Method and system for treating aqueous fluid resulting from fluoropolymer production step

Patent metadata

Field	Value
Publication number	US-11266934-B2
Application number	US-201816615426-A
Country	US
Kind code	B2
Filing date	Jun 27, 2018
Priority date	Jun 27, 2017
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

A method for treating an aqueous fluid resulting from a fluorine-containing polymer production step, the method comprising:separating the aqueous fluid into a solid component and a filtrate using a filter aid.

First claim

The invention claimed is:

1. A method for treating an aqueous fluid comprising a fluorine-containing surfactant resulting from a fluorine-containing polymer production step, the method comprising:
separating the aqueous fluid into a solid component and a filtrate using a filter aid, wherein the solid component comprises at least one of an uncoagulated polymer and a particulate polymer, and the separation is conducted with the filter aid by combining body feed and precoat; and
separating the filtrate into a permeated liquid and a concentrated liquid using a filtration membrane,
wherein the filter aid is diatomaceous earth having an average particle size of 20 μm or more and 60 μm or less.

2. The method according to claim 1 , wherein the solid component comprises the uncoagulated polymer.

3. The method according to claim 1 , wherein the filter aid additionally comprises at least one selected from the group consisting of filter sand, perlite, and cellulose.

4. The method according to claim 1 , wherein the aqueous fluid is separated into the solid component and the filtrate by pressure filtration.

5. The method according to claim 1 , wherein the filtrate has a pH of less than 5.

6. The method according to claim 1 , wherein the fluorine-containing surfactant is one or more selected from the group consisting of a fluorine-containing carboxylic acid represented by formula (i) below and a salt thereof:
X—Rf—COOH  (i)

wherein X is H, F, or Cl; and Rf is a C 1-20 linear or branched fluoroalkylene group, a C 1-20 group having a monooxyfluoroalkylene group, or a C 1-20 group having a polyoxyfluoroalkylene group.

7. The method according to claim 1 , wherein the filtration membrane is a reverse osmosis membrane, a nanofiltration membrane, or an ultrafiltration membrane.

8. The method according to claim 7 , wherein the filtration membrane is a reverse osmosis membrane.

9. The method according to claim 1 , further comprising contacting the concentrated liquid with an adsorbent.

10. The method according to claim 9 , wherein the adsorbent is an ion exchange resin or activated carbon.

Assignees

• Daikin Ind Ltd

Inventors

• Itakura Shouji
• Hatayama Ryou
• Ohashi Mihoko
• Koizumi Michinobu

Classifications

• B01J20/28064

  being in the range 500-1000 m2/g · CPC title

• C02F2209/03

  Pressure · CPC title

• B01J20/106

  Perlite · CPC title

• B01D61/04

  Feed pretreatment · CPC title

• C02F1/444

  by ultrafiltration or microfiltration · CPC title