DE1719481C3 - Use of powder polyethylene as an adsorbent - 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 finely 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 H on be η - W ey I, methods of organic Chemistry, Volume 14/1 (1% 1), page 590, a method for the polymerization of ethylene using 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-grain polyethylene.

From the fact that such a fine powdery Polyethylene had already been manufactured but could not indicate the suitability of this polymer as a Adsorbent for organic solvent vapors and volatile radioactive substances closed will.

For the stated intended use, it is not only necessary that the stated organic Vapors are selectively and completely adsorbed,

ίο but it is also essential that the adsorbed Substance can later be completely desorbed again. That means a suitable one Adsorbent must not show any hysteresis phenomena during adsorption and desorption. A

is such an adsorbent with a high specificity Only then can a surface that does not show any hysteresis phenomena during adsorption and desorption can be obtained when the polymerization of ethylene under the special conditions given below

2 (i

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, produced with the help of ionizing radiation or with a radical initiator at a temperature lower than the melting point of the polyethylene

jo has been used to adsorb organic vapors Solvents and volatile radioactive substances.

It was also found that powder polyethylene subjected to a modification treatment such as a Crosslinking, graft polymerisation or the coating

j-> hen the particles with another polymer Material has been subjected to a particularly good adsorbent results.

The specific surface area of the powdered polyethylene used is in the range of at least 22 m ² / g

■ to 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, alumina, silica gel, and is particularly effective for adsorbing volatiles

■ n fission products.

So far, no macromolecular organic substances have been used as adsorbents. The specific The surface of the usual polyethylene powder is, under favorable circumstances, no greater than 14 mVg.

-, n The powder polyethylene used according to the invention preferably has a specific surface area of at least 30 mVg. It is used to adsorb Vapors of various organic solvents and volatile fission products such as radioactive

-> -> iodine and its organic compounds are used.

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

mi and that no residual adsorption after desorption remains behind.

The adsorbent according to the invention, d. That is, the powder polyethylene can be produced in different ways, where the reaction conditions such as reaction pressure,

κ, radiation dose and type of radiation. Kind and The amount of free radical initiator and the molecular weight of the resulting polyethylene vary. the Has examination with an electron microscope

however, it is confirmed that a particle of powder polyethylene, that by 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, 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 is an electron microscopic photograph of a A sample of the powder polyethylene used according to the invention shows. This photomicrograph was taken with made by an electron microscope at a magnification of 23,000 times; it shows the microstructure of a particle of the powdered polyethylene used in the present invention (hereinafter described as sample A). The whole picture looks like a landscape viewed from an airplane. The part that is like a hill or a tree or a highlighted area represents, means a Particles. The size of this particle ranges from 0.1 to several microns, regardless of the Polymerization conditions other than temperature, although the size of the whole particle in Depending on the conditions fluctuates.

When the polymerization of ethylene is carried out under the above-mentioned conditions, occurs a slight change in the adsorptive capacity of the resulting powder polyethylene. This means, that the powder polyethylene can be produced as an adsorbent, either by batch polymerization or by continuous flow polymerization. However, if the polyethylene intermittently is produced, it is desirable not to use such a high conversion rate; h., it is closed recommend that the conversion be set to 50% or less. If the powder polyethylene with a continuous flow process is established in which monomeric ethylene is repeated in the Reaction zone (irradiation zone) irr: is circulated, it is practically impossible to set a conversion rate to achieve per pass of about 50% and therefore the conversion rate in in this case do not become rocky. Even if the Polymerization in the presence of a solvent or reaction redium in which polyethylene does not dissolve, is performed, the conversion need not be controlled per pass. The others Conditions with the exception of the conversion factor can easily be determined by any person skilled in the art.

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) with the naked eye become smaller and thus the surface area per unit mass, i.e. the specific Surface, decreases. This tendency is remarkable when ethylene is polymerized at a temperature close to the melting point of the resulting polyethylene. Therefore, the polyethylene used for the purposes of the invention / r must have been produced at a temperature, Hie is at least lower than the melting point and preferably lower than 75 ⁰ C. The polyethylene produced at temperatures below room temperature is not inferior to its adsorption capacity generated 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 does not have a 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 the adsorption on the surface of the powder polyethylene, En that this one versus water, other inorganic

2ϊ Substars and some organic compounds preferred selective adsorption for organic substances shows. This was also shown in Example 2 proven experimentally.

