eprintid: 10189981 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/18/99/81 datestamp: 2024-04-05 12:59:16 lastmod: 2024-04-05 12:59:16 status_changed: 2024-04-05 12:59:16 type: article metadata_visibility: show sword_depositor: 699 creators_name: Godts, Sebastiaan creators_name: Steiger, Michael creators_name: Stahlbuhk, Amelie creators_name: Orr, Scott Allan creators_name: Desarnaud, Julie creators_name: De Clercq, Hilde creators_name: Cnudde, Veerle creators_name: De Kock, Tim title: Modeled versus Experimental Salt Mixture Behavior under Variable Humidity ispublished: inpress divisions: UCL divisions: B04 divisions: C04 divisions: F34 keywords: Crystallization, Dissolution, Mixtures, Salts, Vinyl note: © 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0. 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. date: 2024-03-27 date_type: published publisher: American Chemical Society (ACS) official_url: http://dx.doi.org/10.1021/acsomega.4c01486 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2263395 doi: 10.1021/acsomega.4c01486 lyricists_name: Orr, Scott lyricists_id: SAORR49 actors_name: Orr, Scott actors_id: SAORR49 actors_role: owner full_text_status: public publication: ACS Omega issn: 2470-1343 citation: Godts, Sebastiaan; Steiger, Michael; Stahlbuhk, Amelie; Orr, Scott Allan; Desarnaud, Julie; De Clercq, Hilde; Cnudde, Veerle; Godts, Sebastiaan; Steiger, Michael; Stahlbuhk, Amelie; Orr, Scott Allan; Desarnaud, Julie; De Clercq, Hilde; Cnudde, Veerle; De Kock, Tim; - view fewer <#> (2024) Modeled versus Experimental Salt Mixture Behavior under Variable Humidity. ACS Omega 10.1021/acsomega.4c01486 <https://doi.org/10.1021/acsomega.4c01486>. (In press). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10189981/1/godts-et-al-2024-modeled-versus-experimental-salt-mixture-behavior-under-variable-humidity.pdf