DD260931A1 - METHOD FOR PRODUCING A NEW CATIONIC WATER-SOLUBLE FLAKING AGENT - Google Patents

Abstract

The invention relates to a process for the preparation of a novel cationic water-soluble flocculant with high separation efficiency and low fish toxicity. The flocculant is primarily suitable for separation processes in the field of wastewater treatment. According to the invention, a monomeric cationic vinyl ester is first prepared by reacting a halocarboxylic acid vinyl ester with a tertiary amine, which is subsequently polymerized by free-radical polymerization. The polymers obtained can be isolated by precipitation with acetone or used directly as a polymerization solution as a flocculant.

Description

Field of application of the invention

The invention relates to a process for the preparation of a novel cationic flocculant with reduced fish toxicity. The flocculant is mainly suitable for separation processes in the field of wastewater treatment.

Characteristic of the known state of the art

In the clarification and purification of municipal and industrial wastewater flocculants are used to accelerate the separation of suspended solids. Water-soluble, cationic polymers have become more important here. The cationic water-soluble polymers include homopolymers such. As poly (dimethyl-diallylammonium chloride) or polymeric quaternary esters or amides of acrylic acid or copolymers containing cationic groups, for. B. copolymers of acrylamide.

However, these cationic flocculants are acutely toxic to fish (Wasserschadstoffkatalog, ed. By the Institute of Water Management, Berlin, on behalf of the Ministry of Environmental Protection of the GDR, 1979). Also, the very small amounts remaining in the water after separation of the solids cause toxicity problems when the treated water enters natural receiving waters. It has therefore been proposed to detoxify by treating the water treated with a cationic flocculating agent with an anionic polymer (DOS 2942111). However, this process is very complicated and ultimately uneconomical due to additional process stages and increased costs.

Another group of cationic water-soluble polymers are the cationic vinyl esters. Their synthesis is carried out by modifying hemoliferous polymers. SCI monograph no. 26, pp. 131-142 describes the preparation of a cationic vinyl ester by reacting polyvinyl chloroacetate with pyridine. However, the highest attainable degree of quaternization was only 80%, ie. H. Vs of all chain building blocks could not be converted into flocculation-active cationic groups.

Such partially quaternized polymeric α-halocarboxylic acids were used as flocculants. In this case, those polymers are best suited whose Quaternierungsgrad less than 50%, preferably 10 to 30%, is (GB-PS 1073823).

So far, water-soluble cationic vinyl esters have only been prepared by quaternization of polymeric halocarboxylic acids.

The radical polymerization of the monomeric quaternary salts of vinyl chloroacetate is described as impossible (SCI monograph no. 28, p. 141).

Object of the invention

The aim of the invention is an economically favorable production of a new cationic polymeric vinyl ester, which is suitable as a flocculant for wastewater treatment, wherein in addition to the favorable flocculation properties, the treated water after solids separation has only a low fish toxicity and thus eliminates further post-treatment.

Explanation of the essence of the invention

The object of the invention is to produce a water-soluble cationic polymeric vinyl ester in which the proportion of flocculation-active cationic groups is 100% and which has low fish toxicity at high separation efficiency. According to the invention the object is achieved in that first prepared a monomeric cationic vinyl ester and then polymerized by free radical. For the monomer synthesis, a vinylcarboxylate is reacted with a tertiary amine in a molar ratio of 2: 1 to 1: 2 in the presence of potassium iodide in dimethylformamide (DMF) as a solvent at temperatures from -2O ⁰ C to + 2O ⁰ C.

After 0.5-5h, the deposited product is isolated, washed with ethyl acetate and ether and then dried. The preferred halogenocarboxylic acid vinyl esters are vinyl chloroacetate, vinyl-β-chloropropionate, gamma-chlorobutyric acid and cu-chloro-caproic acid vinyl ester. As tertiary amines, trimethylamine, triethylamine, dimethylbutylamine, dimethylhexylamine, dimethyloctylamine, dimethyldecylamine, dimethyldodecylamine, dimethyloctadecylamine and pyridine are preferably used.

The monomeric cationic vinyl esters are then polymerized at 30 ° C-90 ° C free-radically. As initiators any radical generator can be used, for. B. 10 ~ ¹ -10 ~ ⁴ mmol / l azobisisobutyronitrile (AIBN) .- The polymerization takes place in concentrations of the monomer from 0.1 to 3.0 mol · Γ ¹ ; The solvents used are water, lower alcohols (methanol, ethanol, propanol) or mixtures thereof with water (vol. ratio 1: 5 to 5: 1) or with acetone (vol. ratio 1: 5 to 5: 1) , The reaction time is 5-3Oh. The resulting polymers can be isolated by precipitation with acetone. For use as a flocculant, however, the polymerization solution can be used directly without isolation of the polymer.

Because of its high content of flocculation-active cationic groups, the flocculant produced according to the invention has a high separation performance and can be used in a variety of ways for the separation of municipal and industrial wastewaters, which have a low fish toxicity after separation of the solids. This eliminates complex post-treatments.

embodiment example 1

For the monomer synthesis 0.1 mole Chloressigsäurevinylester are dissolved together with 0.1 g of KI in 20 ml DMF and cooled to 20 ⁰ C. To this is added 0.1 mol of trimethylamine. With cooling, it is stirred for 0.5 h. The precipitated white crystals are filtered off with suction and washed with ethyl acetate and ether.

