CN-122028970-A - Method for operating electrodialysis device using organic solvent-containing aqueous solution having anion exchange membrane electrodialysis device manufactured by cross-linking polymerization method

Abstract

The method for operating an electrodialysis device comprises an electrodialysis step of electrodialysis an aqueous solution containing halide ions and a polar organic solvent using an electrodialysis device having an anion exchange membrane produced by a crosslinking polymerization method, wherein the aqueous solution contains 200mg/L or more of iodide ions, and wherein the anion exchange membrane contains an anion exchange membrane in which, when an electrodialysis test is performed using a desalted solution containing iodide ions and sulfate ions, when the residual rate of iodide ions in the desalted solution is 5%, the transmittance (%) of iodide ions (I ‑ ) in the concentrated solution is defined as T I and the transmittance (%) of sulfate ions (SO 4 2‑ ) is defined as T SO4 , and T I /T SO4 is 3.5 or more.

Inventors

• Haseki Masahiko
• NAKAMURA KAORU
• DOI SHOICHI

Assignees

• 株式会社合同资源

Dates

Publication Date

20260512

Application Date

20241002

Priority Date

20231012

Claims (9)

1. 1. A method for operating an electrodialysis device comprising an electrodialysis step of electrodialysis an aqueous solution containing halide ions and a polar organic solvent using an electrodialysis device having an anion exchange membrane produced by a cross-linking polymerization method, The aqueous solution contains more than 200mg/L iodide ions, In the electrodialysis process step of the present invention, The anion exchange membrane comprises an anion exchange membrane in which when an electrodialysis test is performed using a desalted solution containing iodide ions and sulfate ions, when the residual rate of iodide ions in the desalted solution is 5%, the transmittance% of iodide ions I - in the concentrated solution is defined as T I , and the transmittance% of sulfate ions SO 4 2- is defined as T SO4 , and T I /T SO4 is 3.5 or more.
2. 2. A method of operating an electrodialysis unit as claimed in claim 1, wherein, In the electrodialysis step, the polar organic solvent contains an organic solvent having a relative dielectric constant of 5 or more at 25 ℃.
3. 3. A method of operating an electrodialysis unit as claimed in claim 1 or 2, wherein, The aqueous solution contains 0.1% by mass or more and 50% by mass of the polar organic solvent.
4. 4. A method of operating an electrodialysis unit as claimed in claim 1 or 2, wherein, In the electrodialysis step, the concentration of halide ions in the desalted liquid obtained by the absorbance method at the end point is 0.5g/L or more and 5g/L or less.
5. 5. A method of operating an electrodialysis unit as claimed in claim 1 or 2, wherein, The iodide ion is obtained by subjecting one or more selected from the group consisting of iodine I 2 , iodic acid HIO 3 , periodic acid HIO 4 , and an iodine compound to a reduction treatment.
6. 6. A method of operating an electrodialysis unit as claimed in claim 1 or 2, wherein, The anion exchange membrane comprises a base substrate comprising polyolefin, and an ion-selective permeable layer formed on one or both sides of the base substrate.
7. 7. A method of operating an electrodialysis unit as claimed in claim 1 or 2, wherein, In the electrodialysis step, the anion exchange membrane includes an anion exchange membrane immersed in a polar organic solvent having a concentration of 50 mass% and having a rate of change in ion exchange capacity of ±5% or less before and after the immersion treatment.
8. 8. A method of operating an electrodialysis unit as claimed in claim 1 or 2, wherein, In the electrodialysis step, the anion exchange membrane includes an anion exchange membrane having a water content change rate of + -20% or less as measured by the Karl Fischer method before and after the impregnation treatment with isopropyl alcohol having a concentration of 50 mass%.
9. 9. An electrodialysis device for electrodialysis of an aqueous solution containing halide ions and a polar organic solvent, wherein, The electrodialysis device is provided with: A concentrating chamber; Desalination chamber, and An anion exchange membrane and a cation exchange membrane manufactured by a cross-linking polymerization method, which separate the concentrating chamber from the desalting chamber, The aqueous solution contains more than 200mg/L iodide ions, The anion exchange membrane comprises an anion exchange membrane in which when an electrodialysis test is performed using a desalted solution containing iodide ions and sulfate ions, when the residual rate of iodide ions in the desalted solution is 5%, the transmittance% of iodide ions I - in the concentrated solution is defined as T I , and the transmittance% of sulfate ions SO 4 2- is defined as T SO4 , and T I /T SO4 is 3.5 or more.

