Crystallization behavior of NaCl droplet during repeated crystallization and dissolution cycles: An NMR study

Repeated cycles of crystallization and dissolution of the salt crystals inside the pores of a building material can provoke damage to that material. To find effective treatment methods against this damage, a better understanding of the crystallization process is required. For this purpose, a microscopic study on a sodium chloride (NaCl) solution droplet is performed. The crystallization behavior of NaCl during repeated crystallization and dissolution cycles is studied using time lapse microscopy along with Nuclear Magnetic Resonance (NMR). Using NMR non-destructive and simultaneous measurements of hydrogen and dissolved sodium ions were made. The results show that with repeated cycles the number of available foreign nucleation sites for salt crystallization decreases. The resulting decrease of the number of crystals leads to an increase in crystal size. A maximum supersaturation up to 1.16±±0.08 was observed.