In the production of the powder polythene used

jo lens is using the polymerization of ethylene ionizing radiation or a radical initiator. The term "ionizing radiation" includes corpuscular rays such as alpha rays, neutron rays, ] 3-rays, as well as rays from fissure fragments, as well as high-energy electromagnetic Rays such as gamma rays or X-rays. It is a generally accepted fact that this Radiation shows essentially the same effect in chemical reactions. (Compare e.g. Chapiro Radiation Chemistry of Polymeric System; Interscience Pubiisher, 1962, and Charlesby: Atomic Radiation and Polymers; Pergamon Press, 1960.)

If powdered polyethylene is produced with the help of a radical initiator, it must be an initiator that is

4-j at temperatures lower than the melting point of the polyethylene produced decomposes, but the choice of such radical initiators can easily be made by anyone Specialist.

If the powder polyethylene is in the liquid phase or

ίο is generated in a gas-liquid system that 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

5) can isolate preferably as a paste in which the Purchased powder polyethylene is dispersed. Some preferred solvents are water, alcohols, as well Mixtures thereof and liquid carbon dioxide.

Since the adsorbent used according to the invention is a

hu represents macromolecular organic matter, 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 recycled according to the invention is repeated

n "> exposed to sorption and desorption, so can of course the desorption does not take place at temperatures higher than the melting point of the polyethylene. However, the desorption will occur at higher temperatures

17th

.ils "id (.. not higher than (Inn melting point, \ or >> enommeri. so finds cm »half melting · ' (Sintering) in the particle per se or / wipe the l-'iiftikek'hen instead, resulting in a reduction in Oberfüi before nut brings itself, so that thereby the adsorptive capacity is decreased. Therefore, desorption should not be carried out at higher temperatures, but by flowing an inert gas through it or keeping the adsorbent in a vacuum. In this way the desorption can be carried out easily and quickly to the end, and this makes for economical applications is not a disadvantage. A deterioration in the adsorbability of the adsorbent with repeated Adsorption and desorption can be prevented by following the known methods of ι > Networking operated with ionizing radiation.

If a crosslinking treatment is carried out with the aid of ionizing radiation sn d? ^{Rn adso r} b ^pn s, H h the powdered polyethylene, its heat resistance can be improved. In this case: <> all kinds of alpha rays, ^ rays, gamma rays, neutron rays, electron rays, mixed rays and other accelerated corpuscular rays can be used. Their selection and the determination of the irradiation conditions can easily be carried out by a person skilled in the art. The irradiation of the powder polyethylene for crosslinking is preferably carried out in a vacuum, but it can also be carried out in air. When the powder polyethylene is irradiated, e.g. B. with an electron accelerator, a temperature increase of the irradiated material is allowed, but the heating should not take place higher than 75 ° C. A temperature rise above this range can easily be prevented, for example by blowing in cold air. Example 7 illustrates the improvement in 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 applied. The graft polymerization can either be done by converting the powder polyethylene into a liquid Vinyl compound is immersed or soaked with it or by steaming the polyethylene Bringing 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, 13-butadiene.

In either case, the steps necessary for graft polymerizing must be at a lower temperature than the melting point of the polyethylene or the graft polymer, preferably lower than 75 "C be performed. The degree of grafting depends on the properties of the vinyl monomer to be grafted and cannot be determined independently for itself. λ'Tdeii in every l-all soilie but this degree of grafting so L'f'.ieiicM will be that the large specific surface area. • Me cm (haraktcristikiim des due to the polymerization within the above mentioned conditions PuKerpolväthylens is. is not lost: one such Degree of grafting can easily be determined by any professional.

It is recommended that the graft polymerization takes place in the gas phase, because this is the post-treatment simplifies and helps to obtain a large specific surface area on the adsorbent.

A modification of the powder polyethylene adsorbent. similar to how it is 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, wplrhps contains a dissolved polymeric material: this Solvent wets the surface of the polyethylene, but does not dissolve it, so that the polyethylene with the Polymer is coated.

