阅读说明：本技术 包含金属氧化物的多孔材料及其用途 (Porous material comprising metal oxide and use thereof ) 是由 方静华 于 2019-12-18 设计创作，主要内容包括：本发明一般地涉及材料科学领域。更具体地说,本发明涉及包含金属和金属氧化物的多孔材料及其制备和用途。(The present invention relates generally to the field of material science. More particularly, the present invention relates to porous materials comprising metals and metal oxides, their preparation and use.)

1. A material comprising a metal or metal alloy, wherein said metal or said metal alloy has at least one porous metal oxide layer thereon.

2. The material of claim 1, wherein the material has a thickness of about 1 micron to about 1 mm.

3. The material of claim 1 or 2, wherein the metal oxide layer has a thickness of between about 300nm to 1 mm.

4. The material of any one of claims 1 to 3, wherein the metal or metal alloy has a thickness of about 100nm to about 50 microns.

5. The material of any one of claims 1 to 4, wherein the metal oxide layer has a three-dimensionally disordered network of channels, pores in the network of channels having a non-constant diameter.

6. The material of claim 5, wherein the pores have a non-constant diameter in the range of about 1.5nm to about 250nm or in the range of about 1.5nm to about 200 nm.

7. According to the claimsThe material of any one of claims 1 to 6, wherein the metal oxide layer has a thickness of about 200cm³G to about 600cm³A non-constant pore volume in the range of/g.

8. The material of any one of claims 1 to 7, wherein the metal oxide layer has a thickness of about 20m²G and about 50m²Surface area between/g.

9. The material of any one of claims 1 to 8, wherein the material is flexible.

10. The material of any one of claims 1 to 9, wherein the material is in the form of a sheet.

11. The material of any one of claims 1 to 10, wherein the metal or metal alloy has a metal oxide layer on each side.

12. The material of any one of claims 1 to 11, wherein the material is attached to a base structure.

13. The material of claim 12, wherein the base structure is wood, glass, quartz, silicon, water-proof paper, plastic, or cloth.

14. The material of any one of claims 1 to 13, wherein the metal is aluminium, copper, iron, zinc, manganese, palladium or titanium.

15. The material of claim 14, wherein the metal is aluminum.

16. The material of any one of claims 1 to 15, wherein the metal alloy is an aluminum alloy or a zinc alloy.

17. The material of claim 16, wherein the metal alloy is an aluminum alloy.

18. The material of claim 16 or 17, wherein the aluminum alloy comprises or consists of aluminum and one or more of copper, iron, zinc, manganese, palladium, silicon or titanium.

19. The material of claim 18, wherein the aluminum alloy comprises at least 90%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99% Al by weight.

20. A material according to any one of claims 17 to 19, wherein the aluminium alloy is aluminium foil.

21. A material comprising a metal or metal alloy having a porous metal oxide layer on each side, wherein the metal oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter.

22. A material comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter in the range of about 1.5nm to about 250 nm.

23. A material comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels with pores having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the metal oxide layer has a diameter greater than about 20m²Surface area in g.

24. A kind ofA material comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels with pores having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the metal oxide layer has a diameter in the range of about 20m²G and about 40m²Surface area between/g.

25. A flexible sheet comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels with pores having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the metal oxide layer has a diameter in the range of about 20m²G and about 40m²Surface area between/g.

26. A flexible sheet comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels with pores having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the metal oxide layer has a diameter in the range of about 20m²G and about 40m²A surface area between/g, and wherein the aluminum alloy has a thickness between about 3 and 10 microns.

27. A method for preparing a material as defined in claim 1, comprising anodizing the metal or metal alloy in the presence of an electrolyte, wherein the voltage is varied throughout the anodizing.

28. The method of claim 27, wherein the voltage varies between about 0V and about 400V, or between about 0V and about 200V, or between about 0V and about 180V, or between about 0V and about 140V throughout the anodization.

29. A method according to claim 27 or claim 28 wherein the voltage is varied throughout the anodising by first increasing the voltage linearly and then applying the voltage in a series of pulses.

