MEMBRANE

Abstract

A filtration membrane, suitably for water filtration, in which the membrane includes a porous substrate layer and an active layer arranged over at least a part of the substrate layer. The active layer has a lamellar structure comprising at least two layers of two-dimensional material. The two-dimensional material comprises transition metal dichalcogenide. There is also provided methods for making the filtration membranes and compositions for use in those methods.

Claims

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

2. A method of producing a filtration membrane according to claim 1, wherein the membrane comprises a porous substrate layer and an active layer arranged over at least a part of the substrate layer, wherein the active layer has a lamellar structure comprising at least two layers of two dimensional material, and wherein the two-dimensional material comprises transition metal dichalcogenide, the method comprising the steps of: a. optionally preparing the substrate b. contacting the substrate with a coating composition comprising the transition metal dichalcogenide; c. optionally, drying the membrane.

3. The filtration membrane according to claim 1, wherein the membrane is obtained by: a. optionally preparing the substrate b. contacting the substrate with a coating composition comprising the transition metal dichalcogenide; c. optionally, drying the membrane.

4. The filtration membrane according to claim 3, wherein contacting comprises printing the coating composition comprising the transition metal dichalcogenide onto the substrate.

5. (canceled)

6. (canceled)

7. The filtration membrane according to claim 1, wherein the substrate comprises a porous film, porous plate, hollow fibres, or bulky shapes.

8. The filtration membrane to claim 7, wherein the substrate is formed from materials selected from one or more of zeolite, silicon, silica, alumina, zirconia, mullite, bentonite and montmorillonite clay substrate.

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. The filtration membrane according to claim 1, wherein the substrate comprises a porous polymeric film.

14. The filtration membrane according to claim 1, wherein the substrate is formed from materials selected from one or more of polyamide (PA), polysulphone (PSf), polyvinylidene fluoride (PVDF) and thin film composites (TFC).

15. (canceled)

16. (canceled)

17. The filtration membrane according to claim 1, wherein the support is ultrafiltration in which a pore size of the substrate layer is from 0.1 nm to 4000 nm.

18. (canceled)

19. (canceled)

20. The filtration membrane according to claim 1, wherein the substrate has a surface roughness of from 0 to 1 m.

21. The filtration membrane according to claim 1, wherein the surface of the substrate that comprises the active layer is hydrophilic.

22. (canceled)

23. (canceled)

24. The filtration membrane according to claim 1, wherein the active layer has a thickness of from 2 nm to 1 m.

25. The filtration membrane according to claim 1, wherein the transition metal dichalcogenide is according to formula (I)
M.sub.aX.sub.b, (I) wherein with M is a transition metal atom; X is a chalcogen atom; wherein 0<a1 and 0<b2.

26. (canceled)

27. The filtration according to claim 1, wherein the transition metal dichalcogenide is selected from MoS.sub.2, WS.sub.2, MoSe.sub.2, WSe.sub.2.

28. The filtration membrane according to claim 1, wherein the transition metal dichalcogenide is in the form of flakes having an average size of from 1 nm to 5000 nm.

29. The filtration membrane according to claim 1, wherein the size distribution of the transition metal dichalcogenide flakes is such that at least 30 wt % of the transition metal dichalcogenide flakes have a diameter of between 1 nm to 5000 nm.

30. (canceled)

31. The filtration membrane according to claim 1, wherein the average size of the transition metal dichalcogenide is at least 80% of the average pore size of the substrate.

32. (canceled)

33. (canceled)

34. (canceled)

35. The filtration membrane according to claim 1, wherein the active layer further comprises nanochannels.

36. The filtration membrane according to claim 1, wherein the nanochannels in the active layer have a diameter of 1 to 750 nm.

37. (canceled)

38. The filtration membrane according to claim 1, wherein the membrane is configured for water treatment.

39. (canceled)

40. (canceled)

41. (canceled)

42. (canceled)

43. (canceled)

44. The filtration membrane according to claim 43, wherein the composition comprises a surfactant is selected from one or more of sodium cholate, sodium dodecyl sulphate, sodium dodecylbenzenesulphonate, lithium dodecyl sulphate, taurodeoxycholate, ethyl cellulose, lithium hydroxide, Triton X-100, TX-100, IGEPAL CO-890.

45. (canceled)

46. (canceled)

47. (canceled)

48. The filtration membrane according to claim 3, wherein coating composition comprises fibres.

49. The filtration according to claim 48, wherein the fibres are present in the coating composition in a concentration of from 0.01% to 150% of the transition metal dichalcogenide concentration.

50. (canceled)

51. (canceled)

52. (canceled)

53. The filtration membrane according to claim 3, wherein contacting comprises deposition and the concentration of the transition metal dichalcogenide in the coating composition for deposition is from 0.001 mg/ml to 10 mg/ml.

