CN107674165A - A kind of method for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave - Google Patents

Abstract

The invention discloses a method for synthesizing cationic polyacrylamide by using ultrasonic-induced template polymerization. In the method, acrylamide monomer, cationic monomer, deionized water, template and urea are sequentially added into a reaction device, stirred evenly, and adjusted pH value, the system is processed into a uniform solution under ultrasonic radiation, then nitrogen deoxidation is introduced, and the reaction device is immediately sealed after adding the initiator, and finally ultrasonic treatment is performed at a certain frequency to initiate the polymerization reaction, purified, washed and refined, and dried in vacuum The final product is obtained after drying in the box and grinding. The cationic polyacrylamide prepared by the invention has concentrated distribution of cationic monomers, large molecular weight and high charge density, which greatly improves the electric neutralization and bridging capabilities of the flocculant. The invention has short polymerization time, low reaction temperature, high polymerization efficiency and simple experimental operation, reduces energy consumption and production cost. It is suitable for dehydration treatment of drinking water, sewage and sludge, and has good application prospects.

Description

A method for synthesizing cationic polyacrylamide by ultrasonic-induced template polymerization method

technical field

The invention relates to a method for synthesizing cationic polyacrylamide, in particular to a method for synthesizing cationic polyacrylamide by template polymerization induced by ultrasonic waves.

Background technique

Coagulation is to add a coagulant to the wastewater to destroy the stability of the colloid, so that the fine suspended particles and colloid particles gather into coarser particles and settle and separate from the water, so that the wastewater can be purified. Coagulation includes two steps of coagulation and flocculation. Coagulation method is a method commonly used in water treatment, which can be used to reduce the turbidity and chromaticity of water, remove a variety of high molecular organic matter, some heavy metals and radioactive substances, and improve the dehydration performance of sludge. Currently commonly used flocculants can be divided into inorganic flocculants, organic flocculants, composite flocculants and biological flocculants according to their chemical composition. Among them, the cationic polyacrylamide in the organic polymer flocculant has a good adsorption and bridging effect during flocculation due to its long molecular chain, and can absorb many dissolved substances and suspended solids in sewage, and most of the sewage has negative The colloidal property of charge is more suitable for flocculation treatment with cationic polyacrylamide. Therefore, the development of cationic polyacrylamide with wide application range and good treatment effect and economical and energy-saving synthesis technology has broad development prospects.

At present, the synthesis methods of cationic polyacrylamide in my country mainly include two categories, namely, the ion modification method of polyacrylamide and the monomer copolymerization method. The cationic modification of polyacrylamide is mainly realized by methylol reaction or Mannich reaction. The cationic polyacrylamide prepared by this method has the disadvantages of short product storage time, low cationic degree and difficult control of cationic degree. The monomer copolymerization method can be further divided into dispersion polymerization method, aqueous solution polymerization method, inverse (micro) emulsion polymerization method, micellar polymerization method, etc. Their main disadvantages are: 1. Heating or cooling is required in the initiation process, which increases the production cost and consumes too much energy. For example, the patent with publication number CN104877070A "Preparation method of cationic polyacrylamide dry powder" needs to be initiated under the condition of cooling down to 0~3°C; "Molecular flocculant synthesis process" requires heating to be controlled at 60-80°C for polymerization. 2. It takes a long time to initiate polymerization. For example, the publication number is CN106467601A patent "a kind of hydrophobic association cationic polyacrylamide and its preparation method and application", its heating and refluxing polymerization takes 3~6h, and the polymerization time is longer; The patent "an organic polymer flocculant and its preparation method" prepares a water-soluble organic polymer flocculant through a polymerization reaction, which takes 4~14 hours and takes a long time to initiate polymerization. 3. Can not reflect its cationic effect well. Such as the patents whose publication numbers are CN104558405A and CN102964518A mainly adopt the copolymerization method. The cationic monomers of cationic polyacrylamide prepared by these synthetic methods are not uniformly distributed in the polymerization reaction, showing random random arrangement, resulting in too dispersed cationic units and positive charges in the polymer molecule, and cannot fully exert the electrical neutralization function of cationic monomers. .