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 like polydimethylsiloxisanes, polyamides, polyethylene glycol. It is necessary to make the application of these polymers to the Pulverpolyäthylen at a temperature lower than the melting point of the Pulverpolyäthylens and preferably at a temperature lower than 75 ⁰ C. The amount of the applied polymer should controlled so that no reduction of the large specific surface area is which is a characteristic of powder polyethylene obtained by polymerizing ethylene under the above-mentioned conditions.

example 1
(Samples AD)

The following types of polyethylene were tested.

A. A powder polyethylene was prepared by circulating monomeric ethylene at a flow rate of 28 kg / hour through a reaction vessel with a capacity of 101. The temperature was kept at 30 ° C. The contents were irradiated with gamma rays from cobalt-60 (10000OCurie) at a dose of 3.7 · 10 ⁵ rad / hour. The ethylene was kept in the vessel at a pressure of 400 kg / cm ² for the entire time. Its molecular weight was 7 ICH and its density was 0.939 g / cm ³ . Its specific surface area was 101 m ² / g, measured using 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 13kg / hr. was passed through a 101 capacity reaction vessel which was kept ^{at 30 0 C in the circuit.} The contents were exposed to gamma radiation from KobaIt-60 (100 0OC CurieJ at a dose of 3.7 · 10 ⁵ rad / hour. The ethylene was kept in the vessel at a pressure of 225 kg / cnv during the entire reaction time. Its molecular weight is 2 $ 0 ⁴ and its density 0.943 g / cm ^2. Its specific surface area is 134 m ² / g, determined by the BET method. This powdered polyethylene is designated as sample B.

(. Km! 'Ill, ct'poiv iit h ν It was produced by circulating ammonium ethylene at a flow rate of 13 kg / h through a reaction vessel at a temperature of 75 ° C became. The contents were subjected to gamma radiation from cobalt-60 (K) OO (K) Curie) at a dose of 3.7 x 10 'rad / hour. exposed. The ethylene was kept in the vessel at a pressure of 400 kg / cm- during the entire reaction time. Its molecular weight is 2.4 · IO ⁴ and its density 0.43 3 g / ';m-'. Its specific surface area is 30 m-7g as measured by the BFT method. This powder polyethylene is referred to as sample C.

D. Fun powder polyethylene was produced by adding monomeric ethylene at a flow rate of 13 kg / hour. was circulated through an IO I reaction vessel at 90 ° C. The whole was gamma rays from cobalt-60 (100,000 curie) at a dose of 3.7 · 10 'rad / hour. exposed. The ethylene was kept in the vessel under a pressure of 400 kg / cm ² during the entire reaction time. Its molecular weight is 1.7 · 10 ⁴ and its density 0.932 g / cm ² . Its specific surface area is 22 m <7g. measured by the BET method. This powder polyethylene is referred to as sample D.

All of these types of powdered polyethylene were sieved

Table 1

and particles with a size of 0.71 0.33 in diameter are collected, about 0.1-0.2): the powder was exactly in cm ( the container weighed in and the container was placed in a closed container containing liquid isopropyl alcohol After the container had been kept at 25 "C." For 15 hours, the amount of iso-mopyl alcohol attached to the powder polyalcohol in equilibrium with the isopropyl alcohol vapor at 25 ° C. was measured.

At the same time a commercially available one was used for adsorbing Appropriate activated carbon and a commercially available powdered polyethylene (polyethylene powder), the obtained by mechanically pulverizing polyethylene tablets and used for molding is subjected to the same test. The specific surface area of the polyethylene powder is 14 m-7g, measured with the BET method.

The ease of desorption, ^r is an important factor of the Adso is bensmaterials, was also tested by the vessel was evacuated for half an hour at 25 ° C.

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

Sample Λ Commercially available activated carbon polyethylene powder

100

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

Amount of adsorption

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, powdered polyethylene produced by radiation polymerization has sufficient adsorptive capacity and desorption can also be carried out easily. As already mentioned, it is desirable to polymerize the ethylene at a temperature lower than 75 ^{° C. for this purpose.}

Example (A-D)

The adsorption capacity and the remaining adsorption capacity of powdered polyethylene particles 0.71-0.35 mm in diameter obtained by sieving Samples A, B, C and D of Example 1 were tested on different compounds at 25 ° C in the same Weis.: As in example 1, tested. For comparison was In addition, commercially available activated carbon and commercially available powdered polyethylene (polyethylene powder) have been tested. The results are shown in Table 2 below.

