Which method can obtain purer ultrapure water?

There are many methods to obtain ultrapure water, some of which commonly used methods include ion exchange, reverse osmosis, distillation and electrodeposition. Each method has its advantages and disadvantages, and each method and its scope of application will be described in detail below.

1. Ion exchange: Ion exchange is a method of removing impurities by exchanging impurities in water with ions on an ion exchange resin. This method is suitable for removing dissolved ions in water, such as hardness ions, heavy metal ions and organic ions. Ion exchange can efficiently remove ions from water, but cannot remove other small molecule impurities and microorganisms.

2. Reverse osmosis: Reverse osmosis is a method of removing solutes by forcing water through a semi-permeable membrane. This method is suitable for removing dissolved inorganic and organic matters in water, such as salts, heavy metals, organic matters and microorganisms. Reverse osmosis membranes have small pores and high selectivity, and can remove most solutes, but produce a large amount of wastewater.

3. Distillation: Distillation is a method of heating water to boiling and then condensing the resulting vapor into pure water. This method is suitable for removing dissolved ions, organic matter and microorganisms in water. Distillation can produce high-purity water, but the operation is time-consuming and energy-intensive.

4. Electrowinning: Electrowinning is a method that uses the principle of electrolysis to remove ions in water through the action of anode and cathode. This method is suitable for removing dissolved ions and microorganisms in water. Electrowinning can efficiently remove ions from water, but requires the use of electrical energy and special electrolysis equipment.

In addition to the commonly used methods mentioned above, there are other methods that can also be used to obtain ultrapure water, such as nanofiltration, ultraviolet irradiation and ozone oxidation. These methods have unique advantages in specific application areas, such as nanofiltration is suitable for removing particulate matter and macromolecular impurities, and ultraviolet irradiation is suitable for removing microorganisms.

In general, the choice of methods for obtaining ultrapure water should be determined based on application needs and water quality characteristics. In practical applications, a variety of methods are generally used in combination to achieve a higher purification effect. In addition, attention should be paid to the maintenance and periodic testing of equipment during the operation to ensure the stability of water quality and the continuity of purity.