DE1719481B2 - USE OF POWDER POLYAETHYLENE AS AN ADSORPTION AGENT - Google Patents

Description

The invention relates to the use of powder polyethylene with a certain particle size and defined Surface properties, which were produced with the help of a special process, as Adsorbent.

In the present specification, the term "powder polyethylene" is used to distinguish it from the known "polyethylene powder" is used. In the usual process, polyethylene powder is produced, in that polyethylene, obtained in bulk or in the form of lumps, with the help of mechanical or pulverized physicochemical methods. However, it has now been established that one when polymerizing ethylene at a temperature lower than the melting point of the resulting Polyethylene in gas phase or in liquid phase or in a gas-liquid system in which the Polyethylene does not dissolve, with the help of ionizing radiation or a radical initiator already from At the beginning, the polyethylene is obtained in the form of a fine powder. The expression "powder polyethylene" is thus used to designate a fine-powdered polyethylene produced in this way.

It was already known to produce finely powdered polyethylene by polymerizing ethylene at temperatures produce below the melting point of the polyethylene obtained. So in Chem. Engineering Progress 50 (1954) pages 249 to 255 describes a process for the polymerization of ethylene that is used in Room temperature and under irradiation is carried out. In Houben - We y I, methods of organic Chemie, Volume 14/1 (1961), page 590, a method for the polymerization of ethylene with the help a radical-forming catalyst described, which in a solvent at a temperature is carried out below the melting point of polyethylene. This is how you get one Suspension of fine-powdered polyethylene.

The mere fact that such a finely powdered polyethylene had already been produced could not, however, indicate the suitability of this polymer. Adsorbent for organic Lösungsmitteldäm _P r _e and volatile radioactive substances are closed.

For the stated purpose it is not only necessary that the stated organic vapors are selectively and completely adsorbed, but it is also essential that the adsorbed substance can later be completely desorbed again. This means that a suitable adsorbent must not show any hysteresis phenomena during adsorption and desorption. Such an adsorbent having a high specific surface area and exhibiting no hysteresis in adsorption and desorption can only be obtained if the polymerization of ethylene is carried out under the special conditions given below.

The invention relates to the use of powder polyethylene with a specific surface area of not less than 22 m ² / g, which is produced by polymerizing ethylene in the gas phase, liquid phase or a gas-liquid system containing a solvent in which the Polyethylene is insoluble, has been produced with the aid of ionizing radiation or with a radical initiator at a temperature lower than the melting point of the polyethylene, to adsorb vapors of organic solvents and volatile radioactive substances.

It was also found that powder polyethylene subjected to a modification treatment such as a Crosslinking, graft polymerization or coating the particles with another polymer Material has been subjected to a particularly good adsorbent results.

The specific surface area of the powder polyethylene used is in the range of at least 22 m ² / g up to 134 m ² / g. It adsorbs vapors from various organic solvents to the same extent as common inorganic adsorbents, e.g. B. activated carbon, aluminum oxide, silicon dioxide gel, and is particularly effective for adsorbing volatile fission products.

So far, no macromolecular organic substances have been used as adsorbents. The specific surface of the usual polyethylene powder is under favorable circumstances not greater than 14 m ² / g.

The powder polyethylene used according to the invention preferably has a specific surface area of at least 30 m ² / g. It is used to adsorb vapors from various organic solvents and volatile fission products such as radioactive iodine and its organic compounds.

The powder polyethylene used according to the invention shows the conventional adsorbents extraordinary advantage that it shows no inertia during adsorption and thus no hysteresis phenomenon and that no residual adsorption remains after desorption.

The adsorbent according to the invention, d. That is, the powder polyethylene can be produced in different ways, the reaction conditions such as reaction pressure, irradiation dose and type of irradiation, type and The amount of free radical initiator and the molecular weight of the resulting polyethylene vary. the Has examination with an electron microscope

but confirms that a particle of the powder polyethylene, that by polymerizing ethylene at a lower temperature than the melting point of the : n resulting polyethylene, η gas phase or in liquid phase or in a gas-liquid system, -, in which the polyethylene does not dissolve, it contains very many fine particles, which arise from the gaseous Have formed ethylene or the ethylene solution. The size of the particles is about 1 micron and remains practically unchanged regardless of whether the above-mentioned reaction conditions and the molecular weight of the product change as long as the reaction temperature remains constant.