Table 2

link

Vapor pressure

Powder polyethylene obtained by radiation polymerization

(mm Hg) A Commercial activated carbon

Absorp.

Commercially available Polyäthy-Desorp. oil powder

220 714 55.2 1 η τ - 59.8 - 1.6 benzene 96 63 ^ 65.0 28.8 - 61.7 22.5 6.5 Carbon tetrachloride 108 193.4 188.8 107.4 633 117.8 653 - Methyl alcohol 119 88.4 85.7 34.1 8.1 57.2 6.8 -

I oil S ₁ '

IO

link Diimpl - l'iiiserpol 59.3 \; ilines egg 48.8 'iahen - 0.1 I) ll.indelsulilid IC Hamids (Inn k 24 by IK-- 59.8 .U.i hli: nys [i 70.2 ,. ', inei isaliiui id Γ) was in all 14.6 ■ \ kli \ coal iihlK lies Comment:
The remaining adsorbent wedge 30.5 29.6 11.9 l'olyathy- (mm I!;. ') Λ 85.0 Il 91.2 11.4 Absorp. Desorp. lenpiilvei Methyl ethyl ketone 100 4.9 ⁷ .0 35.5 18.0 60.5 29.5 - Isobutyl lactate 21 example 0.7 0.6 20.1 1.3 62.0 31.0 - Styrene 8th / Prnhr F \ 0.1 0.1 14.6 0 62.8 35.0 - n-Hepian 46 0.4 0.4 39.0 - 50.0 23.3 - Formic acid 42 of the samples A. B, C in 1.5 - 86.0 20.0 - N, N-dimethylformamide 4 J 0.4 (all 0, 60.3 39.6 - Dimethyl sulfoxide 12.1 - - water 45.3 - - : "ϊ ^η / ο or less. Example 5 (Sample CA

A 75 ml autoclave was charged with ethylene until the internal pressure had reached 250 kg / cm at 40 ° C. The ethylene was polymerized with the aid of 2,2'-azo-bis-isobutyronitrile at 40 ³ C for 6 hours. A powder polyethylene with a molecular weight of 29.10 ^{4 was} obtained. This Pulv'-rpolväthylen is referred to as sample Fi. His Adsorpiionsfähigkeit was measured as in Example 1 at 2 ^r> 'C. The results are given in Table 3 below.

Table 3

steam Adsorptive capacity (Link) (%) n-heptane 54.4 acetone 35.6 Methyl alcohol 32.3 Isobutyl acetate 33.8 Styrene 27.5 Example 4 (Sample F)

steam
(Link)

Adsorptive capacity

n-heptane

acetone

Methyl alcohol

Isobutyl acetate

Styrene

74.0
59.8
73.8
65.3
27.5

In pressure-resistant steel pipe with an inner diameter of 10 mm and an outer diameter of 20 mm as well a length of 90 m was spiraled into a spiral of 1 m diameter as a tubular reactor wrapped. This tubular reactor had a volume of / l cobalt-60 with 100,000 curie was in the Brought to 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 2} and passed through the reactor at a flow rate of 4.5 m / min at 20 "C. that it was exposed to the gamma radiation of cobalt-60 at a dose of 2.5 x 10 ⁵ rad / hour A powder polyethylene was obtained in the form of a slurry in methyl alcohol, the produced polyethylene was filtered off and dried, its molecular weight was 2.1 · 10 ⁴ and its density 0.955 g / cm ^3. This powder polyethylene is called polyethylene G.

The adsorption capacity of this powder polyethylene was tested as in Example 1 at 25 ° C. the Results are shown in Table 5.

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 10 1 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 (2O ⁰ C). The dose was 3.7 x IO ⁵ rad / hour. A powder polyethylene with a molecular weight of 2.0 × 10 ⁴ and a density of 0.947 g / cm ^{3 was obtained} . This powder polyethylene is referred to as sample F. Its adsorbability was tested as in Example 1. The results are given in Table 4.

