JPH069721A - Method of treating acrylic polymer - Google Patents

Abstract

PURPOSE:To degrade an acrylic polymer by converting the polymer into a specific water-soluble polymer and treating it with microorganisms. CONSTITUTION:An acrylic polymer (a) which is either acrylic acid homopolymer or a hydrophilic salt thereof with a mono-, di-, or trivalent metal, ammonium, or an amine and has a backbone consisting of a unit represented by the formula is converted into a water-soluble polymer with a mol.wt. of 1,000 or lower by adding 0.2-10 pts.wt. oxidizing agent to 1 pt.wt. polymer (a) and oxidizing the same at 40 deg.C or higher, or by irradiating a 10wt.% or lower aqueous solution of the polymer (a) with light having a wavelength of 350nm or below at a temp. between room temp. and the boiling point to photodegrade the same. The resulting water-soluble polymer is aerobically degraded by microorganisms at pH6-8 and 25-37 deg.C in an active sludge, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing an acrylic acid polymer. For more details,
It relates to a method of decomposing an acrylic acid polymer by using a microorganism, for example, by solubilizing and lowering the molecular weight of the acrylic acid polymer by oxidative decomposition and / or photolysis. .

[0002]

2. Description of the Related Art In recent years, acrylic acid polymers have been used in a wide range of applications. For example, fiber processing, thickener,
Applications are expanding in many fields such as dispersants, emulsifiers, papermaking, water treatment flocculants, soil conditioners, slurry inhibitors, and water-absorbing polymers, and the amount used is increasing. Acrylic acid-based polymers are usually harmless, but if a large amount of the polymers are discarded, it is not preferable in terms of environmental pollution, and development of an appropriate treatment method is desired.

Since the influence of synthetic polymer waste on the environment has become a problem, various studies have been conducted for the purpose of developing a method for treating microorganisms. However, to date, there have been few reports of microbial decomposition treatment of acrylic acid polymers. Matsumura et al. Investigated the biodegradability of sodium polyacrylate using general activated sludge and found that the degree of biodegradation of sodium polyacrylate having an average molecular weight of 520 ([biochemical oxygen demand (BOD ₅ ) / theoretical oxygen Required amount (TO
D)] × 100) was 8% and the biodegradability of polyacrylic acid sodium having an average molecular weight of 1070 was 1.3% (Proceedings of Polymers, Vol. 45, pp. 317, 1988).
However, there was no detailed report of a method for degrading high-molecular acrylic acid polymers using microorganisms.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for treating a high-molecular acrylic acid-based polymer by using an acrylic acid-based polymer solubilized and reduced in molecular weight with light or an oxidant to obtain a microorganism such as an activated sludge method. It is intended to provide a method of decomposing using a group.

[0005]

In order to solve the above-mentioned problems, the present inventors solubilized acrylic acid-based polymers by irradiating them with light or ultraviolet rays, or by adding peroxides, ozone, or the like. Or, with respect to the acrylic acid-based polymer having a low molecular weight, it was found that the acrylic acid-based polymer can be decomposed by causing a microorganism having the ability to decompose the acrylic acid-based polymer to act.
The present invention has been completed.

Therefore, the present invention provides a polymer having a molecular weight of 10 obtained by subjecting an acrylic acid polymer to an oxidation treatment and / or a photolysis treatment.
Provided is a method for treating an acrylic acid-based polymer, which comprises decomposing a water-soluble polymer having a molecular weight of 00 or less with a group of microorganisms. The acrylic acid-based polymer which can be decomposed according to the present invention has a basic main chain of the following formula

[0007]

[Chemical 1]

Acrylic acid homopolymer or a monovalent metal salt thereof, a divalent metal salt, a trivalent metal salt, an ammonium salt, an organic amine salt, or the like, which is constituted by and is hydrophilic. Further, a polymer obtained by copolymerizing with acrylic acid using a compound copolymerizable with acrylic acid is also an acrylic acid-based polymer as a target polymer of the decomposition method according to the present invention. As the compound copolymerizable with acrylic acid used in the present invention, various compounds can be used as long as the hydrophilic polymer copolymerized with acrylic acid maintains the hydrophilicity.

