Distillation of Water

There is almost 326,000,000,000,000,000,000 gallons of water (70.8% of Earth's surface) found on Earth. But unfortunately, it is not entirely usable. Distillation is a remarkably easy method that can be employed to remove impurities from water and employs some very simple concepts of physics. It is a known fact, that most of the substances can exist in 3 principle forms, namely, liquid, solid and gas. The same is the case with water. Water, when heated in appropriate amounts, or cooled till the appropriate temperature, it changes its state, from liquid to gaseous and liquid to solid, respectively. This property of water has been used in several different processes and has yielded, great results. For example, James Watt, used the property of water turning into steam to move piston in order to facilitate locomotion.

Indisputably, water is the most important liquid in existence. In fact, it so important that it is often termed to be an essential 'element' that is required for survival. Drinking water and its availability is fast becoming a grave problem for civilization, and people have started looking for several different methods that can be used to purify water. Distillation is the easiest and probably the most basic manner in which water can be purified, by using the liquid's property of changing state, from liquid to gaseous state and vice versa.

What is Distillation of Water?

Distillation of salt water is probably the easiest and the most widely followed process, where water is purified by evaporation and then condensed. In such a process impure water is heated till it reaches a temperature of about 100 degrees Celsius (212 degrees Fahrenheit). Such a high temperature causes water to change state and turn into steam. The steam also leaves behind the impure matter (salt or dirt, impurities, etc) and passes to a condenser. The condenser is at a lower temperature (it's cooler), which causes the steam to again take the form of water, as a result of cooling. This new form of water is absolutely pure and free of minerals as well as impurities. Thus distillation is a basic and simple solution to purify impure water.

Pros and Cons of Distillation
The obvious question that any person might ask is that, why is distillation not used extensively to fulfill the needs of a thirsty civilization. There are some specific reasons that can be logically put forth as an answer...

The first reason is that it is expensive. Distillation in a school laboratory, is on a small-scale, but if you consider distillation of sea water, as a solution to water shortage, you will realize that it would involve billions of tones of fuel and a mammoth quantum of energy. Distillation removes every possible impurity from water including minerals and salts. The human body is incapable of surviving on distilled water for a prolonged period of time, as it does not contain the composition of minerals. These minerals are needed by the body and a deficiency is bound to cause some ailments. The content of salts and minerals also give water a peculiar and welcoming 'taste'. Thus, distillation of drinking water, is not exactly a good idea.

On the pros side, simplicity of operation is probably its biggest advantage. In addition to that, the process of distillation is compatible with other processes. Hence, distillation is used in other industrial processes such as fractional distillation and other miscible liquids or in industrial processes that involve continuous distillation. Distillation is a widely used process in many different petrochemical industries and chemical processes. The advantage of using this process is that it is not only easy, but also provides the purest form of water. A prominent example that you may find in your day-to-day lives is that of car batteries that work on distilled water. The concept of saline solution that is found in hospitals also involve the use of distilled water.

The process of distillation is in fact so advantageous, that experiments and developments are underway that would help scientists to distill water, directly from the sea, with the help of solar energy.