JP2000246011A - Method for treating water absorbable resin-containing waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily treat water absorbable resin-containing waste. SOLUTION: In a method for treating water absorbable resin-containing waste, a salt of a divalent or more metal is added to waste water wherein a water absorbable resin is dispersed in an aq. soln. of a monovalent cation salt to flocculate the water absorbable resin. By this constitution, water absorbable resin-containing waste of every kind considered to be increased still more in the future is effectively treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating waste containing water-absorbing resin. As the degree of water absorption advances, the water-absorbing resin gradually decreases its water-absorbing performance, and eventually loses its performance. The present invention relates to a method for disposing of such a water-absorbent resin, and to a method for treating waste or wastewater containing such a water-absorbent resin.

[0002]

2. Description of the Related Art In many cases, a water-absorbing resin that has absorbed water is in the form of a gel or a gel. Since the water-absorbent resin-containing waste has a large amount of water, its volume and weight are large relative to the weight of the water-absorbent resin, and it is difficult to handle and transport the waste even if it is discarded at a predetermined place. If there is no place that can be abandoned, a method of adding a large amount of water to the gel waste without stopping to make the wastewater in which the water-absorbent resin is dispersed and discharging the wastewater into a river is conceivable. There is a problem of contamination. As another treatment method, a method may be considered in which the waste is heated to remove contained water to make a dried product, but this method has a drawback that a large amount of energy is required for the heating and drying.

[0003] Another example of a water-absorbent resin-containing waste is a waste containing an inorganic salt, water and a highly water-absorbent resin used as a regenerator. When processing such waste,
The waste is separated into a water-absorbent resin portion and a water portion by filtration or the like, the pH of the water portion is adjusted as required, and discharged to a river, and the water-absorbent resin portion is heated and dried. It can be disposed of as solid industrial waste. However, the water-absorbing resin portion separated by filtration has the same problem as described above due to a large amount of water absorption. In addition, since the water-absorbing resin portion contains a large amount of inorganic salts, it is necessary to wash and desalinate with water, and there is also a problem that a large amount of water is reabsorbed during washing with water for desalination.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a processing method capable of easily treating a water-absorbent resin-containing waste in view of the above-mentioned problems.

[0005]

The above-mentioned problems can be solved by the following processing method. (1) A method for treating a water-absorbent resin-containing waste, comprising adding a salt of a divalent or higher polyvalent metal ion to the waste containing the water-absorbent resin, and aggregating the water-absorbent resin in water. . (2) The method for treating a water-absorbent resin-containing waste according to the above (1), wherein the waste containing the water-absorbent resin is wastewater containing a monovalent cation salt. (3) The method for treating a water-absorbent resin-containing waste according to the above (1) or (2), wherein the agglomerated water-absorbent resin is filtered off and then dried. (4) washing the water-absorbent resin separated by filtration before drying
(3) The method for treating a water-absorbent resin-containing waste as described in (3). (5) The salt of the polyvalent metal ion is at least one selected from the group consisting of magnesium chloride, calcium chloride, calcium carbonate, aluminum sulfate, aluminum ammonium sulfate, and potassium aluminum sulfate.
The method for treating a water-absorbent resin-containing waste according to any one of (1) to (4). (6) The method according to any one of (1) to (5) above, wherein the amount of the salt of the polyvalent metal ion is 50 to 2,000 parts by weight per 100 parts by weight of the water absorbent resin contained in the waste. A method for treating waste containing water absorbent resin.

[0006]

[Function] When a salt of a polyvalent metal ion with a valency of 2 or more is added to a water-absorbent resin-containing waste and treated, the water-absorbent resin in the waste is reduced to a solid content having a small water content by the action of the polyvalent metal ion. Aggregate. Therefore, the solid content filtered off is smaller in bulk than a conventional water-absorbing resin filtered out, and can be made into a dry solid by light heating and drying. Further, the salts of the above-mentioned polyvalent metals are adhered to the solids separated by filtration.However, even if the solids are washed with water to remove these adhered salts as necessary, the amount of water re-absorbed by the water washing is not so large. It can be made into a dry solid by light heating and drying.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The water-absorbent resin forming the water-absorbent resin-containing waste which can be treated in the present invention is not particularly limited, and various kinds of water-absorbent resins can be used. Cellulose resins such as starch such as graft-polymerized starch resin, carboxymethylated starch resin, graft-polymerized cellulose resin, carboxymethylated cellulose resin, starch-polyacrylate resin, etc., polyacrylic Synthetic resins such as acid salt resin, poval-polyacrylate resin, polyacrylamide resin, polyoxyethylene resin, isobutylene-maleic acid resin, isoprene-maleic acid resin, etc. are used in the method of the present invention. Can be processed effectively. As the water-absorbing resin, those containing a monovalent cation in a three-dimensional molecular structure and exhibiting a high water-absorbing function by osmotic pressure based on a high ion concentration inside the resin are often used. The water-absorbing resin is not limited to this, and the present invention can be applied to all water-absorbing resins having high water-absorbing function.