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for synthesizing cationic polyacrylamide by using ultrasonic-induced template polymerization to solve the problems of high energy consumption, long polymerization reaction time and uneven distribution of cationic monomers in the existing synthesis method. Uniformity leads to the problem of weak electrical neutralization ability.

In order to achieve the above object, the present invention adopts the following technical scheme: a method for synthesizing cationic polyacrylamide by ultrasonic-induced template polymerization, comprising the following steps:

1) Prepare the reaction system

Add acrylamide monomer and cationic monomer in sequence in the reaction device, then add deionized water, stir evenly until completely dissolved, and form a total monomer aqueous solution, in which the sum of acrylamide monomer and cationic monomer is the total monomer ;

Add template and urea to the total monomer aqueous solution prepared above, stir evenly, adjust the pH value of the above mixed solution to 4.0~5.0, adjust the temperature to 25~45°C, and irradiate with ultrasonic waves, and then fill the reaction device with high Pure nitrogen, completely evacuate the oxygen in the reaction device, quickly add the initiator, and seal the reaction device immediately after mixing evenly; the reaction system includes acrylamide monomer, cationic monomer, urea, initiator and deionized water;

The total monomer accounts for 24% to 40% of the mass of the reaction system, the acrylamide monomer accounts for 18% to 28% of the mass of the reaction system, and the cationic monomer accounts for 6% to 16% of the mass of the reaction system. The urea accounts for 0.2% to 0.4% of the total monomer mass, the initiator accounts for 0.2‰ to 0.8‰ of the total monomer mass, and the balance is deionized water;

The mass ratio of the template to the cationic monomer is 0.36-0.55:1, the template is an anionic polymer, and the molecular weight is 3000-6000;

2) Ultrasonic Initiated Polymerization

Place the mixed solution prepared above in an ultrasonic oscillator at a temperature of 25-45°C, use ultrasonic waves to initiate polymerization, and leave it to stand for 3-5 hours at room temperature to obtain a transparent colloidal polymer that is a cationic Polyacrylamide;

3) Preparation of cationic polyacrylamide powder

The cationic polyacrylamide viscous colloid obtained in step 2) is shredded and granulated into granules, purified, washed and refined with anhydrous acetone and anhydrous ethanol solution for several times respectively, and then dried in a vacuum drying oven Grinding after drying to obtain white solid powder of cationic polyacrylamide.

Further, the anionic polymer described in step 1) is sodium polyacrylate or sodium polymethacrylate.

Further, the power of the ultrasonic wave described in step 1) and step 2) is 100~400W, and the frequency is 45kHz;

Further, the polymerization time described in step 2) is 10-30 minutes.

Further, the ultrasonic radiation time in step 1) is 10-30 minutes.

Further, the cationic monomer in step 1) is acrylamidopropyltrimethylammonium chloride or methacrylamidopropyltrimethylammonium chloride.

Further, the anionic polymer in step 1) is sodium polyacrylate or sodium polymethacrylate.

Further, the initiator described in step 1) is azobisisobutylimidazoline hydrochloride VA-044 or azobisisobutylamidine hydrochloride V-50.

Further, the time for nitrogen filling and deoxygenation described in step 1) is 20-40 minutes.

Furthermore, the cationic polyacrylamide prepared above can be used for dehydration treatment of drinking water, sewage or sludge.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention synthesizes cationic polyacrylamide by means of ultrasonic-induced polymerization. Due to the mechanical effect of ultrasonic waves, the reaction system can be dispersed better and the mass transfer is faster, thereby increasing the reaction rate, and ultrasonic waves have energy, which can make the initiators collide with each other. , Cracking, generating free radicals, thereby initiating the reaction, improving the efficiency of the polymerization reaction, shortening the time of the polymerization reaction, and the minimum polymerization time is 10 minutes. In addition, the reaction environment of the present invention is relatively mild (can be carried out at normal temperature and pressure), and the reaction temperature is low, which not only greatly reduces energy consumption and production cost, but also facilitates the control of the synthesis process.

