ADSORBENT PARTICLE PROCESS MANAGEMENT

Abstract

A method is provided for managing microporous and/or mesoporous and/or macroporous small particle adsorbent powders within a manufacturing process to minimize atmospheric dust. The adsorbent powder is processed by spray-drying to form larger diameter spherical particles. The larger diameter spherical particles are then dispersed in a controlled manner so as to be brought into intimate contact with a substrate. The resultant powder-and-substrate matrix is then subjected to an alternating electrical field (AEF) via an alternating power supply, thereby to reduce the spray-dried powder back to its original small particle state, whilst remaining in intimate contact with the substrate.

Claims

1. A method for processing microporous and/or mesoporous and/or macroporous adsorbent particles comprising: agglomerating the microporous and/or mesoporous and/or macroporous adsorbent particles, by a spray-drying process, to produce a generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder; activating the agglomerated powder by a heating process; bringing the activated agglomerated powder into intimate contact with a substrate to form a powder-substrate matrix; and subjecting the powder-substrate matrix to an alternating electrical field (AEF), to reduce the powder to its pre-agglomerated particle size and state, whilst remaining in intimate contact with the substrate.

2. A method as claimed in claim 1, wherein the generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder has a mean particle size in the range of from 20 m-1000 m.

3. A method as claimed in claim 1, wherein the heating comprises heating the agglomerated powder to a temperature of at least 125 C. for a period of at least 30 minutes.

4. A method as claimed in claim 1, wherein the AEF is generated by a high voltage alternating power supply, optionally with an alternating voltage in a range of from 1 kV to 250 kV.

5. A method as claimed in claim 1, wherein the activating further comprises purging the agglomerated powder with a dried gas, subsequent to the heating.

6. A method as claimed in claim 1, wherein the subjecting is carried out at substantially atmospheric pressure.

7. A method as claimed in claim 1, wherein the microporous and/or mesoporous and/or macroporous adsorbent particles are selected from Zeolites and Metal Organic Frameworks.

8. (canceled)

9. A method as claimed in claim 1 wherein the microporous and/or mesoporous and/or macroporous adsorbent particles are hydrophilic.

10. A method as claimed in claim 1, wherein the microporous and/or mesoporous and/or macroporous adsorbent particles are hydrophobic.

11. A method as claimed in claim 1, wherein the substrate comprises fibres having a length in a range of from 1 mm to 25 mm, and wherein the bringing further comprises: dispersing the fibres within an air-laid chamber; introducing the activated agglomerated powder into the air-laid chamber at a controlled rate; transporting the resultant fibre-powder blend onto a gas-permeable conveyor transport; and applying a low pressure suction force under the gas-permeable conveyor transport to create a web of fibres in intimate contact with the powder.

12. A method as claimed in claim 1, wherein the substrate comprises an air permeable substrate, and wherein the bringing further comprises dispersing the activated agglomerated powder onto a surface of the air-permeable substrate at a controlled rate.

13. A method according to claim 12, wherein the air permeable substrate is fibrous and/or selected from a non-woven fabric, a paper, a woven fabric, and a felt.

14. (canceled)

15. A method as claimed in claim 12, wherein the air permeable substrate is an open cell foam.

16. A method as claimed in claim 12, wherein the air permeable substrate is compostable.

17. A method as claimed in claim 12, further comprising laminating at least one surface of the powder-substrate matrix with a polymer sheet.

18. A method as claimed in claim 17, wherein the polymer sheet is compostable.

19. A method as claimed in claim 17, wherein the polymer sheet is perforated.

20. A method as claimed in claim 17, wherein the polymer sheet is gas-permeable.

21. A method as claimed in claim 1, wherein the resultant powder-substrate matrix is consolidated by applying heat and/or pressure.

22. A method as claimed in claim 11, wherein the resultant powder-substrate matrix is subjected to a heated-through air process to consolidate the fibres by partial melting, and simultaneously to attach the partially melted fibres to powder particles incorporated in the powder-substrate matrix to prevent diffusion of the powder particles from the substrate.

Description

[0049] In order that the present invention may be fully understood, preferred embodiments thereof will now be described in detail, though by way of example only, with reference to the accompanying drawings, in which:

[0050] FIG. 1 shows a typical process layout for spray-drying an adsorbent powder to create a generally spherical, free-flowing, agglomerated adsorbent powder of particle size in the range of 20 m-500 m;

[0051] FIG. 2 shows a typical process layout for incorporating a generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder within an air-laid, non-woven construction and subsequently subjecting the resulting formed web to an Alternating Electrical Field (AEF);

[0052] FIG. 3 shows a typical process layout for dispersing a generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder onto the surface of a pre-manufactured fibrous or porous substrate, and subjecting the resulting matrix to an AEF;

[0053] FIG. 4 shows a typical process layout for applying the generally spherical, free-flowing, agglomerated adsorbent powder by the powder coating process to a pre-manufactured fibrous or porous substrate, and then subjecting the resulting matrix to an AEF; and

[0054] FIG. 5 shows a schematic general arrangement of a typical AEF system.

