An experimental and numerical study of droplet spreading and imbibition on microporous membranes

Bhattacharjee, Debanik; Nazaripoor, Hadi; Soltannia‬, Babak; Ismail, Farhad; Sadrzadeh, Mohtada

doi:10.1016/j.colsurfa.2021.126191

Cited by 8 publications

(4 citation statements)

References 48 publications

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“…In our case, the biofilm itself is the substrate on which wetting occurs. The latter shares several common features with the wetting of nonbiological porous layers by external liquids. − It is recognized that biological surfaces are far from being ideal solid surfaces and as such experimentally measured quantities describing their wetting behavior represent apparent quantities, e.g., apparent contact angles . There are only a few systematic quantitative studies focusing on the physics of the wetting of biofilms by liquids and these studies refer mainly to Bacillus subtilis colonies grown on agar substrates. − Attention to such biofilms stems from their extremely nonwettable character and the technological crucial interest in understanding how hydrophobicity can be reduced to remove deleterious biofilms by cleaning solutions. − It was found that such biofilms are resistant toward water and nonpolar liquids, showing hydrophobic or even omniphobic behavior. , Werb et al and Falcón García et al demonstrate that biofilm colonies show various wetting behavior depending on the selected system and conditions (such as bacterial strain, type of nutrient medium), i.e., from hydrophilic to superhydrophobic behavior.…”

Section: Introductionmentioning

confidence: 99%

Wetting of Dehydrated Hydrophilic Pseudomonas fluorescens Biofilms under the Action of External Body Forces

et al. 2021

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Wetting of dehydrated Pseudomonas f luorescens biofilms grown on glass substrates by an external liquid is employed as a means to investigate the complex morphology of these biofilms along with their capability to interact with external fluids. The porous structure left behind after dehydration induces interesting droplet spreading on the external surface and imbibition into pores upon wetting. Static contact angles and volume loss by imbibition measured right upon droplet deposition indicate that biofilms of higher incubation times show a higher porosity and effective hydrophilicity. Furthermore, during subsequent rotation tests, using Kerberos device, these properties dictate a peculiar forced wetting/spreading behavior. As rotation speed increases a long liquid tail forms progressively at the rear part of the droplet, which stays pinned at all times, while only the front part of the droplet depins and spreads. Interestingly, the experimentally determined retention force for the onset of droplet sliding on biofilm external surface is lower than that on pure glass. An effort is made to describe such complex forced wetting phenomena by presenting apparent contact angles, droplet length, droplet shape contours, and edges position as obtained from detailed image analysis.

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Section: Introductionmentioning

confidence: 99%

Wetting of Dehydrated Hydrophilic Pseudomonas fluorescens Biofilms under the Action of External Body Forces

et al. 2021

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“…This pinch-off phenomenon hinders permeation, since the ejected daughter droplet falls back to the substrate by gravity, rendering the capillary wicking effect invalid. It is also noteworthy from Figure that the present work achieves a penetration time of only tens of milliseconds, even at a high temperature of 500 °C, which is 1 to 2 orders of magnitude smaller than the previous work, , . − For instance, the measured penetration time of poly(ether sulfone) (PES) microporous membranes ranged from 0.3 to 50 s . Besides the measured penetration time of various powder beds (glass ballotini, zinc oxide, and titanium dioxide, etc.)…”

Section: Resultsmentioning

confidence: 50%

“…Our results reveal that these nickel foams exhibit remarkable features such as ultrafast permeation of droplets, high Leidenfrost point exceeding 500 °C, in contrast with known porous surfaces with limited porosity and pore diameter. 31,[37][38][39][40]42,46 Theoretical analysis based on the balance of capillary pressure and vapor pressure demonstrates that these remarkable features are attributed to the superhydrophilic property that promotes capillary wicking, the high porosity that reduces effective thermal conductivity, and the large pore diameter that enhances permeability. Particularly, the latter two factors significantly reduce the vapor pressure, hindering droplet permeation.…”

Section: Discussionmentioning

confidence: 99%

Inhibiting the Leidenfrost Effect by Superhydrophilic Nickel Foams with Ultrafast Droplet Permeation

Wang

et al. 2023

ACS Appl. Mater. Interfaces

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Inhibiting the Leidenfrost effect has drawn extensive attention due to its detrimental impact on heat dissipation in high-temperature industrial applications. Although hierarchical structures have improved the Leidenfrost point to over 1000 °C, the current performance of single-scale structures remains inadequate. Herein, we present a facile high-temperature treatment method to fabricate superhydrophilic nickel foams that demonstrate ultrafast droplet permeation within tens of milliseconds, elevating the Leidenfrost point above 500 °C. Theoretical analysis based on the pressure balance suggests that these remarkable features arise from the superhydrophilic property, high porosity, and large pore diameter of nickel foams that promote capillary wicking and vapor evacuation. Compared to solid nickel surfaces with a Leidenfrost temperature of approximately 235 °C, nickel foams nucleate boiling at high superheat, triggering an order of magnitude higher heat flux. The effects of the pore diameter and surface temperature on droplet permeation behaviors and heat transfer characteristics are also elucidated. The results indicate that droplet permeation is dominated by inertial and capillary forces at low and high superheat, respectively, and moderate pore diameters are more conducive to facilitating droplet permeation. Furthermore, our heat transfer model reveals that pore diameter plays a negligible role in the heat flux at high surface temperatures due to the trade-off between effective thermal conductivity and specific surface area. This work provides a new strategy to address the Leidenfrost effect by metal foams, which may promise great potential in steel forging and nuclear reactor safety.

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“…Wetting, spreading and penetration of liquid droplets into porous substrates are frequent phenomena observed in natural processes and applications [1,2]. A considerable number of substrates used in applications are porous: examples are inkjet printing [3][4][5], irrigation [6][7][8], oil recovery [9][10][11], waste water purification [12], medical treatments [13], painting of exterior surfaces [14], trickle bed reactors [12], and a range of other applications [15]. The vast majority of the experimental research and theory published on wetting and spreading is focussed on smooth and homogenous substrates [16].…”

Section: Introductionmentioning

confidence: 99%

Superspreading Surfactant on Hydrophobic Porous Substrates

Tafireyi,

Littlewood,

Bandulasena

et al. 2023

Colloids and Interfaces

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The wetting behavior of droplets of aqueous surfactant solutions over hydrophobic thin PVDF porous membrane and non-porous hydrophobic PVDF film is investigated for small (~10 μL) droplets of aqueous trisiloxane surfactant solutions: superspreader S 240. The time dependencies of contact angle, droplet radius, wetted area and volume were monitored as well as penetration into the porous substrate. It is shown that the fast spreading of droplets of trisiloxane solutions takes place both in the case of porous and non-porous substrates at a concentration above some critical concentration. It was found that the trisiloxane droplets penetrate into the hydrophobic porous substrates and disappear much faster than on a corresponding hydrophobic non-porous substrate, which was not observed before. This phenomenon is referred to as “superpenetration”.

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An experimental and numerical study of droplet spreading and imbibition on microporous membranes

Cited by 8 publications

References 48 publications

Wetting of Dehydrated Hydrophilic Pseudomonas fluorescens Biofilms under the Action of External Body Forces

Wetting of Dehydrated Hydrophilic Pseudomonas fluorescens Biofilms under the Action of External Body Forces

Inhibiting the Leidenfrost Effect by Superhydrophilic Nickel Foams with Ultrafast Droplet Permeation

Superspreading Surfactant on Hydrophobic Porous Substrates

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