The invention is explained with reference to the figure, which shows an electron microscopic photographic of a π sample of the powder polyethylene used according to the invention. This photomicrograph was taken with an electron microscope at a magnification of 23,000 times; showing the micro structure of a particle of the 2u used in the invention Pulverpolyäthylens (hereinafter referred to as Sample A described above). The whole picture looks like a landscape viewed from an airplane. The part that looks like a hill, or a tree, or a top-lit area means a r> particle. The size of this particle ranges from 0.1 to several microns regardless of the polymerization conditions other than the temperature, although the size of the whole particle varies depending on the conditions. so

When the polymerization of ethylene is carried out under the above-mentioned conditions, there is little change in the adsorbability of the resulting powder polyethylene. This means that the powdered polyethylene can be produced as an adsorbent, either by batch polymerization or by continuous flow polymerization. However, when the polyethylene is intermittently produced, it is desirable not to use such a high conversion ratio, ie, it is that the conversion to 50% or less is set to recommend w. If the powder polyethylene is produced with a continuous flow process in which monomeric ethylene is repeatedly circulated in the reaction zone (irradiation zone), it is practically impossible to achieve a conversion rate per pass of about 50% and therefore the conversion rate in this must Case cannot be controlled. Even if the polymerization is carried out in the presence of a solvent or reaction medium in which polyethylene does not dissolve, the conversion per pass need not be controlled. The other conditions, with the exception of the conversion factor, can easily be determined by any person skilled in the art. η

If the polymerization takes place at a temperature higher than 75 ° C, there is a tendency for the particle unit of the resulting polyethylene to become larger, although the particles (agglomerate), viewed with the naked eye, become smaller and thus the surface area per unit mass, ie the specific surface area, decreases. This tendency is remarkable when ethylene is polymerized at a temperature close to the melting point of the resulting polyethylene. Therefore, the must be generated for the ^ ^r -Zwecke of the invention to use polyethylene at a temperature at least lower than the melting point and preferably lower than 75 ¹ C is. The polyethylene produced at temperatures below room temperature is not inferior in adsorbability than one produced at room temperature. However, at such lower temperatures, the amount of polymerization (rate) is lower and such reaction conditions are not industrially advantageous.

Observations with the electron microscope confirm that the particle unit, which is a particle or agglomerate, has no porous structure. This is why the polyethylene which is used according to the invention as an adsorbent, shows no inertia in adsorption and desorption, as Usual adsorbents in which »pore condensation« takes place and why no residual adsorption remains, which is the disadvantage of the usual adsorbents when they are repeatedly used for adsorption and Desorption can be used, as is also evidenced by the following examples.

The inventive use of powder polyethylene as an adsorbent is based on adsorption on the surface of the powder polyethylene, so that this one compared to water, other inorganic Substances and some organic compounds preferred selective adsorption for organic substances shows. This was also demonstrated experimentally in Example 2.

In the production of the powder polyethylene used, the polymerization of ethylene is carried out with the aid ionizing radiation or a radical initiator. The term "ionizing radiation" includes corpuscular rays such as alpha rays, neutron rays, ^ Rays, as well as rays from fissure fragments, and high-energy electromagnetic rays such as gamma rays or X-rays. It is a generally accepted fact that these rays are essentially involved in chemical reactions show the same effect. (Compare e.g. Chapiro Radiation Chemistry of Polymeric System; Interscience Publisher, 1962, and Charlesby: Atomic Radiation and Polymers; Pergatnon Press, 1960.)

If powdered polyethylene is produced with the aid of a free radical initiator, it must be an initiator which decomposes at temperatures lower than the melting point of the polyethylene produced, but the Selection of such free radical initiators can easily be made by any person skilled in the art.

If the powder polyethylene is produced in the liquid phase or in a gas-liquid system, the is formed by adding a solvent, the solvent must be mixed with monomeric! Ethylene Mix completely or partially, but must not dissolve the resulting polymer and the latter should be used can preferably isolate as a slurry in which the obtained powder polyethylene is dispersed. Some preferred solvents are water, alcohols and mixtures thereof and liquid carbon dioxide.

Since the adsorbent used in the present invention is a macromolecular organic substance, it is it is not expedient to carry out the desorption at an elevated temperature, as is the case with conventional ones inorganic adsorbents takes place. If the adsorbent used in the present invention becomes repeated adsorption and desorption, so naturally the desorption cannot take place at higher temperatures than the melting point of the polyethylene. However, the desorption will occur at higher temperatures

than 50 ^° C., if not higher than the melting point, then "half melting" (sintering) takes place in the particle per se or between the particles, which brings about a reduction in the surface area, so that the adsorption capacity is reduced will. Therefore, desorption should not be carried out at higher temperatures, but by letting an inert gas through it or by keeping the adsorbent in a vacuum. In this way, the desorption can be completed easily and quickly, and this is not a disadvantage for economic purposes. A deterioration in the adsorption capacity of the adsorbent with repeated adsorption and desorption can be prevented by following the known methods of crosslinking with ionizing radiation served.

