JPS5849410A - Cationic polymer flocculant - Google Patents

Abstract

PURPOSE:To provide a cationic polymer flocculant superior in action of dehydrating organic sludge produced from a treatment process of waste water of urban communities and various industries. CONSTITUTION:Vinyl monomer units represented by formulaeIand II are copolymerized by ag. solution polymerization or the like in 30:70-98:2 ratio to form flocks high in density and large in diameter. A monomer producing the unit of formulaIis a salt of (meth)acrylate contg. tertiary amine and an acid, or contg. quaternary amine, and a monomer producing the unit of formula II is (meth) acrylamide contg. tertiary amine and acid salt or contg. quaternary amine salt. Such a flocculant is used in an amount of 0.2-5.0wt% of solid matter in suspension in dehydration filtration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cationic polymer flocculant having excellent solid-liquid separation performance for organic suspensions. More specifically, the present invention relates to a cationic polymer flocculant that has excellent dewatering properties for organic sludge generated in the treatment process of urban wastewater and various industrial wastewater.

Urban wastewater, such as sewage and human waste, and various industrial wastewater, such as chemical, paper, and steel, are generally organic suspensions containing organic suspended solids. Purification of these organic suspensions has become increasingly important in recent years not only from the perspective of environmental conservation, but also for purposes such as recycling for use as water and recovering useful substances.

It is well known that cationic polymer flocculants are widely used for solid-liquid separation of organic suspended solids from organic suspensions1, but conventional cationic polymer flocculants have not met market demands. could not be fully satisfied. That is, in conventional products, the required amount of addition was generally quite large, and the moisture content of the cake separated by solid-liquid separation was often higher than the market demand. Also, solid-liquid separation, especially ν
When performing excessive dehydration, it is usually used in combination with a dehydrator such as a centrifugal dehydrator or a belt press dehydrator, but there are requirements from the dehydrator side, for example, in the case of a centrifugal dehydrator, the flocs must be large and strong. In the case of belt press dehydrators, there are many cases where the requirements such as good releasability from furnace cloth are not fully met, and further improvements in performance have been desired.

The present inventors conducted intensive research in view of the current situation, and as a result, they arrived at the present invention.

That is, the present invention is a copolymer containing a vinyl monomer unit represented by the general formula (1) and a vinyl monomer unit represented by the general formula (2) as essential units, and a copolymer having the general formula t1
) and the unit represented by general formula (2) are in the range of 80 to 98:2 on a molar basis, and has excellent solid-liquid separation performance of an organic suspension. It is a cationic polymer flocculant.

General formula General formula r (In the general formula, R,, R5 are each independently H or a methyl group y R2+ R3+ R4+ R6+ R7+ R
8 is each independently H, an alkyl group or an aralkyl group; A and B are each independently an alkylene group having 1 to 4 carbon atoms, a hydroxyalkylene group having 2 to 4 carbon atoms or a phenylene group; xe and ye are each independently a pair; It is an anion. ) In general formulas (1) and (2), R2+ R3,R
4-R6,R? .

Examples of the alkyl group in the island include a methyl group, isopropyl group, and n-butyl group. Examples of the aralkyl group include a benzyl group.

The alkylene group having 1 to 4 carbon atoms in A and B is -
CH, CH2-, -CH2CH2CH2-, etc. are mentioned, and the hydroxyalkylene group having 2 to 4 carbon atoms is -C
H2CH3SO,, H3O4, So, , HPO,,
CH, CO2, C6H5C0□1CH3C6H, So3
etc.

Among these, preferred from a performance and industrial standpoint are R2, R3, R4, R6, ~ + R8 history is H, methyl group or ethyl group, and A and B are 1'CH, CH, -,
-CH2C) LICH2-+ Xo, Yofti C1
``+ CH35O,', H5O,'', S(), 20te4.

Examples of the monomer that provides the vinyl monomer unit represented by the general formula (1) include the following monomers, one of which,
Two or more types are used.

