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Examining Thermodynamic Changes During Soil Moisture Loss

Rao, SM and Rekapalli, M (2021) Examining Thermodynamic Changes During Soil Moisture Loss. In: Geotechnical and Geological Engineering, 39 (05). pp. 4009-4016.

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Official URL: https://doi.org/10.1007/s10706-021-01739-6


Distribution constant, (Kc) is employed to account for desorption of water molecules from soil particles. When water molecules have strong affinity for soil particles, Kc and moisture desorption is small. Conversely, when water molecules have weak affinity for soil particles, Kc is large and moisture desorption is significant. By approximating the distribution constant, Kc to be equal to thermodynamic equilibrium constant and with the aid of standard equations, insight is obtained into physico-chemical factors responsible for changes in enthalpy, entropy and free energy at equilibrium soil moisture loss condition. Analysis of experimental results showed that moisture desorption from moist pulverized soils is endothermic process as energy is required to overcome physico-chemical and suction bonds between water molecules and surface of soil pores and hydrogen bonds between water molecules. The heat of desorption increases with reduction in environmental relative humidity (aw) as water molecules occupy high binding energy sites at low environmental relative humidity. Moisture desorption is accompanied by increase in entropy as water molecules are disordered in vapor phase than in the liquid state. Trend of �G° values indicate that soil moisture loss becomes increasingly spontaneous (negative �G° values) with reduction in environmental relative humidity, which is supported by the highest Kc at least environmental relative humidity. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.

Item Type: Journal Article
Publication: Geotechnical and Geological Engineering
Publisher: Springer Science and Business Media Deutschland GmbH
Additional Information: The copyright to this article belongs to Springer Science and Business Media Deutschland GmbH.
Keywords: Binding energy; Binding sites; Chemical analysis; Desorption; Entropy; Equilibrium constants; Free energy; Hydrogen bonds; Molecules; Reduction, Distribution constant; Endothermic process; Heat of desorption; Moisture desorption; Physico-chemical factors; Physico-chemicals; Thermodynamic changes; Thermodynamic equilibrium constant, Soil moisture
Department/Centre: Division of Mechanical Sciences > Civil Engineering
Date Deposited: 22 Dec 2021 10:45
Last Modified: 22 Dec 2021 10:45
URI: http://eprints.iisc.ac.in/id/eprint/68207

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