Apparatus for electrodeionization of water

Abstract

Silica and boron are particularly removed at high rate in processing by the electrodeionization apparatus. An electrodeionization apparatus has an anolyte compartment 17 having an anode 11, a catholyte compartment 18 having a cathode 12, concentrating compartments 15, and desalting compartments 16. The concentrating compartments 15 and the desalting compartments 16 are alternately formed between the anolyte compartment 17 and the catholyte compartment 18 by alternately arranging a plurality of anion-exchange membranes 13 and a plurality of cation-exchange membranes 14. The desalting compartments 16 and the concentrating compartments 15 are filled with ion-exchanger. The anion exchanger / cation exchanger volume ratio is 8 / 2 to 5 / 5. Electrode water flows into the anolyte compartment 17 and the catholyte compartment 18. Concentrated water is introduced into the concentrating compartments 15. Raw water is fed into the desalting compartment 16 to produce the deionized water from the desalting compartment 16. Water containing silica or boron at a lower concentration than the raw water is introduced into the concentrating compartments 15 as the concentrated water in a direction from a side near an outlet for the deionized water toward a side near an inlet for the raw water of the desalting compartments 16. At least a part of concentrated water flowing out of the concentrating compartments 15 is discharged out of a circulatory system. <IMAGE>

Description

technical field [0001] The invention relates to an electrodeionization device, in particular to an electrodeionization device with improved removal ratios of silicon and boron. Background technique [0002] Deionized water is used for a variety of purposes, such as in factories for semiconductor production and liquid crystal display production, in industrial facilities for the pharmaceutical industry, food industry, and power generation industry, and even in homes and laboratories. [0003] As described in Japanese Patent No. 1782943, Japanese Patent No. 2751090 and Japanese Patent No. 2699256, electrodeionization equipment is often used to produce deionized water. A conventional electrodeionization apparatus shown in FIG. 2 includes electrodes consisting of an anode 11 and a cathode 12 , an anion exchange membrane (A membrane) 13 and a cation exchange membrane (C membrane) 14 . These thin films are alternately arranged in such a manner that concentration chambers 15 and de...

AI Technical Summary

Problems solved by technology

[0009] The conventional electrodeionization equipment described above cannot remove silicon and boron at extremely high rates

For example, it is difficult to remove silicon at a removal rate of 99.9-99.99% or higher

[0010] There are reports that concentrate water affects product water, but no references to silicon and boron

Filling the electrode chamber with activated carbon or ion exchange resin reduces resistance but not silicon and boron

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