Superhydrophilic–Superhydrophobic Water Harvester Inspired by Wetting Property of Cactus Stem

Abstract

Water harvesting is a core technology for collecting fresh water in arid areas. In this study, we design a three-dimensional cactus stem-inspired water harvesting system (WHS) with directional transport of absorbed fog. The bioinspired WHS consists of two distinct functions. One is an effective water-absorbing function with an antievaporating feature, and the other is an on-demand water-releasing function. The excellent water absorption capability of a mucilage-filled cactus stem covered with a cuticle is mimicked by a cylindrical double structural system (DS) comprising an interpenetrating polymer network (IPN) hydrogel with good water retention capacity and a superhydrophobic copper mesh (SHPM) that prevents the re-evaporation of absorbed water. DS harvests water at a rate of 209 mg cm–2 h–1 and exhibits enhanced water collecting performance, i.e., 1.2, 1.3, and 2 times higher than that of the superhydrophilic IPN hydrogel, SHPM, and pristine copper mesh (PTM), respectively. The detailed fog harvesting mechanism of DS is examined through an X-ray imaging technique, and the water harvesting mechanism is described in terms of volumetric expansion of IPN hydrogel, absorption of microdroplets on mesh humps, and thickness of the water-film between mesh fibers. In addition, the function of water release is demonstrated with the aid of the thermoresponsive property of the IPN hydrogel. This biomimetic WHS may aid in developing effective three-dimensional plant-inspired fog collectors.

Microfabrication and Surface Functionalization of Soda Lime Glass through Direct Laser Interference Patterning

“…This behavior can be explained by taking into account the balance between capillary forces, surface tension, and gravity. For the textured glass surface, it can be assumed that the adhesion forces to the rough hydrophilic surface dominate and the droplet spread takes place in all directions regardless of the texture orientation [ 75 , 76 , 77 ].…”

Energy performance and climate dependency of technologies for fresh water production from atmospheric water vapour

“…81 A hydrogel based on poly-NIPAM, calcium alginate and agarose helices shows a similar oozing process at 40°C. 83 Strong synergy between poly-NIPAM thermo-responsive polymer and chloride-doped polypyrrole (PPy-Cl) was recently achieved in a super moisture-absorbent gel (SMAG). 82 Water vapour is adsorbed on the hygroscopic PPy-Cl phase and transferred to the super-hydrophilic poly-NIPAM, which can store large amounts of liquid water.…”

Mangifera indica Leaf (MIL) as a Novel Material in Atmospheric Water Collection

“…Furthermore, to determine the wettability mechanism of MILs, the WCA before and after the collection was determined. According to Lee et al., 32 liquid droplets show more affinity with a hydrophilic surface with easy water droplet penetration into its microgrooves, causing a low contact angle (CA) value. The CAs before and after water collection were 66.3 and 68.9, respectively, which resonates with the assertion of Lee et al about the hydrophilic surface.…”