JPH08283349A - Amphoteric polymeric flocculant - Google Patents

Abstract

PURPOSE: To obtain an amphoteric polymer flocculant having a good solubility in water and homogeneously dissolving in water to give a transparent solution undergong less deterioration with time by using specified cationic monomer units, specified anionic monomer units, and specified nonionic monomer units. CONSTITUTION: This flocculant consists of cationic monomer units represented by formula I (wherein R1 is H, CH3 or CH2 -C6 H5 ; A is NH or O; B is CH2 -CH2 or CH2 -CH2 -CH2 ; and X is a counter ion and is a halide ion, SO4 or CH3 SO4 ), anionic monomer units represented by formula II (wherein R2 is H or CH3 ; and Y is H, Na, K or NH4 ), nonionic monomer units represented by formula III (wherein R3 to R5 are each H or 1-4C alkyl), and 5-30mol% cationic monomer units represented by formula IV (wherein R6 is R1 ).

Description

Detailed Description of the Invention

[0001]

The present invention relates to various industrial wastewater, sewage,
The present invention relates to an amphoteric polymer flocculant effective for coagulating and dehydrating organic sludge produced by human waste treatment and the like.

[0002]

2. Description of the Related Art Organic sludge produced by various industrial wastewater, sewage treatment, human waste treatment, etc. is usually cationically charged for sludge treatment because the particles constituting it are negatively charged and stably dispersed. The polymeric flocculant was used alone. However, in the conventional method, when sludge decay progresses, the recovery rate of suspended solids (hereinafter abbreviated as SS), the water content of the dehydrated cake, the peelability of the dehydrated cake from the filter cloth, and the like deteriorate. In order to improve these, a method in which a cationic polymer coagulant and an anionic polymer coagulant are used in combination (JP-A-58-215454 and JP-A-58-1397).
99) or a method of using an amphoteric polymer flocculant having both cationic and anionic groups in the same molecule (JP-A-49-6078 and JP-A-53-1492).
No. 92) has been proposed.

However, the method of using a cationic polymer coagulant and an anionic polymer coagulant together shows some improvement in recovery rate of SS, water content of dehydrated cake, peelability of cake, etc. In the case of, the selection of the mixing ratio of each component and the mixing operation are complicated, and an insoluble sticky substance is generated during dissolution, which often causes a trouble.

On the other hand, the method of using the amphoteric polymer flocculant is superior to the conventional method of using the cationic polymer flocculant alone.
Although it has excellent performance in the recovery rate of SS and the water content of the dehydrated cake, it has a poor solubility in water, so that the solution tends to become cloudy or an insoluble gel is easily formed. Since the stability with time is poor, there is a problem that an insoluble matter may be formed over time.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies as to the composition of an amphoteric polymer flocculant that solves the above-mentioned problems, and as a result, have found that a specific cationic monomer unit is contained in the composition. It was found that the inclusion of the compound can significantly improve the solubility of the amphoteric polymer flocculant and the stability of the solution over time, and completed the present invention.

That is, the present invention provides an amphoteric polymer flocculant having excellent solubility in water, which is a problem when using a conventional amphoteric polymer flocculant, and excellent stability of the solution over time. With the goal.

[0007]

The present invention has the general formula (I)
Composed of a cationic monomer unit represented by, an anionic monomer unit represented by the general formula (II), a nonionic monomer unit represented by the general formula (III) and a cationic monomer unit represented by the general formula (IV) The amphoteric polymer flocculant is characterized by containing 5 to 30 mol% of a cationic monomer unit represented by the general formula (IV).

[0008]

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[0009]

[Chemical 6]

[0010]

[Chemical 7]

[0011]

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The present invention will be described in detail below. In the present invention, examples of the monomer that provides the cationic monomer unit represented by the general formula (I) include methacryloyloxyethyl trimethyl ammonium chloride, methacryloyl oxyethyl dimethyl benzyl ammonium chloride, methacryloyl oxyethyl trimethyl ammonium methylsulfate, methacryloyl. Oxyethyl dimethyl ammonium sulfate,
Methacrylamidopropyltrimethylammonium chloride, methacrylamidopropyldimethylbenzylammonium chloride and the like can be mentioned. These cationic monomers may be used alone or in combination of two or more.

