and Toluene–Hexane Binary Systems on Modified Activated Carbons

Enthalpic and Liquid-Phase Adsorption Study of Toluene–Cyclohexane and Toluene–Hexane Binary Systems on Modified Activated Carbons

Experimental Measurement of Bulk Thermal Conductivity of Activated Carbon with Adsorbed Natural Gas for ANG Energy Storage Tank Design Application

Comparative Study of Toluene and Hexane Adsorption on Activated Carbons From Gas and Liquid Phase. Enthalpy and Isotherms

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