If a crosslinking treatment by means of ionizing radiation is applied to the adsorbent, i. H. powder polyethylene, its heat resistance can be improved. In this case you can all kinds of alpha rays, ^ rays, gamma rays, Neutron beams, electron beams, mixed beams and other accelerated corpuscular beam be used. Their selection and the determination of the irradiation conditions can be done by one Carry out a specialist without further ado. The irradiation of the powdered polyethylene for crosslinking is preferably carried out in a vacuum, but it can also be done in air. When the powder polyethylene is irradiated, z. B. with an electron accelerator, there is a rise in temperature of the irradiated material permissible, but the heating should not take place higher than 75 ° C. A temperature rise above this The area can easily be prevented, for example by blowing in cold air. Improving the Example 7 illustrates the heat resistance of polyethylene.

The properties of the adsorbent used in the present invention, i. H. of powder polyethylene, can still can be further improved by graft polymerizing with a vinyl monomer. When it comes to powdered polyethylene Grafting a vinyl compound, the polymerization with ionizing radiation or can a radical initiator or in some other known manner. When you're ionizing yourself Radiation operated, either pre-irradiation or simultaneous irradiation can be used. The graft polymerization can either be done by converting the powder polyethylene into a liquid Dipping vinyl compound or soaking with it or by steaming the polyethylene Brings vinyl compound into contact. In any case, in addition to the vinyl compound, a solvent may be used can be used in which the polyethylene formed does not dissolve.

Vinyl compounds useful in the present invention vary depending on the one desired End product z. B. styrene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylic acid, methacrylic acid, ethyl acrylate, Methyl acrylate, acrylonitrile, acrylamide, 4-vinylpyridine, 1,3-butadiene.

In any case, they have to be graft polymerized necessary steps at a temperature lower than the melting point of the polyethylene or the Graft polymer, preferably lower than 75 ° C are carried out. The degree of grafting depends on the Properties of the vinylnionomer to be grafted on and cannot determine independently for himself alone!

will. In any case, however, this degree of grafting should be so can be controlled that the large specific surface, which is a characteristic of the polymerization powder polyethylene obtained under the above-mentioned conditions is not lost; such a The degree of grafting can easily be determined by any person skilled in the art.

It is recommended that the graft polymerization be carried out in the gas phase because this is the aftertreatment simplifies and helps to obtain a large specific surface area on the adsorbent.

A modification of the powdered polyethylene adsorbent, similar to that achieved by graft polymerisation can be achieved by covering the surface of the powdered polyethylene with another Polymer coated as polyethylene. This is done by dipping powder polyethylene in a solvent, which contains a polymeric material dissolved; this solvent wets the surface of the polyethylene, but does not dissolve it, so that the polyethylene is coated with the polymer.

The polymers to be applied to the surface of the powdered polyethylene are, for. B. Polymers of Styrene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylic acid, methacrylic acid, acrylamide, acrylonitrile, 4-vinyl pyridine and 1,3-butadiene; Condensation polymers such as polydimethylsiloxisanes, polyamides, polyethylene glycol. It is necessary to apply this Polymers on the powder polyethylene at a temperature lower than the melting point of the powder polyethylene and preferably at a temperature lower than 75 ° C. The amount of Polymers to be applied should be controlled so that no reduction in the large specific Surface, which is a characteristic property of powder polyethylene, which is made by polymerizing from ethylene under the above-mentioned conditions.

example 1
(Samples AD)

The following types of polyethylene were tested.

A. A Pulyerpolyäthylen was made by monomeric ethylene at a flow rate of 28 kg / hr. was circulated through a 101 capacity reaction vessel. The temperature was kept at 30 ^° C. The contents were scavenged with gamma rays from cobalt-60 (100,000 curies) at a dose of 3.7 · 10 ⁵ rad / hr. irradiated. The ethylene was kept in the vessel at a pressure of 400 kg / cm ² all the time. Its molecular weight was 7-10 ⁴ and its density 0.939 g / cm \ Its specific surface area was 101 m ² / g, measured with the Brunauer-Emette-Teller (BET) method. (J. Am. Chem. Soc. 60; 309 [1938]). This powder polyethylene is referred to as sample A.