30. The method of claim 29, wherein linearly increasing the voltage comprises: the voltage is increased at a rate between about 0.05V/s and about 0.3V/s or at a rate between about 0.1V/s and about 0.2V/s.

31. The method of claim 29 or claim 30, wherein applying the voltage in a series of pulses comprises: the voltage is repeatedly switched every second between a voltage between 100V and 200V and 0V.

32. The method of any one of claims 29 to 31, wherein the voltage is increased linearly for a time period of between about 10 minutes and about 30 minutes or between about 10 minutes and about 20 minutes.

33. The method of any one of claims 29 to 32, wherein the voltage is increased linearly starting from 0V.

34. The method of claim 33, wherein the voltage is increased linearly from 0V to a voltage between 100V and 200V, or to a voltage between 120V and 180V, or to a voltage between 130V and 150V, or to about 140V.

35. The method of any one of claims 29 to 34, wherein the voltage is applied in a series of pulses for a time period of between about 30 minutes and 150 minutes, or for a time period of between about 50 minutes and 150 minutes, or for a time period of between about 90 minutes and 150 minutes, or for a time period of between about 120 minutes and 150 minutes.

36. The method of any one of claims 27 to 35, wherein the electrolyte is phosphoric acid.

37. The method of any one of claims 27 to 36, wherein anodizing may be performed at a temperature between about 0 ℃ and about 10 ℃ or at a temperature of about 5 ℃.

38. Use of a material according to any one of claims 1 to 26 for absorbing one or more gases.

39. The material of claim 38, wherein the one or more gases is ethylene, carbon dioxide, or oxygen.

40. A method of preserving a product comprising placing the material of any one of claims 1 to 26 in the vicinity of the product.

41. The method of claim 40, comprising placing the product in a container with the material.

42. The method of claim 40, comprising placing the product with the material in a container and sealing the container.

43. The method of claim 42, wherein the container is flushed with an inert gas prior to sealing.

44. The method of claim 40, comprising wrapping the product with the material.

45. The method of any one of claims 40 to 44, wherein the product is a perishable product.

46. The method of claim 45, wherein the perishable product is a fruit or a vegetable.

47. The method of claim 46, wherein the perishable product is fruit.

48. The method of claim 47, wherein the fruit is banana, apple or cherry.

49. A method for slowing the ripening of fruit produce comprising placing a material according to any one of claims 1 to 26 in the vicinity of the produce.

50. The method may include placing the fruit product in a container with the material.

51. The method may include placing the fruit product with the material in a container and sealing the container.

52. The method of claim 51, wherein the container is flushed with an inert gas prior to sealing.

53. The method according to claim 49, comprising wrapping the fruit product with the material.

54. The method of any one of claims 49 to 53, wherein the fruit product is banana, apple or cherry.

55. Use of a material according to any one of claims 1 to 26 for refreshing a product.

56. Use of a material according to any one of claims 1 to 26 for slowing the ripening of fruit products.

57. A method for purifying water comprising contacting the water with a material according to any one of claims 1 to 26.

58. A material obtained by the method of any one of claims 27 to 37.

Technical Field

The present invention relates generally to the field of material science. More particularly, the present invention relates to porous materials comprising metals and metal oxides, their preparation and use.

Background

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

Porous materials such as Anodized Aluminum (AAO) are self-organizing materials having a honeycomb structure formed by a high density array of uniform and parallel pores. Porous AAOs are formed by electrochemical oxidation (anodization) of aluminum in an acidic electrolyte. By using the new anodization process, the present inventors have prepared improved metal-based materials with porous oxide layers that find applications in many different fields, particularly in the field of fruit preservation.

Disclosure of Invention

In a first aspect, the present invention provides a material comprising a metal or metal alloy, wherein the metal or metal alloy has at least one porous metal oxide layer thereon.

The metal may be aluminium, copper, iron, zinc, manganese, palladium or titanium. In one embodiment, the metal is aluminum.

The metal alloy may be an aluminum alloy or a zinc alloy. In one embodiment, the alloy is an aluminum alloy.

