WO2018130365A1 - Adsorber comprising polyelectrolyte layers and a particulate adsorber material on a carrier, use thereof, and breathing apparatus comprising the adsorber - Google Patents

Abstract

The invention relates to an adsorber comprising at least one carrier provided with polyelectrolyte material comprising anionic and cationic polyelectrolyte layers and a particulate adsorber material. The invention also relates to the use of the adsorber as a filter for breathing air or water, and to a breathing apparatus, such as a respirator or a respiratory circuit appliance provided with the adsorber.

Description

 Drägerwerk AG & Co. KGaA, Moislinger Allee 53-55, 23558 Luebeck

Adsorber comprising on a support polyelectrolyte layers and a particulate Adsorbermaterial, its use and respirator with the adsorber

The present invention relates to an adsorber comprising at least one carrier provided with polyelectrolyte material comprising anionic and cationic polyelectrolyte layers and a particulate adsorber material. Furthermore, the invention relates to the use of the adsorbent as a filter for breathing air or water and a respirator, such as a respirator or a breathing circuit device, equipped with the adsorber.

State of the art

Activated carbon is used as such and coated in filters of various kinds as Adsorbermaterial. If activated charcoal is also supplemented with metal salts, its capacity for many gaseous toxins is improved. This is e.g. described in DE10201 1 1 14133 A1. In addition to activated carbon, other inorganic adsorber materials are known. These include zeolites, bentonites or alumina. Boron nitride is also described as an adsorbent material, e.g. by Chen et at., Nature Comm. 2013, 1777.

Coatings of thin layers of polyelectrolytes on a carrier material are known. The layers can be prepared, for example, by alternately immersing a suitable support material in aqueous solutions of polycations and polyanions. In this way, coatings with a defined number of layers can be produced. This is described, for example, in DE 4026978 A1.

The article "Multifunctional layer-by-layer carbon nanotube-polyelectrolyte thin film for strain and corrosion sensing" by Kenneth J Loh, Junhee Kim, Jerome P Lynch, Nadine Wong Shi Kam and Nicholas A Kotov in Smart Materials and Structures, Volume 16, No. 2 (published February 9, 2007 - IOP Publishing Ltd.) discloses a layer construction of polyelectrolyte layers on carbon nanotubes. However, the above-described laminations have found no use as adsorbers for water or respiratory gases. Object of the invention

Object of the present invention is to provide novel adsorber for water, air or breathing gases. The adsorber material and any other active centers should be spatially decoupled, so that they can perform their function unaffected by each other, even against different pollutants to be bound.

Summary of the invention

The object of the invention is achieved by the subject matter of the independent claims. Advantageous embodiments are described in the subclaims or below.

The present invention relates to an adsorber comprising polyelectrolyte and particulate Adsobermaterial. The polyelectrolyte is characterized by a layered structure of polyelectrolyte layers (polyelectrolyte cation layer followed by polyelectrolyte anion layer and vice versa). Adsorber particles are incorporated in the polyelectrolyte. The adsorbers produced in this way can be used as filter materials, for example as inserts in gas masks or respiratory protection filters, or else as water filters. Furthermore, the present invention comprises a method for producing these adsorber materials.

For the incorporation of nonpolar materials in a polyelectrolyte layer, the surfaces of these non-polar materials advantageously have a sufficiently high electrical charge or polarizability. So the surface of activated carbon is non-polar. Although a small number of hydroxyl and / or carboxyl groups can be produced on the surface of such adsorber materials by any oxidation processes, this is not sufficient to permanently permanently install the adsorber materials in a polyelectrolyte layer.

To increase the polarity of the surface of nonpolar materials, for example, polyelectrolytes with hydrophobic side chains can be used. In this case, the hydrophobic side chains are ideally deposited on the surfaces of the nonpolar materials and the ionic groups of the polyelectrolytes orientate themselves to the outside and ensure a sufficient charge density on the surface. Whether this procedure also leads to success for activated carbon or boron nitride while retaining the adsorptive properties has not been known hitherto. For example, it could be assumed that the polyelectrolytes with their hydrophobic groups settle on the surface of the activated carbon or boron nitride particles in such a way that access to the pores of the adsorber materials is made difficult or even blocked, as a result of which the adsorption capacity should be drastically reduced.