Specific examples thereof include monoethylenically unsaturated carboxylic acids such as methacrylic acid, maleic acid, crotonic acid, fumaric acid, itaconic acid, citraconic acid and aconitic acid, and monovalent metal salts thereof. , Divalent metal salts, trivalent metal salts, ammonium salts and organic amine salts,

Ethylene, propylene, isobutylene, n
-C2-C4 α-olefins such as butylene; methyl (meth) acrylate, ethyl (meth) acrylate,
Isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate,
Acrylic acid or methacrylic acid alkyl ester having 4 to 8 carbon atoms, such as isobutyl (meth) acrylate;

Hydroxyethyl (meth) acrylate,
Hydroxyalkyl of acrylic acid or methacrylic acid having 5 to 8 carbon atoms, such as hydroxy-n-propyl (meth) acrylate, hydroxyisopropyl (meth) acrylate, hydroxy-n-butyl (meth) acrylate, and hydroxyisobutyl (meth) acrylate. ester;
Polyether mono (meth) acrylate having 6 to 104 carbon atoms such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol mono (meth) acrylate;

2-sulfoethyl (meth) acrylate,
2-sulfopropyl (meth) acrylate, 3-sulfopropyl (meth) acrylate, 1-sulfopropane-
2-yl (meth) acrylate, 2-sulfobutyl (meth) acrylate, 3-sulfobutyl (meth) acrylate, 4-sulfobutyl (meth) acrylate, 1-sulfobutan-2-yl (meth) acrylate, 1-sulfobutane-3- Yl (meth) acrylate, 2-sulfobutan-3-yl (meth) acrylate, 2-methyl-
2-sulfopropyl (meth) acrylate, 1,1-dimethyl-2-sulfoethyl (meth) acrylate and other sulfoalkyl (meth) acrylates having 4 to 10 carbon atoms;

Sulfoethoxy polyethylene glycol mono (meth) acrylate, sulfopropoxy polyethylene glycol mono (meth) acrylate, sulfobutoxy polyethylene glycol mono (meth) acrylate,
Sulfoethoxy polypropylene glycol mono (meth)
C7-197 sulfoalkoxy polyalkylene glycol mono (meth) acrylates such as acrylate, sulfopropoxy polypropylene glycol mono (meth) acrylate, sulfobutoxy polypropylene glycol mono (meth) acrylate, and monovalent metal salts thereof, Valent metal salts, trivalent metal salts, ammonium salts and organic amine salts;

Polyethylene glycol monoallyl ether, polypropylene glycol monoallyl ether, polyethylene glycol polypropylene glycol monoallyl ether, polyethylene glycol monomethallyl ether, polypropylene glycol monomethallyl ether, polyethylene glycol polypropylene glycol monomethallyl ether and the like having 5 to 104 carbon atoms. Polyalkylene glycol mono (meth) allyl ethers;

4 carbon atoms such as vinyl acetate and propenyl acetate
~ 7 acetic acid alkenyl esters (the acetic acid alkenyl esters can be polymerized and hydrolyzed to form part or all of vinyl alcohol); styrene, p-methylstyrene, and other fragrances having 8 to 10 carbon atoms Group vinyls; C5-C10 aminoethyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate;

(Meth) acrylamides having 3 to 12 carbon atoms such as (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide; 2-acrylamido-2-methylsulfonic acid, vinylsulfonic acid, C2-C4 monoethylenically unsaturated sulfonic acids such as allyl sulfonic acid;

Monoethylenically unsaturated phosphones having 2 to 4 carbon atoms such as vinylphosphonic acid and allylphosphonic acid; (meth) acrylonitrile, acrolein, allyl alcohol and the like, and one or more of them may be used. I can. The acrylic acid-based polymer to be decomposed according to the present invention further includes a modified treatment product of the above various acrylic acid polymers or acrylic acid copolymers. That is, a substance modified with a compound capable of reacting with a carboxyl group contained in the above-mentioned polymer may be an object of the decomposition method according to the present invention.

