Godts, Sebastiaan;
Steiger, Michael;
Stahlbuhk, Amelie;
Orr, Scott Allan;
Desarnaud, Julie;
De Clercq, Hilde;
Cnudde, Veerle;
(2024)
Modeled versus Experimental Salt Mixture Behavior under Variable Humidity.
ACS Omega
10.1021/acsomega.4c01486.
(In press).
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Abstract
This study investigates the kinetics of salt mixture crystallization under relative humidity (RH) conditions, varying between 15 and 95% (at 20 °C), to inform applications in built heritage preservation, geology, and environmental sciences. We focused on commonly found, sulfate-rich and calcium-rich salt mixtures containing five to six ions, Cl–, NO3–, Na+, and K+, including or excluding less common Mg2+, and including either an excess of SO42– or Ca2+, with respect to gypsum. Using time-lapse micrographs and dynamic vapor sorption, we explore how crystallization and dissolution behavior depend on RH and mixture composition under constant temperature. A range of RH change rates were studied to simulate realistic weather events. Microstructural analyses through environmental scanning electron microscopy (ESEM) confirmed the crystal habit corresponding with RH transitions. Phases predicted from thermodynamic modeling (ECOS/RUNSALT) were confirmed using micro-Raman spectroscopy, X-ray diffraction (XRD), and elemental mapping via energy-dispersive X-ray spectroscopy (EDX). We identify a strong correlation between phase transition kinetics and RH change rates, with crystallization deviating by −15% and dissolution by +7% from modeled values under rapid (several seconds) and slow (several days) RH changes. These insights are important for preservation strategies in built heritage, salt deposition, and dissolution mechanisms in diverse geological and realistic environmental contexts, laboratory experiments, future modeling efforts, and the understanding of stone decay in general.
| Type: | Article |
|---|---|
| Title: | Modeled versus Experimental Salt Mixture Behavior under Variable Humidity |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/acsomega.4c01486 |
| Publisher version: | http://dx.doi.org/10.1021/acsomega.4c01486 |
| Language: | English |
| Additional information: | © 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0. |
| Keywords: | Crystallization, Dissolution, Mixtures, Salts, Vinyl |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment > Bartlett School Env, Energy and Resources |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10189981 |
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