Title:
PURE WATER PREPARATION PROCESS
Document Type and Number:
Japanese Patent JP3826497
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To prevent the clogging of a reverse osmosis(RO) membrane separation device generated by a Cu hydroxide by doping a chelate agent into Cu containing water of specified pH value and then reverse osmosis separated in the case of preparing pure water by the reverse osmosis membrane separation of Cu containing water.
SOLUTION: When Cu exists in used ultrapure water in a semiconductor manufacturing process and a liquid crystal manufacturing process, a Cu hydroxide is formed in a pure water preparation process formed of a carbonic acid removal device 1, ultraviolet oxidization device 2, a preparation filter membrane separation device 3 and RO membrane separation devices 4 and 5, and the generation of the problem of clogging of RO membranes is feared. A chelate agent, therefore, is doped into a section positioned all over from the latter part of an HCl doped site in the preceding stage of a carbonic acid removal device 1 to the preceding stage of an NaOH doped site in the preceding stage of the ultraviolet oxidization device 2 wherein the pH of water is 5 or less, preferably between a reducing agent doped site and the NaOH doped site. Cu ions are turned into a Cu compound stabilized chemically to prevent the formation of Cu(OH)2 by the arrangement.
Inventors:
Shin Sato
Masahiro Furukawa
Masahiro Furukawa
Application Number:
JP16738997A
Publication Date:
September 27, 2006
Filing Date:
June 24, 1997
Export Citation:
Assignee:
Kurita Water Industries Ltd.
International Classes:
B01D61/04; C02F1/44; B01D65/08; C02F1/00; C02F9/00; (IPC1-7): C02F1/44; B01D61/04; C02F1/00; C02F9/00; C02F9/00; C02F9/00
Domestic Patent References:
| JP7328391A | ||||
| JP6380804A | ||||
| JP5016357A |
Attorney, Agent or Firm:
Tsuyoshi Shigeno