[0008] Examples of the water-absorbent resin-containing waste include gels, gel-like or jelly-like wastes (hereinafter, collectively referred to as gel-like wastes) consisting only of the water-absorbent resin that has sufficiently absorbed water.
Wastewater in which the water-absorbing resin that has absorbed water is present in a dispersed state such as a colloid or suspension in a dispersion medium such as an aqueous solution of inorganic salts contained in water or waste, or in other states (hereinafter referred to as resin-dispersed wastewater). It is. The water-absorbent resin contained in the water-absorbent resin-containing waste may be one or a mixture of two or more of the above-described water-absorbent resins. Further, when the content of the water-absorbent resin in the waste is about 0.1 to 20% by weight, preferably about 0.5 to 10% by weight, an effective treatment can be performed by the present invention.

[Quantitative determination method of the content of the water-absorbent resin contained in the water-absorbent resin-containing waste] A sample of 100 to 500 g (weight: W1) is collected from the water-absorbent resin-containing waste to be treated. Contains water-soluble components such as salts of monovalent cations, and was used as a water diluent, filtered and further washed with water to remove those water-soluble components, and then the water-soluble components were removed. The sample is dried by heating at 100 to 120 ° C. for 5 to 15 hours to obtain a dry solid having a constant weight, and the amount W2 is weighed. The content (% by weight) of the water-absorbing resin contained in the resin dispersion wastewater is calculated by (W1 / W2) × 100.

In the present invention, the water-absorbent resin-containing waste is treated by adding a salt of a divalent or higher polyvalent metal ion (hereinafter referred to as a polyvalent metal salt) to reduce the water-absorbent resin in the waste. Aggregate. Examples of polyvalent metal salts include the second of the new periodic table of magnesium, calcium, barium and the like (the same applies hereinafter).
Group 13 elements, such as aluminum and gallium,
Hydrochlorides, nitrates, sulfates, etc., of Group 14 elements such as tin,
Inorganic acid salts such as carbonates, and organic acid salts such as acetic acid and oxalic acid can be effectively used. The polyvalent metal salt may be a double salt of such a polyvalent metal and an alkali metal or ammonium group. Examples of the polyvalent metal salt include magnesium chloride, magnesium nitrate, magnesium sulfate, calcium chloride, calcium carbonate, barium nitrate, aluminum sulfate, aluminum ammonium sulfate, potassium aluminum sulfate, and tin nitrate. Among them, salts of Group 2 elements such as magnesium and calcium and salts of aluminum, particularly at least one selected from the group consisting of magnesium chloride, calcium chloride, calcium carbonate, aluminum sulfate, aluminum ammonium sulfate, and potassium aluminum sulfate are preferred. .

The amount of the polyvalent metal salt used is 5 to 100 parts by weight of the water-absorbing resin contained in the water-absorbing resin-containing waste.
0 to 2000 parts by weight. The content of the water-absorbent resin can be determined by the above-described quantitative method. When the amount of the polyvalent metal salt used is less than 50 parts by weight per 100 parts by weight of the water-absorbing resin, the effect of coagulating the water-absorbing resin contained in the waste is poor because the amount of the polyvalent metal salt is too small. If the amount is more than 2,000 parts by weight, the aggregating action of the water-absorbing resin is saturated and the use of the polyvalent metal salt is wasted. The amount of polyvalent metal salt used is
More preferably, it is 100 to 1000 parts by weight per 100 parts by weight of the water absorbent resin. In this case, when the polyvalent metal salt to be used has water of crystallization, the amount of the polyvalent metal salt used is the value of the portion excluding the water of crystallization, and two or more kinds of salts are used. If so, the value of the total amount is used.

In the treatment of waste containing water-absorbent resin,
The polyvalent metal salt can be mixed with the water-absorbent resin-containing waste as a solid or as an aqueous solution and brought into contact with stirring. In order to make the contact between the polyvalent metal ion and the water-absorbent resin-containing waste as good as possible, the polyvalent metal salt is preferably in the form of an aqueous solution, especially about 0.1 to 10% by weight, especially about 0.2 to 5% by weight. It is preferably an aqueous solution of about weight%. The temperature at which the polyvalent metal salt is brought into contact with the absorbent resin-containing waste is from room temperature to 95 ° C.
Degree, particularly preferably about 50 to 80 ° C., and the time is 10 to
About 120 minutes, especially about 20 to 60 minutes is preferable.