The aluminum alloy may comprise or consist of Al and one or more of copper, iron, zinc, manganese, palladium, silicon or titanium.

The aluminum alloy may comprise at least 90%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99% Al by weight.

In one embodiment, the metal alloy is aluminum foil.

The material may have a thickness of about 1 micron to about 1 mm.

The metal oxide layer may have a thickness of between about 300nm and 1 mm.

The metal or metal alloy may have a thickness of between about 100nm to about 50 microns.

The metal oxide layer may have a three-dimensional disordered network of channels, the pores in the network of channels having a non-constant diameter.

The pores may have a non-constant diameter in the range of about 1.5nm to about 250nm, or about 1.5nm to about 200 nm.

The metal oxide layer may have a thickness of about 200cm³G to about 600cm³A non-constant pore volume in the range of/g.

The metal oxide layer may have a thickness of about 20m²G to about 50m²Surface area between/g.

The material may be flexible.

The material may be in the form of a sheet.

The metal or metal alloy may have a metal oxide layer on each side.

The material may be attached to a base structure.

The substrate structure may be wood, glass, quartz, silicon, waterproof paper, plastic or cloth.

In one embodiment of the first aspect of the invention, there is provided a material comprising a metal or metal alloy having a porous metal oxide layer on each side, wherein the metal oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter.

In another embodiment of the first aspect of the invention, there is provided a material comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter in the range of about 1.5nm to about 250 nm.

In another embodiment of the first aspect of the invention, there is provided a material comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the metal oxide layer has a diameter greater than about 20m²Surface area in g.

In another embodiment of the first aspect of the invention, there is provided a material comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the gold is present in the pores of the network of channelsThe metal oxide layer has a thickness of about 20m²G and about 40m²Surface area between/g.

In another embodiment of the first aspect of the invention, there is provided a flexible sheet comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter in the range of about 1.5nm to about 250nm, and wherein the metal oxide layer has a diameter in the range of about 20m²G and about 40m²Surface area between/g.

In another embodiment of the first aspect of the invention, there is provided a flexible sheet comprising an aluminum alloy having a porous oxide layer on each side, wherein the oxide layer has a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter in the range of about 1.5nm to about 250nm, wherein the metal oxide layer has a diameter in the range of about 20m²G and about 40m²A surface area between/g, and wherein the aluminum alloy has a thickness between about 3 microns and 10 microns.

In a second aspect, the present invention provides a method for preparing a material as defined in the first aspect, comprising: anodizing the metal or metal alloy in the presence of an electrolyte, wherein the voltage is varied throughout the anodizing.

The voltage may vary between about 0V and about 400V, or between about 0V and about 200V, or between about 0V and about 180V, or between about 0V and about 140V throughout anodization.

The voltage may be varied throughout the anodization by first linearly increasing the voltage and then applying the voltage in a series of pulses.

Linearly increasing the voltage may include increasing the voltage at a rate between about 0.05V/s and about 0.3V/s, or at a rate between about 0.1V/s and about 0.2V/s.

Applying the voltage in a series of pulses may include repeatedly switching the voltage between 100V and 200V and 0V per second.

The voltage may be increased linearly for a period of time lasting between about 10 minutes and about 30 minutes, or between about 10 minutes and about 20 minutes.

The voltage can be increased linearly from 0V.

The voltage may be increased linearly from 0V to a voltage between 100V and 200V, or to a voltage between 120V and 180V, or to a voltage between 130V and 150V, or to a voltage of about 140V.

The voltage may be applied in a series of pulses for a period of time between about 30 minutes and 150 minutes, or for a period of time between about 50 minutes and 150 minutes, for a period of time between about 90 minutes and 150 minutes, or for a period of time between about 120 minutes and 150 minutes.

The electrolyte may be phosphoric acid.

Anodization may be performed at a temperature between about 0 ℃ and about 10 ℃, or at a temperature of about 5 ℃.

In a third aspect, the present invention provides the use of a material of the first aspect for absorbing one or more gases.

The one or more gases may be ethylene, carbon dioxide and/or oxygen.