The compounds used for modification are shown below, for example, ethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, polyoxypropylene, oxyethyleneoxypropylene block copolymer, Polyhydric alcohols such as diethanolamine, triethanolamine, pentaerythritol, sorbitol, sorbitan fatty acid ester, hydroxyacetic acid glycol monoester, lactic acid glycol monoester, hydroxybivalic acid neopentylene glycol ester, and polyvinyl alcohol polyvinyl acetate ;

Poly δ-containing hydroxyl groups at both ends
Lactone polymers containing hydroxyl groups at both terminals such as caprolactone; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol Polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, resorcin diglycidyl ether, 1,6-hexanediol diglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester , P-hydroxybenzoic acid glycidyl ester ether, etc. Rishijiru compounds;

Ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine,
Polyvalent amines such as phenylenediamine; 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate), 1,8-hexamethylenediethyleneurea, diphenylmethane-bis-4,4'-
Polyhydric aziridines such as N, N′-diethyleneurea; polyhydric aldehydes such as glutaraldehyde and glyoxal; polyhydric isocyanates such as 2,4-toluylene diisocyanate and hexamethylene diisocyanate. Two or more types are used.

Further, a cross-linked polymer can be a target polymer of the present invention. For example, a (meth) acrylic acid crosslinked polymer, a saponified crosslinked product of a (meth) acrylic acid ester monovinyl acetate non-polymer, a starch-acrylic acid salt graft polymer and a crosslinked product thereof, etc., a water absorption capacity of 10 to 1,000. A typical water-absorbing polymer having As the water-absorbent polymer, those used in paper diapers, sanitary products such as sanitary products, and other products can be decomposed by the present invention. Further, the water-absorbent polymer adhering to the inside of the water-absorbent polymer manufacturing apparatus can also be easily decomposed by the method of the present invention.

In the present invention, various physicochemical treatments are used to lower the molecular weight of the acrylic acid-based polymer before the acrylic acid-based polymer is decomposed by using the above microorganisms. By using a method of previously oxidizing with peroxide or ozone, or irradiating with ultraviolet rays, the high molecular weight acrylic acid polymer that requires a long time for biodegradation can be made into a low molecular weight, and the biodegradation treatment is more effective. It is possible to

Various methods can be used for lowering the molecular weight of the acrylic acid-based polymer, but a method of oxidizing with a peroxide or ozone and a method of irradiating with ultraviolet rays are particularly effective. The molecular weight reduction by the peroxide in the present invention can be carried out by using a water-soluble inorganic peroxide such as persulfate or perchlorate, and among them, hydrogen peroxide is particularly effective. . The polymer has a low molecular weight by using 0.2 parts by weight or more of the above oxidant with respect to 1 part by weight of the polymer and performing heat treatment at 40 ° C. or more.

If the ratio of the oxidant is 0.2 parts by weight or less, the molecular weight may not be efficiently reduced. However, if the amount of the oxidant is too large, not only the improvement of the effect corresponding to it is not recognized, but it may adversely affect the microorganism in the treatment of the microorganism, so the ratio of the oxidant is 10 parts by weight relative to 1 part by weight of the polymer. The amount is preferably not more than 5 parts, more preferably not more than 5 parts by weight. However, more oxidizing agents can be used.

The remaining oxidizing agent can be removed, for example, by making the aqueous solution alkaline and then heating it. Further, the heat treatment at 40 ° C. or higher is preferable because there is a possibility that the molecular weight cannot be efficiently reduced unless the heat treatment is performed at 40 ° C. or higher. The heat treatment method can be carried out without particular limitation as long as the effective component of the oxidizing agent present immediately before or during the heat treatment is at least the specified amount. The combined use of metal ions is also effective. Solubilization or molecular weight reduction with ozone in the present invention can be carried out by blowing air or an ozone-containing gas generated from oxygen into the polymer. The pH is not particularly limited, but a neutral to alkaline side is particularly desirable.

