The principle of RO reverse osmosis membrane:
The pore diameter of reverse osmosis membrane is mostly 1 nanometer (1nm=10^-9m), and its separation objects are dissolved ions and organic matter with a molecular weight of several hundred or more.
A membrane that can only pass through solvent but not solute is generally called an ideal semipermeable membrane.
When the solvent and solution (or two solutions of different concentrations) are placed on both sides of the membrane, the pure solvent will naturally pass through the semipermeable membrane and spontaneously move to the solution (or from a low solution to a high concentration solution) side. Flow, this phenomenon is called Osmosis.
When the osmosis process proceeds to the level of the solution, a pressure is generated to offset the tendency of the solvent to flow toward the solution, that is, equilibrium is reached. This pressure is called the osmotic pressure of the solution.
The size of the osmotic pressure depends on the type, concentration and temperature of the solution and has nothing to do with the membrane itself.
In this case, if an external pressure greater than the osmotic pressure is applied to the liquid surface of the solution, the solvent will reverse the original osmosis direction and begin to flow from the solution to the solvent side. This is called reverse osmosis. ), any separation method of concentrating or purifying solutions based on this principle is generally called a reverse osmosis process.
Reverse osmosis is a reverse migration movement of osmosis. It is mainly driven by pressure and relies on the interception of a semipermeable membrane to force the solvent and solute in the solution to separate.
The higher the concentration of the solution, the greater the osmotic pressure value.
The pressure to be applied during the reverse osmosis process must be much greater than the osmotic pressure value of the solution within the allowable range of the system and membrane strength, generally several times to nearly dozens of times the osmotic pressure value.
When the aqueous salt solution contacts the surface of the porous semipermeable membrane, a layer of water molecules is selectively adsorbed on the solution interface of the membrane. Under the action of reverse osmosis pressure, pure water flows out through the capillary action of the membrane. And continuously flows out to form an interface pure water layer.
As for the removal of organic matter, it belongs to the screening mechanism. Therefore, this is related to the molecular weight and shape of the organic matter.
Membranes with larger pore sizes are generally used in the ultrafiltration range and are called ultrafiltration membranes. The pores of ultrafiltration membranes are 2nm-10nm, while the pores of reverse osmosis membranes are 0.3nm-2nm.
Therefore, reverse osmosis membrane filtration can better remove various bacteria, such as the smallest bacteria "Pseudomonas aeruginosa" (3000×10m); it can also filter out various viruses, such as influenza virus (800×10m); Remove pyrogen (10-500×10m).
Application scope of foldable RO reverse osmosis equipment for Wastewater Treatment:
Preparation of sterile, pyrogen-free purified water in the pharmaceutical and pharmaceutical industries;
Ultrapure water for electronics and power industries;
biomedical water;
water for chemical and cosmetic ingredients;
Brackish water, seawater desalination;
Dispensing of solutions used in the electroplating and coating industries, cleaning and rinsing of parts;
Cleaning, transportation and cooling water in precision machinery, special materials, optoelectronic materials and quartz products industries;
Purify drinking water, food and beverage water
Solid-liquid Separation.
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