It has now surprisingly been found that the adsorber materials are encased by the polyelectrolytes without great influence on the adsorption capacity. The investigations carried out have shown that the adsorber properties of the investigated adsorber materials are only slightly reduced in the polyelectrolyte layers. However, the prerequisite for this is that the particulate adsorber material used is brought into contact with a polyelectrolyte layer, advantageously coated in a separate step, so that incorporation into a polyelectrolyte layer on the support can be realized.

Detailed description of the invention

Suitable adsorbent materials are different activated carbons, zeolites, bentonites, alumina, silica gels, metal-organic frameworks (MOF ^'s ) but also supramolecular complexing agents such as cyclodextrins, cucurbiturils, calixarenes or resorcinarenes. Boron nitride can also be used as adsorbent material.

Suitable anionic polyelectrolytes with hydrophobic side chains are, for example, polystyrenesulfonate, polycarboxylic acids, poly (meth) acrylic acids, polyvinylphosphonic acid, polyphosphoric acid, pectins, amidopectins, alginates and heparins. Included here are polymers, also as copolymers, which have corresponding side groups, in particular carboxyl, sulfonic acid, sulfuric acid, phosphonic acid or phosphoric acid side groups.

Suitable cationic polyelectrolytes are, for example, polyvinylamine, polyvinylammonium chloride, polyethyleneimine and polyvinylpyridine. Included here are polymers, also as copolymers, which have corresponding side groups, in particular amine, imine or pyridine side groups. For coating the adsorber materials present as powder or granules, for example, an aqueous solution of the polyelectrolytes is suitable. Since boron nitride zBidR has a negative surface charge, a cationic polyelectrolyte such as polyvinylamine or polyethyleneimine should be suitably used to envelop the adsorber.

According to one embodiment of the invention, the particulate adsorber material is enveloped by either an anionic polyelectrolyte layer or a cationic polyelectrolyte layer, preferably by a cationic polyelectrolyte layer. According to another embodiment, the particulate adsorber material is first coated with a cationic followed by an anionic polyelectrolyte layer, or the particulate adsorbent material is first coated with an anionic followed by a cationic polyelectrolyte layer (the latter variant is preferred). A polyelectrolyte layer is preferred or not more than two complementary polyelectrolyte layers are applied to the particulate adsorber material. The cationic polyelectrolyte layer, in particular polyvinylamine, is preferably the only (particularly preferred) or the last polyelectrolyte layer on the particulate adsorber material.

The particulate adsorbent material may be "deposited" on a complementary polyelectrolyte layer of the carrier, but is preferably embedded in the sequence of polyelectrolyte layers on the carrier, respectively.

Also, inorganic salts, which are preferably sparingly soluble or even insoluble, can be coated in the form of powdered and / or granulated salts by means of anionic polyelectrolytes, such as polyvinylamine or polyethyleneimine. In this way, enveloped adsorber materials and coated metal salts can be incorporated separately into absorber layers of support materials, whereby the adsorber capacity of the activated carbon is not influenced by the metal salts, as is usually the case in the direct impregnation of the activated carbon with metal salts.

Suitable inorganic salts are copper, platinum, palladium and zinc salts. The layered structure of the polyelectrolyte layer has the advantage over direct impregnation of activated carbon with metal salts that the adsorber capacity of the adsorber materials is not reduced. The carrier is preferably a textile carrier material. Nonwovens, fiber bundles and fabrics, for example of plastic materials such as polyester and / or polyacrylamide but also glass and rockwool, are suitable as textile carrier matehal for applying the polyelectrolyte layers and the particulate adsorber. In order to achieve a sufficient surface charge, the starting materials are preferably first coated with a cationic polyelectrolyte, such as polyvinylamine or polyethyleneimine. Such modified polymer surfaces are suitable for the construction of polyelectrolyte layers.

The carrier can also be used untreated. However, pretreatment increases the adhesion on the fiber surface. The anchoring of linear polyvinylamines on textile surfaces is described in DE102005026596. A description of the polyvinylamine modification of surfaces for building molecular layers can also be found in: M. Meilikhov, K. Yusenko, E. Schollmeyer, C. Mayer, H.-J. Bushman, R.A. Fischer: "Stepwise deposition of metal organic frameworks on flexible synthetic polymer surfaces", Dalton Trans. 40, 4838 (201 1). This method can also be used for this method.

The coating of the adsorbent materials takes place in solutions of anionic or cationic polyelectrolytes, preferably in aqueous solutions. The polar adsorber materials can then be bound to a support. By alternately laminating the carrier material with cationic and anionic polyelectrolyte solutions, it is thus possible to produce polyelectrolyte layers with a defined layer thickness.

