Characteristics of RO Reverse Osmosis Water Purification System
RO reverse osmosis water purification system is the core component for achieving reverse osmosis, which is an artificial semi-permeable membrane with specific characteristics designed to mimic biological membranes. It is generally made of high molecular weight materials such as cellulose acetate membranes, aromatic polyhydrazide membranes, and aromatic polyamide membranes. The diameter of surface micropores typically ranges from 0.5 to 10 nm, and the permeability is dependent on the membrane's chemical structure. Some high molecular weight materials exhibit good rejection of salts but have relatively low water permeability. Others have chemical structures with a greater number of hydrophilic groups, resulting in faster water permeation. Therefore, an ideal RO reverse osmosis water purification system should have an appropriate permeation rate or desalination efficiency.
The RO reverse osmosis water purification system should possess the following characteristics:
1.High desalination efficiency under high flow rates.
2.High mechanical strength and long service life.
3.Ability to function effectively at low operating pressures.
4.Resistance to chemical or biological impacts.
5.Minimal sensitivity to factors such as pH value and temperature.
6.Easy sourcing of membrane materials, simple processing, and low cost.
The structure of RO reverse osmosis water purification systems can be classified into two types: asymmetric membranes and homogeneous membranes. The commonly used membrane materials include cellulose acetate and aromatic polyamide. The components of these systems can be hollow fiber, spiral wound, plate and frame, or tubular configurations. They can be applied in various chemical unit operations such as separation, concentration, and purification, primarily used in the production of pure water and water treatment industries.
Principle of RO Reverse Osmosis Water Purification System: Reverse osmosis, also known as hyperfiltration, is a membrane separation process that separates solvents from solutions under a pressure difference. Applying pressure to the liquid on one side of the membrane causes solvent molecules to move in the opposite direction of natural osmosis when the applied pressure exceeds the osmotic pressure. As a result, the low-pressure side of the membrane yields the permeate, which is the solvent that passes through, while the high-pressure side collects the concentrate, which is the concentrated solution. In the case of seawater desalination, the low-pressure side yields freshwater, while the high-pressure side yields brine. The permeation rate of the solvent, represented by the hydraulic permeability coefficient (Kh), in reverse osmosis is given by N = Kh(Δp – Δπ), where Δp is the transmembrane pressure difference and Δπ is the osmotic pressure difference between the solutions on both sides of the membrane. For dilute solutions, the osmotic pressure (π) is given by π = iCRT, where i represents the number of ions formed by the dissociation of solute molecules, C is the solute concentration in moles, R is the molar gas constant, and T is the absolute temperature. Reverse osmosis typically uses asymmetric or composite membranes. The equipment commonly used for reverse osmosis is the hollow fiber or spiral wound membrane separation device. RO reverse osmosis water purification systems can effectively remove various inorganic ions, colloidal substances, and large molecular solutes from water, producing purified water. They can also be used for the preconcentration of high molecular weight organic solutions. Due to its simplicity and low energy consumption, reverse osmosis has experienced rapid development in the past 20 years. It is widely applied in seawater and brackish water desalination, boiler water softening, wastewater treatment, as well as in combination with ion exchange for the production of high-purity water. Its application scope is expanding, and it is being increasingly utilized in the concentration, separation, and purification of dairy products, fruit juices, biochemicals, and biological preparations.