Reverse osmosis membrane evaluation index

Generally speaking, the reverse osmosis membrane should have the following properties:

The per unit area on a large permeable capacity, high desalination rate;

Mechanical strength, porous support layer compaction effect;

The good chemical stability, acid resistance, alkali corrosion and microbial corrosion;

The uniform structure, long service life, slow performance decline;

The film is easy, cheap, adequate raw materials.

Therefore on the reverse osmosis membrane evaluation index can be downloaded from the following analysis:

In 1, the desalting rate and permeable salt rate

Rate of desalination by reverse osmosis membrane -- from the system the water removal of soluble impurity concentration percentage.

Permeable salt rate -- the water soluble impurities through membrane percentage. The desalting rate = (1 - to produce water salinity / water salinity ) x 100%

Permeable salt rate = 100% desalination rate

Reverse osmosis membrane desalination rate in its manufacturing forming have been fixed, desalination rate depends on the reverse osmosis membrane surface ultrathin and salt density, desalting layer denser desalting rate is higher, at the same time, lower the water yield. Reverse osmosis of different material removal rate was mainly composed of material structure and molecular weight of the decision, reverse osmosis membrane elements on ion and complex monovalent ion removal rate can be more than 99%, the monovalent ions such as: sodium ion, potassium ion, chlorine ion removal rate is slightly lower, but also more than 98%; the molecular more than 100 organic matter removal rate can reach 98%.

In 2, production of water ( water flux )

Water production ( flux ) -- to reverse osmosis system capacity in unit time, namely through the membrane water content, usually use tons / hour or gallons per day to express.

Permeate flow rate -- the permeate flow rate and also the reverse osmosis membrane element yield important index. The unit membrane area through the liquid flow rate, usually in gallons per square foot per day ( GFD ) said. High penetration rate will lead to a perpendicular to the membrane surface flow speed to accelerate, aggravate membrane pollution.

In 3, recovery rate

Recovery - a membrane system in water into water or liquid through percentage. Membrane recycling rate of system in the design have been identified, is based on the presupposition of inlet water and set. Recovery is usually wish to maximize in order to enhance economic efficiency, but should be within a membrane system for salt and other impurities supersaturated precipitation as its limit value. Recovery rate = ( water flow rate and influent flow ) x 100%