Table 4

Table 5 Adsorptive capacity steam (° / o) (Link) 49.5 n-heptane 44.9 acetone 40.5 Methyl alcohol 38.9 Isopropyl alcohol 39.6 Isobutyl acetate 38.9 Styrene Example 6 (Sample H)

A 0.5 l autoclave was charged with 100 ml of a 10 wt ° / o aqueous solution of tertiary butyl alcohol and charged with ethylene until the internal pressure at 30 ^c C 400 kg / cm ² was reached. The reaction mixture (an aqueous phase in which a small amount of ethylene dissolves and a gas phase consisting of ethylene and vapors of water and alcohol) was emitted with a jamma radiation of K.obalt-60 with 100,000 Curie at a dose of 5 × 10 ⁵ rad / hour Irradiated at 20 ^° C. for 20 minutes. A powder polyethylene is formed which was dispersed in the aqueous solution of tertiary butyl alcohol. The powder polyethylene thus produced was

"(! Filtered and dried. Its molecular weight is 4 × 10 * and a density of 0.4 57 g / cir. ^1. This powder polyethylene is used as a sample Il bc / calibrated. The adsorption capacity of this powder is 111 y I e 11 s was as in example 1. at 25 "C pi ii. The results are contained in the table (j.

Table 6 Adsorptive capacity steam
(Link) 71.0
47.4
41.2
42.1
39.6
Λ 1 λ n-heptane
acetone
Methyl alcohol
Isopropyl alcohol
Isobutyl acetal
C. I Example 7
(Sample I)

That according to Example 1 by irradiation polymerisalion obtained powder polyethylene A, the particle size of which was 0.71-0.35 mm, was with the help of a Resonance transformer, d. H. with an electron accelerator of an electron beam of 2,000,000 eV with a dose of 20 · 10 'rad / sec. irradiated in such a way that crosslinking of the polyethylene took place. The whole Dose was 100 Mrad. This modified by crosslinking powder polyethylene is used as sample I. designated.

The susceptibility to adsorption of the thus modified powdered polyethylene was determined for n-heptane at 25 ° C., as in Example 1. A value of 82.5% was obtained. The adsorption capacity does not change through crosslinking with the help of electron beams. The effect of crosslinking on the heat resistance of the polyethylene was tested in the same manner as in Example 1. For this purpose, the vapor of n-heptane was adsorbed on the modified Piilverpolyäthylen at 25 ° C and the vacuum desorption was carried out at 25 ⁰ C and at 55 ° C. The adsorption and desorption were carried out several times, and the change in the adsorption capacity was checked. It was found that the crosslinking caused by irradiation prevents a reduction in the adsorption capacity. The results are given in Table 7.

Table 7 Desorption 0 1000 Mrad Adsorptic ability temperature 25 ° C Radiation dose 85.0% 82.5% 0 1000 Mrad 23.8% 52.8% 28.0% 59.3% Again 22.6% 51.4% fetching the 27.5% 56.2% Desorption 85.0% 82.5% 25.4% 52.3% 0 713% 61.9% 1 77.2% 68.0% 2 71.8% 63.4% 3 74.3% 64.2% 4th 72.5% 02.5% 5

Example 8
(Sample |)

Sample A was sieved and the particles with

■ 1–0.71 mm in diameter were collected. The collected powder was enclosed in a thin glass ampoule in a vacuum and with an electron beam of 2.5 ^{· 10 h} eV from a Cockcraft-Walton cleaner at a dose of 3 · 10 'rad / sec. at a

"Total dose of 50 Mrads irradiated. After the irradiation, the vial was opened and it was Styrene vapor introduced up to the saturation vapor pressure at 25'C so that it can be mixed with the pre-blasted powder polyethylene 12 hours to graft polymerize in

■ 'touch came. A powder graft polymer in which.! 2 % By weight of styrene was grafted on. It was determined by the infrared absorption spectrum of a UuFnUS byCn! iCJuprCSSCFi hci'gc.SiCiiiCTi ι iiiViS iuCiuiii ·

adorns. This graft polymer powder is used as a sample | 'ι denotes.

The adsorption capacity of the sample | was measured in the same manner as in Example 1.

