| Popis: |
In this study, we performed a direct contact membrane distillation and successfully demonstrated the non-invasive imaging of surfactant-induced wetting using optical coherence tomography. This method enabled us to investigate the wetting kinetics, which was found to follow a "three-region" relationship between the wetting rate and surfactant concentration: the (i) nonwetted region, (ii) concentration-dependent region, and (iii) concentration-independent region at low, intermediate, and high surfactant concentrations, respectively. This wetting behavior was explained by the "autophilic effect", i.e., the wetting was caused by the transfer of surfactants from the water-vapor interface to the unwetted membrane and rendered this membrane hydrophilic, and then the wetting frontier moved forward under capillary forces. At region-(i), the surfactant concentration in the water-vapor interface ( |