B. A polyethylene was made by using ethylene at a flow rate of 13 kg / hour. was passed through a 101 capacity reaction vessel which was kept ^{at 30 0 C in the circuit.} The contents were subjected to gamma radiation of cobalt-60 (100,000 Curie) at a dose of 3.7 x 10 ⁵ rad / hour. exposed. The ethylene was kept in the vessel at a pressure of 225 kg / cm ² during the entire reaction time. Its molecular weight is 2.8 x 10 6 "and its density 0.943 g / cm ^2. Its specific surface area is 134 m ² / g, determined using the BET method. This powdered polyethylene is referred to as sample B.

(ο

C. Ιϋη powder polyethylene was produced by adding monomeric ethylene at a flow rate of 13 kg / Stcl. by a K sive Rcaktionsgefiiü) I at a temperature of 75 ^'1 C was circulated. The contents were exposed to gamma radiation of cobalt-60 (100,000 Curie) at a dose of 3.7 · 10 "rad / hour. The ethylene was in the vessel at a pressure of 400 kg / cm- Its molecular weight is 2.4 × 10 ⁴ and its density 0.933 g / cm.Its specific surface area is 30 m ² / g, measured with the BET method.

D. A powder polyethylene was produced by adding monomeric ethylene at a flow rate of 13 kg / hour. led through a 10 ^{l reaction vessel at 90 0} C in the circuit. The whole was exposed to gamma rays from cobalt-60 (100,000 Curie) at a dose of 3.7 x 10 "rad / hour. The ethylene was kept in the vessel under a pressure of 400 kg / cm- during the entire reaction time Its molecular weight is 1.7 · 10 ′ and its density 0.932 g / cm ^2. Its specific surface area is 22 m ² / g, measured by the BET method. C. This powdered polyethylene is referred to as sample D.

All of these powder polyethylenes were sieved and particles 0.71-0.35 mm in size Diameters are collected. About 0.1-0.2 g des Powder was weighed exactly into a jar and the jar into a closed container, the liquid one Containing isopropyl alcohol. After holding the container at 25 "C for 15 hours, the Amount of isopropyl alcohol adsorbed on the powdered polyethylene in equilibrium with the isopropyl alcohol vapor measured at 25 "C.

At the same time, a commercially available activated carbon suitable for adsorbing and a commercially available one powdered polyethylene (polyethylene powder) obtained by mechanical pulverization of polyethylene tablets obtained and used for molding was subjected to the same test. The specific The surface of the polyethylene powder is 14 m - '/ g, measured with the BET method.

The ease of desorption, which is an important factor in the adsorbent material, was also observed tested by evacuating the vessel for half an hour at 25 ° C.

The test results are given in Table 1. Table 1 - Adsorption and desorption of Isopropyl alcohol on powdered polyethylene, produced by radiation polymerisation.

Table 1

sample
A.

Commercially available
Activated carbon

Commercially available polyethylene powder

Amount of adsorbent (g)
Amount of adsorption (g)
Adsorption capacity (%) =

Amount of adsorption j ""

Amount of adsorbent
Amount of residual adsorption (g)
Residual Adsorption Capacity (%) =

Amount of residual adsorption

Amount of adsorbent

100

0.1952 0.2223 0.1558 0.1283 0.2324

0.1018 0.1088 0.0339 0.0076 0.1344

52.1 48.9 22.3 5.9 57.7

0.0010 0.0011 0.0006 0.0003 0.0386

0.5 0.5 0.4 0.2 16.6

0.4991
0.0131

2.6

0.0008

0.2

As these results show, if powder polythene has already been mentioned, it is desirable to use ethylene for this

len, prepared by the Bestrahlungspolymcrisaation purpose at a temperature lower than 75 ^'1 C

has a sufficient adsorptive capacity and r, polymerize, the desorption can also be carried out easily. As

Example 2
(A - D)

The adsorption capacity and the remaining adsorption capacity of the powder polythene particles 0.71-0.35 mm in diameter obtained by sieving samples A, B, C and D of Example 1 were measured on various compounds at 25 ¹¹ C in the same manner as in Example 1, checked. For comparison, commercially available activated carbon and commercially available: powdered polyethylene (polyethylene powder) were tested. The results are shown in the table below
contain.