54. (canceled)

55. (canceled)

56. The filtration membrane according to claim 3, wherein the viscosity of the coating composition is from 1 to 100 cPa.

57. The filtration membrane according to claim 3, wherein the surface tension of the coating composition is from 1 to 150 mN/m.

58. (canceled)

59. (canceled)

60. (canceled)

61. The filtration membrane according to claim 3, wherein the concentration of the transition metal dichalcogenide in the coating composition is from 0.05 mg/ml to 4 mg/ml.

62. (canceled)

63. (canceled)

64. (canceled)

65. (canceled)

66. The filtration membrane according to claim 3, wherein the coating composition has a Z number of between 1 and 16.

67. The filtration membrane according to claim 4, wherein the printing is drop on demand (DOD) inkjet printing.

68. The filtration membrane according to claim 67, wherein the nozzle size of the inkjet printer is from 5 um to 100 um.

69. A filtration device comprising the filtration membrane according to claim 1.

70. The filtration device according to claim 69, wherein the filtration device is a gravity filtration device.

Description

EXAMPLES

[0115] Example 1: 1 kg molybdenum disulfide was immersed in butyllithium solution in hexane for 48 hours in an atmosphere of argon. The mixture was then filtered and washed with hexane. Exfoliation was achieved after the residue was added with 10 g sodium cholate and sonicated in water and centrifuged at 4000 rpm a couple of times. The dispersion was then diluted to a concentration of 0.5 mg/ml for coating. The obtained dispersion was then applied to polysulphone substrate which was surface treated with UV-ozone for 20 min, using a Pixdro LP50 equipped with Xaar 1002 head assembly. Following drying under ambient conditions, the performance of the resultant membrane was then assessed and found to exhibit improvement of multi-valent ions rejection rate to 90% in comparison to an uncoated membrane.

[0116] Example 2: An initial MoS.sub.2 concentration of 1 mg/ml was made by dispersing MoS.sub.2 in a sodium cholate/water solution of surfactant concentration of 0.05 mg/ml in a stainless vessel by probe sonication (750 W at 40-75% amplitude) for 25 min. The dispersion was then settled for 2 hours and the top layer of the dispersion was then decanted and centrifuged at rpm of 3000 for 10 mins. The resultant dispersion was then diluted to a concentration of 0.5 mg/ml and deposited on a porous membrane using vacuum deposition. The material was then dried at room temperature. The performance of the resultant membrane was assessed and found to exhibit an improvement of at least 40% of water flux rate versus an uncoated membrane with salt rejection of 90%.

[0117] Example 3: An initial MoS.sub.2 concentration of 1 mg/ml was made by dispersing MoS.sub.2 in a sodium cholate/water solution of surfactant concentration of 0.05 mg/ml in a stainless vessel by probe sonication (750 W at 40-75% amplitude) for 25 mins. The dispersion was then settled for 2 hours and the top layer of the dispersion was then decanted and centrifuged at rpm of 3000 for 25 mins. Cu(OH).sub.2 nanostrands of 1% weight equivalent to MoS.sub.2 was then added to the dispersion and mixed with magnetic stirring. The resultant dispersion was then diluted to a concentration of 0.2 mg/ml and deposited on a porous membrane using vacuum deposition. Ethylenediaminetetraacetic acid water solution was filtered to remove the nanostrands and create nanochannels, followed by filtration of deionised water to remove any residual acid. The material is then dried at room temperature. The performance of the resultant membrane was assessed and found to exhibit an improvement of at least 100% of water flux rate compared to an uncoated membrane, and improvement of ion rejection of 90% compared to 0% of an uncoated membrane.

[0118] Example 4: An initial MoS.sub.2 concentration of 1 mg/ml was made by dispersing MoS.sub.2 in a sodium cholate/water solution of surfactant concentration of 0.05 mg/ml in a stainless vessel by probe sonication (750 W at 40-75% amplitude) for 30 mins. The dispersion was then settled for 2 hours and the top layer of the dispersion was then decanted and centrifuged at rpm of 3000 for 10 mins. Zr(OH).sub.2 nanostrands having length of <5 um and weight equivalent of 1% to MoS.sub.2 was added to the dispersion and mixed with magnetic stirring. The obtained dispersion was then applied to surface treated polysulphone (UV-ozone, 20 min) using a Pixdro LP50 equipped with Xaar 1002 head assembly having nozzle size of 60 um. Ethylenediaminetetraacetic acid water solution was filtered to remove the nanostrands and create nanochannels, followed by filtration of deionised water to remove any residual acid. The material was then dried at room temperature. The performance of the resultant membrane was assessed and found to exhibit an improvement of over 100% of water flux rate compared to an uncoated membrane, and improvement of ion rejection of 90% compared to 0% of an uncoated membrane.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.