In a fourth aspect, the present invention provides a method for preserving a product comprising placing the material of the first aspect in proximity to the product.

The method may include placing the product in a container with the material.

The method may include placing the product with the material in a container and sealing the container.

The container may be flushed with an inert gas prior to sealing.

The method may include wrapping the product with the material.

The product may be a perishable product.

The perishable product may be a fruit or a vegetable.

The fruit may be banana, apple or cherry.

In a fifth aspect, the present invention provides a method for slowing the ripening of fruit produce, comprising placing the material of the first aspect in the vicinity of the produce.

The method may include placing the fruit product in a container with the material.

The method may include placing the fruit product with the material in a container and sealing the container.

The container may be flushed with an inert gas prior to sealing.

The method may include wrapping the fruit product with the material.

The fruit product may be banana, apple or cherry.

In a sixth aspect, the present invention provides the use of the material of the first aspect for refreshing a product.

The product may be as described in the fourth aspect.

In a seventh aspect, the present invention provides the use of the material of the first aspect for slowing ripening of fruit products.

In an eighth aspect, the present invention provides a method for purifying water comprising contacting water with the material of the first aspect.

In a ninth aspect, the present invention provides a material obtained by the method of the second aspect.

Define a limit

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. Thus, in the context of this specification, the term "comprising" means "including primarily, but not necessarily solely".

In the context of this specification, the terms "a" and "an" are used herein to refer to one or more than one (i.e., at least one) of the grammatical object. For example, "an element" means one element or more than one element.

The term "about" is understood to refer to a range of numerical values that one of ordinary skill in the art would consider equivalent to the recited values in the context of performing the same function or result.

Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1: time dependence of voltage associated with the preparation of a material according to one embodiment of the present invention.

FIG. 2: a graph of nitrogen absorption and pore volume for a material prepared according to one embodiment of the present invention.

FIG. 3: a material prepared according to one embodiment of the invention, wherein: (a) is a photograph of a sample of material; (b) is a schematic diagram of the material structure, (c) and (d) are SEM images showing a top view and a side view, respectively. It can be seen that the pores are disordered and have different pore sizes.

FIG. 4: energy dispersive X-ray spectroscopy (EDS) measurements and elemental mapping of aluminum foil used to prepare a material according to one embodiment of the invention.

FIG. 5: EDS measurements and elemental mapping of materials made from aluminum foil, according to one embodiment of the invention.

FIG. 6: XRD patterns of materials prepared according to one embodiment of the present invention after calcination at 1400 ℃.

FIG. 7: appearance of bananas using different preservation methods from day 1 to day 40. (a) The banana cluster is shown before the freshness test begins. (b) The state of bananas after 10 days of storage is shown, with banana #1 on the left, banana #2 in the middle and banana #3 on the right. (c) The status of bananas #2 and #3 after 40 days of storage is shown, with banana #2 on the left and banana #3 on the right.

FIG. 8: appearance of banana #2 and banana #3 on day 48. Banana #2 is on the left and banana #3 is on the right.

FIG. 9: using KMnO₄And DA index of apples preserved with a material (denoted "Tec") prepared according to one embodiment of the present invention.

FIG. 10: photographs of apples after storage for 81 days (above dashed line) in the presence of a material prepared according to one embodiment of the invention and 81 days (below dashed line) under controlled conditions.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The present invention broadly relates to a material comprising a metal or metal alloy having at least one porous metal oxide layer thereon.

In some embodiments, the metal is aluminum, zinc, or a first or second row transition metal. In other embodiments, the metal is aluminum, copper, iron, zinc, manganese, palladium, or titanium. In one embodiment, the metal is aluminum. The metal alloy may be an aluminum alloy or a zinc alloy. The aluminum alloy may include or consist of aluminum and one or more of copper, iron, zinc, manganese, palladium, silicon, titanium, and unavoidable impurities. The aluminum alloy may comprise at least 80%, or at least 81%, or at least 82%, or at least 83%, or at least 84%, or at least 85%, or at least 86%, or at least 87%, or at least 88%, or at least 89%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99% aluminum by weight or by mole percent. In one embodiment, the metal alloy is aluminum foil.