[0055] Referring first to FIG. 1, there is shown a typical process layout, generally indicated 100, for spray-drying an adsorbent powder. An adsorbent powder and water solution, suspension or mixture 10 is fed into a nozzle 3, coincident with an atomising gas 9. The resulting mixture exits the nozzle 3 in a spray configuration into a drying chamber 4, where it is mixed with a drying gas 1, that has been heated by a heating element 2. After exiting the drying chamber 4, the now dried, generally spherical, free-flowing, agglomerated adsorbent powder passes into chamber 5 prior to entering the cyclone chamber 6. Within the cyclone chamber 6, the dried, generally spherical agglomerated powder is collected in the bottom of the chamber 8, whilst the drying gas exits the system via a discharge orifice 7.

[0056] Referring now to FIG. 2, there is shown a typical process layout, generally indicated 200, for forming an air-laid web structure 15. The air-laid web structure 15 is formed by blending fibres, introduced into an air-laid chamber 13 via port 12, in combination with the generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder emerging from the spray-drying step described above with reference to FIG. 1, which is injected into the air-laid chamber 13 via port 11. The web is formed by the forming head 14 and transported to a conveyor system 16. The fibre and powder web matrix is then transported through an Alternating Electrical Field (AEF) system 17, 18 where the powder is reduced to its original pre-agglomerated state whilst remaining in intimate contact with the fibre matrix 15. Immediately after the AEF process, the now AEF-treated fibre and adsorbent powder matrix 19 may be consolidated into a thin structure 21 by heated compression rollers 20.

[0057] Referring now to FIG. 3, there is shown a typical process layout, generally indicated 300, for dispersing a generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder 26 onto a pre-manufactured non-woven substrate 22. The powder 26 is dispersed onto the surface of the pre-manufactured non-woven substrate 22 via a conventional metered scattering head 25 which in turn is fed by a hopper 23 where the generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder emerging from the spray-drying step described above with reference to FIG. 1 is stored in bulk form 24. After dispersing the powder 26 onto the surface 27 of the pre-manufactured non-woven 22, the fabric and adsorbent powder matrix is then transported through an AEF system 17, 18 where powder is reduced to its original pre-agglomerated state, whilst remaining in intimate contact with the fabric matrix. Immediately after the AEF process, the now AEF-treated fabric and adsorbent powder matrix 19 may be consolidated into a thin structure 21 by heated compression rollers 20.

[0058] Referring now to FIG. 4, there is shown an alternative process layout, generally indicated 400, for dispersing the generally spherical, free-flowing, spray-dried, agglomerated adsorbent powder 26 emerging from the spray-drying step described above with reference to FIG. 1, onto a pre-manufactured non-woven substrate 22. The powder 26 is dispersed onto the surface 27 of the substrate 22 via an automated powder coating gun 28 which is fed from a pump via tube 30. Simultaneously, a positive electrostatic charge is applied to the adsorbent powder 26 as it is discharged, at 29, from the automated powder coating gun onto the surface 27 of the non-woven fabric substrate 22. The powder 26 is attracted to the non-woven fabric substrate 22 by the transport system 32 of the non-woven fabric substrate 22 being earthed, at 31. The non-woven fabric and adsorbent powder matrix is then transported through an AEF system 17, 18 where the powder is reduced to its original pre-agglomerated state, whilst remaining in intimate contact with the fabric matrix. Immediately after the AEF process, the fabric and adsorbent powder matrix 19 may be subjected to a heated-through air process 33 to consolidate the fibres of the pre-manufactured non-woven substrate by partial melting, whilst simultaneously attaching said fibres to the powder particles now in their original pre-agglomerated state, again by partial melting of the fibres.

[0059] Referring now to FIG. 5, there is shown a schematic representation of a typical general arrangement of an Alternating Electrical Field (AEF) system, generally indicate 500, as utilised in the process steps described above with reference to FIGS. 2 to 4. A discharge gap 36 is situated between high voltage electrodes 34 separated by barrier material 35. A high voltage alternating current generator 37 and grounding point 38 completes the system. The Alternating Electrical Field is applied to the target material within the discharge gap 36 at atmospheric pressure.

