How does seawater become freshwater in large quantities?

Desalination is the use of seawater desalination to produce fresh water. It is an open source incremental technology to realize the utilization of water resources, which can increase the total amount of fresh water, and is not affected by time, space and climate, with good water quality and gradually reasonable, which can ensure a stable water supply for coastal residents such as drinking water and industrial boiler water supply.

A large amount of seawater is desalined into fresh water, and it is necessary to apply it to chemical engineering, and there are ways to desalinate it in industry.

There are many ways to desalinate seawater. There are ancient evaporation methods, electrodialysis methods, ion exchange methods, etcThere are "molecular sieves" filtration methods and so on.

Desalination of seawater is done by heating the seawater to evaporate it, and then cooling the steam and collecting it to become fresh water.

In the early days, the thermal method was used with high energy consumption, and later there was electrodialysis, and then there was reverse osmosis, and the cost of seawater desalination continued to decrease, and it became more and more popular. At present, there is no more cost-effective technology than reverse osmosis (large-scale application), from the principle of osmotic pressure, there is not much room to reduce costs, and it is hoped that with the development of science and technology, there will be new feasible technologies born, which is inevitable.

What about the seawater? When a large amount of desalination is made into fresh water, it is enough to pass a large amount of water and then form fresh water.

I think it's just that seawater is purified into fresh water like distilled water, and then it becomes fresh water.

I don't know much about this, but the fact that the sea water rushes into the rocks may be the result of this situation that has created its own freshwater problem.

It is possible to process the child through some chemical and physical methods, and it becomes a but.

The evolution of seawater into freshwater may have its own mechanism, but I don't know very well.

1.Distillation. Seawater is heated so that the water in it turns into steam, which is then allowed to condense.

Since the salts dissolved in seawater do not come out with steam, the resulting water is distilled water that is almost pure water. However, both heating and condensation require energy. Kilojoules of energy are required for every 1 gram of water evaporated.

Therefore, this method can save the emergency, but it is not a long-term solution.

2.Ion exchange method. The salts dissolved in water are in the form of cations and anions.

If there is something that can move these ions away, then the water is purified. Ion exchange resins have such capabilities. Ion exchange resin is a water-insoluble polymer material with a network structure.

It resembles a big tree with many branches, each with a pocket on it. When seawater passes, the cations exchange the hydrogen ions in the cation exchange resin "pocket", the anions exchange the hydroxide ions in the anion exchange resin "pocket", and the hydrogen ions and hydroxide ions meet to become water.

3.Reverse osmosis. Osmosis is a very common natural phenomenon in nature.

For example, plants rely on the penetration of roots to absorb water, and osmosis balance is also extremely important for human life activities. Osmosis is achieved by relying on a material called a semi-permeable membrane. The semi-permeable membrane allows water to pass through freely, which is not possible with other chemicals in the water.

If the left side of the semi-permeable membrane is pure water and the right side is the solution, there will be much more water passing through the semi-permeable membrane from the pure water side than the water passing through the semi-permeable membrane on the right side of the solution. This is because the saturated vapor pressure above the pure water is greater than the saturated vapor pressure above the solution.

Three spikes of seawater desalination late planting method:

1. Freezing method, that is, freezing seawater to freeze it, and the salt is separated when the liquid seawater becomes solid ice.

2. Reverse osmosis method, also known as ultrafiltration method, uses a semi-permeable membrane that only allows solvents to pass through and solutes to separate seawater from fresh water.

3. Solar land combustion energy method, solar distillation method is to use a simple solar distiller to separate seawater from fresh water.

Seawater: This is a large amount of liquid in the ocean. The average depth of the ocean is about 3,800 m. Seawater has been found to contain more than 80 chemical elements, and the total salt content is about one.

Three methods of seawater desalination: reverse osmosis, solar energy, and low-temperature distillation.

1. Reverse osmosis method

Commonly known as ultrafiltration, this method uses a semi-permeable membrane that only allows solvents to pass through and solutes to pass through.

It separates seawater from fresh water. Under normal circumstances, fresh water diffuses to the seawater side through a semi-permeable membrane, so that the liquid level on the seawater side gradually rises until a certain height does not stop, this process is called osmosis. If a greater than seawater osmotic pressure is applied to the seawater side.

, then the pure water in the seawater will reverse osmosis into the fresh water. The biggest advantage of the reverse osmosis method is energy saving.

2. Solar energy method

Solar distillation is the use of a simple solar still. The still consists of a tank with a black porous felt core floating cavity covered by a transparent, closed glass covering the top. Sunlight.

It is projected through a transparent covering layer onto the bottom of a black adiabatic trough and converted into thermal energy.

3. Low temperature distillation

Low-temperature multi-effect seawater desalination technology refers to the distillation desalination technology with the maximum evaporation temperature of brine less than 70. It features a series of horizontal tubes sprayed on the falling film evaporator.

In series, a certain amount of steam is used to input the first effect, and the evaporation temperature of the latter effect is lower than that of the previous effect, and then through multiple evaporation and condensation, distilled water with many times the amount of steam is obtained.

of the desalination process.