MEMBRANE AND METHOD OF PRODUCING THE SAME

Abstract

A separation membrane suitably for water separation. The membrane includes a porous substrate layer and an active layer arranged over at least a part of the substrate layer. The active layer includes a lamellar structure comprising at least two layers of treated two-dimensional material.

Claims

1. A separation membrane comprising a porous substrate layer and an active layer arranged over at least a part of the substrate layer, wherein the active layer comprises a lamellar structure comprising at least two layers of treated two-dimensional material.

2. A method of producing a separation membrane according to claim 1, the method comprising the steps of: a. optionally preparing a substrate, optionally by treating the substrate with chemical treatment and/or radiation treatment, and/or plasma treatment, and/or thermal treatment; b. contacting the substrate with a composition comprising a two-dimensional material, optionally by forming a first layer of the composition comprising a two-dimensional material and then applying a further layer of the composition comprising a two-dimensional material to the first layer; a layer may optionally be dried before application of the subsequent layer; c. optionally, drying the membrane. d. treating the two-dimensional material applied in step (b) to cause a change to the functional groups of the two-dimensional material, such as by application of high energy radiation such as laser radiation, chemicals, heat, thermal heat and/or pressure to the two-dimensional material; optionally by treating a first layer of the composition before application and subsequent treatment of a further layer of the composition; e. optionally, drying the membrane.

3. The membrane according to claim 1, wherein at least one of the coating layers of the active layer is different to another coating layer of the active layer.

4. The method according to claim 2, wherein at least one of coating layer is different to another coating layer.

5. The membrane according to claim 1, wherein the active layer comprises nanochannels having a diameter of from 1 to 100 nm

6. A method of producing a separation membrane of claim 1, the method comprising the steps of: a. optionally preparing a substrate b. contacting the substrate with a coating composition comprising two-dimensional material and nanofibres; c. removing the nanofibres by contacting the membrane produced by step (b) with mild acid, such as an acid having a pH of from 1 to 6; d. treating, and preferably reducing, the two-dimensional material, preferably by laser treatment, chemical treatment, and/or thermal treatment; e. optionally, drying the membrane.

7. The membrane according to claim 1, wherein the substrate comprises a polymeric substrate, a polymeric substrate containing inorganic filler, a ceramic substrate, a composite substrate, a metal substrate, an inorganic substrate, inorganic-organic substrate, woven filament, and/or non-woven, and/or a casted substrate.

8. The membrane according to claim 1, wherein the substrate is in the form of a porous film, porous plate, porous hollow fibre substrate, tubular fibre substrate, or a bulky porous material.

9. The membrane according to claim 1, wherein the polymeric substrate is selected from one or more of polyamide (PA), polysulphone (PSf), polyvinylidene fluoride (PVDF), and thin film composite (TFC), such as polysulphone supported polyamide composite substrate.

10. The membrane according to claim 1, wherein the average size of the pores of the substrate may be from 0.1 nm to 30,000.

11. The membrane according to claim 1, wherein the active layer is formed from a coating composition comprising the two-dimensional material.

12. The membrane according to claim 11, wherein the coating composition comprises two-dimensional material with a carrier and/or an additive.

13. The membrane according to claim 1, wherein the two-dimensional material comprises one or more of graphene or derivative thereof, silicene, germanene, stanene, boron-nitride, carbon nitride, metal-organic nanosheets, polymer, graphene aerogel, 2D metal-organic frameworks, 3D metal-organic frameworks, and/or transition metal dichalcogenides and derivatives thereof.

14. The membrane according to claim 1, wherein the two-dimensional material comprises graphene or derivative thereof.

15. The membrane according to claim 14, wherein the graphene or derivative thereof is selected from one or more of graphene oxide, reduced graphene oxide from graphene oxide, reduced graphene oxide via bottom-up process, oxidised graphene via treatments from graphite, functionalised graphene, functionalised graphene oxide, functionalised reduced graphene oxide, and/or functionalised oxidised graphene, composites thereof, dispersions thereof.