Table 2

link

acetone

benzene

Tetrachloro carbon dioxide

Methyl alcohol

steam Obtained powder polyethylene 71.5 B. 55.2 C. 19.7 I) I liiiulclsiililii •In· 1 IiU) (U-K pressure 63.5 65.0 28.8 Activated carbon üliliilu ". by irradiation polymerisation 193.4 188.8 107.4 l'olyillhy (mm Hg) 88.4 85.7 14.1 (ι. », J AI) MMp. DeMMp. Inipiilvei 220 A. 8.1 V), H Ul 96 dl, 7 ?.?, · '■> <i, ^r > If 108 I! 7.8 li '),) 119 ^r > 7 "? left H.

10

l'imsel / ιιημ steam - l'iilvcrpolväthylen received Ilen 59.3 Ii 48.8 C. 35.5 - 0.1 I) I laiulelsiihlic hey 5 Trade link pressure 24 by irradiation polymerisulion 59.8 70.2 20.1 D was in all I4, b Activated carbon usual
Polyälhy
lenpiilvci (mm Hg) Comment:
The remaining adsorption capacity A. 30.5 29.6 14.6 11.9 Absorp. Desorp. - 100 85.0 91.2 39.0 11.4 b0.5 29.5 - Methyl ethyl ketone 21 4.9 7.0 1.5 18.0 62.0 31.0 - Isobutyl acetate 8th example 0.7 0.6 0.4 1.3 62.8 35.0 - Styrene 46 (Sample E) 0.1 0.1 0 50.0 23.3 - n-heptane 42 0.4 0.4 - 86.0 20.0 - Formic acid Ν, Ν-dimethylformamide 4 of the samples A, H. C and - 60.3 39.6 - Dimethyl sulfoxide 3 Cases 0.5% 12.1 - - water 45.3 - Or less. Example : (Sample G)

An autoclave with a capacity of 75 ml was charged with ethylene until the internal pressure had reached 250 kg / cm ² at 40 "C. The ethylene was polymerized with the aid of 2,2'-azo-bis-isobutyroniiril at 40" C. for 6 hours . A powder polyethylene with a molecular weight of 29 · 10 ^{4 was} obtained. This powder polyethylene is referred to as sample E. Its adsorption capacity was measured as in Example 1 at 25 ° C. The results are given in Table 3 below.

Table 3

steam
(Link)

n-heptane

acetone

Methyl alcohol

Isobutyl acetate

Styrene

Adsorption capacity (o / o)

54.4 35.6 32.3 33.8 27.5

Example 4 (sample F)

Ethylene was mixed with 24 mol% of liquefied carbon dioxide (a reaction medium or solvent which does not dissolve polyethylene) and the mixture was passed through a 101-capacity reaction vessel at a flow rate of 17 kg / hour. circulated in an irradiation zone for cobalt-60 at 100,000 curie. The internal pressure of the reactor was kept at 400 kg / cm ² (20 ° C). The dose was 3.7 · 10 ^r 'rad / hour. A powder polyethylene with a molecular weight of 2.0 · 10 ⁴ and a density of 0.947 g / cm ^{1 was obtained} . This powder polyethylene is referred to as sample F. Its adsorbability was tested as in Example 1. The results are shown in Table 4.

Table 4

steam
(Link)

n-heptane

acetone

Methyl alcohol

Isobutyl acetate

Styrene

Adsorptive capacity

74.0 59.8 73.8 65.3 27.5

A pressure-resistant steel pipe with an inner diameter of 10 mm and 20 mm outer diameter and a length of 90 m became spiral into one Spiral with a diameter of 1 m wound as a tubular reactor. This tubular reactor hold a volume of 7 1, cobalt-60 with 100,000 curies was placed in the center of the spiral.

Ethylene with a content of 43.5% by weight methyl alcohol, in which polyethylene does not dissolve, was injected at 400 kg / cm and passed through the reactor at a flow rate of 4.5 m / min at 20 ^° C. that it is the gamma radiation of cobalt-60 with a dose of 2.5 · 10 ^r> rad / h. was exposed. A powder polyethylene was obtained in the form of a pulp in methyl alcohol; the polyethylene produced was filtered off and dried. Its molecular weight was 2.1 × 10 "and its density 0.955 g / cm ^1. This powder polyethylene is referred to as polyethylene G.

The adsorptive capacity of this powder compound was tested as in Example I at 25 ° C. The results are shown in Table 5.