EXAMPLE 1

[0060] Cellulosic fibres in a range of lengths between 5 mm-15 mm were fed into the receiving chamber of a pilot line air-laid, non-woven fabric manufacturing machine at a target areal weight of 50 gm.sup.2 (gsm), coincident with activated, generally spherical, spray-dried, free-flowing agglomerated adsorbent powder, wherein the particle size of at least 95% of the powder was in the range of 100 m-150 m in diameter, at an areal target dispersion weight of 50 gm.sup.2 (gsm). The resulting blend of fibres and powder was transported onto a mesh conveyor and subjected to a low air pressure suction force to create the basic web of a fibre and powder matrix. The web matrix was then subjected to an AEF discharge field of 25 kV and 55 Hz at the rate of at least 0.5 seconds per linear meter. After exposure to the AEF, the web was then subjected to a high pressure, heated nip-roll system to consolidate the fibres into a sheet, whilst coincidentally encapsulating the now processed adsorbent powder within the fibre matrix.

[0061] Samples were taken of the now processed adsorbent powder from randomly selected sections of the manufactured roll and were measured for particle size distribution by means of laser diffraction spectrometry. More than 98% of the particles were found to be in the range of 0.5 m-4 m, thereby maximising the adsorbent efficiency of the powder.

EXAMPLE 2

[0062] A pre-manufactured, polyester fibre, non-woven fabric of areal weight 50 gm.sup.2 (gsm) was scattered on one surface with an activated, generally spherical, spray-dried, free-flowing, agglomerated adsorbent powder, wherein the particle size of at least 95% of the powder was in the range of 100 m-150 m in diameter, via a conventional controlled scattering device at a rate of 50 gm.sup.2 (gsm). Immediately following the controlled scattering process, the non-woven fabric and adsorbent powder matrix was subjected to an AEF of 25 kV and 55 Hz for a period of at least 0.5 seconds per linear meter, and then rewound via a tensioning device to create a roll.

[0063] The non-woven fabric and adsorbent powder matrix was then laminated on both surfaces in a secondary process, with a polymer alloy sheet of polybutyrate adipate terephthalate (Polybutyrate or PEAT) and polylactic acid (PLA) at 40 m thickness, using a polylactic acid based adhesive system to create a laminate structure suitable for containing liquids, whilst simultaneously adsorbing odours emanating from those liquids or liquid vapours.

[0064] Upon inspection of sections of the roll taken at random from the entire length of the manufactured roll, it was found that the powder had reverted back to its original state and particle size.

[0065] Samples were taken of the now processed adsorbent powder from the randomly selected sections of the manufactured roll, and were measured for particle size distribution by means of laser diffraction spectrometry. More than 98% of the particles were found to be in the range of 0.5 m-4 m, thereby maximising the adsorbent efficiency of the powder.

EXAMPLE 3

[0066] A pre-manufactured, polyester fibre, non-woven fabric of areal weight 50 gm.sup.2 (gsm) was placed upon a conductive support which was connected to earth by a suitable copper grounding cable. The conductive support was located within an enclosed structure incorporating a negative pressure dust recovery system. Using a Nordson Encore HD Automatic Powder Gun, activated, generally spherical, spray-dried, free-flowing, agglomerated adsorbent powder, wherein the particle size of at least 95% of the powder was in the range of 100 m-150 m in diameter, was positively charged as it exited via said Powder Gun, assisted by dry compressed air, onto the surface of the now earthed non-woven fabric. The powder was attracted to the surface of the non-woven fabric due to the attractive electrostatic charge between the powder and the now grounded non-woven substrate. The target areal weight of dispersion of the adsorbent powder onto the surface of the non-woven fabric was 50 gm.sup.2 (gsm).

[0067] Following the dispersion of the adsorbent powder onto the surface of the non-woven fabric, the entire matrix was subject to an AEF of 25 kV and 55 Hz for a period of at least 0.5 seconds per linear meter of matrix.

[0068] The entire matrix was then subjected to a heated-through air process to partially melt the fibres of the non-woven fabric and thereby bond the fibres of the non-woven fabric together, whilst coincidentally bonding the now processed activated adsorbent powder to the fibres by partial melting of the fibres adjacent to said powder particles.

[0069] Samples were taken of the now processed adsorbent powder from randomly selected sections of the manufactured roll and were measured for particle size distribution by means of laser diffraction spectrometry. More than 98% of the particles were found to be in the range of 0.5 m-4 m thereby maximising the adsorbent efficiency of the powder.