Na jarosite dissolution rates The effect

Na-jarosite dissolution rates measured at temperatures 277 K, 295 K, and 323 K and at pH values of 1, 2, 8, and 10 in dilute solutions yield significant insights into the mineral’s stability. The dissolution rates follow a derived rate equation, indicating minimization between pH 3 and 4 while increasing with heightened activity of both H+ and OH-. Results show that Na-jarosite dissolution rates are comparably faster than those of K-jarosite, suggesting minimal impact of K–Na substitution in the dissolution rate. The faster dissolution rates observed for Na-jarosite imply shorter estimated lifetimes in aqueous environments, despite similar activation energies when compared to K-jarosite. Lifetimes calculated for 1 mm jarosite particles, representative of the maximum potential particle size at Meridiani Planum, exhibit a considerable range from less than 1 year at pH 10 and 295 K to approximately 200 years at lower temperatures and pH 3-4. These findings provide a maximum estimate for fluid-Na-jarosite contact time, essential for understanding the mineral's behavior in extraterrestrial aqueous systems.