The material may have a thickness of between about 5 microns and about 1mm, or between about 5 microns and about 500 microns, or between about 5 microns and about 400 microns, or between about 5 microns and about 300 microns, or between about 5 microns and about 200 microns, or between about 5 microns and about 100 microns, or between about 5 microns and about 90 microns, or between about 5 microns and about 80 microns, or between about 5 microns and about 70 microns, or between about 5 microns and about 60 microns, or between about 5 microns and about 50 microns, or between about 5 microns and about 40 microns, or between about 5 microns and about 30 microns, or between about 5 microns and about 20 microns, or between about 5 microns and about 15 microns, or between about 7.5 microns and about 12.5 microns.

The metal oxide layer may have a thickness of between about 300nm and about 1mm, or between about 1 micron and about 100 microns, or between about 1 micron and about 90 microns, or between about 1 micron and about 80 microns, or between about 1 micron and about 70 microns, or between about 1 micron and about 60 microns, or between about 1 micron and about 50 microns, or between about 1 micron and about 40 microns, or between about 1 micron and about 30 microns, or between about 1 micron and about 20 microns, or between about 5 microns and about 15 microns, or about 10 microns.

The metal or metal alloy may have a thickness between about 100nm and about 50 microns, or between about 500nm and about 50 microns, or between about 1 micron and about 40 microns, or between about 1 micron and about 30 microns, or between 1 micron and about 20 microns, or between about 5 microns and about 15 microns, or between about 3 microns and about 10 microns.

In some embodiments, the metal oxide layer comprises a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter. Thus, the material may be both mesoporous and microporous. In some embodiments, the pores have a non-constant diameter in the range of about 1.5nm to about 250nm, or about 1.5nm to about 200 nm.

The metal oxide layer may have a thickness of about 200cm³G and about 600cm³Between/g, or at about 250cm³G and about 600cm³Between/g, or at about 250cm³Between/g and about 550cm3/g, or at about 275cm³G and about 500cm³Between/g, or at about 300cm³G and about 500cm³Between/g, or at about 350cm³G and about 450cm³Between/g, or at about 375cm³G and about 425cm³Between/g, or about 400cm³Non-constant pore volume in g.

The metal oxide layer may have a thickness of about 20m²G and about 50m²Between/g, or about 20m²G and about 48m²Between/g, or about 20m²G and about 46m²Between/g, or about 20m²G and about 44m²Between/g, or about 20m²G and about 42m²Between/g, or about 20m²G and about 40m²Between/g, or about 20m²G and about 38m²Between/g, or about 20m²G and about 36m²Between/g, or about 20m²G and about 34m²Between/g, or about 20m²G and about 30m²A ratio of,Or at about 22m²G and about 28m²Between/g, or at about 23m²G and about 27m²Between/g, or about 26m²Surface area in g.

In some embodiments, the material is a flexible sheet.

In some embodiments, the metal or metal alloy may have a metal oxide layer on each side. In case the material comprises only a single metal oxide layer, the material may be attached to the base structure. Examples of substrate structures include, but are not limited to, wood, glass, quartz, silicon, water-resistant paper, plastic, and cloth. The substrate structure may be any structure that is not sensitive to the acid used in the anodization process.

The material according to the invention can be conveniently prepared at low cost starting from the selected metal or metal alloy in a single anodization step. The voltage is continuously varied throughout the anodization process. Without wishing to be bound by any particular theory, the inventors believe that continuously varying the voltage throughout the anodization process provides a highly porous oxide layer having a three-dimensionally disordered network of channels, the pores in the network of channels having a non-constant diameter. This optimizes the porosity and surface area of the resulting material. The surface area of the material may be about 0.1m specific surface area²The known ordered anodized aluminum oxide per gram is mostly more than two orders of magnitude.

After the anodization process, the metal in the oxide layer is oxidized. For example, Al will change to Al₂O₃Or Al_xO_yFe will become FeO or Fe₂O₃Cu will become CuO or Cu₂O。

In some embodiments, the voltage is varied throughout the anodization process by first linearly increasing the voltage, for example, at a rate between about 0.05V/s and about 0.3V/s, or at a rate between about 0.1V/s and about 0.2V/s, and then applying the voltage in a series of pulses.

