Surface Potential Driven Water Harvesting from Fog

Abstract

Access to clean water is a global challenge, and fog collectors are a promising solution. Polycarbonate (PC) fibers have been used in fog collectors but with limited efficiency. In this study, we show that controlling voltage polarity and humidity during the electrospinning of PC fibers improves their surface properties for water collection capability. We experimentally measured the effect of both the surface morphology and the chemistry of PC fiber on their surface potential and mechanical properties in relation to the water collection efficiency from fog. PC fibers produced at high humidity and with negative voltage polarity show a superior water collection rate combined with the highest tensile strength. We proved that electric potential on surface and morphology are crucial, as often designed by nature, for enhancing the water collection capabilities via the single-step production of fibers without any postprocessing needs.

The Significance of Electrical Polarity in Electrospinning: A Nanoscale Approach for the Enhancement of the Polymer Fibers' Properties

“…PVDF [ 173 ] fibers produced from the lower polymer solution concentration (22%), at 60% of relative humidity and in the same solvents as above, also resulted in a wrinkled surface and similar average diameters, 1.39 ± 0.58 µm (PVDF+) and 1.37 ± 0.57 µm (PVDF−), respectively. In the electrospinning of PC, [ 153 ] the same morphology and fiber size were seen for the positive and negative voltage polarity produced from DMF and tetrahydrofuran (THF) solvents and at 25% and 40% RH. The surface of fibers became wrinkled, and the average fiber diameters were ≈ 2.30 ± 0.51 µm, ≈ 2.80 ± 0.50 µm for 25% and 40% RH, respectively.…”

“…In the case of electrospun PC− meshes, [ 153 ] the water contact angle was significantly higher (≈ 130°) than for PC+ (≈ 112°). Authors attributed this effect to the repulsion of water molecules due to different surface chemistry and higher surface potential for the (−) fibers.…”

“…[67] Random PMMA+ had a lower maximum Reproduced with permission under the CC-BY 4.0 license. [153] Copyright 2021, the Authors. Published by American Chemical Society.…”

How does the electric field make a droplet exhibit the ejection and rebound behaviour on a superhydrophobic surface?

“…2020), water harvesting (Ilyas & Swingler 2015; Damak & Varanasi 2018; Ura et al. 2021), gas absorption (Hao et al. 2018; Solomatin, Shlegel & Strizhak 2019), inkjet printers (Mohammadi, Movahhedy & Khodaygan 2019; Rahman et al.…”

“…Although the droplet collision seems simple and short, it is actually a rather complex physical process, with many potential mechanisms and interesting dynamic behaviours that are yet to be revealed. In particular, the droplet impacting on an SH substrate in an electric field deserves special attention and research, as it plays a fundamental role in a variety of applications, such as droplet three-dimensional manipulation (Kim et al 2007;Chae et al 2015;Nauruzbayeva et al 2020), water harvesting (Ilyas & Swingler 2015;Damak & Varanasi 2018;Ura et al 2021), gas absorption (Hao et al 2018;Solomatin, Shlegel & Strizhak 2019), inkjet printers (Mohammadi, Movahhedy & Khodaygan 2019;Rahman et al 2021;Zhu & Chiarot 2021) and lab-on-a-chip technology (Zhang et al 2019;Mozaffari et al 2021;Sun et al 2021). When the droplet impacts on an SH surface, it will spread, retract, stretch and rebound (Yarin 2006;Lee et al 2015).…”