2. The present invention adopts a template polymerization method to form cationic fragments with a block structure. By adding an anionic polymer with a long linear molecular chain structure to the polymerization solution as a template, an electrostatic attraction will occur between the negatively charged template and the positively charged cationic monomer, making the cationic monomer along the template molecular chain Directional continuous arrangement, when the polymerization reaction starts, the continuous adjacent cationic monomers are more likely to undergo a synthesis reaction, thereby forming a block structure in which the cationic units in the polymer molecule are continuously adjacent. That is, cationic fragments of block structure are formed in the molecular chain of the flocculant (cationic polyacrylamide) synthesized by the present invention, and the distribution of cationic monomers on the synthesized cationic block is concentrated, and the charge density is high, so the flocculant can be greatly improved. Electrical neutralization and bridging capabilities.

3. The cationic polyacrylamide prepared by the present invention has concentrated distribution of cationic monomers on the synthesized cationic block and high charge density, so it can greatly improve charge neutralization, adsorption bridging ability and flocculation efficiency. The molecular weight of cationic polyacrylamide is higher, the molecular weight is on the order of 10 ⁶ , and the cationic degree is higher.

4. In the process of preparing cationic polyacrylamide, the selected acrylamide has a controllable molecular weight, the ultrasonic instrument used is simple, and the selected raw materials are all commercially available materials, which are cheap and easy to select. Therefore, the present invention has strong controllability, simple operation and low cost. The products can be widely used in water treatment fields such as water supply and drainage. It can be used for both water purification and sludge treatment.

detailed description

The present invention will be described in further detail below in conjunction with specific embodiments. The raw materials used in the following examples are all commercially available products. Among them, the common commercially available flocculant is P(AM-DAC), AM: acrylamide, DAC: acryloyloxyethyltrimethylammonium chloride, molecular weight: 5-6 million, cationic degree 30-40%, Zhongbang brand Cationic polyacrylamide, Zhengzhou, Henan.

1. A method for synthesizing cationic polyacrylamide using ultrasonic wave-induced template polymerization

Example 1

1) Weigh 8.4 g of acrylamide and 3.6 g of acrylamidopropyltrimethylammonium chloride in turn, and put them into a reagent bottle. Add 28 g deionized water again, stir, the mass concentration of preparing total monomer is the total monomer solution of 30%;

2) Add 1.66 g sodium polyacrylate (molecular weight 3300) and 0.12 g urea to the above total monomer solution, stir well, then add sodium hydroxide solution or hydrogen chloride solution, and adjust the pH value of the above mixed solution to 4.5; The temperature was kept at 30°C, and irradiated with ultrasonic waves for 30 minutes, then filled with high-purity nitrogen to remove oxygen for 30 minutes, quickly added 20 mg of initiator azobisisobutylimidazoline hydrochloride (VA-044), and immediately sealed the reagent bottle;

3) At 35°C, place the above-prepared mixed solution in an ultrasonic oscillator, use ultrasonic waves to initiate, the frequency is 45kHz, the power is 400W, after the polymerization reaction for 10 minutes, it is aged at room temperature for 4 hours to obtain a colorless and transparent The colloidal polymer substance is cationic polyacrylamide.

4) The viscous colloid of cationic polyacrylamide is cut and granulated into granules, purified, washed and refined with anhydrous acetone and anhydrous ethanol solution for 3 times respectively, and then dried in a vacuum drying oven Grinding after drying to obtain white solid powder of cationic polyacrylamide.

The colloid titration method was used to detect that the molecular weight of the substance was 5.83X10 ⁶ , the solid content was 29.6%, and the cationic degree was 29.7%.

Example 2

1) Weigh 9.8 g of acrylamide and 4.2 g of methacrylamidopropyltrimethylammonium chloride in turn, and put them into a reagent bottle. Add 26 g deionized water again, stir, the mass concentration of preparing total monomer is the total monomer solution of 35%;

2) Add 1.99g sodium polymethacrylate (molecular weight 4200) and 0.14g urea to the above total monomer solution, stir well, then add sodium hydroxide solution or hydrogen chloride solution, and adjust the pH value of the above mixed solution to 4.5; Then keep the temperature at 35°C, and irradiate with ultrasonic waves for 30 minutes, then fill with high-purity nitrogen to remove oxygen for 30 minutes, quickly add 25 mg of initiator azobisisobutylamidine hydrochloride V-50, and immediately seal the reagent bottle;

3) At 35°C, place the above-prepared mixed solution in an ultrasonic oscillator, use ultrasonic waves to initiate, the frequency is 45kHz, the power is 300W, after polymerization for 20 minutes, it is aged at room temperature for 4 hours to obtain a colorless and transparent The colloidal polymer substance is cationic polyacrylamide.