100 g of a 2 molar solution of the resulting monomer in methanol are added to 1 × 10 ^-2 mol / l of AIBN and polymerised under N ₂ for 10h at 65 ⁰ C. Subsequently, the polymer is precipitated by pouring into excess acetone.

Example 2-12

A list of the preparation variants of the flocculant according to the invention is given in Table 1 and Table 2.

Table 1: Monomer synthesis

Monomer starting substances T t

No acid amine Molverh. ° C h

I vinyl chloroacetate

Il vinyl chloroacetate

In vinyl chloroacetate

IV vinyl chloroacetate

V chloroacetic acid vinyl ester

VI vinyl chloroacetate

VII vinyl chloroacetate

VIII vinyl chloroacetate

IX β-chloropropionic vinyl radicals

X γ-chlorobutyric acid vinyl ester XI ω-chloro-caproic acid vinyl ester

triethylamine 1: 1 -15 3 dimethylbutylamine 1: 1 -15 3 pyridine 1: 1 -15 3 dimethylhexylamine 1: 2 -15 3 dimethyloctylamine 2: 1 + 15 25 dimethyldecylamine 1: 1 -10 5 dimethyldodecylamine 1: 1 -5 0.5 dimethyloctadecylamine 1: 2 -2 3 trimethylamine 1: 1 -15 3 trimethylamine 1: 1 +5 13 Trimethvlamin 1: 1 +20 30

Table 2: Polymerization

monomer solvent AIBN temperature Time No., mol-r ¹ mol-r ^{1 0} C H 1.3 methanol ΙΟ " ² 30 30 11.3 methanol 10- ² 30 30 111.2 methanol ΙΟ " ² 50 10 IV, 1 methanol 10 " ³ 90 10 V, 1 water 10 ~ ¹ 70 5 VI, 1 Methanol / water 5: 1 io- ⁴ 70 15 VII, 1 Methanol / water 1: 1 ΙΟ " ² 50 10 VIII, 1 Methanol / water 1: 5 ΙΟ " ¹ 60 8th IX, 1 Methanol / acetone 1: 1 io- ¹ 60 8th X, 0.1 Methanol / Aceton5: 1 io- ³ 60 10 Xl, 0.1 Methanol / acetone 1: 5 io- ³ 60 10

Example 3

100 ml of a suspension of kaolin in water with a solids content of 1 g / l was treated at 20 ° C in separate experiments, first with a polymeric quaternary ester of acrylic acid and then with the polymers according to the invention prepared as a flocculant. The additional amount of flocculant was 5 mg / l. After sedimentation of the solids, the clear effluent, which had a pH of 8.5, was separated and tested for toxicity to 10 rainbow trout each. In the case of the polymeric quaternary ester of acrylic acid, 6 of the 10 fish were dead after 100 hours. In the case of the polymers according to the invention all fish were alive after the same time.

Example 4

100 ml of a suspension of kaolin having a solids content of 0.5 g / l was added at 2O ⁰ C 1 mg / l of said polymer in Table 3 as a 0.1% solution mixed undiOminmit 200 U / min using a stirrer. The time was measured according to which a constant transparency arose and the achieved value of the transparency. The results are shown in Table 3.

Table 3: flocculation experiments

polymer Constant transparency after transparency min % According to US-PS 1073823, Quaternization degree 30% 12.9 75.1 according to Example 1 12.0 85.3 I 12.0 85.1 Il 12.2 83.0 III 12.1 83.2 IV 12.3 82.2 V 12.3 81.9 Vl 12.4 80.6 VII 12.5 80.2 VIII 12.7 78.3 IX 12.1 83.1 X 12.2 83.0 xl 12.3 82.5

Claims (7)

1. A process for the preparation of a novel cationic water-soluble flocculant, characterized in that a vinyl halocarboxylate with a tertiary amine in a molar ratio of 2: 1 to 1: 2 in the presence of potassium iodide in a dimethylformamide solution at temperatures from -20 ⁰ C to +20 ⁰ C implemented and the resulting cationic vinyl ester is then polymerized with a free-radical initiator. 2. The method according to claim 1, characterized in that the polymerization of the cationic vinyl ester in solution in a concentration of 0.1 to 3.0 mol / l at 30 ⁰ C to 9O ⁰ C within 5 to 30 hours. 3. The method according to claim 1 and 2, characterized in that is used as the radical initiator azobisisobutyronitrile. 4. The method according to claim 1, characterized in that are used as Halogenarbonsäurevinylester chloroacetic acid ^ ß-chloropropionic, γ-chlorobutyric acid or ω-Chlorcapronsäurevinylester. 5. The method according to claim 1, characterized in that as tertiary amines trimethyl, triethyl, dimethylbutyl, dimethylhexyl, Dimethyloctyl-, dimethyldecyl, dimethyldodecylamine or pyridine is used. 6. The method according to claim 1 and 2, characterized in that are used as the solvent water or lower alcohols. 7. The method according to claim 1,2 and 3, characterized in that methanol, ethanol or propanol or mixtures thereof with water or acetone, each in a volume ratio of 5: 1 to 1: 5, are used.