Examples of the monomer that gives the anionic monomer unit represented by the general formula (II) include acrylic acid, methacrylic acid, and their sodium salts, potassium salts, ammonium salts and the like. Further, one kind of these anionic monomers may be used, or 2
You may use it in combination of 2 or more types.

As the monomer giving the nonionic monomer unit represented by the general formula (III), acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N , N-diethyl methacrylamide and the like. These nonionic monomers may be used alone or in combination of two or more. The nonionic monomer is used for the purpose of adjusting the molecular weight and ionic equivalent of the amphoteric polymer flocculant.

In the present invention, in order to greatly improve the solubility of the amphoteric polymer flocculant and the stability of the solution over time,
It is essential that the composition of the amphoteric polymer flocculant contains a cationic monomer unit represented by the general formula (IV).

Specific examples of the monomer that provides the cationic monomer unit represented by the general formula (IV) include acryloyloxyethyltrimethylammonium chloride, acryloyloxyethyldimethyldimethylbenzylammonium chloride, acryloyloxyethyltrimethylammonium methylsulfate and acryloyloxy. Examples thereof include ethyldimethylammonium sulfate, acrylamidopropyltrimethylammonium chloride, acrylamidopropyldimethylbenzylammonium chloride and the like.

These cationic monomers may be used alone or in combination of two or more. This cationic monomer unit must be contained in the amphoteric polymer flocculant composition in an amount of 5 to 30 mol%. If it is less than 5 mol%, the effect of improving the solubility and stability of the solution with time is insufficient, and if it exceeds 30 mol%, the solubility and stability of the solution with time deteriorate.

The amphoteric polymer flocculant of the present invention is produced by an aqueous solution polymerization method, a reverse phase suspension polymerization method, a reverse phase emulsion polymerization method or the like, and the representative case will be described below.

The monomer concentration in the polymerization system of the total amount of the above-mentioned cationic monomer, anionic monomer and nonionic monomer in producing the amphoteric polymer flocculant of the present invention is not particularly limited, but is 20 to 85% by weight. Is preferred. When the concentration is less than 20% by weight, the productivity is low, and when it exceeds 85% by weight, problems occur such that the monomer is not completely dissolved in water and the temperature rise of the system due to heat of polymerization becomes too large.

In order to produce the amphoteric polymer flocculant of the present invention, deoxygenation is carried out by passing an inert gas such as nitrogen into an aqueous solution of a monomer mixture, and a polymerization initiator is added to carry out polymerization. The pH of the aqueous solution is preferably 3.5 or less. Polymerization in a pH range exceeding 3.5 causes problems such as the tendency that insoluble matter is generated in the produced polymer. This is because the carboxyl group of the anionic monomer is non-dissociated and there is no interaction between the ionic groups in the low pH range, whereas the carboxyl group of the anionic monomer dissociates and functions as an anionic group at high pH. It is considered that the interaction between ionic groups promotes the tendency of polymer salt formation during the polymerization process.

As the polymerization initiator, known radical polymerization initiators such as thermal decomposition type initiators, redox initiators and photopolymerization initiators can be used, and these are used alone or in combination to carry out polymerization.

As the thermal decomposition type initiator, azobisisobutyronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (2,4-dimethylpaleronitrile) , 4,4′-azobis (4-cyanopentanoic acid) and the like.

As the redox initiator, oxidizing agents such as ammonium persulfate, potassium persulfate, hydrogen peroxide and cumene hydroperoxide, and sodium formaldehyde sulfoxylate, thioglycolic acid, L-ascorbic acid, dimethylaminopropionitrile are used. , Sodium bisulfite, β-mercaptoethanol, and a reducing agent such as a divalent iron salt.

As the photopolymerization initiator, those generally referred to as photoinitiators or photosensitizers such as benzoin and its alkyl ethers, benzyl ketals, benzophenone and its derivatives or azo compounds are used.

