Ultra-pure water treatment refers to the water with extremely low impurities:
Inorganic ionized impurities such as Ca, Mg, Na, K, Fe, Fe, Mn, Al, HCO, CO3, SO4, Cl2, NO3, NO2, SiO3, PO4, etc.
Organic substances such as alkyl benzene sulfonate, oil, organic iron, organic aluminum and other hydrocarbons;
Particles, such as dust, iron oxide, aluminum, colloidal silicon, etc.
Microorganism, such as bacteria, plankton and algae, etc.
Dissolve gases such as N2, O2, CO2, H2S, etc.
The resistivity values of ionized impurities in ultra-pure water are measured.
In theory, only H and OH ions in pure water conduct electricity.
At 25 ℃ ultrapure water resistivity is 18.3 (megohm · cm), generally is about 15 ~ 18 (megohm · cm).
Organic matter content in ultrapure water by the determination of organic carbon content, specified in the electronics industry ultrapure water content is 50 ~ 200 micrograms per liter, and demand is greater than 1 micron in diameter particulate matter within each 1 ml content is 1 ~ 2, microbial every 1 ml of 0 ~ 10.
Modern adopt pretreatment, electrodialysis, ultraviolet radiation sterilization, reverse osmosis, ion exchange, ultrafiltration and all kinds of membrane filtration technology, make the ultrapure water resistivity of 18 was achieved at 25 ℃ (megohm · cm).
According to different water quality and user requirements, the preparation process of ultra-pure water can be divided into three steps: pretreatment, desalination and fine treatment.