The enveloping of the adsorbent materials takes place in solution, preferably in aqueous solutions. The coated and therefore polar adsorbent materials can then be bound to a support.

The coating is applied, for example, by introducing the selected particulate adsorber or a mixture of different adsorbers or the inorganic salt or a mixture of different adsorbers into a solution of a suitable polyelectrolyte with stirring. In this way, the adsorber particles are coated with the polyelectrolyte and subsequently coated on a complementary polyelectrolyte layer by immersing a corresponding carrier with the complementary electrolyte layer as the outermost polyelectrolyte layer in the solution of the complementary polyelectrolyte and with the coated particulate adsorber or the coated particulate inorganic salt , The latter polyelectrolyte then also forms the next layer on the support

Between two solutions with complementary polyelectrolyes, preferably a rinsing solution, such as water, if appropriate plus wetting agent, is used to rinse off unbound constituents.

On the other hand, it is also possible to apply the particulate adsorber without coating to a suitable outer polyelectrolyte layer of the support and subsequently to cover it by a layer of a complementary polyelectrolyte and to install it in this case.

It is likewise possible initially to provide the particulate adsorber materials with a layer sequence of complementary polyelectrolytes before they are "docked" to a polyelectrolyte layer of the carrier, wherein the docking itself forms a polyelectrolyte layer on the carrier.

The following examples illustrate the invention without being limited to the examples.

1 . Production of coated carrier webs

The starting material used was a polyester (polyethylene terephthalate (PET)) fabric. For preparation, the textile material was immersed in an aqueous solution of polyvinylamine (c = 0.4 mmol / L) for about 5 minutes, then dried at 70 ° C and then fixed at 160 ° C for 6 minutes. Subsequently, the textile material was washed extensively with a methanol / water mixture (1: 1) to remove unreacted polyvinylamine from the surface. 2. Preparation of the polyelectrolyte-coated adsorber materials

2a: 0.35 g of pulverulent coal charcoal and 5 g of polystyrenesulfonic acid (PSSS) (18% strength by weight) were stirred into 100 ml of distilled water to give a dispersion.

2b: 3.5 g of pulverulent charcoal activated carbon and 5 g of polystyrenesulfonic acid (PSSS) (18% strength by weight) were stirred into 100 ml of distilled water to give a dispersion.

2c: 3.5 g of finely powdered coconut shell activated carbon and 5 g of polystyrene sulfonic acid (PSSS) (18% strength by weight) were stirred into 100 ml of distilled water to give a dispersion.

2d: 1.0 g of boron nitride powder was dispersed in 100 ml of distilled water and then 2.5 g of polyvinylamine (20-22% by weight) were added to the dispersion.

2e: 5.0 g of copper carbonate were dispersed in 100 ml of distilled water and then 4.8 g of polyvinylamine (20-22 wt.%) Were added to the dispersion.

3. Coating of the carrier material with a particulate adsorber component

3a: PET tissue equipped with fixed PVA was immersed in a dispersion of Example 2a for one minute. Thereafter, the textile material was washed with distilled water. It was then immersed in a 1% by weight aqueous solution of polyvinylamine for 1 minute. Then it was rinsed again with distilled water.

This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers. This is shown schematically in FIG.

3b: PET tissue equipped with fixed PVA was immersed in a dispersion of Example 2b for one minute. Thereafter, the textile material was washed with distilled water. It was then immersed in a 1% by weight aqueous solution of polyvinylamine for 1 minute. Then it was rinsed again with distilled water. This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers.

3c: PET tissue equipped with fixed PVA was immersed in a dispersion of Example 2c for one minute. Thereafter, the textile material was washed with distilled water. It was then immersed in a 1% by weight aqueous solution of polyvinylamine for 1 minute. Then it was rinsed again with distilled water.

This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers.

3d: PET fabric equipped with fixed PVA was washed with distilled water and then immersed in a 1% aqueous solution of polyacrylic acid (MW = 18000 Da) for 1 minute. Then it was rinsed again with distilled water. Thereafter, it was immersed in a dispersion of Example 2d for one minute.

This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers.

4. Coating of the carrier material with an adsorber component and a metal salt

4a: PET tissue equipped with fixed PVA was immersed in a dispersion of Example 2b for one minute. Thereafter, the textile material was washed with distilled water. It was then immersed for 1 minute in an aqueous dispersion of Example 2e. Then it was rinsed again with distilled water.

