Survival on the Island starts with a female boss

Chapter 18 Exploring the Plan
After careful discussion and planning, Ma Yongqiang and Yu Tina, using all available knowledge, finally decided on three plans to find fresh water.

The first is to explore the depths of the woods on the island, because in general, where trees grow, it is almost certain to have fresh water resources.

It's just that there is a great possibility that it is an underground river. Of course, if you are lucky, you may also find a stream, pool and other fresh water sources on the surface.

The second is to use seawater distillation to desalinate. This method requires certain tools, if it can overcome difficulties.

Egg water distilled from seawater is the cleanest, almost free of other impurities and bacteria, so you don’t have to worry about the water being blocked like the first method, as it contains pathogenic bacteria bred by animal carcasses.

The third method is to use the seawater siphon phenomenon, put a simple rope into the seawater, and siphon the water to a high place through the siphon phenomenon.

A large part of the impurities in the filtered seawater will be filtered out through the rope, and fresh water that can be used for drinking can also be obtained.

According to Yu Tina, she is a talented student after all, and she is well-informed about the application of some knowledge of physics and technology.

The third method is also applied in desalination of seawater in the scientific field, but it is applied more professionally in the scientific field.

In professional terms, it is called the ion exchange method.

Salts soluble in water exist in the form of cations and anions.If there is something that can remove these ions, the water will be purified.Ion exchange resins have this capability.

Ion exchange resin is a polymer material that is insoluble in water with a network structure.

It's like a big tree with many branches, and each branch has a pocket.

After the seawater passes through, the cations exchange hydrogen ions with the "pockets" of the cation exchange resin, and the anions exchange hydrogen ions with the "pockets" of the anion exchange resin, and the hydrogen ions and hydrogen ions meet to become water.

Since ion exchange is reversible, acid and base can be exchanged in opposite directions for renewal, so that the ion exchange resin can be reused.

However, ion exchange has limited capacity and requires large amounts of acid and base to "regenerate" the resin.

If it is used in large quantities for seawater desalination, the cost is too high, so at present this technology is mainly used in the further purification of water.

Therefore, this seawater purification method in the world is only suitable for a small-scale experimental state, because the cost is too high, and it has not been fully promoted yet.

There is another method called reverse osmosis
Osmosis is a very common natural phenomenon in nature.

For example, plants rely on the osmosis of their roots to absorb water, and osmotic balance is also extremely important to human life activities.Permeation is achieved by means of a material called a semipermeable membrane.

A semi-permeable membrane allows water to pass through freely, while other chemicals in the water cannot pass through.If the left side of the semipermeable membrane is pure water and the right side is the solution, the water passing through the semipermeable membrane from the pure water side will be much more than the water passing through the semipermeable membrane on the right side of the solution.This is because the saturated vapor pressure over pure water is greater than the saturated vapor pressure over a solution.

When both the pure water and the solution are under the pressure of 1.01×105 Pa (1 standard atmospheric pressure), the power driving the movement of water molecules is determined by the saturated vapor pressure.Therefore, the liquid level on the side of pure water drops, and the liquid level on the other side of the solution rises. When a certain liquid level difference is reached, the equilibrium is reached. This is the phenomenon of osmosis.The cuticle at the root of a plant is such a semipermeable membrane.

The situation is reversed if a pressure is applied above the solution such that the total pressure above the solution is greater than the atmospheric pressure above the pure water.At this time, the power to drive water molecules through the semi-permeable membrane depends on the pressure difference between the two sides.The greater the pressure difference, the more water in the solution will flow through the semipermeable membrane to the pure water.

The method of making fresh water from seawater by reverse osmosis is also called "membrane technology".Its key lies in the semipermeable membrane.This layer of film must have a certain strength, because the first treatment process is to be pressurized;

Second, it must be [-] percent selective, allowing only water to pass through, and no other chemical substances can pass through; finally, it should have a large throughput to speed up the preparation process.The existing problems of semi-permeable membranes are high cost and short service life.The higher the concentration of the solution being treated, the shorter the lifetime of the membrane.If these two problems can be solved, membrane technology will become the most promising method for seawater desalination.

This also shows from the side that if the seawater is so easily purified, the world will not worry about the problem of fresh water.

The main problem facing the two of them at present is how to obtain the daily water necessary for adults?

　Let’s write here for today, let’s talk about it tomorrow depending on the situation.

　　Another question for everyone, do you think the content is too watery?Is there any need to change it?
　　
　
(End of this chapter)