Apparatus for producing acidic aqueous solution and method for producing acidic aqueous solution

Patent metadata

Field	Value
Publication number	US-2022242757-A1
Application number	US-202017640297-A
Country	US
Kind code	A1
Filing date	Sep 4, 2020
Priority date	Sep 5, 2019
Publication date	Aug 4, 2022
Grant date	—

Abstract

An apparatus (100) for producing an acidic aqueous solution includes: an electrodialyzer (110) that has a monovalent ion perm-selective ion-exchange membrane and separates wastewater containing chloride ions and alkali metal ions into electrodialysis concentrated water and electrodialysis diluted water by an electrodialysis treatment; an electrolyzer (120) includes an anode that that electrolyzes the electrodialysis concentrated water to produce an acidic aqueous solution; and a first circulator (13) that circulates at least some of the acidic aqueous solution to the wastewater supplied to the electrodialyzer (110), and that adjusts a pH of the wastewater supplied to the electrodialyzer to 3 to 9.

First claim

1 . An apparatus for producing an acidic aqueous solution, comprising:
an electrodialyzer that has a monovalent ion perm-selective ion-exchange membrane and separates wastewater containing chloride ions and alkali metal ions into electrodialysis concentrated water and electrodialysis diluted water by an electrodialysis treatment; an electrolyzer that comprises an anode that electrolyzes the electrodialysis concentrated water to produce an acidic aqueous solution; and a first circulator that circulates at least some of the acidic aqueous solution to the wastewater supplied to the electrodialyzer, and that adjusts a pH of the wastewater supplied to the electrodialyzer to 3 to 9.

2 . The apparatus for producing an acidic aqueous solution according to claim 1 , further comprising a second circulator that circulates at least some of the acidic aqueous solution to the electrolyzer.

3 . The apparatus for producing an acidic aqueous solution according to claim 1 , wherein, in the electrolyzer, the anode is a hydrogen gas diffusion electrode.

4 . The apparatus for producing an acidic aqueous solution according to claim 1 , further comprising a sodium hypochlorite producing device that electrolyzes a part of the electrodialysis concentrated water to produce a sodium hypochlorite aqueous solution.

5 . The apparatus for producing an acidic aqueous solution according to claim 1 , further comprising a hydrogen peroxide producing device that electrolyzes a part of the electrodialysis concentrated water to produce hydrogen peroxide.

6 . The apparatus for producing an acidic aqueous solution according to claim 1 , wherein the electrodialyzer performs the electrodialysis treatment on the wastewater in which the concentration of the chloride ions is 0.01 mg/L or more.

7 . The apparatus for producing an acidic aqueous solution according to claim 1 , wherein the electrodialyzer performs the electrodialysis treatment on the wastewater in which the concentration of the alkali metal ions is 0.01 mg/L or more.

8 . The apparatus for producing an acidic aqueous solution according to claim 1 , wherein the anode includes a conductive metal substrate and a catalyst layer.

9 . The apparatus for producing an acidic aqueous solution according to claim 8 , wherein the thickness of the conductive metal substrate is 0.05 to 5 mm.

10 . The apparatus for producing an acidic aqueous solution according to claim 8 , wherein the thickness of the catalyst layer is 0.1 to 100 μm.

11 . The apparatus for producing an acidic aqueous solution according to claim 8 , wherein the porosity of the anode is 10 to 95%.

12 . The apparatus for producing an acidic aqueous solution according to claim 8 , wherein the anode further includes an underlayer made of a valve metal base alloy containing tantalum and titanium components between the conductive metal substrate and the catalyst layer.

13 . The apparatus for producing an acidic aqueous solution according to claim 4 , wherein a discharge pipe for the sodium hypochlorite aqueous solution produced by the sodium hypochlorite producing device is connected to a discharge pipe for the wastewater.

14 . The apparatus for producing an acidic aqueous solution according to claim 1 , wherein, in the electrolyzer, a cathode is an oxygen gas diffusion electrode.

15 . The apparatus for producing an acidic aqueous solution according to claim 5 , wherein a discharge pipe for the hydrogen peroxide produced by the hydrogen peroxide producing device is connected to a discharge pipe for the wastewater.

16 . A method for producing an acidic aqueous solution, comprising:
an electrodialysis process in which wastewater containing chloride ions and alkali metal ions is separated into electrodialysis concentrated water and electrodialysis diluted water by an electrodialysis treatment; an electrolysis process in which the electrodialysis concentrated water is electrolyzed to produce, by an anode comprised in an electrolyzer, an acidic aqueous solution; and a first circulating process in which at least some of the acidic aqueous solution is circulated to the wastewater supplied in the electrodialysis process, and in which a pH of the wastewater supplied to the electrodialysis process is adjusted to 3 to 9.

17 . The method for producing an acidic aqueous solution according to claim 16 , further comprising
a second circulating process in which at least some of the acidic aqueous solution is used in the electrolysis process.

18 . The method for producing an acidic aqueous solution according to claim 16 , wherein the electrolysis process is performed by a hydrogen oxidation reaction.

19 . The method for producing an acidic aqueous solution according to claim 16 , further comprising
a sodium hypochlorite producing process in which a part of the electrodialysis concentrated water is electrolyzed to produce a sodium hypochlorite aqueous solution.

20 . The method for producing an acidic aqueous solution according to any one of claims 16 to 19 , further comprising
hydrogen peroxide producing process in which a part of the electrodialysis concentrated water is electrolyzed to produce hydrogen peroxide.

Assignees

• De Nora Permelec Ltd

Inventors

• Ozawa Manabu
• Nishiki Yoshinori
• Kato Masaaki
• Morita Rie

Classifications

• C02F2001/46166

  Gas diffusion electrodes · CPC title

• C02F1/4674

  with halogen or compound of halogens, e.g. chlorine, bromine · CPC title

• C02F1/4672

  by electrooxydation · CPC title

• C02F2001/46161

  Porous electrodes · CPC title

• C02F2001/46142

  Catalytic coating · CPC title