Definition of reverse osmosis:

Reverse osmosis, also known as reverse osmosis, is a membrane separation process that uses pressure differences to separate solvents from solutions. When the pressure on one side of the membrane exceeds its osmotic pressure, the solvent moves in the opposite direction of natural osmosis. This results in the permeate, which is the solvent, being collected on the low-pressure side of the membrane, and the concentrate, which is the solution, being collected on the high-pressure side. If seawater is treated with reverse osmosis, fresh water is obtained on the low-pressure side, while brine is obtained on the high-pressure side.

Because it is opposite to the direction of natural osmosis, it is called reverse osmosis. According to the different osmotic pressure of various materials, the reverse osmosis pressure greater than the osmotic pressure can be used, that is, reverse osmosis method, to achieve the purpose of separation, extraction, purification and concentration.

The basic principle of reverse osmosis:

Place equal volumes of dilute solutions (such as fresh water) and concentrated solutions (such as seawater or salt water) on either side of a container, separated by a semipermeable membrane. The solvent from the dilute solution will naturally pass through the membrane and flow towards the concentrated solution side. As a result, the liquid level on the concentrated solution side will rise above that on the dilute solution side, creating a pressure difference that leads to osmotic equilibrium.

This pressure difference is known as osmotic pressure. The magnitude of osmotic pressure depends on the type, concentration, and temperature of the concentrated solution, and is independent of the properties of the semipermeable membrane. If a pressure greater than the osmotic pressure is applied to the side of the concentrated solution, the solvent from the concentrated solution will flow into the dilute solution, moving in the opposite direction of the original osmosis. This process is referred to as reverse.

Application of water treatment:

Compared with other traditional separation processes, reverse osmosis separation process has its unique advantages:

(1)Pressure is the main driving force of reverse osmosis separation process, and the energy consumption is low without phase change of energy intensive exchange.

(2)Reverse osmosis does not require a large amount of precipitants and adsorbents, low operating costs.

(3)Reverse osmosis separation engineering design and operation is simple, construction period is short.

(4)Reverse osmosis has high purification efficiency and is environmentally friendly. Therefore, reverse osmosis technology has been widely used in domestic and industrial water treatment, such as desalination of seawater and brackish water, production of medical and industrial water, preparation of pure water and ultrapure water, treatment of industrial wastewater, food processing concentration, gas separation, etc.

Research and Development:

Reverse osmosis, known for its low energy consumption and high efficiency, is one of the most widely used separation technologies. The performance of reverse osmosis membranes is crucial to the process’s efficiency, making the development of these membranes a key focus in the membrane industry both domestically and internationally. In recent years, new materials like graphene and carbon nanotubes have shown exceptional water transport capabilities, making them a focal point in the research of new reverse osmosis membrane materials.

Reverse osmosis membrane has played an important role in water treatment and desalination of seawater and brackish water. With the implementation of China’s strictest “Ten Water Articles”, it can be predicted that reverse osmosis water treatment technology and new reverse osmosis membrane research and development will usher in new opportunities for development.

In the commercialization of reverse osmosis membranes, there is a significant performance gap between domestic products and foreign counterparts. This may be due to a lack of comprehensive understanding of the relationship between film formation, membrane structure, and membrane performance under large-scale continuous production conditions. Research into the mechanisms of film formation, the relationship between continuous film formation conditions and membrane structure, and the evaluation of the application.