Chitosan-graphene oxide membranes and process of making the same

• US 10,639,592 B2
• Filed: 07/31/2018
• Issued: 05/05/2020
• Est. Priority Date: 08/07/2017
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America), The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Original Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Inventors: Griggs, Christopher S., Mattei-Sosa, Jose A., Gurtowski, Luke A., Greenlee, Lauren F., Abolhassani, Mojtaba
• Primary Examiner(s): McCracken, Daniel C.
• Application Number:
  US16/050,425
• Publication Number:
  US 20190039027A1
• Time in Patent Office: 644 Days
• CPC Class Codes: B01D 2313/66 Biodegradability of parts of the module
• CPC Class Codes: B01D 2315/10 Cross-flow filtration
• CPC Class Codes: B01D 2323/21815 Acids
• CPC Class Codes: B01D 2325/28 Degradation or stability over time
• CPC Class Codes: B01D 63/10 Spiral-wound membrane modules
• CPC Class Codes: B01D 67/0011 Casting solutions therefor
• CPC Class Codes: B01D 67/0013 Casting processes
• CPC Class Codes: B01D 67/0079 Manufacture of membranes comprising organic and inorganic components
• CPC Class Codes: B01D 67/00793 Dispersing a component, e.g. as particles or powder, in another component
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/06 Flat membranes
• CPC Class Codes: B01D 69/148 Organic/inorganic mixed matrix membranes
• CPC Class Codes: B01D 71/021 Carbon
• CPC Class Codes: B01D 71/0211 Graphene or derivates thereof
• CPC Class Codes: B01D 71/08 Polysaccharides
• CPC Class Codes: C02F 1/44 by dialysis, osmosis or reverse osmosis general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268
• CPC Class Codes: C02F 2101/306 Pesticides
• CPC Class Codes: C02F 2101/308 Dyes; Colorants; Fluorescent agents

Abstract

This invention relates generally to a chitosan-graphene oxide membrane and process of making the same. The nanocomposite membrane can filter water and remove contaminants without fouling like other commercially-available polymer-based water filters. The membrane can be used as a flat sheet filter or can be engineered in a spiral filtration module. The membrane is scalable and tunable for many water contaminants including pharmaceuticals, pesticides, herbicides, and other organic chemicals. The membrane uses chitosan, which is low-cost, renewable biopolymer typically considered to be a waste product and the second most abundant biopolymer on Earth, thus making the membrane an environmentally-friendly product choice.

Claims

1. A process for making a chitosan-graphene oxide composite membrane, said process comprising the steps of:

selectively mixing graphene oxide with purified water, wherein said graphene oxide has a first flake size between about 80 nm and about 105 nm in diameter or a second flake size between about 0.3 μ

m and about 0.7 μ

m in diameter, wherein said first flake size produces said chitosan-graphene oxide composite membrane with a layered graphene oxide internal morphology structure and said second flake size produces said chitosan-graphene oxide composite membrane with a dispersed graphene oxide internal morphology structure;

mixing chitosan with an acid;

preparing a casting solution comprising said chitosan and said graphene oxide;

evaporating said casting solution under reduced pressure to make said chitosan-graphene oxide composite membrane having said layered or said dispersed internal morphology structure.

2. The process of claim 1 wherein said step of preparing said casting solution further comprises the step of mixing said graphene oxide and said chitosan to form a homogenous mixture.

3. The process of claim 1 wherein said acid is acetic acid, malic, succinic acid, glycolic acid, oxalic acid, adipic acid, citric acid, formic acid, carboxylic acid, sulfonic acid, muriatic acid, tannic acid or a combination thereof.

4. The process of claim 1 wherein said membrane is a scalable chitosan-graphene oxide composite membrane.

5. The process of claim 1 wherein said membrane is a flat sheet chitosan-graphene oxide composite membrane.

6. The process of claim 5 further comprise the step of preparing a spiral wound chitosan-graphene oxide composite membrane from said flat sheet chitosan-graphene oxide composite membrane.

7. The process of claim 1 wherein said casting solution comprises up to about 25% by weight graphene oxide and up to about 75% by weight chitosan.

8. The process of claim 1 wherein a ratio of said chitosan to said graphene oxide is between about 4:

1 and about 6;

1 w/w.

9. The process of claim 8 wherein said ratio of said chitosan to said graphene oxide is about 5:

1 w/w.

10. The process of claim 1 further comprising between about 16% and about 25% by weight graphene oxide.

11. The process of claim 1 further comprising the step of physically confining the chitosan-graphene oxide composite membrane between microfiltration membranes.

12. The process of claim 11 wherein said microfiltration membranes are nitrocellulose microfiltration membranes.

13. The method of claim 1 further comprising the step of selectively controlling and/or adjusting liquid filtration and sorption performance of said chitosan-graphene oxide composite membrane based on said first flake size or said second flake size of said graphene oxide.

14. The method of claim 1 further comprising the step of selectively controlling and/or adjusting a crystallinity of said chitosan-graphene oxide composite membrane based on said first flake size or said second flake size of said graphene oxide.

15. The method of claim 1 further comprising the step of selectively controlling and/or adjusting a chemical speciation of said chitosan-graphene oxide composite membrane based on said first flake size or said second flake size of said graphene oxide.

16. The method of claim 1 further comprising the step of selectively controlling and/or adjusting a structure order of said chitosan-graphene oxide composite membrane based on said first flake size or said second flake size of said graphene oxide.

17. The method of claim 1 further comprising the step of selectively controlling and/or adjusting at least one membrane mechanical property of said chitosan-graphene oxide composite membrane based on said first flake size or said second flake size of said graphene oxide.