CN1331770C - Flocculant of cation of millicron SiOx compound polyacrylamide and preparing method thereof - Google Patents

Abstract

The invention relates to a nano-SiOx composite polyacrylamide cationic flocculant and a preparation method thereof; the flocculant uses a coupling agent to modify the surface of the nano-SiOx, the modified nano-SiOx is dispersed in an aqueous solution containing acrylamide, and Composite initiators initiate free radical solution polymerization to obtain nano-SiOx composite polyacrylamide gel, and then use HCHO, HN(CH ₃ ) ₂ and BrCH ₂ CH ₃ to functionalize the obtained gel through Mannich reaction to obtain nano-SiOx composite polyacrylamide gel. Acrylamide cationic flocculant; the flocculant has the characteristics of moderate molecular weight, fast flocculation speed, good anti-aging and degradation performance, and less residual monomer.

Description

Nano-SiOx composite polyacrylamide cationic flocculant and preparation method thereof

technical field

The invention relates to a cationic flocculant in water treatment, in particular to a nano-SiOx composite polyacrylamide cationic flocculant and a preparation method thereof.

Background technique

Flocculation and coagulation are important technical links in the process of sewage treatment. In some cases, the process of flocculation and coagulation alone can complete wastewater treatment alone. Therefore, flocculants and coagulants are important aspects of the research and development of new wastewater treatment processes and new materials, and the corresponding products are huge in quantity and variety. Compared with other flocculants, polyacrylamide and its derivatives flocculants have the advantages of less dosage, fast flocculation speed, and less sludge generation. They are widely used in water treatment, especially wastewater treatment, and are still in rapid development. Polyacrylamide is prepared by free radical aqueous polymerization of acrylamide, and polyacrylamide as a flocculant or coagulant is also used in the state of aqueous solution, however, commercially available polyacrylamide is generally a dry product in powder form. This is because liquid polyacrylamide is prone to degradation and denaturation during transportation and storage, thus losing the flocculation or coagulation effect. Liquid polyacrylamide needs to be dehydrated and stored dryly, and dry polyacrylamide needs to be dissolved with water before use, which consumes energy, wastes water resources, and forms a source of waste water pollution. The dissolution rate of dry polyacrylamide and its derivatives is slow, and it takes tens of minutes or even several hours to completely dissolve, and because of some changes in physical and chemical properties during the drying process, the dry state of polyacrylamide and its derivatives There is always a certain amount of sieve residue in the dissolution process, which is laborious and wastes resources. At the same time, the dissolved and prepared polyacrylamide aqueous solution must be used up as soon as possible, otherwise the flocculation effect will be lost due to aging degradation, and the storage time should generally not exceed 48 hours. Therefore, the development of new formulations of high-performance polyacrylamide and its derivatives flocculants is of great significance.

Nanoparticles are widely used in the modification of polymer materials due to their nano-effects such as quantum size effect, small size effect, surface effect and macroscopic quantum tunneling effect, and form a series of new high-performance materials. There are different residual bonds and hydroxyl groups in different bonding states on the surface of nano-SiOx, which has high surface activity. Its strong absorption of ultraviolet light and good reflection of infrared light are beneficial to enhance the anti-aging of polymer materials. performance. However, the agglomeration of nanoparticles affects their dispersion in polymer materials, and it is difficult to disperse uniformly in polymer systems only by physical mixing.

Chinese patent application CN1303821A discloses a "nano ultra-high-efficiency flocculant", which is to disperse metal oxide nanoparticles such as SiOx and Al ₂ O ₃ in various polyacrylamide flocculants by mechanical stirring; The agglomeration of metal oxide nanoparticles such as SiOx and Al ₂ O ₃ makes their dispersion effect in polymer flocculants poor. U.S. Patent No. 5,176,891 discloses the blending of nano-scale polyaluminosilicate microsol and polyacrylamide cationic polymer; in the application.

Contents of the invention

The purpose of the present invention is in order to provide a kind of nano-SiOx composite polyacrylamide cationic flocculant, this flocculant has electric neutral cation, superabsorptive nano-SiOx and the entanglement effect of high molecular weight polymer chain simultaneously, has constituted effective Cooperating with the flocculation system improves its flocculation performance, and due to the introduction of nano-SiOx, it effectively reduces the light absorption and degradation of polyacrylamide chains, so that the flocculant has good anti-aging performance.

Another object of the present invention is in order to provide a kind of preparation method of nano-SiOx composite polyacrylamide cationic flocculant, this method is to introduce modified SiOx into polyacrylamide, so that SiOx can be well dispersed in polyacrylamide , and form a more uniform dispersion system to improve the performance of polyacrylamide.

The purpose of the present invention can be achieved through the following measures:

A nano-SiOx composite polyacrylamide cationic flocculant, the flocculant is prepared by adding modified nano-SiOx in the process of polyacrylamide by a known method, where x is 1.2-1.6, and a redox initiator is used to initiate free radicals The aqueous solution polymerization reaction obtains the nano-SiOx composite polyacrylamide hydrogel, and then performs functionalization reaction on the nano-SiOx composite polyacrylamide hydrogel to obtain the nano-SiOx composite polyacrylamide cationic flocculant.

