In the same operating current, with the increase of the conductivity of the raw water, the conductivity of the EDI water also increases. Because the raw water conductivity is low, the content of ions is also low, at the same time, low ion concentration makes in the pale room resin and membrane surface formation of the potential gradient is also large, which leads to the degree of dissociation of water enhancement, the limit of the current increases, the production of H + and OH - the number of more, so that the fill in the pale room in the regeneration of the anion and cation exchange resin is good.
When the conductivity of the raw water is 21.5μS/cm, the conductivity of the EDI effluent has been very small (0.1-0.05μS/cm) with the increase of the operating current, which is because the smaller the conductivity of the raw water is, the more intense the dissociation of hydrolysis is, and the more H+ and OH- are produced, the better the regeneration of the resin electricity is (so that it maintains a good exchange performance). When the operating current continues to rise, H + and OH - in addition to regeneration of the resin is also used to load the current, so the degree of dissociation of water in the pale room continues to increase, making ion exchange and resin regeneration gradually reached a balance, the conductivity of the produced water tends to stabilize. Therefore, the raw water conductivity is one of the most important factors affecting the quality of produced water. When the feed water conductivity is high, the quality of produced water decreases with the increase of operating current. Conductivity of raw water for 100μS/cm curve, for example, when the operating current from 0 gradually increased to 5A when the conductivity of EDI water from 0.17μS/cm rose to 0.5μS/cm or so (water quality has decreased), the reason is that the concentration of polarization in high salinity is small, hydrolysis is weak, the resin is almost no regeneration, then the ion exchange plays a major role in a short time. The resin is saturated by salt ions, and then the resin mainly plays the role of enhancing ion migration.
Regardless of the high or low salt content of the feed water, two five EDI equipment have good desalination effect (desalination rate & gt; 99%), the conductivity of the water can reach the standard of high purity water (conductivity & lt; 1μS/cm).
Conductivity (T.D.S): the conductivity of water that is the reciprocal of the resistance of water, usually used to indicate the purity of water. Hospital high-purity water equipment water quality and operating voltage is closely related. Operating voltage is too small is not enough in the pure water discharged before the ions from the pale room to move out, electrodialysis process and the resin electric regeneration process is relatively weak, at this time the main process of ion exchange. As the operating voltage increases the degree of water dissociation increases, the resin regeneration effect is good, so that the conductivity of fresh water decreases, when the operating voltage increases to a certain extent when the ion exchange process and the resin regeneration process reaches a balance, the conductivity of the water to further decline and stabilize. However, too large an operating voltage will cause excessive water ionization and ion counter-diffusion and reduce the quality of produced water. Therefore, it is recommended that EDI run at the appropriate voltage.