The molecular weight reduction by ultraviolet rays in the present invention can be carried out by irradiating the polymer with light having a wavelength of 350 nm or less. The temperature is not particularly limited and may be within the range of room temperature to the boiling point. By the above method, the molecular weight of the polymer can be reduced, but the molecular weight reduction rate is greatly related to the concentration of the polymer, and the lower the concentration, the easier the molecular weight reduction. When the polymer concentration is high, the molecular weight reduction may not be performed effectively, and for example, 10% by weight or less,
It is efficient to perform the molecular weight reduction treatment at a polymer concentration of preferably 5% by weight or less, and more preferably 2% by weight or less.

Further, in the treatment of the water-absorbing polymer which is a cross-linked polymer, the treatment for lowering the molecular weight is carried out with the water-absorbing polymer absorbed. In that case, the ratio of water is preferably 50 times or more with respect to 1 part by weight of the water-absorbent polymer. If the weight ratio of water is less than 50 times, the water-absorbent polymer may not be solubilized to a level at which it can be decomposed. When using water in this weight ratio, it is not necessary to consider the water absorption capacity of the water absorbent polymer to be treated, for example, from the amount less than or equal to the water absorption capacity of the water absorbent polymer to be treated to the amount exceeding the water absorption capacity. The amount may be selected appropriately.

However, even if an excessively large amount of water is used, the efficiency of disposal is lowered, so that it is usually 10% by weight of the water-absorbent polymer.
It is 00 times or less. If the amount of water is more than 1000 times, it may be economically unfavorable. When the water-absorbing polymer to be treated is absorbing water containing various components such as urine, the solid content in such water is generally negligible, so the weight ratio of water is, for example, It is determined by dividing the sum of the amount of urine and the amount of water added by the weight of the water-absorbing polymer. Water absorbed by the water-absorbent polymer is simply water or an aqueous solution.

As described above, the acrylic acid-based polymer has a low molecular weight. By this treatment, the acrylic acid-based polymer is solubilized and the molecular weight is reduced to a level of 1000 or less. According to the present invention, it is also possible to use a combination of photolysis treatment, for example, UV degradation treatment and oxidative degradation treatment. For example, in the case of a cross-linked polymer, it is preferable to first treat the polymer with ultraviolet rays or hydrogen peroxide to reduce the molecular weight to some extent, then to reduce the molecular weight to 1,000 or less by ozone treatment, and then perform biological treatment. Furthermore, the ultraviolet treatment, the ozone treatment, and the peroxide treatment can be combined in any order and the processing can be performed in any order.

By allowing a group of microorganisms such as activated sludge to act on the thus obtained low molecular weight soluble polymer, the decomposition treatment can be effectively carried out. The decomposition treatment is carried out under aerobic conditions and the temperature is 25 to 3
A pH of 7 ° C and a pH of 6 to 8 are suitable. As a concrete method of the treatment under the aerobic conditions, for example, an activated sludge method, a sprinkling filter method, an immersion filter method, a microbial cell immobilization method and the like can be used. The activated sludge method is particularly preferable.

[0031]

EXAMPLES Next, the present invention will be described more specifically by way of examples. In the following examples, the biodegradability of the polyacrylic acid-based polymer pretreated by the method of the present invention was evaluated by the biodegradation test method based on JIS K-0102. The test method based on JIS K-0102 is as follows.

Preparation of basal culture medium A, B, C and D liquids defined in JIS K-0102-1981 factory drainage test method, biochemical oxygen consumption amount were added in a proportion of 3 ml per 1 l of distilled water. Add from A in order. Liquid A: 21.75 g of dipotassium phosphate, 8.5 g of monopotassium phosphate, and disodium phosphate dodecahydrate in 1 liter of water 44.
Dissolve 6 g and 1.7 g ammonium chloride. Solution B: magnesium sulfate heptahydrate 22.5 in 1 liter of water
g, is dissolved. Liquid C: 27.5 g of calcium chloride (anhydrous) in 1 liter of water,
Dissolve. Solution D: 0.25 g of iron (III) chloride hexahydrate is dissolved in 1 liter of water.

Preparation of Test Solution A 300 ml Meyer flask was charged with the following amounts of the basal culture medium and the sample to adjust the pH to 7 (using NaOH). next,
Injecting pure culture sludge based on the Chemical Substances Control Law as a biological source,
A total of 100 ml of test solution is used. Sample 100ppm Pure culture sludge 30ppm Caustic soda pH7 Basic culture medium Total 100ml.