(1-A) Salt of 8th grade nitrogen-containing (meth)acrylate and acid [(meth)acrylate refers to acrylate or/and methacrylate. Same below. ] (1) Salts of dialkyl or alkylaralkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate sulfate, phethylaminoethyl (meth)acrylate hydrochloride, etc. (H) dialkyl or alkylaralkylaminohydroxyalkyl ( Salt of meth)acrylate = 3-diethylamino-2-hydroxypropyl (meth)acrylate acetate, etc. (1-B) Quaternary nitrogen-containing (meth)acrylate (i) (
Meta) acryloyloxyalkyl trialkyl or hasialkyl aralkylammonium halide or methyl sulfate: (meth) acryloyloxyethyl diethyl methyl ammonium methyl sulfate, (meth) acryloyloxyethyl trimethyl ammonium chloride, (meth) acryloyloxyethyl Dimethylbenzylammonium chlorite sodium (it) (meth)acryloyloxyhydroxyalkyl trialkyl or dialkylaralkyl ammonium halide or methyl sulfate: 3-methacryloyl waxy 2-hydroxypropyltrimethylammonium bromide, etc. still represented by general formula (2) Examples of monomers that provide vinyl monomer units include the following monomers, and one or more of these monomers may be used.

(2-A) Salt of 9th grade nitrogen-containing (meth)acrylamide and acid (1) Salt of dialkyl or alkylaralkylaminoalkyl (meth)acrylamide Nidiethylaminoethyl (meth)acrylamide hydrochloride.

diethylaminoethyl (meth)acrylamide sulfate,
Diethylaminomethylacrylamide acetate, dimethylaminomethyl (meth)acrylamide hydrochloride, etc. (it) Salts of dialkyl or alkylaralkylaminohydroxyalkyl (meth)acrylamide: 8-
Dimethylamino-2-hydroxypropylacrylamide sulfate, etc. (2-B) Quaternary nitrogen-containing (meth)acrylamide (1)
(meth)acryloylaminoalkyltrialkyl or dialkylaralkyl ammonium halide or methyl sulfate: (meth)acryloylaminoethyltrimethylammonium methylsulfate, (meth)acryloylaminomethyldimethylbenzylammonium bromide, etc. fii) (meth)acryloylaminohydrokinealkyltri Alkyl or dialkylaralkyl ammonium halide or methyl sulfate: (meth)
The copolymer of the present invention such as acryloylaminohydroxypropyltrimethylammonium chloride may be a copolymer containing only the monomer units of general formulas (1) and (2), but if the copolymer is water-soluble Yes, and the ratio of monomer units of general formulas (1) and (2) is 80 near 0
The copolymer may further contain other vinyl monomer units in the range of 98:2 to 98:2. Other monomers that provide vinyl monomer units include nonionic vinyl monomers [methyl (meth)acrylate + (meth)acrylonitrile, (meth)acryldiallylammonium chloride, p-styryltrimethylammonium chloride. etc.) can be mentioned. Among these, methyl methacrylate and acrylamide are preferred from the performance and industrial viewpoints.

In the present invention, the ratio of the monomers of general formulas (1) and (2) is from 80 to 98.0 on a molar basis. :2, preferably 50:50 to 95:5.

The cationic flocculant of the present invention has general formula (1) as an essential component.
and (2), and contain these monomer units in a specific ratio as described above. A known cationic flocculant other than the cationic flocculant of the present invention, for example, a cationic flocculant containing a monomer unit of general formula (1) as a cationic monomer unit, but not a monomer unit of general formula (2). When solid-liquid separation of an organic suspension is performed using a cationic flocculant containing less than 2 moles of cationic flocculant, the cationic flocculant of the present invention is generally formed even if the cationic flocculant has the same molecular structure and cationic degree. The flock is bulky and dense.
In many cases, the moisture content of the concentrated solution or cake after dehydration is high. Furthermore, the strength of the flocs is low, and the recovery rate of S, S, and S during centrifugal dehydration is often insufficient.