Also the desorption capacity. which is an important property of an adsorbent. was in the same . '"> 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 remaining adsorption was less than 0.1 wt%. From this table it is evident that the powdered polyethylene is grafted onto the styrene has sufficient adsorbability for common organic compounds and easily lets desorb.

Example 9
(Sample K)

The powder poly ethylene used in Example 8 (sample A) was with electrons under the conditions of Example 8 irradiated.

The irradiated powder polyethylene was with monomer Contacted vinyl acetate vapor introduced into the ampoule at a pressure equal to corresponds to a vapor pressure at 25 ° C; thus gas phase graft polymerization was carried out for 12 hours carried out at 25 ° C. It became a graft polymer powder obtained in which 77 wt .-% vinyl acetate was grafted. 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 Sample K was measured in the same manner as in Example 1; the results are contained in Table 9

Table 9

Adsorption capacity of a powdered polyethylene onto which vinyl acetate was grafted at 25 ° C.

Adsorbed Vapor pressure Adsorptive capacity link mm Hg Wt% 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 46 273 Tetrachlor 108 46.0 carbon water 24 U

Example 11
(Sample M)

Polyethylene glycol dissolves in diethyl ether, but not Polyethylene.

The above-mentioned sample B was dissolved in a diethyl ether solution immersed in polyethylene glycol, the powder was taken out and left the Evaporate diethyl ether. Then the powder was further dried in vacuo. This way of working was carried out at 25 ° C. In this way, the polyethylene with 20 wt .-% polyethylene glycol coated.

The thus obtained, coated with polyethylene glycol powder polythene is referred to as sample M.

The adsorbability of Sample M was measured as in Example 1. The results are in the table 11 summarized

In each case, the residual adsorption was not greater than 0.1 wt. ^U / r.

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 brought into contact with monomeric ethyl acrylate vapor in the ampoule via a break-open closure at the pressure corresponding to the vapor pressure at 25 ° C. In this way, the vapor phase graft polymerization was carried out ^{at 25 ° C. for 12 hours.} A graft copolymer powder was obtained in which 171% by weight of ethyl acrylate had been grafted on. The powder thus obtained was identified as a graft polymer by an infrared absorption spectrum with a film made by hot pressing. The adsorbability of this graft polymer (L) was measured as in Example 1. The results are shown in Table 10.

Table 10

Adsorption capacity of powder polythene, onto which ethyl acrylate was grafted, at 25 ° C.

Adsorbed Vapor pressure adsorption capacity Wt% link 58.5 mm Hg 27.4 acetone 225 21.4 Methyl alcohol 119 42.7 Isopropyl alcohol 43 52.3 Isobutyl acetate 21 8.9 Styrene 8th 77.5 n-heptane 46 Tetrachlor 108 0.6 carbon ar clic residual adsorption not greater than water 24 In each crease w 0.1 wt%.

Table 11

Adsorbability of organic polymer powder · adsorbent made by coating the top surface of powder polyethylene with polyethylene glycol at 25 ° C.

Adsorbed Vapor pressure Adsorptive capacity link ii in ed Wt% acetone 225 78.0 Methyl alcohol 119 95.0 Isopropyl alcohol 43 80.7 Isobutyl acetate 21 563 Styrene 8th 25.8 n-heptane 46 303 Tetrachlor 108 80.0 carbon water 24 64.6

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

It can be seen from Table 11 that the organic polymer powder adsorbent is sufficient Has adsorption capacity for common organic compounds and desorption occurs easily.

Example 12
(Rehearse)

Polystyrene does not dissolve in carbon tetrachloride, but polyethylene does not.

The powder polyethylene, Sample A, was sieved. The particles with a diameter of 0.71-0.35 mrr 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 got further mad Vacuum dried. In this way eir powder polyethylene was obtained, the surface of which was 20.Ί % By weight of polystyrene was coated. This procedure was carried out at 25 ° C. That way Coated powder polyethylene is designated as Sample N.

The adsorbability of Sample N was measured in the same manner as in Example 8.

The results are summarized in Table 12 grasps.

Table 12

Adsorbability of a powdered organic polymer adsorbent prepared by coating the Surface of powder polyethylene with polystyrene (sample N) at 25 ° C.

