تحلية الماء بواسطة اللدائن ذات المسام ، والكهرباء .. كتاب في سبيل موسوعة علمية

Desalination of water using plastics
Porous, electrostatic

This method is based on electricity, which is energy. Electricity is one of the last energies that man has discovered, known, and treated.

The high school student knows that table salt is composed of two elements, sodium and chlorine, and that this salt is dissolved in water and is dissolved into its two atoms: the sodium atom, which carries a positive charge of electricity. And an atom of chlorine, which carries a negative charge of electricity (they call the atom dissolved in water with its special electrical charge, an ion. A person does not feel this electricity when he drinks water with its salt, because the two charges are equal). If we direct an electric current (coming through wires from an electric battery, for example) into the solution, that

(Desalination of sea water using porous plates and electricity):

The first form: a container containing sea water. The electricity comes to it from a battery (not shown in the drawing), so its current enters and exits through the two poles (positive + and negative -) after it passes through sea water, which is salt and water. This first figure shows how the sodium atoms and chlorine atoms (from which the salt is formed) are distributed before the current passes. As for the two black lines, they represent two porous plates of plastic (plastic), the right one of which is painted with a substance that prevents chlorine from passing through its pores, and the left one is painted with a substance that prevents sodium from passing through it. its pores)

The second figure: represents what happens when an electric current passes through a salt solution (seawater), where the sodium goes and where the chlorine goes, and where chlorine is prevented from passing and where it is allowed. The same applies to sodium.

The third figure: represents the final result, completed
The water between the two porous plates is made of both chlorine and sodium, that is, from salt, so what is between them is fresh water.)

We dip the positive electrode into one end of the solution, and the negative electrode into the other end, then we pass the current on. The sodium atoms, which are positive, move toward the negative electrode, and the chlorine atoms, which are negative, move toward the positive electrode. Therefore, the table salt decreases in the middle of the solution, and then it becomes sweet.

This is the basis of the method. What it lacks is a barrier that prevents the sodium atoms from passing through it, and a barrier that prevents the chlorine atoms from passing through it. Or more correctly, two porous plates made of plastic (coated), one of which is coated with a material that allows the chlorine atoms to pass through its pores but does not allow the sodium atoms. We have shown the plate. The other is coated with another material that allows sodium atoms to pass through its pores but not chlorine atoms, so that both chlorine and sodium are allowed to leave the middle box but are not allowed to enter it.

So, these two plates eventually hold fresh water between them.

This is one cell. But the factory contains a large vessel of salt water, in which are set up very many cells, separated by these plates, one after the other: one that prevents sodium, followed by a second that prevents chlorine, followed by a third that prevents sodium, and so on. If an electric current is applied, it results in the solution with its blocked cells, a cell containing fresh water, followed by a cell containing the sea water that we started with, the salt of which has increased, followed by another cell containing fresh water, and so on.

This method treats brackish water, the salinity of which does not exceed 6 parts of salt per thousand of water, not sea water, which contains about 35 parts of salt per thousand of water. I mean, in this way, the water that comes out of the ground and from mines is treated, and it contains an amount of salt that prevents animals and humans from drinking it, as well as plants. This method clears it to a large extent.

In Kuwait, an American company makes desalination in this way. It is known in English as electrodialysis, meaning separation by electricity.

Its men visited me in my office when they started their work in Kuwait, and I learned from them that their goal was to establish a pilot plant that would reduce the salt of groundwater in the Sulaibikhat area, which is low in salt, to one part in a thousand, to irrigate the land, and to half a part in a thousand for people to drink. They actually established the factory, and I learned that its water is now used to irrigate the land.

I also learned from them that they had set up a factory in Dhahran, Saudi Arabia, at the oil company Aramco, which produces about 450 cubic meters per day of fresh water. They also have a factory in Bahrain, which produces about 300 cubic meters of fresh water per day.

It is clear, of course, that this method does not bring the price of water down to the current market price today. But it works when necessary. Establishing its pioneering factories in Kuwait, Bahrain, and Dhahran, which are desert areas, indicates a necessity.

I was also visited by a Polish man who claimed to have a method like this, which is even useful in desalinating sea water. When I explained the matter to him, he refused to reveal it until after writing a contract. Then he disappeared.