The above reaction system containing the water-absorbent resin-containing waste and the polyvalent metal salt may be acidic, neutral or alkaline, but is generally preferably neutral to alkaline. In particular, the water-absorbent resin in the waste is a polyacrylate-based resin, a poval-polyacrylate-based resin, a polyacrylamide-based resin, a polyoxyethylene-based resin, or isobutylene-maleic acid among the water-absorbent resins described above. In the case of synthetic resins such as resin-based resins and isoprene-maleic acid-based resins, it is preferable to make the reaction system alkaline at least at pH 8. Such alkalinization can be achieved by adding an alkaline salt such as sodium carbonate and sodium borate.

The treatment method of the present invention can be used particularly effectively when a regenerator material containing an inorganic salt, water and a superabsorbent resin is treated as waste after use. In the waste, inorganic salts such as hydrochlorides of alkali metals and ammonium groups, nitrates, sulfates, carbonates and other inorganic acid salts, acetic acid, organic acid salts such as oxalic acid, for example, sodium chloride, sodium sulfate, carbonate It contains a large amount of monovalent cation salts such as sodium, ammonium nitrate and potassium acetate. When these wastes are separated from water by a water-absorbent resin, the water-absorbent resin still contains a large amount of water and contains a large amount of the inorganic salt, and thus cannot be directly disposed of or incinerated. . When washed with water to remove inorganic salts, the water-absorbent resin becomes more and more moist.

The above-mentioned waste is easy to treat according to the present invention, and is preferable as an object to be treated. That is, the water-absorbing resin is strongly agglomerated by adding a polyvalent metal salt in the presence of a monovalent cation salt to separate a large amount of water.
At the same time, salts of monovalent cations are also separated therefrom. The water-absorbent resin portion from which water has been separated by means of filtration or the like has a remarkably low water content as compared with the case where the polyvalent metal salt is not added, so that both the capacity and the weight are significantly reduced. Further, most of the monovalent cation salt is contained in the filtrate from which the water-absorbing resin has been separated, so that it is subjected to dilution and pH adjustment and then discarded.

The filtered water-absorbing resin still contains some monovalent cation salts and polyvalent metal salts added as a flocculant, which can be removed by washing with water. According to the method of the present invention, this water washing can be performed with a small amount of water, and the water absorption by the water washing is very small as compared with the case where the polyvalent metal salt is not added. After the water-absorbent resin after washing is dried,
It can be disposed of as flammable plastic waste. Further, since the aqueous solution filtered out contains a polyvalent metal salt, it can be used for the next treatment of the water-absorbent resin-containing waste.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, and the remarkable effects of the present invention will be clarified with reference to Comparative Examples.

Example 1 (case of starch-based water-absorbing resin) 23.3% by weight of sodium chloride, 5.0 of sodium sulfate
% By weight, 1.2% by weight of sodium carbonate, 4% by weight of a water-absorbent resin (trade name: ST-100, manufactured by Sanyo Chemical Co., Ltd., sodium polyacrylate / graft starch), and resin dispersion wastewater (pH: : 7.3) to be treated, 200 g of this was heated to 80 ° C. and 2 liters of calcium chloride aqueous solution (calcium chloride concentration: 2% by weight)
And stirred for 30 minutes while maintaining the liquid temperature at 80 ° C. As a result, the water-absorbing resin aggregated and precipitated at the bottom of the reaction vessel. Then, the contents of the reaction vessel were suction-filtered using a filter paper to separate the solid content of the above resin into a salt solution and a salt solution, and the salt solution was collected for treating other water-absorbent resin-containing waste. On the other hand, the solid content after filtration was washed with about 2 liters of hot water (tap water) at 80 ° C., and the washing water was discharged after adjusting the pH. The water content of the solid content after the washing was measured according to the method for determining the content of the water-absorbent resin described above, and was 63 ml. The solid content is 11
Heating in an oven at 0 ° C. for 2.5 hours was sufficient for drying.

Example 2 A treatment was performed in the same manner and under the same conditions as in Example 1 except that a 1.5% by weight aqueous solution of magnesium chloride was used instead of the 2% by weight aqueous solution of calcium chloride. As a result, the water content of the solid after washing with hot water at 80 ° C. was 63 ml. The solid was sufficiently dried by heating in an oven at 110 ° C. for 2.5 hours.

Example 3 A treatment was performed in the same manner and under the same conditions as in Example 1 except that a 1.0% by weight aqueous solution of aluminum sulfate was used instead of the 2% by weight aqueous solution of calcium chloride. As a result, the water content of the solid after washing with hot water at 80 ° C. was 63 ml. The solid was sufficiently dried by heating in an oven at 110 ° C. for 2.5 hours.