16. The membrane according to claim 14, wherein the graphene or derivative thereof is selected from one or more graphene oxide, reduced graphene oxide, hydrated graphene, amino-based graphene, alkylamine functionalised graphene oxide, ammonia functionalised graphene oxide, amine functionalised reduced graphene oxide, octadecylamine functionalised reduced graphene oxide, hydrazide functionalised graphene, hydrazine functionalised graphene, amide functional graphene, amine PEG functionalised graphene, graphene composite, and/or polymer graphene aerogel.

17. The membrane according to claim 14, wherein the graphene or derivative thereof is graphene oxide.

18. The membrane according to claim 14, wherein the atomic oxygen content of the two-dimensional material is the range of from 1% to 60%.

19. The membrane of claim 1, wherein the composition comprises fibres.

20. The membrane of claim 11, wherein the coating composition is coated onto the substrate using bar coating, flexo-coating, ink-jet printing, screen coating or slot coating.

21. The membrane of claim 1, wherein the active layer comprises multiple coating layers.

22. The membrane of claim 1, wherein the coating layers of the active layer comprise a gradient of decreasing, increasing or variable reduction level in the two-dimensional material through the active layer.

23. The membrane of claim 1, wherein the two-dimensional material is treated by exposing the two-dimensional material to radiation, chemical treatment, pressure treatment and/or thermal treatment.

24. The membrane of claim 1, wherein the two-dimensional material is treated by exposing the two-dimensional material to laser radiation.

25. The membrane of claim 1, wherein the two-dimensional material is chemical treated.

26. The membrane of claim 1, wherein the two-dimensional material is treated by subjecting the two-dimensional material to thermal treatment applied to the coating composition or to treatment of the membrane post coating.

27. The membrane of claim 1, wherein the atomic oxygen and/or nitrogen content of the treated two-dimensional is from 0% to 65%.

28. The membrane of claim 1, wherein the active layer comprises a first layer comprising two-dimensional material having a first oxygen content and a second layer comprising two-dimensional material having a second oxygen content, wherein the first and second oxygen contents are different.

29. The membrane of claim 28, wherein the first oxygen content is between 30 and 50% and the second oxygen content is between 1 and 30%.

30. The membrane of claim 28, wherein the layer comprising the first oxygen content is arranged between the substrate and the second layer comprising the second oxygen content.

31. The membrane of claim 1, wherein the treated two-dimensional material has a thermal conductivity in a range of from 0.1 W/mK to 6,000 W/mK.

32. The membrane of claim 1, wherein the treated two-dimensional material has an electrical conductivity of in a range of from 1×10.sup.−6 S/m to 600,000 S/m.

33. The membrane of claim 1, wherein the treated two-dimensional material comprises amino groups; aliphatic amino groups, porphyrin-functionalised secondary amino groups, and/or 3-amino-propyltrialkoxysilane groups.

34. The membrane of claim 1, wherein the treated two-dimensional material comprises amino-based graphene , isocyanate modified GO, octadecylamine functionalised reduced graphene oxide, polymer graphene aerogel, azide-, alkyne-functionalised GO, poly(allylamine) modified, DNA or protein modified (non-covalent).

35. The membrane of claim 1, wherein the treated two-dimensional material comprises functional groups attached toward the edge of the two-dimensional material, such as NO.sub.2, —NH.sub.2, —SO.sub.3H, halide, —Na, —MgBr and/or —SH groups.

36. (canceled)

37. The membrane of claim 1, wherein treatment of the two-dimensional material forms channels in the form of closed or open loop, pattern of an electronic circuit, a grid and/or artistic patterns.

38. (canceled)

39. The membrane of claim 1, wherein the membrane is for oil/water separation, molecule separation, pharmaceutical separation for removal of pharmaceutical residues in the aquatic environment, drug separation, bio-filtration, for example separation between micro-organisms and water, desalination, suitably sea water desalination, or selective ion separation, and nuclear waste water separation for removal of nuclear radioactive elements from nuclear waste water, heavy metal removal, bio-refinery, laundry water treatment, milk condensation, for blood treatment such as physiological separation to replace damaged kidney filter and blood separation, and/or separation of bio-platform molecules derived from sources such as plants, for industrial water treatment, for example, industrial laundry waste water, food and beverage manufacturing, chemical production waste water, paper processing, waste water from landfill and agriculture, dairy and cheese production including brine water treatment from cheese production, milk concentration, protein recovery from crops such as potatoes.

