Liquid purification or separation – Processes – Chemical treatment
Reexamination Certificate
1999-06-28
2003-09-30
Popovics, Robert J. (Department: 1724)
Liquid purification or separation
Processes
Chemical treatment
C210S759000, C210S764000, C210S767000, C210S501000, C210S504000, C210S505000, C210S508000, C210S645000, C424S443000, C424S667000, C264SDIG004
Reexamination Certificate
active
06627088
ABSTRACT:
Midnight of PCT/EP94/04092 filed Dec. 13, 1994 Depth-type filter for killing microorganisms and inactivating viruses and its use
BRIEF DESCRIPTION OF THE INVENTION
The present invention relates to shaped articles which are suitable as biocidal depth-type filters and consist of fibrous materials and, embedded therein, particles of crospovidone-iodine or crospovidone-hydrogen peroxide. The invention furthermore relates to layer filters containing at least one of the shaped articles as depth-type filter layer. The invention also relates to the use of the shaped articles and of the layer filters for killing microorganisms or inactivating viruses for liquids containing such.
Water, blood or blood products, but also other body fluids or injection solutions, are purified by filtering these products. If it is desired at the same time as the purification also to achieve killing of pathogenic organisms, it is necessary to combine the filtration and purification step with measures which also bring about corresponding inactivation or killing of patho-genic organisms. Various processes and apparatus have been disclosed for this purpose. Thus, WO-92/040 31 discloses that blood, blood derivatives and other body fluids can be purified with soluble PVP-iodine products (povidone-iodine) by killing patho-genic organisms without this harming the substances to be purified. For this purpose, the liquid to be purified is treated with the povidone-iodine, and the liquid treated in this way is then passed through filters. The killed organisms and other impurities then remain in the filter cake, while the liquid which drains off contains the purified products. Although such a process is perfectly effective, it is a multistage-process in which first the dissolved povidone-iodine is brought into contact with the liquid to be purified and subsequently filtration is then carried out. The distinct advantage of this process is that the dissolved povidone remains issolved in the filtrate in this case (even after removal of the iodine) and is virtually impossible to remove again therefrom. The consequence of this is that a product of such a process can no longer be administered directly because it still contains the povidone which does not pass the kidneys. DE-41 19 288 furthermore discloses the purification of pharmaceutical or biological and other liquids by layer filtration. Since such liquids are intended to be free of foreign constituents, especially metal ions, after the purification step, the only substances which can be used for such filters are those with which contamination of the filtrate by metals is not to be expected. This is why DE-41 19 288 proposes the use of filtration aids which have a low metal ion content and are preferably free of metal ions, such as fine highly dispersive polymer granules, micronized celluloses or mixtures of these substances as filtration-active component. Kieselguhr or perlite, which might be effective filtration aids, are unsuitable because of the metal content.
WO 93/06911 describes a process for the filtration of blood using crospovidone-iodine in powder form. This is applied in the form of a bed to a filter. The process requires a crospovidone-iodine with a substantially uniform particle size of 40-150 &mgr;m. This is industrially elaborate to produce. In addition, the killed micro-organisms remain in the filtrate and must be removed therefrom. The separation of the cellular components of the blood, which have been filtered off, from the crospovidone-iodine is also elaborate and is difficult to implement on the industrial scale because of the narrow particle size distribution for the particle sizes required for use.
WO 94/00161 describes the treatment of blood or biological tissue with povidone-H
2
O
2
complexes as biocidal substances, it being possible to use both povidone and crospovidone as basis for the complexes. The biological materials can be treated in an apparatus in which layers of various biocidal substances are arranged one above the other.
DETAILED DESCRIPTION OF THE INVENTION
It was an object of the invention to find depth-type filters consisting of materials such that the purification and, at the same time, the killing of pathogenic organisms and inactivation of viruses in liquids which contain them can be carried out advantageously and without great elaboration. Connected with this object is the use of such a depth-type filter for killing pathogenic organisms in the production of pure water, pharmacological solutions, especially injection solutions, and blood plasma products.
We have found that this object is achieved by the shaped articles which are suitable as biocidal depth-type filters and are defined at the outset, layer filters consisting of one or more shaped articles of this type, and the use thereof for killing micro-organisms and inactivating viruses in liquids containing them.
The shaped articles according to the invention contain as biocidal substance for killing microorganisms or inactivating viruses crospovidone-iodine or crospovidone-hydrogen peroxide (crospovidone-H
2
O
2
). Crospovidone-iodine is the name given to the iodine complex which is based on crosslinked PVP (PVPP, crospovidone) and is used according to the invention.
Free iodine is in equilibrium with the iodine bound in the complex. This proportion as active component is always replenished in a concentration range from 0.5 to 6, preferably 1 to 3, ppm from the iodine pool in the complex.
The iodine can be bound in this complex in various amounts. The commercial products contain from 9.0 to 12.0% by weight of available iodine, but products with an available iodine content of from 1 to 20% by weight are suitable for the present invention. The particle size of the crospovidone-iodine is from 0.5 to 600 &mgr;m. Crospovidone-iodine with a particle size distribution from 0.5 to 250 &mgr;m is preferably used. The average particle size is from 30 to 40 &mgr;m. The specific surface area of the crospovidone-iodine particles is from 0.8 to 6, preferably 1.8 to 2.5, m
2
/g [BET method], the apparent density is from 0.1 to 0.35, preferably 0.18 to 0.25, g/ml.
The crospovidone-iodine is present in the shaped articles suitable as depth-type filters in amounts of from 0.5 to 75% by weight, preferably 10 to 50% by weight, particularly preferably 20 to 40% by weight, based on the total weight of the dried shaped article. These amounts depend, on the one hand, on the amount of available iodine present in the crospovidone-iodine and, on the other hand, on the nature of the material to be purified. It is possible to use in a layer filter itself depth-type filters with different amounts of crospovidone-iodine.
In the particulate crosprovidone-H
2
O
2
which is likewise suitable as biocidal substance, the H
2
O
2
is likewise bound in the form of a complex to the crosslinked polyvinylpyrrolidone. The particle sizes of the crospovidone-H
2
O
2
are in the range from 0.5 to 600 &mgr;m, preferably from 0.5 to 250 &mgr;m. The specific surface area of suitable particles is from 0.8 to 6.0, preferably 1.8 to 2.5, m
2
/g (BET method), the apparent density is 0.1 to 0.35, preferably 0.18 to 0.25, g/ml. Complexes of crospovidone and H
2
O
2
of this type can be prepared by known processes.
The particles of the biocidal substance are embedded in the shaped articles consisting of fibrous materials. The shaped articles consist of fibrous materials which are known for the manufacture of paper and filters, especially cellulose fibers. A suitable fibrous material is, for example, micronized cellulose consisting of pure alpha-cellulose with a residue on ignition not exceeding 0.3%. The length of the fibers in the alpha-cellulose used can be in the range from 10 to 300 &mgr;m and, preferably 18 to 200 &mgr;m, and an average fiber thickness of from 5 to 30 &mgr;m is expedient.
Various additives can be added to adjust the required surface potential. To achieve a positive surface potential it is possible to add a polyamido-amine-epichlorohydrin resin, and for a negative surface potential to add modified
Breitenbach Jörg
Fussnegger Bernhard
Lang Siegfried
Oechsle Dietmar
BASF - Aktiengesellschaft
Keil & Weinkauf
Popovics Robert J.
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