Biodegradation test 1) A Mayer flask is covered with a cotton plug and cultured in a constant temperature shaking incubator adjusted to 25 ± 3 ° C. while rotating and shaking at a speed of 150 times / M. At the same time, a blank test containing only the basal culture medium is also conducted. 2) To determine the degree of biodegradation, at the start of culture and on the 7th day,
10 ml from each flask on the 14th, 21st and 28th days
Perform sampling. 3) The collected test liquid was immediately centrifuged (3000rp).
The sludge is allowed to settle for 10 minutes, and the supernatant is analyzed by total organic carbon (TOC) and gel permeation chromatography (GPC).

Calculation of biodegradability From the TOC measurement value of the culture solution at the start of culture and at the time of culturing for t days, the biodegradability after t days is calculated by the following formula.

[0036]

[Equation 1]

Dt (TOC): Biodegradation (%) after t days by TOC method So: TOC value (mg / L) of test solution at the start Bo: Blank test value (mg / L) St: After t days TOC value (mg / L) of the test solution of Bt: Blank test value (mg / L) after t days

Example 1. After adding 2 mL of 30% hydrogen peroxide to 30 mL of a solution of 0.2% sodium polyacrylate (average molecular weight 20000), the mixture was heated at pH 7 and 80 ° C. for 3 days to obtain a product having an average molecular weight of 500. This was concentrated to dryness, the obtained dried solid was adjusted to an aqueous solution (pH 7) having a predetermined concentration, and then a biodegradability test was conducted using standard activated sludge in accordance with JIS K0102. The decomposition rate of the product on the 28th day of culture was 57%.

Example 2. Example 1 was repeated using a cross-linked polyacrylate (absorbent polymer). Cross-linked polyacrylate concentration 0.2%, hydrogen peroxide concentration 0.2%,
Treatment was performed at 80 ° C. for 10 minutes to obtain a treated product having a molecular weight of 700 (measured by GPC; a calibration curve was prepared using a sodium acrylate oligomer. The same applies hereinafter). Biodegradation rate is 36
%Met.

Example 3. Example 1 was repeated with the polyacrylate crosslinked product. The polyacrylic acid salt crosslinked product was treated at a concentration of 0.2% and a hydrogen peroxide concentration of 0.2% at 120 ° C. for 3 days to obtain a treated product having a molecular weight of 600. Biodegradation rate is 5
It was 0%.

Example 4. Example 1 was repeated using a polyacrylic acid crosslinked product. Polyacrylic acid crosslinked product concentration 0.2
%, Hydrogen peroxide concentration 2%, and treated at 80 ° C. for 3 days to obtain a treated product having a molecular weight of 500. The biodegradation rate was 50%.

Example 5. Acrylic acid-maleic acid copolymer (composition: acrylic acid / maleic acid = 7/3, molecular weight 6
Example 1 was repeated using The copolymer was treated at 80 ° C. for 3 days at a hydrogen peroxide concentration of 2% to obtain a treated product having a molecular weight of 400. The biodegradation rate was 86%.

Example 6. Acrylic acid-maleic acid copolymer (composition: acrylic acid / maleic acid = 2/8, molecular weight 2
000) was used to repeat Example 1. The copolymer was treated at a concentration of 0.2% and hydrogen peroxide at a concentration of 2% at 80 ° C. for 1 day to obtain a treated component having a molecular weight of 500. The biodegradation rate was 80%.

Example 7. Acrylic acid-vinyl alcohol copolymer (composition: acrylic acid / vinyl alcohol = 9 /
Example 1 was repeated with 1, molecular weight 10,000). The copolymer concentration is 0.2%, the hydrogen peroxide concentration is 2%,
The product was treated at 80 ° C. for 3 days to obtain a treated product having a molecular weight of 500. The biodegradation rate was 70%.

Example 8. Acrylic acid-hydroxyethyl methacrylate copolymer (composition: acrylic acid / HEMA
= 5/1, molecular weight 10,000) Example 1 was repeated. Copolymer concentration 0.2%, hydrogen peroxide concentration 2
% At 80 ° C. for 3 days to obtain a treated component having a molecular weight of 500. The biodegradation rate was 72%.

