Vacuum Evaporation

Vacuum evaporation is a process where atmospheric pressure is reducing for create vapor of any liquid at minimum temperature. It is easily to describe for boiling of water. When atmospheric pressure is reduced, boiling temperature of water also decreased from 100˚C (212˚F) to lower. Standard atmospheric pressure is 1 bar (at Sea level). If you create vacuum for boiling water then it can turns into vapor in room temperature.

The normal boiling point of water is 99.97˚C (211.9˚F) at a 1 atm (101.325 kPa) pressure.  IUPAC (International Union of Pure and Applied Chemistry) recommended standard boiling point of water is 99.61˚C (211.3˚F) at a standard pressure of 100 kPa (1 bar).

If you boil water on top of Mount Everest (Approximately height 8848m or 29029 ft), you need to create only 71˚C (160˚F) temperature. You can find pressure about 34 kPa on the top of Everest. Why these things will happen? Ok, water needs pressure to stay in liquid forms. This pressure keeps water molecules together. So, if you reduced the pressure, the bonding of water molecules will break down at low temperature.

Vacuum evaporation process using many industries for remove water or other liquids without any chemical reaction. At normal pressure water boiled at 100˚C (212˚F) and if you applied this temperature in any liquid solution, it can be changed its property and some chemical reaction can happened. By reducing pressure, liquids vaporize and boil at lower temperature; so, the solvents come off a lot faster then at atmospheric pressure. This process applied to food and removed water; you can store this food for long time without spoiling. Salt, Sugar, oil etc industries are applying this process.