The voltage may be linearly increased from 0V for a time period between about 10 minutes and about 30 minutes, or between about 10 minutes and about 20 minutes. The voltage may be increased linearly from 0V to a voltage between 100V and 200V, or to a voltage between 120V and 180V, or to a voltage between 130V and 150V, or to a voltage of about 140V.

The voltage may be applied in a series of pulses for a period of time between about 30 minutes and 150 minutes, or for a period of time between about 50 minutes and 150 minutes, for a period of time between about 90 minutes and 150 minutes, or for a period of time between about 120 minutes and 150 minutes.

The electrolyte may be phosphoric acid, however those skilled in the art will appreciate that other acids may be used, such as sulfuric acid, nitric acid, and oxalic acid. In some embodiments, mixtures of one or more acids may be used.

Typically, anodization is performed at a temperature between about 0 ℃ and about 10 ℃. In some embodiments, the anodization is performed at a temperature of about 5 ℃.

It has been found that by starting with an aluminium alloy (aluminium foil) and using the following anodising method, it is possible to produce an oxide layer with a high porosity on either side, a surface area of about 26g/m²A pore diameter in the range of 1.5nm to 200nm and a pore volume up to about 400cm³Per g of aluminum-based material.

Phosphoric acid electrolyte (0.3M) and a temperature of 5 ℃.

Linearly increasing the voltage from 0V to 140V at a rate of about 0.16V/s, followed by:

applying a pulse voltage of 140V/0V per second; and wherein

Total anodising time 150 minutes.

In the case of anodizing the alloy, it will be understood that a plurality of oxides will be produced corresponding to one or more of the constituent metals. When anodization is performed on pure or high purity metals, oxides of other metals may be incorporated into the metal oxide layer during anodization by using a counter electrode corresponding to the metal oxide desired to be incorporated.

Depending on the intended use of the material, it may be desirable to include one or more transition metal oxides, such as copper and iron, in the oxide layer.

The morphology of the structure may be altered by altering one or more of the anodization parameters: voltage, temperature, acid, electrolyte, and time range.

In the case of materials attached to the base structure, a metal or metal alloy layer must be attached to the base structure before anodization proceeds.

The material according to the invention may be used for capturing/absorbing gases such as, for example, ethylene, carbon dioxide and/or oxygen. The material may also be used for preserving products, such as perishable products like fruits and vegetables, and for slowing the ripening of fruits.

When used for preserving/slowing fruit ripening, it has been found that it is not necessary to wrap the fruit with this material. Much less material can be used to achieve a freshness effect than is required to wrap each fruit. For example, a freshness-preserving effect can be achieved by placing a piece of material in a container together with the fruit and sealing the container. Boxes/containers for transporting and storing fruit can be configured with this material to preserve the fruit while being transported and stored. The freshness effect has been found to last up to 10 weeks.

Fruit preservation using the material according to the invention is significantly more cost-effective than other alternatives such as refrigeration and refrigeration combined with a controlled inert atmosphere.

In both domestic and commercial environments, materials may be placed in the cold storage section of a refrigerator or in the bottom of a fruit bowl to help keep freshness.

Fruits that may be preserved using the method of the present invention include, but are not limited to, bananas, apples, and cherries.

Examples of the invention

EXAMPLE 1 preparation of an aluminium alloy-based Material

Aluminum foil (DSD aluminum, 97% purity) was anodized in an electrochemical cell to form mesoporous and microporous metal oxide layers on both sides of the foil.

Anodization uses an aluminum anode and a carbon cathode. The cell included a jacketed glass beaker connected to a water cooler (John-Mirror). Cooling water was supplied to a jacketed glass beaker to control the temperature of the electrolyte. Phosphoric acid (0.3M) was used as the electrolyte, and the temperature of the electrolyte was maintained at about 5 ℃ throughout the process. The voltage is varied continuously in order to be able to produce a three-dimensionally disordered network of channels in the metal oxide layer, the pores in the network of channels having a non-constant diameter. The voltage initially increases linearly from 0V to 140V at a rate of about 0.16V/s, and then switches repeatedly every second between 140V and 0V at pulsed voltages. FIG. 1 shows the time versus voltage for a total anodization time of 9000 seconds.