Among these polymerization initiators, a photopolymerization initiator is preferable from the viewpoint of productivity and easy control of polymerization, and the addition amount thereof is preferably about 10 to 2000 ppm with respect to the total amount of monomers. If the amount of the photopolymerization initiator used is less than 10 ppm, the effect as a polymerization initiator is small and 2000 ppm
When it exceeds the above range, there are many cases in which disadvantages such as a decrease in the molecular weight of the obtained polymer occur. As the light used for irradiation, light in a wide wavelength range from ultraviolet to visible can be used according to various photopolymerization initiators as described above, but light having a dominant wavelength between 250 and 500 nm is preferable. It is better to use. Therefore, a high pressure mercury lamp, an ultra high pressure mercury lamp, a fluorescent chemical lamp, or the like is suitable as the light source.

As the polymerization temperature, the starting temperature is 5 to 40 ° C.
Depending on the degree, polymerization may be carried out in an adiabatic system, or polymerization may be carried out while removing the heat of polymerization from the outside by a sheet polymerization method or the like, but the latter is more preferable from the viewpoint of productivity and ease of polymerization control. .

In obtaining the amphoteric polymer flocculant of the present invention,
A chain transfer agent, a metal scavenger, a defoaming agent, a release agent, a release agent and the like may be added to the monomer mixture as needed.

A hydrous gel or solid polymer is obtained by the above-mentioned polymerization method, and the desired powdery amphoteric polymer flocculant can be obtained by drying and pulverizing the polymer, if necessary. .

The amphoteric polymer flocculant of the present invention may be used in combination with other cationic polymers or anionic monomers, if necessary, and may be used in the range that does not adversely affect the dehydration treatment. You may mix and use components other than polymers, such as sodium and sulfamic acid, and also use it together with an inorganic flocculant, such as a sulfuric acid band, polyaluminum chloride, ferric chloride, ferrous sulfate, and polyferric sulfate. be able to.

The amphoteric polymer flocculant of the present invention is dissolved as an aqueous solution of about 0.1 to 1% by weight in the same manner as an ordinary polymer flocculant, and is then dissolved in the sludge to be treated or the SS content in the waste water. A floc is formed by adding about 0.2 to 5% by weight, and then dehydration treatment is performed. As the dewatering device, various known sludge dewatering devices, such as a screw decanter, a screw press, and a belt press, can be used.

[0031]

EXAMPLES The present invention will be described in more detail below with reference to examples. The following methods were used to measure the salt viscosity of the aqueous solution, the cation degree, the water solubility, and the evaluation of the stability of the solution over time. VTS has the following meaning.

(1) Salt viscosity (1% η _s ) 5 g of a sample was dissolved in 495 g of deionized water to prepare 500 g of a 1% by weight aqueous solution, and sodium chloride 5.84 was added thereto.
After dissolving g, it was measured using a B-type viscometer under the conditions of No. 1 rotor and 6 rpm.

(2) Cationic Degree 1 g of a 1% by weight sample aqueous solution was precisely weighed in a conical beaker, 100 g of deionized water was added thereto, and the pH was adjusted to 3 with an acetic acid aqueous solution, followed by stirring for about 1 minute. Then add a few drops of toluidine blue indicator and titrate with N / 400 potassium polyvinylsulfate (PVSK) reagent. The titration rate was 2 ml / min, and the end point was the point when the test water changed from blue to reddish purple and was kept for 10 seconds or more. The cation degree is calculated by the following formula.

[0034]

[Equation 1]

(3) Water-Solubility 5 g of the sample was put in 495 g of deionized water, stirred for 4 hours, and the degree of cloudiness of the aqueous solution was evaluated by visual observation. Further, the aqueous solution was filtered through a 80-mesh filter, and the insoluble matter was measured by measuring the weight of the captured material.

(4) Stability of dissolution solution with time 0.5 g of a sample was dissolved in 497.5 g of city water to prepare a 0.5% by weight solution, and the solution was heated to 30 ° C.
The state of the liquid when left to stand for 7 days was visually observed to evaluate the temporal stability of the dissolved liquid.

(5) VTS (Volatile Res)
“Idue of Total Solid: Ignition loss material” This is the amount of a substance that volatilizes when the evaporation residue is ignited, and mainly indicates the amount of an organic substance.

