Controlling salt deposition patterns using engineered substrates and thermal gradients

Abstract Preferential salt deposition and spreading influence both natural processes and industrial applications. This study examines salt deposition patterns in evaporating sessile drops and within capillary menisci above a brine pool. Temperature- and concentration-dependent surface tension induce...

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Main Authors: Zhao Xia, Qi Liu, J. Carlos Santamarina
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-025-01772-y
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author Zhao Xia
Qi Liu
J. Carlos Santamarina
author_facet Zhao Xia
Qi Liu
J. Carlos Santamarina
author_sort Zhao Xia
collection DOAJ
description Abstract Preferential salt deposition and spreading influence both natural processes and industrial applications. This study examines salt deposition patterns in evaporating sessile drops and within capillary menisci above a brine pool. Temperature- and concentration-dependent surface tension induces Marangoni flow, which transports high-concentration liquid to the cooler side of the droplet where nuclei form and grow. Substrates with mixed thermal diffusivities and externally imposed thermal gradients can alter salt deposition patterns by controlling the direction of Marangoni flow. When connected to a brine pool, salt deposition creates a salt coating that can spread on vertical substrates. Spreading begins when crystals remain confined against the substrate: small crystals nucleating higher in the transition zone of capillary menisci have a higher likelihood of staying in place due to larger capillary forces. Salt spreading on a vertical substrate can be halted by imposing a downward thermal gradient to reverse the Marangoni flow direction within the capillary menisci or by engineering the surface roughness to reduce wettability. Horizontally roughened surfaces impede salt spreading; vertically roughened surfaces see the formation of stable crystals within short induction times, followed by rapid spreading as corner flow facilitates solution transport along interconnected roughness and through the porous salt coating.
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spelling doaj-art-1bce080e2bcb4a05b931c7dc292a0fc42025-08-20T02:03:30ZengNature PortfolioScientific Reports2045-23222025-05-011511910.1038/s41598-025-01772-yControlling salt deposition patterns using engineered substrates and thermal gradientsZhao Xia0Qi Liu1J. Carlos Santamarina2The University of Texas at AustinChina Huadian CorporationGeorgia Institute of TechnologyAbstract Preferential salt deposition and spreading influence both natural processes and industrial applications. This study examines salt deposition patterns in evaporating sessile drops and within capillary menisci above a brine pool. Temperature- and concentration-dependent surface tension induces Marangoni flow, which transports high-concentration liquid to the cooler side of the droplet where nuclei form and grow. Substrates with mixed thermal diffusivities and externally imposed thermal gradients can alter salt deposition patterns by controlling the direction of Marangoni flow. When connected to a brine pool, salt deposition creates a salt coating that can spread on vertical substrates. Spreading begins when crystals remain confined against the substrate: small crystals nucleating higher in the transition zone of capillary menisci have a higher likelihood of staying in place due to larger capillary forces. Salt spreading on a vertical substrate can be halted by imposing a downward thermal gradient to reverse the Marangoni flow direction within the capillary menisci or by engineering the surface roughness to reduce wettability. Horizontally roughened surfaces impede salt spreading; vertically roughened surfaces see the formation of stable crystals within short induction times, followed by rapid spreading as corner flow facilitates solution transport along interconnected roughness and through the porous salt coating.https://doi.org/10.1038/s41598-025-01772-yMarangoni flowSessile dropletsBrine evaporationHybrid substrateThermal gradientSurface roughness
spellingShingle Zhao Xia
Qi Liu
J. Carlos Santamarina
Controlling salt deposition patterns using engineered substrates and thermal gradients
Scientific Reports
Marangoni flow
Sessile droplets
Brine evaporation
Hybrid substrate
Thermal gradient
Surface roughness
title Controlling salt deposition patterns using engineered substrates and thermal gradients
title_full Controlling salt deposition patterns using engineered substrates and thermal gradients
title_fullStr Controlling salt deposition patterns using engineered substrates and thermal gradients
title_full_unstemmed Controlling salt deposition patterns using engineered substrates and thermal gradients
title_short Controlling salt deposition patterns using engineered substrates and thermal gradients
title_sort controlling salt deposition patterns using engineered substrates and thermal gradients
topic Marangoni flow
Sessile droplets
Brine evaporation
Hybrid substrate
Thermal gradient
Surface roughness
url https://doi.org/10.1038/s41598-025-01772-y
work_keys_str_mv AT zhaoxia controllingsaltdepositionpatternsusingengineeredsubstratesandthermalgradients
AT qiliu controllingsaltdepositionpatternsusingengineeredsubstratesandthermalgradients
AT jcarlossantamarina controllingsaltdepositionpatternsusingengineeredsubstratesandthermalgradients