Connecting wettability, topography, and chemistry in a simple lipid-montmorillonite system

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:555

Article

Kessenich, Brenda L.¹  Pokhrel, Nihit¹  Nakouzi, Elias²  Newcomb, Christina J.²  Flury, Markus^3,4  Maibaum, Lutz¹  De Yoreo, James J.^2,5 

[1] Univ Washington, Dept Chem, Box 351700, Seattle, WA 98195 USA

[2] Pacific Northwest Natl Lab, Phys Sci Div, POB 999,MS K2-01, Richland, WA 99352 USA

[3] Washington State Univ, Dept Crop & Soil Sci, Pullman, WA 99164 USA

[4] Washington State Univ, Dept Crop & Soil Sci, Puyallup, WA 98371 USA

[5] Univ Washington, Mat Sci & Engn, 302 Roberts Hall,Box 352120, Seattle, WA 98195 USA

关键词: Soil water repellency;    Soil organic matter;    Clay;    Molecular dynamics;    Nanotopology;   

DOI  :  10.1016/j.jcis.2019.07.075

来源: Elsevier

【 摘 要 】

Hypothesis: While soil water repellency causes a variety of undesirable environmental effects, the underlying mechanism is unknown. We investigate the coupled effects of chemical characteristics and surface topology in a simple model system of two lipids, DSPE (1,2-distearoyl-sn-glycero-3-phosphoethanolamine) and DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine), and a clay substrate. These closely-related lipids allowed the study of how a small change in chemical structure influences the surface hydrophobicity. Experiments: Techniques ranging from molecular (simulations) to nanoscopic (atomic force microscopy) to microscopic (fluorescence microscopy) to macroscopic (contact angle measurements) were used to explore interactions at all length scales. The wettability was assessed from initial contact angle and time-dependent changes in droplet shape. Findings: The lipid distribution depended on the lipid's melting temperature: solid lipids did not spread evenly through the film, while liquid ones did. However, the initial contact angle did not change appreciably with the addition of DSPE or DOPE. Only DSPE heated above its melting temperature induced significant changes. In addition to the initial contact angle, quantitative variables extracted from the change in droplet shape over time correlated with the film topography or lipid distribution. These results define a new quantitative approach to investigating partially-wettable soils and provide a potential rationale for why clays can remediate water-repellent soils. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free