[Example 1], [Comparative Example 1] The molar composition ratio of the monomers was set to the value shown in Table 1, and the monomer concentration was 6
1300 g of 0% by weight aqueous solution was prepared, and 2-hydroxy-2-methyl-propiophenone (manufactured by MARK, trade name: Darocur 1173) was used as a photopolymerization initiator.
Is 100 ppm, and hypophosphorous acid is 30 p as a chain transfer agent.
pm was added. The amount of hypophosphorous acid was such that the salt viscosity (1% η _s ) of the obtained polymer was 700 ± 150 mPa · s.
Was adjusted so that This monomer mixed solution at 25 ° C
The pH was adjusted to 2.5 while stirring with, and then the atmosphere was replaced with nitrogen for 30 minutes for deoxidation.

Next, the mixed solution is added to about 23 cm × 23 cm.
It was poured into a container of × 20 mm, and a polyethylene terephthalate film (12 μm thick) coated with polyvinylidene chloride (4 μm thick) was covered thereon with a film (16 μm). Water at 25 ° C. was sprayed at 2 liters / minute from the lower surface of the container to cool the reaction system. Further, in order to know the degree of progress of the polymerization, the surface temperature of the upper surface film can be measured with a radiation thermometer IR-0510 manufactured by Minolta Co., Ltd.

Polymerization is started by irradiating ultraviolet rays from above with a fluorescent chemical lamp manufactured by Mitsubishi Electric Corporation.
The UV irradiation condition is 2 until the surface temperature rises by 3 ℃.
After irradiating with W / m ² , until the maximum temperature reached 25 minutes, the
Irradiation was performed at 5 W / m ² , and irradiation was further performed at 60 W / m ² for 10 minutes in order to reduce the residual monomer to complete the polymerization.

The obtained sheet polymer was crushed to 60
After drying at 15 ° C. for about 15 minutes, the powdery polymer was pulverized to obtain a powdery polymer, and 10% by weight of sulfamic acid was mixed with the polymer to obtain a sample.

[Examples 2, 4, 5, 6] [Comparative Example 2,
4,5] A sample was obtained in the same manner as in Example 1 except that the monomer composition was changed to the quantitative ratio shown in Table 1 and hypophosphorous acid was used as the chain transfer agent at 40 ppm.

[Example 3] [Comparative Example 3] A sample was obtained in the same manner as in Example 1 except that the monomer composition was changed to the quantitative ratio shown in Table 1 and hypophosphorous acid was set to 60 ppm as a chain transfer agent. . Table 1 collectively shows the salt viscosity, the cation degree, the water solubility, and the temporal stability of the solution of the samples obtained in each of the above Examples and Comparative Examples.

[0044]

[Table 1]

Next, using the sample obtained in Example 2, the following flocculant dehydration test was conducted. In a 300 ml beaker, sludge (pH = 6.32, conductivity = 0.6 ms / c)
m, SS = 3.35%, VTS = 80.3%, fiber content =
(5.0%) was taken in 200 ml, and 0.5% by weight of the solution was added thereto so that the amount of polymer added was 500 ppm, and the mixture was stirred with a stirrer at 1000 rpm for 30 seconds to coagulate the sludge. After measuring the floc diameter at this time, put the coagulated sludge into a Buchner funnel lined with a filter cloth,
The amount of filtrate after 2 seconds was measured. Next, the sludge on the Buchner funnel was sandwiched between two filter cloths and squeezed at a pressure of 0.5 kg / cm ² for 60 seconds to determine the water content of the cake. as a result,
The floc diameter was 7 mm, the amount of filtrate after 10 seconds was 90 ml, and the water content of the cake was 81.0% by weight, which confirmed that the polymer had good performance.

[0046]

The amphoteric polymer flocculant of the present invention is not only excellent in flocculation and dehydration performance, but also has good solubility in water, is uniformly and transparently dissolved, and is extremely little deteriorated with time. It has excellent practicality.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08F 220/56 MNC C08F 220/56 MNC

Claims (1)

[Claims] 1. A cationic monomer unit represented by the general formula (I), an anionic monomer unit represented by the general formula (II), a nonionic monomer unit represented by the general formula (III) and a general formula (IV) An amphoteric polymer flocculant composed of the cationic monomer units shown, containing 5 to 30 mol% of the cationic monomer unit represented by the general formula (IV). Embedded image Embedded image Embedded image [Chemical 4]