Designing Plastrons for Underwater Bubble Capture: From Model Microstructures to Stochastic Nanostructures


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Date

2024-09-04

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

Bubbles and foams are often removed via chemical defoamers and/or mechanical agitation. Designing surfaces that promote chemical-free and energy-passive bubble capture is desirable for numerous industrial processes, including mineral flotation, wastewater treatment, and electrolysis. When immersed, super-liquid-repellent surfaces form plastrons, which are textured solid topographies with interconnected gas domains. Plastrons exhibit the remarkable ability of capturing bubbles through coalescence. However, the two-step mechanics of plastron-induced bubble coalescence, namely, rupture (initiation and location) and subsequent absorption (propagation and drainage) are not well understood. Here, the influence of 1) topographical feature size and 2) gas fraction on bubble capture dynamics is investigated. Smaller feature sizes accelerate rupture while larger gas fractions markedly improve absorption. Rupture is initiated solely on solid domains and is more probable near the edges of solid features. Yet, rupture time becomes longer as solid fraction increases. This counterintuitive behavior represents unexpected complexities. Upon rupture, the bubble's moving liquid-solid contact line influences its absorption rate and equilibrium state. These findings show the importance of rationally minimizing surface feature sizes and contact line interactions for rapid bubble rupture and absorption. This work provides key design principles for plastron-induced bubble coalescence, inspiring future development of industrially-relevant surfaces for underwater bubble capture.

Publication status

published

Editor

Book title

Volume

11 (33)

Pages / Article No.

2403366

Publisher

Wiley-VCH

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Edition / version

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Date collected

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Subject

bubble absorption; bubble coalescence; bubble rupture; superhydrophobic; super liquid repellent

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Funding

853257 - De-railing scaling: From fundamentals of crystallization fouling on nano-materials to rational design of scale-phobic surfaces (EC)

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