Table 5

steam
·'"' (Link)

Adsorptive wedge

n-heptane

acetone

Methyl alcohol

Isopropyl alcohol

Isobutyl acetate

Styrene

49.5
44.9
40.5
38.9
39.6
38.9

Example 6
(Probell)

Kin 0, ^r ) I autoclave was charged with 100 ml of a K wt .-% aqueous solution of tertiary butyl alcohol and with ethylene until the internal pressure had reached 30 "C 400 kg / cm-'. The reaction mixture (an aqueous phase in which a small amount of ethylene dissolves, and a gas phase of ethylene and vapors of water and alcohol) was emitted by gamma radiation from cobalt-60 with 100,000 curie at a dose of 5 · 10 ^r 'rad /Hours. Irradiated for 20 minutes at 20 ° C. A powdered polyethylene is formed which was dispersed in the aqueous solution of tertiary bulyl alcohol. The powdered polyethylene thus produced was

filtered off and dried. Its molecular weight is 9x10 'and its density is 0.937 g / cm ¹ . This powder polyethylene is referred to as sample H. The adsorption capacity of this powdered polyethylene was tested, as in Example I, at 25 ° C. The results are shown in Table 6.

Table 6 Adsorptive capacity steam (%) (Link) 71.0 n-heptane 47.4 acetone 41.2 Methyl alcohol 42.1 Isopropyl alcohol 39.6 Isobutyl acetate 41.4 Styrene Example 7 (Sample I)

The powder polyethylene A obtained by radiation polymerization according to Example I, the particle size of which was 0.71-0.35 mm, was transformed with the aid of a resonance transformer, ie with an electron accelerator of an electron beam of 2,000,000 eV at a dose of 20 IO ⁴ rad / sec . irradiated so that crosslinking of the polyethylene took place. The total dose was 100 Mrads. This crosslinked modified polyethylene powder is referred to as sample I.

The adsorption capacity of the so modified powder polyethylene was for n-heptane at 25 ° C, as in Example 1, determined. A value of 82.5% was obtained. The adsorption capacity changes through cross-linking with the help of electron beams not. The effect of crosslinking on heat resistance The polyethylene was tested in the same manner as in Example 1. For this, the steam from n-heptane adsorbed on the modified powder polyethylene at 25 ° C and the vacuum desorption was at 25 ° C as well as at 55 ° C. The adsorption and desorption occurred several times and the change the adsorption capacity was checked. It was found that this was caused by irradiation Crosslinking prevents a reduction in adsorptive capacity. The results are in Table 7 specified.

Table 7 Desorption 55 ° C 1000 Mrad Adsorptive capacity Temple j door 0 25 ° C Radiation dose 82.5% 0 1000 Mrad 52.8% 85.0% 59.3% Again 23.8% 51.4% fetching the 28.0% 56.2% Desorption 85.0% 82.5% 22.6% 52.3% 0 71.3% 61.9% 27.5% 1 77.2% 68.0% 25.4% 2 71.8% 63.4% 3 74.3% 1) 4.2% 4th 72.5% 62.5% 5

Example 8
(Sample J)

Sample A was sieved and the -0.71 mm diameter particles were collected. The collected powder was vacuum sealed in a thin glass ampoule and ^{exposed to an electron beam of 2.5 x 10 7 h} eV from a Coekcraft-Walton accelerator at a dose of 3 x 10 8 rad / sec. irradiated at cinci total dose of 50 Mrad. After irradiation, the vial was opened and it was introduced to the saturated vapor pressure at 25 ^C C styrene vapor, so he came up with the long pre-irradiated Pulverpolyäthylen 12 hrs. To Pfropfpolymerisicren into contact. A powder graft polymer in which 32% by weight of styrene was grafted was obtained. It was identified by the infrared absorption spectrum of a film made therefrom by hot pressing. This graft polymer powder is used as a sample | designated.

The adsorbability of Sample J was measured in the same manner as in Example 1.

The desorption capacity, which is an important property of an adsorbent, has also been increased Way checked.

The results are given in Table 8.

Table 8 Vapor pressure Adsorptive capacity Adsorbed mm Hg Wt% link 225 33.9 acetone 119 23.9 Methyl alcohol 43 22.1 Isopropyl alcohol 21 32.2 isobutyl acetate 8th 41.4 Styrene 46 39.0 n-heptane 108 67.0 Tetrachlor carbon 24 0.7 water

In each case the residual adsorption was less than 0.1% by weight. From this table it is evident that the powder polyamide grafted onto the styrene has sufficient adsorbability for common organic compounds and easily lets desorb.

Example 9
(Sample K)

The powder polyethylene used in Example 8 (sample A) was irradiated mi: electrons under the conditions of Example 8.

