Reverse osmosis membrane and reverse osmosis equipment
① reverse osmosis membrane:
1) Structure:
Is a semi-permeable membrane that allows only water molecules to pass through. The thickness of the membrane is generally 100 to 200 nanometers, and has an asymmetric cross-sectional structure. It mainly consists of three layers: a surface dense layer, a pore diameter of about 8 to 10 angstroms, 10 microns, desalination mainly in this layer, the other side of the porous support layer, loose structure, pore diameter of about 1000 ~ 4000, between the intermediate transition layer, pore diameter of about 200.
2) Performance:
The key of reverse osmosis separation is to require reverse osmosis membrane has a high water permeability and desalination performance, the reverse osmosis membrane should have the following properties: unit membrane area of the permeable rate, high desalination; mechanical strength; chemical stability Long service life, low performance degradation, abundant raw materials, low price, the membrane process is relatively simple, easy to operate, easy to operate.
3) Classification:
According to the material is divided into: cellulose membrane and non-cellulose membrane.
According to the structure is divided into: asymmetric membrane and composite membrane.
According to the shape is divided into: diaphragm and hollow fiber. Water treatment commonly used in the following film:
② reverse osmosis device:
There are plate and frame, tube, roll, hollow fiber type, disc type or disc type.
1) plate and frame type reverse osmosis:
Advantages: device is strong, can withstand high pressure. Disadvantages: poor flow state, easy to form concentration polarization, equipment costs and covers an area of large.
2) tubular reverse osmosis:
Advantages: water flow in good condition, easy to install, easy to clean, easy to replace. Disadvantages: the volume per unit area is small, covers an area of larger.
3) roll reverse osmosis:
Advantages: the unit volume within the membrane loading area, water flow state is good, compact. Disadvantages: water pretreatment requirements strict, or easy to plug.
4) hollow fiber type reverse osmosis:
Advantages: in the unit volume within the membrane loading area, no pressure materials, compact structure. Disadvantages: easy to plug, cleaning difficulties, the most demanding water pretreatment, pollution index requirements ≤ 3.