4) The cationic polyacrylamide viscous colloid was cut into granules and made into granules, which were purified, washed and refined with anhydrous acetone and anhydrous ethanol solution for four times respectively, and then dried in a vacuum drying oven Grinding after drying to obtain white solid powder of cationic polyacrylamide.

The colloid titration method was used to detect that the molecular weight of the substance was 5.10 X10 ⁶ , the solid content was 34.6%, and the cationic degree was 29.8%.

Example 3

1) Weigh 11.2 g of acrylamide and 4.8 g of acrylamidopropyltrimethylammonium chloride in turn, and put them into a reagent bottle. Add 24 g deionized water again, stir, the mass concentration of preparing total monomer is the total monomer solution of 40%;

2) Add 2.3g sodium polyacrylate (molecular weight 3300) and 0.16g urea to the above total monomer solution, stir well, then add sodium hydroxide solution or hydrogen chloride solution, adjust the pH value of the above mixed solution to 4.5; Keep the temperature at 35°C, and irradiate with ultrasonic wave for 30 minutes, then fill it with high-purity nitrogen to remove oxygen for 30 minutes, quickly add 25 mg of initiator azobisisobutylimidazoline hydrochloride (VA-044), and seal the reagent bottle immediately;

3) At 35°C, place the above-prepared mixed solution in an ultrasonic oscillator, use ultrasonic waves to initiate, the frequency is 45kHz, and the power is 200W. After polymerization for 30 minutes, it is aged at room temperature for 4 hours to obtain a colorless and transparent The colloidal polymer substance is cationic polyacrylamide.

4) The viscous colloid of cationic polyacrylamide was shredded and granulated into granules, purified, washed and refined with anhydrous acetone and anhydrous ethanol solution for 5 times respectively, and then dried in a vacuum drying oven Grinding after drying to obtain white solid powder of cationic polyacrylamide.

The colloidal titration method was used to detect that the molecular weight of the substance was 5.10 X10 ⁶ , the solid content was 39.1%, and the cationic degree was 29.7%.

2. Product application effect

1. The test sludge water is taken from the sludge of the secondary settling tank of Chongqing Jiguanshi Wastewater Treatment Plant (pH: 6.94, moisture content: 98.9%, Zeta potential -24.8mV, VSS/TSS=0.73, density: 0.978mgl/L): Prepare 10 "coagulation test mixers" (ZR4-6 Zhongrun Co., Ltd.) with 1000 mL deionized water respectively, and then add 500ml sludge respectively.

Test method: The prepared sewage was randomly divided into 2 groups, 5 parts in each group, one group was the control group (adding common commercially available flocculants), and the other group was the example group (adding the cationic polyacrylamide prepared in Example 3 powder).

Add 40 mg/L commercially available flocculant or the cationic polyacrylamide solution prepared in Example 3 to the homogeneous kaolin suspension, respectively. The mixed solution was first stirred at a high speed of 250 rpm for 5 minutes, and then mixed at a low speed of 50 rpm for 15 minutes. Subsequently, the supernatant was obtained after free sedimentation for 30 minutes.

The moisture content of the mud cake after the cationic polyacrylamide treatment prepared by the invention reaches 72.8%. Under the same conditions, the water content of mud cake is 4% lower than that of ordinary commercially available flocculants. Therefore, the cationic polyacrylamide prepared by the invention can be used for sludge dewatering.

2. Test sewage: Prepare 10 "coagulation test mixers" (ZR4-6 Zhongrun Co., Ltd.) with 1000 mL deionized water respectively, then add 0.5g kaolin, stir at 200rpm for 5 minutes, and ultrasonically oscillate for 1 minute. Prepare a homogeneous kaolin suspension.

Test method: The prepared sewage was randomly divided into 2 groups, 5 parts in each group, one group was the control group (adding common commercially available flocculants), and the other group was the example group (adding the cationic polyacrylamide prepared in Example 2 powder).