This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers. 4b: PET tissue equipped with fixed PVA was immersed in a dispersion of Example 2c for one minute. Thereafter, the textile material was washed with distilled water. It was then immersed for 1 minute in an aqueous dispersion of Example 2e. Then it was rinsed again with distilled water.

This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers.

4c: PET fabric equipped with fixed PVA was immersed in a dispersion of Example 2d for one minute. Thereafter, the textile material was washed with distilled water. It was then immersed for 1 minute in an aqueous dispersion of Example 2e. Then it was rinsed again with distilled water.

This process can be repeated as often as desired, according to the present example, it was repeated 20 times to increase the number of polyelectrolyte layers.

5. adsorber properties of the materials prepared according to Examples 3a-3d and 4a in aqueous media

It was found that the dye Basic Blue 3 (CAS number 33203-82-6) is well suited for investigating the adsorber properties in aqueous solutions. The adsorption measurements on the pure adsorber materials in aqueous solution took place spectrophotometrically at 654 nm. A solution of 10 ml of 1% solution of Basic Blue 3 was used, which was mixed with citrate buffer consisting of 19.2 g of citric acid and 4.0 g of solid sodium hydroxide 1 liter of water, made up to 1 liter. For this purpose, after a contact time of 300 minutes, in which the solution was shaken gently, the concentration decrease of the dye in the solution was determined. The following adsorber performance results were obtained:

Coal carbon particles: 1, 2 ± 0,3 mmol / g,

 Coconut shell activated carbon particles: 0.4 ± 0.1 mmol / g and

 Boron nitride powder: not determinable by the method

Copper carbonate: not determinable by the method To investigate the adsorber performance of the adsorber-containing polyelectrolyte-coated textile materials, samples obtained according to Examples 3a-d were used. The samples, the weight of which was accurately known, were immersed in 25 ml of the Basic Blue 3 solution for 300 minutes with gentle shaking of the solution. Subsequently, the spectrophotometric determination of the dye concentration in the solution.

By way of example, Figure 3 shows the adsorption of Basic Blue 3 by polyelectrolyte layers with hard coal particles on a fabric (Example 3a). As the number of layers of coal particles increases, so does the amount of dye adsorbed.

Taking into account the adsorber performance of this hard coal powder (1, 2 ± 0.3 mmol / g), it is possible to calculate the content of hard coal powder per gram of fabric and per layer of particulate adsorber material. Analogously, one obtains for all investigated tissues:

Tissue 3a: 0.6 ± 0.2 mg carbon per gram of tissue and layer,

Tissue 3b: 0.9 ± 0.2 mg carbon per gram of tissue and layer,

Tissue 3c: 0.4 ±. 0.1 mg of carbon per g of fabric and layer, and

3d tissue: no dye adsorption.

These results clearly show that the polyelectrolyte coating of the adsorber has no negative influence on the adsorption properties.

6. Characterization of Adsorber Material (Adsorber Component and Metal Salt) Prepared according to Example 4a

The detection of copper in the coating was carried out qualitatively with the aid of energy-dispersive X-ray spectroscopy. However, it was not possible to quantify the amount of copper, since the lowest layers are shielded as the number of polyelectrolyte layers increases.

Due to the interaction of the copper in the CuCO3 with the amino groups of the polyvinylamine, a change in the color of the surface of the particles is expected. This can be detected by UV-Vis spectroscopy. For this, one measures the reflection of the light on the samples. An increase in absorption is observed with increasing number of CuCO3-containing layers.

7. adsorber properties of the materials produced according to Examples 3a-3d and 4a with respect to noxious gases

2 x 2 cm and embedded in a reactor. Subsequently, the tissue with a volume flow of 0.25 L / min and 20 ° C and a humidity of 70% r. F. (relative humidity) and a predetermined concentration of noxious gas (see Table 1) flows through until the predetermined concentration of the noxious gas (desired limit) behind the coated fabric is reached. The filtered volume is measured.

For comparison, the fabric with 20 layers of pure Polyelektrolytbe- coating (10 times PSSS and 10 times PVA) was examined by the same method on its adsorbability and given an equivalent amount of the activated carbon and the boron nitride used on nonwoven. For this purpose, first a fleece with the edge length of 2 x 2 cm was embedded in the reactor and then the fine powder (from 2 b - d) distributed evenly with a glass rod on the nonwoven.

The results obtained are summarized in Table 1.

