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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

Evolution of the surface tension of the three types of liquids as a function of time using a 1 M sodium chloride aqueous solution, a 1 M manganese chloride aqueous solution, and pure water.
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f6: Evolution of the surface tension of the three types of liquids as a function of time using a 1 M sodium chloride aqueous solution, a 1 M manganese chloride aqueous solution, and pure water.

Mentions: A modified setup was developed to monitor the variation in the surface tension as the time increased. A standard platinum plate was mounted on a highly sensitive balance system and immersed in a beaker with approximately 20 ml of a solution. The force was recorded and converted to surface tension with software by considering the geometrical dimensions of the platinum plate. The details of the surface tension are shown in Fig. 6 The surface tension of water was 71.6 mN/m and exhibited no obvious change with time. The surface tension of the sodium chloride aqueous solution increased during the initial 20 minutes and then remained stable. The increase in the surface tension of sodium chloride aqueous solution compared to that of pure water is consistent with previous studies25. Surprisingly, the surface tension of the manganese chloride solution is much smaller than the surface tension of water and exhibited a continuous decrease for approximately three hours prior to becoming stable. These phenomena may be due to the formation of a thin film on the surface of the manganese chloride solution. The manganese chloride tended to accumulate on the surface due to its ability to decrease the surface tension. The sodium chloride increased the surface tension, which resulted in its depletion from the surface and precipitation in the bottom of the droplet. The manganese chloride exhibits a stronger interaction with water molecules. Therefore, the aggregated manganese chloride formed a film with water to self-suppress the evaporation of the droplet. The film was metastable and exhibited no crystal structure because no X-ray diffraction (XRD) peaks were observed in the XRD experiment (PANalytical X’pert Pro). There was a large variation in the time required for the stabilization of the surface tension. For example, the surface tension of the sodium chloride aqueous solution stabilized in approximately 20 minutes, and the manganese chloride aqueous solution required approximately three hours. This result inspired a direct approach for determining the reorientation time of the water molecules, which typically requires complicated technology262728.


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)

Evolution of the surface tension of the three types of liquids as a function of time using a 1 M sodium chloride aqueous solution, a 1 M manganese chloride aqueous solution, and pure water.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Evolution of the surface tension of the three types of liquids as a function of time using a 1 M sodium chloride aqueous solution, a 1 M manganese chloride aqueous solution, and pure water.
Mentions: A modified setup was developed to monitor the variation in the surface tension as the time increased. A standard platinum plate was mounted on a highly sensitive balance system and immersed in a beaker with approximately 20 ml of a solution. The force was recorded and converted to surface tension with software by considering the geometrical dimensions of the platinum plate. The details of the surface tension are shown in Fig. 6 The surface tension of water was 71.6 mN/m and exhibited no obvious change with time. The surface tension of the sodium chloride aqueous solution increased during the initial 20 minutes and then remained stable. The increase in the surface tension of sodium chloride aqueous solution compared to that of pure water is consistent with previous studies25. Surprisingly, the surface tension of the manganese chloride solution is much smaller than the surface tension of water and exhibited a continuous decrease for approximately three hours prior to becoming stable. These phenomena may be due to the formation of a thin film on the surface of the manganese chloride solution. The manganese chloride tended to accumulate on the surface due to its ability to decrease the surface tension. The sodium chloride increased the surface tension, which resulted in its depletion from the surface and precipitation in the bottom of the droplet. The manganese chloride exhibits a stronger interaction with water molecules. Therefore, the aggregated manganese chloride formed a film with water to self-suppress the evaporation of the droplet. The film was metastable and exhibited no crystal structure because no X-ray diffraction (XRD) peaks were observed in the XRD experiment (PANalytical X’pert Pro). There was a large variation in the time required for the stabilization of the surface tension. For example, the surface tension of the sodium chloride aqueous solution stabilized in approximately 20 minutes, and the manganese chloride aqueous solution required approximately three hours. This result inspired a direct approach for determining the reorientation time of the water molecules, which typically requires complicated technology262728.

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