Figure 2 shows BET measurements of the prepared materials. Calculated surface area 26.4m²/g。

Fig. 3 depicts photographs, structures and SEM images of the prepared materials.

Figure 4 shows EDS and elemental mapping of the aluminum foil prior to anodization. (a) The aluminum foil used is shown to contain aluminum, iron, copper and silicon. All elements are evenly distributed in the foil. After anodization, the surface converts to an oxide phase.

Figure 5 shows EDS and mapping of the anodized aluminum layer. The oxygen peak is clearly seen in the map. Phosphorus is also present in the fabricated structure presumably from the electrolyte. To identify the element, a sample of the material prepared was calcined at 1400 ℃ for 3 hours. XRD analysis showed the production of AIPO upon anodization₄(see fig. 6).

EXAMPLE 2 use of Material for preserving bananas

Six green bananas from a single string aerated with ethylene were collected from the flemington market, new south welsh, australia (see fig. 7 (a)). After separation, banana #1 was selected as a control sample and placed in a glass container (11.5cm × 19cm × 6cm) and sealed in a zipper lock bag. Nitrogen was applied to purge air from the bag. Banana #2 was subjected to the same conditions as banana #1, except 0.8g KMnO₄The powder is added to the bottom of the container. Banana #3 was covered with the material prepared as in example 1 above. Bananas #1, #2 and #3 were then placed in the dark for the following periods of time. Then using DA instrumentThe chlorophyll content of each banana was measured. DA instrumentThe DA index was allowed to be determined, ranging from 0, indicating maximum maturation, to 5, indicating complete acidification.

After 10 days, banana #1 turned yellow, while bananas #2 and #3 remained somewhat green, as shown in fig. 7 (b). After 40 days, bananas #2 and #3 were a mixture of yellow and green (fig. 7 (c)). After 48 days, bananas #2 and #3 both turned yellow. However, banana #2 possesses many black spots and is internally contaminated. Banana #3 remained yellow and remained uncontaminated inside (see fig. 8).

The test shows that the material of the invention is more KMnO than KMnO in the aspect of banana preservation₄Is more effective.

EXAMPLE 3 use of materials for keeping apples fresh

The material prepared as described in example 1 above (2 pieces of 22.5cm x 15.0cm each) was placed in a glass container having the following dimensions: 23 cm x 35 cm x 6 cm. Four apples were then placed on top of the material. To retain moisture, a slightly moist tissue is also placed in the container. The entire container was covered with aluminum foil and stored at room temperature in the dark.

Six glass containers having the following dimensions are also provided: 11.5cm by 19cm by 6 cm. Each pair of containers was prepared as follows:

a. two apples were placed in a container on top of the material prepared as described in example 1 above. The size of the material is 22.5cm multiplied by 15.0 cm;

b. 0.8g of KMnO₄The powder was spread evenly on the bottom of the container and the soft tissue was placed in KMnO₄On top of the powder, two apples were placed on top of a paper towel.

c. Two apples were placed in a container (control).

All containers were covered with aluminum foil and then sealed in zipper lock bags. The bag was purged with nitrogen to remove air and stored at room temperature in the dark.

After 24 days, use DA instrumentThe level of chlorophyll in the apples was measured. As shown in FIG. 9, all apples had chlorophyll on day 1The levels are similar, about 0.20-0.25. However, after 24 days, the chlorophyll content of apples preserved using this material decreases much more slowly than apples stored under its conditions. This clearly shows that the rate of ripening is significantly reduced in the presence of the present material. In addition, control apples rotted after 32 days, and KMnO after 35 days₄The preserved apples are also rotten. At 81 days, apples that were kept fresh using only the material as described in example 1 did not rot (see fig. 10).

Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.