Add 40 mg/L commercially available flocculant or the cationic polyacrylamide solution prepared in Example 2 to the homogeneous kaolin suspension respectively. The mixed solution was first stirred at a high speed of 250 rpm for 5 minutes, and then mixed at a low speed of 50 rpm for 15 minutes. Subsequently, the supernatant was obtained after free sedimentation for 30 minutes.

The turbidity removal rate of the cationic polyacrylamide prepared by the invention is as high as 95%. Under the same conditions, the turbidity removal rate is 5% higher than that of ordinary commercially available flocculants. Therefore, the cationic polyacrylamide prepared by the invention can be used for removing high turbidity kaolin wastewater.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A kind of 1. method for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, it is characterised in that including Following steps：

   1）Prepare reaction system：

   Acrylamide monomer and cationic monomer are sequentially added in reaction unit, then adds deionized water, is stirred To being completely dissolved to obtain the total monomer aqueous solution；Wherein acrylamide monomer and cationic monomer sum are total monomer；

   Template and urea are added into the above-mentioned total monomer aqueous solution, is stirred, the pH value of above-mentioned mixed solution is adjusted to 4.0 ~ 5.0, temperature is adjusted to 25 ~ 45 DEG C, and with Ultrasonic Radiation, High Purity Nitrogen is then filled with into reaction unit, by reaction unit Oxygen is emptied completely, and rapidly joins initiator, after being well mixed, seals reaction unit immediately；

   The total monomer accounts for the 24% ~ 40% of reaction system quality, the acrylamide monomer account for reaction system quality 18% ~ 28%, the cationic monomer accounts for the 6% ~ 16% of reaction system quality, and the urea accounts for the 0.2% ~ 0.4% of total monomer quality, described Initiator accounts for 0.2 ‰ ~ the 0.8 ‰ of total monomer quality, and surplus is deionized water；

   The reaction system includes acrylamide monomer, cationic monomer, urea, initiator and deionized water；

   Wherein, the template and cation mono body mass ratio are 0.36 ~ 0.55：1, the template is anionic polymer, and point Son amount is 3000 ~ 6000；

   2）Ultrasonic wave initiated polymerization：

   The mixed solution of above-mentioned preparation is placed in ultrasonic oscillation device, temperature is 25 ~ 45 DEG C, is drawn using ultrasonic wave Hair, polymerisation occurs, at room temperature static curing 3 ~ 5 hours, it is cation poly- third that transparent gum polymers matter, which is made, Acrylamide；

   3）Prepare PAMC powder：

   By step 2）The PAMC thick gel of acquisition, graininess is made by shredding granulation, uses successively respectively Anhydrous propanone and ethanol solution are repeatedly purified, wash and refined, and are then ground after being dried in vacuum drying chamber, are made PAMC white solid powder.
2. 2. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, step 1）Described anionic polymer is Sodium Polyacrylate or sodium polymethacrylate.
3. 3. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, step 1）With step 2）Described in the power of ultrasonic wave be 100 ~ 400W, frequency 45kHz.
4. 4. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, step 2）Described in polymerization time be 10 ~ 30min.
5. 5. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, step 1）Described in the Ultrasonic Radiation time be 10 ~ 30min.
6. 6. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, the step 1）Cationic monomer is acrylamido propyl trimethyl ammonium chloride or Methacrylamide propyl group Trimethyl ammonium chloride.
7. 7. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, the step 1）Middle anionic polymer is Sodium Polyacrylate or sodium polymethacrylate.
8. 8. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, step 1）Described in initiator be the isobutyl imidazoline hydrochloride VA-044 of azo two or the NSC 18620 hydrochloric acid of azo two Salt V-50.
9. 9. the method according to claim 1 for triggering matrix polymerization method synthesizing cationic polyacrylamide using ultrasonic wave, Characterized in that, step 1）Described in time of nitrogen charging deoxygenation be 20 ~ 40min.
10. 10. a kind of application of PAMC, it is characterised in that by the sun prepared by any one of claim 1 ~ 9 Cationic polyacrylamide is used for drinking water, sewage or sludge dewatering treatment.