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Surface evolution of manganese chloride aqueous droplets resulting in self-suppressed evaporation.

Zeng X, Zhang Y, Xia Z, Wang L, Wang C, Huang Y, Shen R, Wen W - Sci Rep (2015)

Bottom Line: A fantastic and extraordinary phenomenon was observed during the evaporation of a water droplet doped with manganese chloride.The MnCl2-doped water droplets were maintained in a relative humidity (RH) of 50% at 40 °C for more than a week and for longer than two months at a temperature of 25 °C.In contrast, a pure water droplet can only be sustained for a few minutes.

View Article: PubMed Central - PubMed

Affiliation: Nano Science and Technology Program / Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.

ABSTRACT
The exchange kinetics of liquid water, which are of fundamental interest and have potential applications, remain unclear. A fantastic and extraordinary phenomenon was observed during the evaporation of a water droplet doped with manganese chloride. As observed from the evolution of this type of droplet, a thin film was formed on the surface with an exothermic phase transition, resulting in self-suppressed evaporation. The MnCl2-doped water droplets were maintained in a relative humidity (RH) of 50% at 40 °C for more than a week and for longer than two months at a temperature of 25 °C. In contrast, a pure water droplet can only be sustained for a few minutes. The self-suppressed evaporation of doped water may be due to the special hydration of the accumulated manganese and chloride ions at the surface, decreasing the surface tension.

No MeSH data available.


Related in: MedlinePlus

TGA test.(a) The comparison of the three types of water droplets, 0.5 M sodium chloride aqueous solution and 0.5 M manganese chloride aqueous solution, when temperature was maintained at 40 °C. The inset shows the relationship between the temperature and time for the evaporation of the manganese chloride droplet. (b) the relationship between phase transition time and the concentration of the manganese chloride under different temperature.
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f2: TGA test.(a) The comparison of the three types of water droplets, 0.5 M sodium chloride aqueous solution and 0.5 M manganese chloride aqueous solution, when temperature was maintained at 40 °C. The inset shows the relationship between the temperature and time for the evaporation of the manganese chloride droplet. (b) the relationship between phase transition time and the concentration of the manganese chloride under different temperature.

Mentions: To validate the observed phenomena, thermogravimetric analysis (TGA) was used to determine the thermal stability and evaporation process of the three types of droplets. All of the measurements were performed in air to simulate the situations that occur in the natural environment. With the temperature maintained at 40 °C, the proportion of retained weight was recorded as a function of increasing time. As shown in Fig. 2a, the droplet of pure water volatilized in approximately 30 minutes, and for the volatilization of the droplet with 0.5 M sodium chloride, only sodium chloride remained after approximately 40 minutes. However, the droplet containing 0.5 M manganese chloride continuously shrank in the beginning but did not exhibit obvious changes after approximately 38 minutes, and approximately 22% of its weight remained, which is much greater than the weight of the manganese chloride contained in the droplets. These results indicated that a significant volume of water was still present.


Surface evolution of manganese chloride aqueous droplets resulting in self-suppressed evaporation.

Zeng X, Zhang Y, Xia Z, Wang L, Wang C, Huang Y, Shen R, Wen W - Sci Rep (2015)

TGA test.(a) The comparison of the three types of water droplets, 0.5 M sodium chloride aqueous solution and 0.5 M manganese chloride aqueous solution, when temperature was maintained at 40 °C. The inset shows the relationship between the temperature and time for the evaporation of the manganese chloride droplet. (b) the relationship between phase transition time and the concentration of the manganese chloride under different temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4544006&req=5

f2: TGA test.(a) The comparison of the three types of water droplets, 0.5 M sodium chloride aqueous solution and 0.5 M manganese chloride aqueous solution, when temperature was maintained at 40 °C. The inset shows the relationship between the temperature and time for the evaporation of the manganese chloride droplet. (b) the relationship between phase transition time and the concentration of the manganese chloride under different temperature.
Mentions: To validate the observed phenomena, thermogravimetric analysis (TGA) was used to determine the thermal stability and evaporation process of the three types of droplets. All of the measurements were performed in air to simulate the situations that occur in the natural environment. With the temperature maintained at 40 °C, the proportion of retained weight was recorded as a function of increasing time. As shown in Fig. 2a, the droplet of pure water volatilized in approximately 30 minutes, and for the volatilization of the droplet with 0.5 M sodium chloride, only sodium chloride remained after approximately 40 minutes. However, the droplet containing 0.5 M manganese chloride continuously shrank in the beginning but did not exhibit obvious changes after approximately 38 minutes, and approximately 22% of its weight remained, which is much greater than the weight of the manganese chloride contained in the droplets. These results indicated that a significant volume of water was still present.

Bottom Line: A fantastic and extraordinary phenomenon was observed during the evaporation of a water droplet doped with manganese chloride.The MnCl2-doped water droplets were maintained in a relative humidity (RH) of 50% at 40 °C for more than a week and for longer than two months at a temperature of 25 °C.In contrast, a pure water droplet can only be sustained for a few minutes.

View Article: PubMed Central - PubMed

Affiliation: Nano Science and Technology Program / Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.

ABSTRACT
The exchange kinetics of liquid water, which are of fundamental interest and have potential applications, remain unclear. A fantastic and extraordinary phenomenon was observed during the evaporation of a water droplet doped with manganese chloride. As observed from the evolution of this type of droplet, a thin film was formed on the surface with an exothermic phase transition, resulting in self-suppressed evaporation. The MnCl2-doped water droplets were maintained in a relative humidity (RH) of 50% at 40 °C for more than a week and for longer than two months at a temperature of 25 °C. In contrast, a pure water droplet can only be sustained for a few minutes. The self-suppressed evaporation of doped water may be due to the special hydration of the accumulated manganese and chloride ions at the surface, decreasing the surface tension.

No MeSH data available.


Related in: MedlinePlus