Description

Method for operating electrodialysis device using organic solvent-containing aqueous solution having anion exchange membrane electrodialysis device manufactured by cross-linking polymerization method Technical Field The present invention relates to a method for operating an electrodialysis device and an electrodialysis device. Background Various techniques for electrodialysis of iodine-containing waste solutions have been developed so far. As such a technique, for example, a technique described in patent document 1 is known. In the waste liquid, divalent ions such as sulfate ions (SO 42-) may coexist in addition to iodine components such as iodide ions (I -). For example, sulfate ions are contained in the waste liquid at a concentration of usually 1g/L or more and not more than the saturation solubility of sulfate, and more usually about 20 to 50 g/L. Patent document 1 describes a method in which a stock solution containing an inorganic anion having iodine and an inorganic anion having fluorine and contained in a desalting chamber is subjected to electrodialysis using a monovalent selective anion exchange membrane or the like (claim 1, example, etc. of patent document 1). Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2021-079318. Disclosure of Invention Problems to be solved by the invention However, as a result of the study by the present inventors, there is room for improvement in the selective permeability of halide ions to organic solvents in the electrodialysis method described in patent document 1. That is, since it is generally known that the ion exchange membrane is damaged by the organic solvent, in the conventional electrodialysis method, as shown in patent document 1, a pretreatment is used in which the organic solvent (organic matter) contained in the waste liquid is burned and removed before electrodialysis. For this reason, there has been no sufficient study on a technique of performing electrodialysis using an ion exchange membrane in a solution containing an organic solvent. Means for solving the problems The present inventors have studied an electrodialysis method for a solution containing an organic solvent, and as a result, have found that the selective permeability of halide ions to an organic solvent can be improved by appropriately controlling the compactness of an ion-selective permeable layer in an anion exchange membrane, in addition to using an anion exchange membrane having relatively high solvent resistance. Intensive studies based on this knowledge have been conducted, and the following results have been obtained. It was found that the anion exchange membrane produced by the crosslinking polymerization method was less soluble in an organic solvent and had solvent resistance than the anion exchange membrane produced by the casting method. The casting method is a method in which an ion exchange resin is dissolved or dispersed in a solvent to prepare a casting stock solution, and the casting stock solution is cast on a base film and then dried. The anion exchange membrane manufactured by the casting method is partially dissolved in an organic solvent and cannot be used for electrodialysis. Regarding the compactness of the ion-selective permeable layer, it was found that the ratio (T I/TSO4) of the transmittance of iodide ions (I -) to the transmittance of sulfate ions (SO 42-) measured by a predetermined electrodialysis test was used as an index, and thus stable evaluation was possible. Further, by using a highly selective anion exchange membrane having T I/TSO4 of a predetermined value or more, the selective permeability of halide ions to polar organic solvents can be improved. Based on such knowledge, the present invention has been completed. According to one aspect of the present invention, there is provided the following method of operating an electrodialysis device and the electrodialysis device. 1. A method for operating an electrodialysis device comprising an electrodialysis step of electrodialysis an aqueous solution containing halide ions and a polar organic solvent using an electrodialysis device having an anion exchange membrane produced by a cross-linking polymerization method, The aqueous solution contains more than 200mg/L iodide ions, In the electrodialysis process step of the present invention, The anion exchange membrane comprises an anion exchange membrane in which when an electrodialysis test is performed using a desalted solution containing iodide ions and sulfate ions, when the residual rate of iodide ions in the desalted solution is 5%, the transmittance (%) of iodide ions (I -) in a concentrated solution is defined as T I, and when the transmittance (%) of sulfate ions (SO 42-) is defined as T SO4, T I/TSO4 is 3.5 or more. 2. A method of operating an electrodialysis unit as claimed in claim 1, wherein, In the electrodialysis step, the polar organic solvent contains an organic solvent having a relative diele