40. The membrane of claim 1, wherein the membrane is for water separation comprising desalination or oil and water separation, or for chemical separation.

41. The membrane of claim 1, wherein the two-dimensional material is treated after application of the two-dimensional material to the substrate layer.

42. The membrane of claim 11, wherein the two-dimensional material is treated by subjecting the two-dimensional material to thermal treatment applied to the coating composition or to treatment of the membrane post coating.

Description

EXAMPLES

Example 1—Preparation of Reduced Graphene Oxide Membrane Via Multilayer Coating Using Different Graphene-Based Materials

[0164] An ink containing 1 mg/ml graphene oxide with atomic oxygen content of 40% was coated to a polysulfone substrate with pore size of 25 nm using flexo coating technique, and the coating thickness was about 20 nm. Following drying under ambient conditions, another ink containing 1 mg/ml reduced graphene oxide with atomic oxygen content of 10% was coated to the surface of coated graphene oxide from above, using flexo coating, and the coating thickness was about 20 nm. The performance of the resultant membrane was then assessed and found to exhibit improvement of life span by 100% and dye molecules rejection rate by 50% compared to reduced graphene oxide only coating.

Example 2—Preparation of Reduced Graphene Oxide Membrane with Substrate Treatment and Different Graphene-Based Materials

[0165] A polysulfone substrate with pore size of 25 nm was soaked in 0.25 M NaOH for 20 min and then washed by deionised water and dried at 40° C. for 1 hour. An ink containing 1 mg/ml graphene oxide with atomic oxygen content of 40% was then coated to the substrate using flexo coating technique, and the coating thickness is about 20 nm. Following drying under ambient conditions, another ink containing 1 mg/ml reduced graphene oxide with atomic oxygen content of 10% was coated to the surface of coated graphene oxide from above, using flexo coating, and the coating thickness is about 20 nm. The performance of the resultant membrane was then assessed and found to exhibit improvement of life span by 200% and dye molecules rejection rate by 50% compared to reduced graphene oxide only coating.

Example 3—Preparation of Reduced Graphene Oxide Membrane with Post Treatment Method

[0166] A polysulfone substrate with pore size of 25 nm was soaked in 0.25 M NaOH for 20 min and then washed by deionised water and dried at 40° C. for 1 hour. An ink containing 1 mg/ml graphene oxide with atomic oxygen content of 40% was then coated to the substrate using flexo coating technique, and the coating thickness is about 40 nm. Following drying under ambient conditions, the coated surface was then soaked in 0.1 M sodium borohydrate water solution for 0.5 hour. The performance of the resultant membrane was then assessed and found to exhibit dye molecules rejection by 60% compared to 0% of uncoated substrate.

Example 4—Preparation of a Separation Membrane by Post Treatment

[0167] A polysulfone substrate with pore size of 25 nm was soaked in 0.25 M NaOH for 20 min and then washed by deionised water and dried at 40° C. for 1 hour. An ink containing 1 mg/ml graphene oxide with atomic oxygen content of 40% mixed with 0.5 mg/ml Cu(OH).sub.2 nanostrands with diameter of 2 nm and length of 1 um, was then coated to the substrate using flexo coating technique, and the coating thickness was about 100 nm. Following drying under ambient conditions, the coated surface was then soaked in 0.1 M sodium borohydrate water solution for 0.5 hour to reduce graphene oxide, and filtered with 0.15 M ethylenediaminetetraacetic acid to dissolve nanostrands and create nanochannels. The performance of the resultant membrane was then assessed and found to exhibit an significant improvement of flux rate of at least 300% and dye molecules rejection rate of 40% in comparison to graphene oxide coated membrane.

[0168] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0169] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0170] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0171] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.