The irradiated powder polyethylene was brought into contact with monomeric vinyl acetate vapor, which in the ampoule was inserted at a pressure equivalent to a vapor pressure at 25 "C; in this way was graft polymerized in bulk for 12 hours carried out at 25 "C. It became a graft po Polymer powder obtained in which 77% by weight of vinyl acetate were grafted on. From the powder thus obtained was determined by infrared absorption spectrum of a film made from the powder by hot pressing ensured that it is a graft polymer. This graft polymer powder is referred to as Sample K. the Adsorbability of the sample K was in the same Way as measured in Example 1; the results are in tier T.-ihrllp 9 pnlh: ilinn

Table 9

Adsorptive wedge of a powdered polyethylene onto which vinyl acetate was grafted at 25 ° C.

Adsorbed Vapor pressure Adsorptive capacity link mm Hg % By weight acetone 225 40.8 Methyl alcohol 119 27.6 isopropyl alcohol 43 24.8 Isobutyl acetate 21 30.5 Styrene 8th 36.0 n-heptane 46 27.3 Tetrachlor 108 46.0 carbon water 24 1.3

Example 11
(Sample M)

Polyethylene glycol dissolves in diethyl ether.nichi; iber Polyethylene.

The above-mentioned Sample B was put into a diethyl ether solution of polyethylene glycol, the powder was taken out and the Evaporate dietary ether. Then the powder was further dried in vacuo. This way of working was carried out at 25 ° C. That way it was the polyethylene is coated with 20% by weight of polyethylene glycol.

The polyethylene glycol-coated powdered polyethylene obtained in this way is referred to as sample M.

The adsorptive capacity of the sample M became as in Example 1 measured. The results are summarized in Table 11.

In each case the residual adsorption was no greater than 0.1 Ge w, -o / o.

Example 10
(Sample L)

The polyethylene used in Example 8 (Sample A) was subjected to electron beams under the same Conditions as in Example 8 irradiated.

The irradiated powder polyethylene was with monomer Ethyl acrylate vapor in the ampoule through a breakaway closure at the pressure in contact brought, which corresponds to the vapor pressure at 25 ° C. In this way, vapor phase graft polymerization was carried out for 12 hours carried out at 25 ° C. A graft polymer powder was obtained in which the 171 Wt .-% ethyl acrylate were grafted. The powder thus obtained was measured by infrared absorption spectrum identified as a graft polymer with a film made by hot pressing. The adsorption capacity this graft polymer (L) was measured as in Example 1. The results are in Table 10 contain.

Table 10

Adsorption capacity of powdered polyethylene onto which ethyl acrylate has been grafted at 25 ° C.

Adsorbed Vapor pressure adsorption capacity Hg weight o / o link 58.5 mm 27.4 acetone 225 21.4 Methyl alcohol 119 42.7 isopropyl alcohol 43 52.3 Isobutyl acetal 21 8.9 Styrene 8th 77.5 n-heptane 46 Tetrachlor 108 0.6 carbon Rcsiadsorption not greater i water 24 In any case w ar the 0.1 wt%.

Table 11

Adsorption capacity of organic polymer powder adsorbent, produced by coating the surface of the powdered polyethylene with polyethylene glycol. at 25 ° C.

Adsorbed Vapor pressure Adsorptive wedge link mm Hg Wt% acetone 225 78.0 Methyl alcohol 119 95.0 isopropyl alcohol 43 80.7 Isobutyl acetate 21 j6.3 Styrene 8th 25.8 n-heptane 46 30.5 Tetrachlor 108 80.0 carbon water 24 64.6

In each case, the residual adsorption was not greater than 0.1% by weight.

From Table 11 it can be seen that the organic polymer powder adsorbent has sufficient adsorption capacity for common organic Has compounds and desorption occurs easily.

Example 12
(Rehearse)

Polystyrene dissolves in carbon tetrachloride, but not polyethylene.

The powder polyethylene, Sample A, was sieved. The particles with a diameter of 0.71-0.35 mm are collected and immersed in a carbon tetrachloride solution of polystyrene. The powder was taken out and allowed to evaporate carbon tetrachloride; then the powder was further im Vacuum dried. In this way, a powder polyethylene was obtained, the surface with 20.4 Wt .-% was coated polystyrene. This procedure was carried out at 25 ° C. That way Coated powder polyethylene is designated as Sample N.

The adsorbent wedge of sample N was determined in the same way as in Example! 8 measured

The results are summarized in Table 12.

Table 12

Adsorption capacity eircs powdered organic Polymer adsorbent made by coating the surface of powdered polyethylene with polystyrene (Sample N) at 25 ° C.