Example 4 A treatment was performed in the same manner and under the same conditions as in Example 1 except that a 3% by weight aqueous solution of aluminum ammonium sulfate was used instead of the 2% by weight aqueous solution of calcium chloride. As a result,
The water content of the solid content after washing with warm water at 80 ° C. is 6
It was 3 milliliters. The solid was sufficiently dried by heating in an oven at 110 ° C. for 2.5 hours.

Example 5 A treatment was performed in the same manner and under the same conditions as in Example 1 except that a 3% by weight aqueous solution of potassium aluminum sulfate was used instead of the 2% by weight aqueous solution of calcium chloride. As a result, 80
The water content of the solid after washing with warm water at ℃ was 63 ml. The solid was sufficiently dried by heating in an oven at 110 ° C. for 2.5 hours.

Example 6 (Synthetic resin type water-absorbing resin case) 23.3% by weight of sodium chloride, 5% by weight of sodium sulfate, 2% by weight of sodium carbonate, water-absorbing resin (water absorption) (trade name KI manufactured by Kuraray Co., Ltd.) Gels, isobutylene-maleic acid-based resin) were treated in the same manner and under the same conditions as in Example 1 except that 5% by weight of resin-dispersed wastewater (having a pH of 9.9 and alkalinity) consisting of 5% by weight of water and the remainder was treated. . As a result, the water content of the solid after washing with warm water at 80 ° C. was 50 ml. The solid content is 11
Heating in an oven at 0 ° C. for 2.5 hours was sufficient for drying.

Example 7 A treatment was performed in the same manner and under the same conditions as in Example 6, except that a 1.5% by weight aqueous solution of calcium carbonate was used instead of the 2% by weight aqueous solution of calcium chloride. As a result, the water content of the solid after washing with hot water at 80 ° C. was 63 ml. The solid was sufficiently dried by heating in an oven at 110 ° C. for 2.5 hours.

Comparative Example 1 (Comparative Example of Example 1) Resin dispersion wastewater to be treated in Example 1 was poured into 2 liters of tap water at room temperature, and 3
After stirring for 0 minutes, the contents of the reaction vessel were filtered using a 25 μm pore sieve, and the solids on the sieve were washed with about 2 liters of tap water. The water content of the solid after washing was 500 ml. The solid content is 1
It took 8 hours to dry sufficiently in a 10 ° C. oven.

Comparative Example 2 (Comparative Example of Example 1) The resin-dispersed wastewater to be treated in Example 1 was put into 2 liters of tap water heated to 80 ° C., and stirred for 30 minutes while maintaining the temperature at 80 ° C. Then, the content of the reaction vessel was filtered using a sieve having a pore size of 25 μm, and the solid content on the sieve was washed with about 2 liters of tap water at 80 ° C. The water content of the solid after washing was 1100 ml. The solid content is 1 to dry sufficiently in an oven at 110 ° C.
It took two hours.

[0027]

According to the present invention, as described above,
Wastes containing water-absorbing resins, which have been extremely difficult to treat conventionally, can be easily treated. Today, water-absorbent resins are used as disposable diapers for children and the elderly and as sanitary materials for women due to their extremely high water absorbency. It is widely used as a gelling agent for forming a non-flowable gel, and its annual usage is expected to continue to increase in the future. An increase in the amount of water-absorbing resin used means an increase in waste containing the resin, and the present invention can greatly contribute to the treatment of such waste.

Claims (6)

[Claims] Claims: 1. Treatment of a water-absorbent resin-containing waste, wherein a salt of a divalent or higher polyvalent metal ion is added to the water-absorbent resin-containing waste to cause the water-absorbent resin to aggregate in water. Method. 2. The method according to claim 1, wherein the waste containing the water-absorbent resin is wastewater containing a salt of a monovalent cation. 3. The method for treating a water-absorbent resin-containing waste according to claim 1, wherein the coagulated water-absorbent resin is filtered off and then dried. 4. The method for treating a water-absorbent resin-containing waste according to claim 3, wherein the filtered water-absorbent resin is washed with water before drying. 5. The salt of a polyvalent metal ion is at least one selected from the group consisting of magnesium chloride, calcium chloride, calcium carbonate, aluminum sulfate, aluminum ammonium sulfate, and potassium aluminum sulfate. The method for treating a water-absorbent resin-containing waste according to any one of the above. 6. The amount of the salt of the polyvalent metal ion to be used is 50 to 50 parts by weight per 100 parts by weight of the water absorbent resin contained in the waste.
The method for treating a water-absorbent resin-containing waste according to any one of claims 1 to 5, wherein the amount is 2000 parts by weight.