In addition, when using a belt press dehydrator, generally P cloth (
The releasability from the P material) is insufficient and the F fabric (P material) is likely to be contaminated.

On the other hand, it contains a monomer unit of general formula (2), and contains a monomer unit of general formula (1)
The fact is that even if the cationic flocculant does not contain monomer units, or even if it does contain less than 80 moles of cationic flocculants, it is still far from eliminating the above-mentioned drawbacks, and its practical value is not particularly recognized.

The present inventors have solved the above-mentioned problems using general formulas (1) and (
The problem was solved at once by incorporating the monomer units of 2) into the polymer chain in a specific proportion.

When other vinyl monomer units are present, the proportion of these single units in the copolymer is usually 70 molti or less, preferably 50 molti or less. When the ratio exceeds 70 molar ratio, solid-liquid separation performance generally becomes insufficient.

The method for producing the copolymer in the present invention is not particularly limited, and the monomer providing the vinyl monomer unit of (1) and the general formula (
It can be produced very easily industrially by copolymerizing with a monomer that provides a vinyl monomer unit (2). Specifically, copolymerization can be carried out by known methods, such as aqueous solution polymerization, emulsion polymerization using water and an organic solvent, suspension polymerization, and precipitation polymerization. In the case of aqueous solution polymerization, a monomer aqueous solution is prepared so that the monomer concentration is usually 10 to 90% by weight,
After purging the system with an inert gas, a known polymerization catalyst [persulfates such as ammonium persulfate, bromates such as sodium bromate, organic peroxides such as be/silver oxide, azo compounds such as azobisisobutyro] Add a nitrile and a redox catalyst, such as a combination of a peroxide (benzoyl peroxide, H2O2, etc.) and a reducing agent (sodium bisulfite, ferrous salt, etc.) to O~80
Copolymerization can be carried out within several hours at a temperature of about °C, and a copolymer can be obtained very easily.

The obtained copolymer has an intrinsic viscosity of at least 1.0 or more.
If the intrinsic viscosity is less than 1.0, when the copolymer is used as a flocculant, it cross-links and adsorbs the component particles in the organic suspension. The basic performance of the polymer flocculant used to form flocs is insufficient, and therefore the solid-liquid separation performance is also insufficient. Intrinsic viscosity is 80°
C measured in an aqueous solution of I N NaNO3.

The cationic polymer flocculant of the present invention is made of the copolymer described above and has excellent solid-liquid separation performance for organic suspensions.

The above organic suspensions include organic sludge generated from sewage, human waste, and other various industrial wastewaters such as activated sludge treatment and digestion; dyeing wastewater, paper, etc.; Examples include organic waste liquid; papermaking process tenopalf slurry; and chemical solutions such as cultured strains of antibiotics such as beninrin. Among these, organic sludge is preferred.

When performing solid-liquid separation (coagulation sedimentation, filtration dehydration) of an organic suspension using the cationic polymer flocculant of the present invention, the amount of flocculant added (solid content equivalent) is Usually 0.2 to 5.0% by weight based on the solid content of the suspension.
, preferably 0.5 to 2.0% by weight. When coagulation and sedimentation are carried out, the amount is usually 0.01 to 1.0% by weight, preferably 0.05 to 0.5% by weight.

When adding, the flocculant is preferably in the form of an aqueous solution;
It is usually added to the organic suspension as a 0.1-0.5% (as solids) aqueous solution. The method of adding the flocculant is not particularly limited, and any known method such as coagulation sedimentation or filtration and dehydration can be used.

When performing filtration and dehydration, a known dehydrator (centrifugal dehydrator, belt press type (squeezing type) dehydrator 5 gravity type dehydrator 9 capillary type dehydrator, pressure dehydrator, vacuum dehydrator, etc.) can be used. . Preferred are centrifugal dehydrators, belt press dehydrators and gravity dehydrators.

