Crystallization of sodium sulfate on hydrophilic/hydrophobic surfaces during drying: An NMR study

摘要

Sodium sulfate is recognized as a salt with probably the most damaging capabilities when crystallizing in porous media. The three main crystalline phases which can be formed are thenardite (Na_2SO_4, anhydrous salt), decahydrate (Na_2SO_4·10H _2O) and the thermodynamically metastable heptahydrate (Na _2SO_4·7H_2O). In this study, using a setup in which nuclear magnetic resonance was combined with a digital microscope, we have investigated crystallization by the drying of sodium sulfate droplets on hydrophilic/hydrophobic surfaces in order to see, which crystalline phase is formed.