Adsorbed. ·;
link Vapor pressure Adsorptive capacity mm Hg Wt% acetone 225 23.5 Methyl alcohol 119 12.0 Isopropyl alcohol 43 13.2 Isobutyl acetate 21 42.1 Styrene 8th 38.5 n-heptane 46 28.5 Tetrachlor 108 86.0 carbon water 24 00

in each case the residual adsorption was not greater than 0.1% by weight.

Example 13
(Samples AN)

An artificial gas like the one that flows out of reactors was produced. It contained 200 microcuria each

(μθ) / 1 radioactive bromine ("-'Br ₂ ), radioactive iodine (^ ¹ Ji), radioactive krypton ( ⁸⁵ Kr) and radioactive methyl iodide (CHj ^1J1 J), the remainder being air. This gas was through a with The column had an inner diameter of 3 cm, a length of 20 cm, the amount of each powder filled was 35 g, the particle size of which was 0.7-1 mm; the gas was forced through with water pressure by lifting a water surface at a rate of 20 ml / min. (The water surface was coated with liquid paraffin to prevent the radioactive material from dissolving in water.) A small amount of gas was passed through the silicone rubber stoppers of the openings for Samples were taken, which were fitted with Hypoderm syringes at both ends of the column, and the gas was analyzed with the aid of radio gas chromatography.

The results are compiled in the table below. In the table, »means withheld (%) «The radioactivity of the gas after it has passed through the column in relation to the Radioactivity before it has passed through the column multiplied by 100. The measurement error of the retained Proportion, caused by the background effect (back grounded, i.e. by naturally occurring radioactivity, was 1-2%.

Radioactive components Adsorbent
AWAY 231
7th
3 259
2 C. D. E. F. G H Br
before adsorption (μθί / 1)
after adsorption (μθϊ / 1)
withheld (%) 225
5
2 191
7.5
4th 205
3
1.5 212
4th
2 194
2
1 173
19th
11th 157
6th
4th 241
29
12th 215
15th
7th I.
before adsorption (μο / 1)
after adsorption (μθί / 1)
withheld (%) 194
6th
3 204
98
48
225
4.5
2 191
6th
3 190
4th
2 190
25th
13th 190
9.5
5 204
30th
15th 200
20th
10 Kr
before adsorption (μο / 1)
after adsorption (μο / Ι)
withheld (%)
CH ₃ I.
before adsorption (μο / 1)
after adsorption (μΟί / Ι)
withheld (%) 204
88
43
231
2
1 204
84
41
223
2
1 203
79
39
220
2
1 203
116
57
219
13th
6th 203
104
51
217
6.5
3 201
119
59
211
17th
8th 201
123
61
204
22nd
11th continuation Adsorbent
1 y Radioactive components 191
6th
3 κ L. IV! N active
money Wet
active
money Br
before adsorption (μθί / 1)
after adsorption (μο / Ι)
withheld (%) 199
4th
2 231
9
4th 205
6th
3 162
2
1 161
1 168
3
2 151
137
91 I.
before adsorption (μθ / 1)
after adsorption (μο / 1)
withheld (%) 201
10
5 200
8th
4th 198
1.7 198
1.4 199
6th
3 199
175
88

17th

iA

7 19481

IIIilscl / ιιημ

Radioactive components Allv-rt J K L. M. N active Wet 1 money active money Kr 200 201 200 199 199 before adsorption (μθ / 1) 201 78 126 136 146 144 200 201 after adsorption (μο / Ι) 91 39 63 68 73 72 191 201 withheld (%) 45 96 100 CH3l 209 204 202 200 198 before adsorption (μθ / 1) 203 9.4 ! 6 24 6th 10 202 200 after adsorption (μθ / 1) 4th 4.5 8th 12th 3 5 4th 170 withheld (%) 2 For this 1 Sheet drawings 2 85

Claims (4)

M 19481 claims: 1. Use of Pulverpolyäthyk nt a specific surface of not less than 22 m ² / g, which by polymerizing ethylene in the gas phase, liquid phase or a gas-liquid system containing a solvent in which the polyethylene produced is insoluble , with the aid of ionizing radiation or with a radical initiator at a temperature lower than the melting point of polyethylene, for adsorbing vapors of organic solvents and volatile radioactive substances. 2. Use according to claim 1, characterized in that the powder polyethylene by a post-treatment with ionizing radiation has been crosslinked. 3. Use according to claim 1, characterized in that the powder polyethylene is a Vinyl monomer has been grafted on. 4. Use according to claim 1, characterized in that the particles of powder polyethylene have been coated with a polymeric material.