1 shows the schematic structure of polyelectrolyte layers on a carrier material (blue: polycations, red: polyanions). Between each immersion in a polyelectrolyte solution is rinsed with water. This corresponds to the first comparative example of Table 1

2 shows the schematic structure of polyelectrolyte layers on a carrier material (blue: polycations, red: polyanions) and coated adsorber material. Between each immersion in a polyelectrolyte solution is rinsed with water.

Fig. 3 shows the adsorption of the dye Basic Blue 3 on PET fabric which has been coated with polyelectrolyte layers containing hard coal activated carbon particles, depending on the number of activated carbon particle layers. Table 1 :

Filtered volume (in L) through the use of 4 cm ² coated tissue

 AS = hard coal activated carbon

AK = coconut shell activated carbon

BN = boron nitride

Claims

claims 1 . Adsorber comprising at least one carrier provided with polyelectrolyte material comprising anionic and cationic polyelectrolyte layers and a particulate adsorber material in or on the polyelectrolyte material. 2. Adsorber according to claim 1, wherein the particulate adsorbent material is selected from one or more members of the group comprising activated carbon, a zeolite, a bentonite, an alumina and boron nitride, preferably activated carbon and / or boron nitride. 3. Adsorber according to claim 1 or 2, wherein the particulate Adsorbermaterial is encased in either an anionic polyelectrolyte layer or a cationic polyelectrolyte layer, preferably a cationic polyelectrolyte layer, or  - The particulate Adsorbermaterial is first coated with a cationic followed by an anionic Polyelektrolytschicht, or  - The particulate Adsorbermaterial is first coated with an anionic followed by a cationic Polyelektrolytschicht and the coated particulate adsorbent material is preferably embedded in each of the polyelectrolyte layers of the adsorber. 4. Adsorber according to at least one of the preceding claims, wherein the particulate adsorber is boron nitride and is preferably coated with a cationic polyelectrolyte layer. 5. Adsorber according to at least one of the preceding claims, wherein the carrier is a textile carrier material, in particular a fabric, a knitted fabric, a nonwoven fabric, a fiber or a fiber bundle. 6. Adsorber according to at least one of the preceding claims, wherein the textile carrier material is a polyester, a polystyrene, a polyacrylate, a Poly (meth) acrylate, a polycarbonate or a polyacrylamide comprises or consists thereof. 7. Adsorber according to at least one of the preceding claims, wherein the anionic polyelectrolyte layer is made of one or more members of the group comprising polymers having sulfonate, sulfate, carboxylic acid, phosphonate and / or phosphate side groups. 8. Adsorber according to at least one of the preceding claims, wherein the cationic polyelectrolyte layer is made of one or more members of the group comprising polymers having amine, imine, ammonium or piperidine side groups. 9. adsorber according to at least one of the preceding claims, wherein the adsorber in the sum comprises at least 4, preferably at least 15, anionic and cationic polyelectrolyte layers and also independently thereof - the outermost layer is a cationic polyelectrolyte layer. 10. Adsorber according to at least one of the preceding claims, wherein the adsorber can be prepared by immersion in one or more liquid media comprising one or more polyelectrolytes and / or adsorber materials, preferably by alternately immersing in a solution of an anionic polyelectrolyte and a cationic polyelectrolyte with incorporation of particulate adsorber materials by immersion in a dispersion containing adsorber materials coated with polyelectrolyte. 1 1. Adsorber according to claim 10, wherein at least one of the liquid media comprises the particulate adsorbent material, preferably together with at least one anionic polyelectrolyte and / or a cationic polyelectrolyte. 12. Adsorber according to at least one of the preceding claims, wherein the polyelectrolyte layer further comprises compounds of copper, platinum, palladium, iron, and / or zinc, preferably as carbonates, hydroxides or oxides. 13. A process for the preparation of the adsorbent according to one of the preceding claims by multiple, alternating immersion of the carrier or the coated carrier in a liquid medium containing anionic polyelectrolytes and another medium containing cationic polyelectrolytes, wherein at least one of the liquid media comprises the adsorber, preferably all anionic polyelectrolytes or all cationic polyelectrolytes. 14. Use of the adsorber according to one of claims 12 to 12 as a respiratory protection filter or for water purification. 15. Breathing apparatus, in particular respiratory filter mask or Kreislaufatemgerät, comprising the adsorber according to one of claims 1 to 12 as a respiratory protection filter, preferably in the form of an exchangeable cartridge.