Impact of type of salt and ambient conditions on saline water evaporation from porous media

Abstract

HIghlights• Evaporation from porous media saturated with different salt solutions was investigated • Effects of ambient temperature, relative humidity and type of salt were discussed • Salt precipitation does not necessarily limit the evaporative flux • Strong direct correlation between evaporation and surface salt precipitation was found AbstractSaline water evaporation from porous media is important in many processes such as soil salinization, CO 2 sequestration, crop production and water management. This process is influenced by the transport properties of porous media, properties of the evaporating solution and external conditions. In this work, we investigated the effects of external conditions and type of salt on the drying behaviour of sandy media and on the dynamics of surface salt precipitation. To do so, a comprehensive series of evaporation experiments were conducted using 33 columns packed with sand saturated with salt solutions. The evaporation experiments were conducted in an environmental chamber to investigate the effects of relative humidity, ambient temperature and type of salt on the evaporation process. Sodium Chloride, Calcium Chloride and Potassium Iodide with a wide range of concentration were used to saturate the sand columns mounted on digital balances. A digital camera was fixed at the surface of the sand packs to record the dynamics of salt precipitation at the surface. The results provide further confirmation that ambient conditions are the controlling factors during stage-1 evaporation of pure water. Additionally, the minor impact of the presence of precipitated salt at the surface on the saline water evaporation during the early stages of the process is discussed. Strong correlations between the cumulative water losses and the precipitation at the surface were found under different ambient conditions. The results obtained from different types of salt highlight the significant influence of the relationship between the saturated vapour pressure and salt concentration on the general dynamics of the process.

NaCl Crust Architecture and Its Impact on Evaporation: Three‐Dimensional Insights

“…The exact location of nucleation centers, their spatial density, and rate of formation may be affected by various parameters such as evaporation rates and humidity (Desarnaud et al, 2015;Shokri-Kuehni, Norouzi, et al, 2017), porous media grain and pore dimensions (Norouzi Rad et al, 2013;Zehnder & Arnold, 1989) and distribution Nachshon, Shahraeeni, et al, 2011), grain angularity (Norouzi & Shokri, 2014), and solute concentrations (Bergstad et al, 2017). Nevertheless, the rate of ESC formation and its upward growth varied between the different soils.…”

New insights into saline water evaporation from porous media: Complex interaction between evaporation rates, precipitation, and surface temperature

“…Evaporation of saline water from porous media is important in many environmental, engineering, and hydrological processes including vegetation and plant growth, soil salinization, land-atmosphere interaction, functioning of the ecosystem, and crop production [Rodriguez-Navarro and Doehne, 1999;Suweis et al, 2010;Ott et al, 2015;Bergstad and Shokri, 2016]. This has motivated many researchers to investigate various aspects of this process including the effects of grain size, wettability, heterogeneity, and external conditions [Huinink et al, 2002;Guglielmini et al, 2008;Nachshon et al, 2011aNachshon et al, , 2011bEloukabi et al, 2013;Norouzi Rad et al, 2015;Jambhekar et al, 2015;Börnhorst et al, 2016;Dai et al, 2016;Shokri-Kuehni et al, 2017].…”

“…Saline water evaporation is influenced by transport properties of the porous media, properties of the evaporating solution, external conditions (wind, radiation, ambient temperature, and relative humidity), and precipitation of salt crystals [Norouzi Rad et al, 2013;Shokri, 2014;Jambhekar et al, 2015;Shokri-Kuehni et al, 2017]. During evaporation, solute is transported, via capillary-induced liquid flow, from a wet zone to the evaporation surface resulting in increasing solute concentration close to the vaporization plane [Guglielmini et al, 2008].…”

Drying of Salt Solutions from Porous Media: Effect of Surfactants

“…This invasion of salt solutions is eventually followed by drying and concomitant crystallization of the dissolved salts. The latter significantly influence the drying kinetics of porous structures, and previous studies have reported counterintuitive trends in drying kinetics when salts are present B Mohsin J. Qazi m.j.qazi@uva.nl 1 Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands (Veran-Tissoires et al 2012;Desarnaud et al 2015;Shokri-Kuehni et al 2017;Bergstad and Shokri 2016;Bergstad et al 2017). Depending on the environmental conditions, the salt precipitation can alter the drying process by forming a salt crust that blocks the evaporation from the core of the stones (Desarnaud et al 2015;Gupta et al 2014;Grementieri et al 2017).…”

“…This often happens at low relative humidity, where the initial drying is rapid. On the other hand, for drying at higher relative humidity, different salt precipitation dynamics at the surface enables continuous hydraulic conductivity and can even enhance the evaporation process (Desarnaud et al 2015;Gupta et al 2014;Shokri-Kuehni et al 2017;Veran-Tissoires et al 2012). This then leads to the counterintuitive result that the total drying time can be longer at a low relative humidity.…”