Adsorbed Vapor pressure Adsorptive capacity link mm Hg Wt% acetone 225 233 Methyl alcohol 119 12.0 Isopropyl alcohol 43 13.2 Isobutyl acetate 21 42.1 Styrene 8th 38 ^ n-heptane 46 283 Tetrachlor 108 86.0 carbon water 24 0.0

In each case, the residual adsorption was no greater than 0.1% by weight / b.

Example 13 (Samples A-N)

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

(μθϊ) / | radioactive bromine ( ⁸² Bn), radioactive iodine ( ¹³¹ Jj). radioactive krypton ( ⁸⁵ Kr) and radioactive methyl iodide (CH ₃ ¹³¹ J). with the rest being air. This gas was passed through a glass column filled with powdered polyethylene (each sample AN). The column had an internal diameter of 3 cm and a length of 20 cm; the amount of powder filled in each case was 35 g, the particle size of which was 0.7-1 mm; the gas was forced through with water pressure by

into a water surface at a speed of 20 ml / min. (The water surface was coated with liquid paraffin to dissolve of the radioactive material in water.) A small amount of gas was

schuk plug of the openings for sampling

taken from both ends of the column with

Hypodermic syringes were provided. The gas was

analyzed with the help of radio gas chromatography

The results are in the table below

2Ii compiled. 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 flowed through the column, multiplied by 100. The measurement error of the returned

a part caused by the background effect, i.e. H. by naturally occurring radioactivity, was 1-2%.

Radioactive components

Adsorbent A B

Br

before adsorption (μθ / 1) 225 231 212 194 173 157 241 215 after adsorption (μθ / 1) 5 7th 4th 2 19th 6th 29 15th withheld (%) 2 3 2 1 11th 4th 12th 7th I.
before adsorption (μο / Γ) 194 191 191 190 190 190 204 200 after adsorption (μο / Ι) 6th 7.5 6th 4th 25th 93 30th 20th withheld (%) 3 4th 3 2 13th 5 15th 10 Kr before adsorption (μθΐ / 1) 204 204 204 203 203 203 201 201 after adsorption (μΟ / Γ) 88 98 84 79 116 104 119 123 withheld (%) 43 48 41 39 57 51 59 61 CH ₃ I. before adsorption (μθί / 1) 231 225 223 220 219 217 211 204 after adsorption (μο / Ι) 2 4.5 2 2 13th 6.5 17th 22nd withheld (%) 1 2 1 1 6th 3 8th 11th

continuation

Radioactive components

Br

before adsorption (μθ / l)
after adsorption (μθ / 1)
withheld (%)

VOi of adsorption (μθ / 1)
inn Ii of adsorption ((iCi / l)
/ iirrückjdialten (%)

Adsorbent 259 K L. M. N active Wet I I 2 money active <1 231 205 162 Ibt money 191 205 9 6th 2 1 168 151 6th 3 4th 3 1 <1 3 137 3 1.5 201 200 198 198 2 91 199 10 8th 1.7 1.4 199 199 4th 5 4th <1 <I. 6th 175 2 3 88

continuation

18th

Radioactive constituents adsorbent
II

Active wet carbon activated carbon

before adsorption after adsorption (μο / Ι) withheld (%)

CHaI

before adsorption (μθ / 1) retained after adsorption (%)

201 200 201 200 199 199 200 201 91 78 126 136 146 144 191 201 45 39 63 68 73 72 96 100 203 209 204 202 200 198 202 200 4th 9.4 16 24 6th 10 4th 170 2 4.5 8th 12th 3 5 2 85

1 sheet of drawings

Claims (4)

Patent claims: 1. Use of powder polyethylene with a specific surface area of not less than 22 mVg, which by polymerizing ethylene in the gas phase, liquid phase or a Gas-liquid system that uses a solvent contains, in which the polyethylene produced is insoluble, with the help of ionizing radiation or with a free radical initiator at a temperature lower than the melting point of the polyethylene has been manufactured to adsorb organic solvent vapors and volatile radioactive substances. 2. Use according to claim 1, characterized in that the powder polyethylene by a post-treatment with ionizing radiation cross-linked wc; that is. 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.