Example 9. Acrylic acid-polyethylene glycol monoacrylate copolymer (composition: acrylic acid /
Example 1 using EO = 1.6 / 1, molecular weight 4000)
Was repeated. The copolymer was treated at a concentration of 0.2% and a hydrogen peroxide concentration of 2% at 80 ° C. for 3 days to obtain a treated product having a molecular weight of 400. The biodegradation rate was 90%.

Example 10. A solution of 0.1% sodium polyacrylate (average molecular weight 5000) was applied for 3 days at room temperature for 15 days.
When UV irradiation was performed from a distance of cm using a UV sterilization lamp (15W x 1), the average molecular weight was 70.
0 product was obtained. This is concentrated to dryness, and the obtained dried solid is adjusted to an aqueous solution (pH 7) having a predetermined concentration, and then JIS K0
A biodegradability test was carried out using standard activated sludge according to 102. The decomposition rate of the product on the 28th day of culture was 27%.

Example 11. Example 10 was repeated using sodium polyacrylate (average molecular weight 5000). A treated product having a molecular weight of 500 was obtained with a sodium polyacrylate concentration of 0.1% and a UV treatment time of 5 days. The biodegradation rate was 55%.

Example 12 Example 10 was repeated using sodium polyacrylate (MW 20,000). A treated product having a molecular weight of 600 was obtained after 5 days of UV treatment using sodium polyacrylate at a concentration of 0.1%. The biodegradation rate was 30%.

Example 13. Example 10 was repeated using a cross-linked polyacrylate (water-absorbing polymer). A treated product having a molecular weight of 500 was obtained with a polyacrylic acid salt crosslinked product concentration of 1% and a UV treatment time of 10 days. The biodegradation rate was 50%.

Example 14 Example 10 was repeated using a cross-linked polyacrylate (water-absorbing polymer). A treated product having a molecular weight of 600 was obtained with a polyacrylate cross-linkage concentration of 0.1% and a UV treatment time of 5 days. The biodegradation rate was 39%.

Example 15 Example 10 was repeated using an acrylic acid-maleic acid copolymer (composition: acrylic acid / maleic acid = 7/3, molecular weight 60,000). The concentration of this copolymer is 0.1%, and the molecular weight is 7 when the UV treatment time is 3 days.
00 was obtained. The biodegradation rate was 29%.

Example 16. Example 10 was repeated using an acrylic acid-maleic acid copolymer (composition: acrylic acid / maleic acid = 2/8, molecular weight 2000). The concentration of this copolymer is 0.1%, and the molecular weight is 500 when the UV treatment time is 3 days.
A processed product of The biodegradation rate was 51%.

Example 17 Acrylic acid-vinyl alcohol copolymer (composition: acrylic acid / vinyl alcohol = 9
Example 10 was repeated using / 1, molecular weight 10,000). A treated product having a molecular weight of 600 was obtained with a concentration of this copolymer of 0.1% and a UV treatment time of 3 days. The biodegradation rate was 40%.

Example 18. Acrylic acid / hydroxyethyl methacrylate copolymer (composition: acrylic acid / HEM
Example 10 using A = 5/1, molecular weight 10,000)
Was repeated. A treated product having a molecular weight of 600 was obtained with a concentration of this copolymer of 0.1% and a UV treatment time of 3 days. Biodegradation rate is 4
It was 2%.

Example 19 Example 10 was repeated using an acrylic acid-polyethylene glycol monoacrylate copolymer (composition: acrylic acid / EO = 1.6 / 1, molecular weight 4000). A treated product having a molecular weight of 500 was obtained with a concentration of this polymer of 0.1% and a UV treatment time of 3 days. The biodegradation rate was 49%.

Example 20. After adjusting the pH of a 1% sodium acrylate (average molecular weight 20,000) solution to 11 using a sodium hydroxide solution, ozone (Nihon Ozonizer 0-1-2) was blown for 5 hours at room temperature. An ozone oxidant having an average molecular weight of 800 was obtained. This is concentrated to dryness, and the obtained dried solid is prepared into an aqueous solution (pH 7) having a predetermined concentration, and then JIS KO1 is used according to Example 2.
According to No. 02, a biodegradability test was conducted using standard activated sludge. The decomposition rate of the product on day 28 of culture was 26%.

