Water desorption isotherms and net isosteric heat of desorption on lignite

Wan, Keji; He, Qiang; Miao, Zhenyong; Liu, Xuejing; Huang, Shaomeng

doi:10.1016/j.fuel.2015.12.054

Cited by 48 publications

(27 citation statements)

References 27 publications

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“…The observation that the values of ΔH ads are larger than ΔH H₂O also indicates that intermolecular bonding between water molecules and the sorption sites is higher than that between water molecules of the condensed pure water (Masuzawa & Sterling, ). A similar trend has been reported for water vapor adsorption on sodium montmorillonite (Mooney et al, ), Marcellus shale (Tang et al, ), lignite (Wan et al, ), and on foods (Quirijns et al, ).…”

Section: Resultssupporting

confidence: 79%

Water Vapor Sorption Properties of Illinois Shales Under Dynamic Water Vapor Conditions: Experimentation and Modeling

Sang

Liu

Elsworth

2019

Water Resources Research

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Water vapor adsorption/desorption isotherms are measured on five shales from Illinois basin by dynamic vapor sorption method. The experimental adsorption data are modeled by the Guggenheim, Anderson, and De Boer model and the Freundlich model over the entire range of measured relative humidity (Rh) values (0–0.95). Modeling results show that shale hydration is controlled by surface chemistry at low Rh through a strong intermolecular bonding, while is mainly influenced by the pore structure at high Rh (>0.9) through capillary condensation. This is consistent with the progressive decrease of isosteric heat of adsorption with water content, obtained by the Clausius‐Clapeyron equation. Exceptionally, for the one shale containing 8.6% montmorillonite, mesopore condensation only accounts for 33% of the measured water adsorption even at Rh ~0.95 due to the limited external pores and the important role of clay swelling. The specific surface area defined by Guggenheim, Anderson, and De Boer analysis as available for water adsorption is larger than that available for low‐pressure N2 adsorption due to the complex surface chemistry. The one shale rich in expansive montmorillonite and with a large interlayer capacity for water but inaccessible to N2 molecules conditions this result. Among the other four shales, one with high kerogen content behaves the highest water adsorption, possibly due to the high content of oxygen‐containing functional groups and the potentially high pore volume of kerogen. These findings contribute to a better understanding of water storage and transport behavior in shales and impact behavior relevant to structures and reservoirs founded in such media.

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Section: Resultssupporting

confidence: 79%

Water Vapor Sorption Properties of Illinois Shales Under Dynamic Water Vapor Conditions: Experimentation and Modeling

Sang

Liu

Elsworth

2019

Water Resources Research

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“…A linear relationship between the water holding capacity and the amount of oxygen functional groups was experimentally observed, proving that the oxygen-containing functional groups are the active sites for water vapor sorption (Kaji et al 1986). It was experimentally observed that the coal rank was an important factor that influences the amount of oxygen functional groups in coal (van Krevelen 1993). The experimental data showed that the hydroxyl groups were abundant in brown coal and were predominant with phenolic compounds, followed by the carboxyl groups and methoxy groups (-OCH 3 ).…”

Section: Background and Previous Studiesmentioning

confidence: 77%

Water sorption on coal: effects of oxygen-containing function groups and pore structure

Liu

et al. 2021

Int J Coal Sci Technol

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Coal-water interactions have profound influences on gas extraction from coal and coal utilization. Experimental measurements on three coals using X-ray photoelectron spectroscopy (XPS), low-temperature nitrogen adsorption and dynamic water vapor sorption (DVS) were conducted. A mechanism-based isotherm model was proposed to estimate the water vapor uptake at various relative humidities, which is well validated with the DVS data. The validated isotherm model of sorption was further used to derive the isosteric heat of water vapor sorption. The specific surface area of coal pores is not the determining parameter that controls water vapor sorption at least during the primary adsorption stage. Oxidation degree dominates the primary adsorption, and which togethering with the cumulative pore volume determine the secondary adsorption. Higher temperature has limited effects on primary adsorption process.The isosteric heat of water adsorption decreases as water vapor uptake increases, which is found to be close to the latent heat of bulk water condensation at higher relative humidity. The results confirmed that the primary adsorption is controlled by the stronger bonding energy while the interaction energy between water molecules during secondary adsorption stage is relatively weak. However, the thermodynamics of coal-water interactions are complicated since the internal bonding interactions within the coal are disrupted at the same time as new bonding interactions take place within water molecules. Coal has a shrinkage/swelling colloidal structure with moisture loss/gain and it may exhibit collapse behavior with some collapses irreversible as a function of relative humidity, which further plays a significant role in determining moisture retention.

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“…Meanwhile, the q stn (KJ/mol) could be calculated by applying the Clausius-Clapeyron equation ( Equation 2 ) ( Tsami, 1991 ) to the isotherms obtained at different working temperatures, assuming that the q stn does not vary with the temperature ( Wan et al., 2016 ). Data were taken from a w for each of the isotherms at different temperatures for a given equilibrium moisture content.…”

Section: Methodsmentioning

confidence: 99%

Sorption isotherms and thermodynamic properties of the dry silage of red tilapia viscera (Oreochromis spp.) obtained in a direct solar dryer

Echavarría

Torres

Montoya

2021

Heliyon

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The sorption isotherms, thermodynamic properties and calculation for confirming the isokinetic theory of dry chemical silage of red tilapia viscera ( Oreochromis spp.) obtained in a direct passive solar dryer were determined. Sorption isotherms were carried out at 15, 25, 35 and 45 °C using a static gravimetric method. The curves obtained were adjusted to eight equations. The isosteric heat of sorption (net and total) and the thermodynamic parameters were determined based on the Clausius-Clapeyron equation and the enthalpy–entropy compensation theory was applied to adsorption isotherms. The sorption isotherms obtained were of type III of Brunauer classification. The Peleg model best described the experimental data. In all cases, the isosteric heat decreased while the moisture content increased. The value of isokinetic temperature (T B ) was found to be less than harmonic mean temperature (T hm ), the sorption of water in dry chemical silage is therefore controlled by entropic mechanisms and proceeds spontaneously.

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Water desorption isotherms and net isosteric heat of desorption on lignite

Cited by 48 publications

References 27 publications

Water Vapor Sorption Properties of Illinois Shales Under Dynamic Water Vapor Conditions: Experimentation and Modeling

Water Vapor Sorption Properties of Illinois Shales Under Dynamic Water Vapor Conditions: Experimentation and Modeling

Water sorption on coal: effects of oxygen-containing function groups and pore structure

Sorption isotherms and thermodynamic properties of the dry silage of red tilapia viscera (Oreochromis spp.) obtained in a direct solar dryer

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