The flocculant of the present invention may be used in combination with other flocculants if necessary. Other polymer flocculants used in combination include polyacrylamide, acrylamide-sodium acrylate copolymer, acrylamide copolymer, methacryloyloxyethyl trimethylammonium chloride copolymer, remer, chitosan, polyethidanimine, polyvinylimidacillin,
Examples include polydimethyldiallylammonium chloride and sodium polyacrylate, and inorganic flocculants include polyaluminum chloride, bread earth sulfate, and ferric chloride.

Examples include ferrous sulfate 2 coal.

Further, as a method of using the flocculant in combination, the other flocculant may be added after the flocculant of the present invention is added, or the order of addition may be reversed, or they may be added at the same time.

The cationic flocculant of the present invention forms flocs with high density and large diameter, and is at a practically satisfactory level in terms of breakage by mechanical force and peeling from P fabric (F material). In addition, it can be easily produced industrially as will be described later, and is extremely useful for solid-liquid separation of organic suspensions.

Although it is not clear why unexpectedly excellent effects were obtained by simultaneously containing the monomer units of general formulas (1) and (2) in a specific proportion, one speculation is that It is thought that the difference may have occurred in the adsorption of the cationic polymer to the turbid substance and the configuration or arrangement of the adsorbed polymer.

Since the cationic flocculant of the present invention exhibits the above effects, it is useful as a flocculant for various organic suspensions, and is particularly useful as a flocculant for dewatering organic sludge.

The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 9515.80/20.5015 of methacryloyloxyethyltrimethylammonium chloride and acryloylaminopropyltrimethylammonium chloride
Flocculant A consisting of a copolymer with a solenoid ratio of 0.

B and C were each made into 0.2% aqueous solutions, and activated sludge from a sewage treatment plant and surplus sludge from treatment (solid content 0.9%, p
H6,9) 50,1 for each sludge in 200ml
00 and 150 ppm were added to cause flocculation. Next, this mixture was transferred to a Nutsche fitted with a nylon furnace cloth, filtered naturally, and the amount of filtrate was measured 15 seconds after the start of filtration.
Comparative products A', B', and C' in the case of 00 were also added to excess sludge and subjected to a dewatering test.

The results are shown in Table 1. (Note 1) Methacryloyloxethyltrimethylammonium chloride/Tacryloylaminoprohyde? Lolimethylammonium chloride.

(Molar ratio) (Note 2) Measured at 80°C in IN NaNo3 Example 2 Flocculant D of the present invention Copolymer of acrylamide, diethylaminoethyl methacrylate hydrochloride and dimethylaminopropylacrylamide sulfate (molar ratio Fi80: 50:20) (intrinsic viscosity 4.5) Comparative product B Copolymer of acrylamide and diethylaminoethyl methacrylate hydrochloride (molar ratio i; tso:'ro) (intrinsic viscosity 4.8) Comparative product E' Acrylamide and Copolymer with dimethylaminopropylacrylamide sulfate (mole ratio: 80N0) (intrinsic viscosity: 4.4) Example 1 Excess sludge used in ~8 20
After adding 120 ppm to 0 ml to cause agglomeration,
The cake was dehydrated using a heald press, and the moisture content of the cake and the releasability from the oven cloth were examined.

The results are shown in Table-2.

Table-2

Claims (1)

[Claims] Vinyl monomer units represented by general formula (1) and general formula (2)
) is a copolymer containing the vinyl monomer unit represented by formula (1) as an essential unit, and the vinyl monomer unit represented by general formula (1) and the vinyl monomer unit represented by general formula (2) 1. A cationic polymer flocculant having excellent solid-liquid separation performance for organic suspensions, characterized in that the ratio is in the range of 80:0 to 98:2 on a molar basis. General formula (in the general formula, R,, R5 are each independently H or methyl group + R2+ R3+ R4+ R6+ R7+ R
8 is each independently H, an alkyl group or an aralkyl group; A and B are each independently an alkylene group having 1 to 4 carbon atoms, a hydroxyalkylene group having 2 to 4 carbon atoms or a tahaphenylene group; Anion de Ruru. )