Example 21. Example 20 was repeated using an acrylic acid-maleic acid copolymer (composition: acrylic acid / maleic acid = 7/3, molecular weight 60,000). The concentration of this copolymer is 1%, and the molecular weight is 80 after 5 hours of ozone treatment.
A processed product of 0 was obtained. The biodegradation rate was 25%.

Example 22. A polyacrylic acid salt crosslinked product (water-absorbing polymer) having a polymer concentration of 0.5% was subjected to ultraviolet ray irradiation for 24 hours as described in Example 10 to give a molecular weight of 22.0.
00 was obtained. This was subjected to ozone treatment for 5 hours as described in Example 20 to obtain a treated product having a molecular weight of 500, and further subjected to biodegradation treatment as described in Example 20. The biodegradation rate was 57%.

Example 23. A polyacrylic acid crosslinked product (water-absorbing polymer) having a polymer concentration of 1% was treated with 1% hydrogen peroxide at 80 ° C. for 24 hours as described in Example 1 to obtain a treated product having a molecular weight of 44,000. It was this,
Ozonated for 5 hours as described in Example 20,
A treated product with a molecular weight of 700 was obtained and further biodegraded as described in Example 20. The biodegradation rate was 38%.

Comparative Example 1. Sodium polyacrylate (molecular weight 20,000) and sodium polyacrylate (molecular weight 50
00) was subjected to a biodegradation test without pretreatment. The biodegradation rate was 0%.

Comparative Example 2. Sodium polyacrylate (molecular weight 20,000) was treated in the same manner as in Example 1 with its concentration of 0.2% and hydrogen peroxide concentration of 0.2% at 25 ° C. for 3 days to give a molecular weight of 17,000. A processed product of The biodegradation rate was 0%.

Comparative Example 3. 0.2% of crosslinked polyacrylate (water-absorbing polymer) was treated in the same manner as in Example 1 at a hydrogen peroxide concentration of 0.2% at 25 ° C. for 10 days to obtain a gel-like product. It was The biodegradation rate was 0%.

Comparative Example 4. Example 10 was repeated using sodium polyacrylate (molecular weight 5000). Sodium polyacrylate concentration 10%, UV treatment time 5 days molecular weight 4
000 processed products were obtained. The biodegradation rate was 0%.

Comparative Example 5. Example 10 was repeated using sodium polyacrylate (molecular weight 5000). A treated product having a molecular weight of 1300 was obtained with a sodium polyacrylate concentration of 0.1% and a UV treatment time of 1 day. The biodegradation rate was 9%.

Comparative Example 6. The same biodegradability test as in Example 10 was conducted using sodium polyacrylate (molecular weight: 5000), concentration: 0.1%, and no UV treatment. As a result, biodegradation rate is 0%
Met.

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Claims (6)

[Claims] 1. An oxidation treatment of an acrylic acid-based polymer and / or
Alternatively, a method for treating an acrylic acid-based polymer, which comprises decomposing a water-soluble polymer having a molecular weight of 1000 or less obtained by photodecomposition treatment with a group of microorganisms. 2. The method for treating an acrylic acid-based polymer according to claim 1, wherein the method for oxidizing the acrylic acid-based polymer is an oxidation reaction with a peroxide. 3. The method for treating an acrylic acid-based polymer according to claim 1, wherein the oxidation treatment method for the acrylic acid-based polymer is an oxidation treatment with ozone. 4. The method for treating an acrylic acid polymer according to claim 1, wherein the photolysis method for the acrylic acid polymer is photolysis by visible light or ultraviolet light. 5. The treatment of the acrylic acid-based polymer is a combination treatment of two or three kinds of oxidation treatment with peroxide, oxidation treatment with ozone, and photolysis treatment with visible light or ultraviolet light. The method according to 1. 6. The treatment method is an activated sludge method.
5. The method according to any one of 5 above.