The modified nano-SiOx is modified with a coupling agent on the nano-SiOx; the coupling agent is (γ-epoxypropylene) propyl-triethoxysilane.

The redox initiator is an aqueous solution of oxidant ammonium persulfate and reducing agent N, N, N', N'-tetramethylethylenediamine, and the added redox initiator is oxidant ammonium persulfate and reducing agent sodium sulfite Aqueous solution; the equivalent ratio of oxidizing agent to reducing agent is the same.

The functionalization reaction of the nano-SiOx composite polyacrylamide hydrogel is that the nano-SiOx composite polyacrylamide hydrogel is subjected to Mannich cationic modification reaction with formaldehyde, dimethylamine and ethyl bromide.

Another object of the present invention can also be achieved through the following measures:

A preparation method of nano-SiO composite polyacrylamide cationic flocculant, comprising the steps of:

(1) Carry out surface modification and modification of nano-SiOx earlier;

(2) Preparation of polyacrylamide and compounding with nano-SiOx;

A, by mass ratio is 1: (6-10) after adding water in modified nano-SiOx, obtains white suspension;

b. Add acrylamide to the white suspension in step a above to react to obtain acrylamide and nano-SiOx dispersion; wherein the mass ratio of modified nano-SiOx to acrylamide (2-6):100.

c. Add a redox initiator to the dispersion in step b above at 0.3-0.5% by mass, react at room temperature for 1-3 hours; heat up to 40-55°C, and react for 1-3 hours to obtain a reaction solution; Adding 0.15-0.3% initiator of acrylamide mass to the reaction solution to continue the reaction for 0.5-2 hours to obtain a white nano-SiOx composite polyacrylamide hydrogel;

(3) Nano-SiOx composite polyacrylamide hydrogel is subjected to known cationic modification.

The preparation method of the nano-SiOx composite polyacrylamide cationic flocculant is characterized in that it also includes feeding nitrogen into the acrylamide and nano-SiOx dispersion liquid to remove oxygen between the above (2) step a and b.

The surface modification and modification of the nano-SiOx include the following steps: add anhydrous alcohol solvent to the nano-SiOx in a volume ratio of 1: (1-3) to soak, and then in the alcohol solution of the above-mentioned SiOx Adding a coupling agent at a ratio of 1: (1-3), ultrasonically oscillating and reacting for 1-4 hours, and then extracting with alcohol to obtain modified nano-SiOx; x in SiOx is 1.2-1.6.

The coupling agent in the above (1) step is (γ-epoxypropylene) propyl-triethoxysilane.

Adding water to SiOx in the above step (2)a also includes the use of ultrasonic oscillation reaction.

The known cationic modification of the nano-SiOx composite polyacrylamide hydrogel described in the above (3) step includes the following steps: formaldehyde and dimethylamine are mixed in a volume ratio of 0.4-1.0, and the pH of the mixture is adjusted to be 3 -4, according to the volume ratio (0.5-0.8): 1.0, add the above mixture into the nano-SiOx composite polyacrylamide hydrogel, and then adjust the pH of the reaction system to 8-9; react at 30-45°C for 1-3 hours ; When the sol after the above reaction is diluted to 4-5 times of the original volume, according to the volume ratio of formaldehyde and ethyl bromide 1: (0.5-2), add ethyl bromide in the above-mentioned diluted solution, and stir the reaction at room temperature After 12-30 hours, the nano-SiOx composite polyacrylamide cationic flocculant is obtained.

The redox initiator in the described (2)c step is an oxidizing agent ammonium persulfate and a reducing agent N, N, N', N'-tetramethylethylenediamine aqueous solution, and the added redox initiator is an oxidizing agent Ammonium persulfate and reducing agent sodium sulfite aqueous solution; the equivalent ratio of oxidant and reducing agent is the same.

Compared with the prior art, the present invention has the following advantages:

1. The flocculant of the present invention has the entanglement of electrically neutral cations, superabsorptive nano-SiOx and high-molecular-weight polymer chains, especially the quantum size effect, small size effect, surface effect and macroscopic quantum tunneling effect of nanoparticles Such nano-effects doubled the adsorption and bridging function of polyacrylamide to suspended particles in water, and constituted an effective synergistic flocculation system to improve flocculation performance.

2. Due to the introduction of nano-SiOx in the present invention, and there are different residual bonds and hydroxyl groups in different bonding states on the surface of nano-SiOx, the flocculant of the present invention has very high surface activity and has a strong absorption effect on ultraviolet light and has a strong absorption effect on infrared light. The reflective ability is also great, which effectively reduces the light absorption and degradation of polyacrylamide chains. The introduction of nano-SiOx makes the flocculant have good anti-aging performance.

3. The flocculant of the present invention has excellent anti-aging properties due to the introduction of nano-SiOx, and can exist in a gel state at room temperature without degradation; it saves the drying process of the gel and the use of dry powder flocculants The previous dissolution process improves the flocculation performance, reduces product energy consumption and environmental pollution in the production process.

4. The flocculant of the present invention can be used not only in the sludge flocculation and dehydration process in sewage treatment, but also in the coagulation and sedimentation process in sewage treatment, and can partially remove pollution such as COD, NH ₄ ⁺ -N in sewage thing.

5. The preparation method of the present invention is to modify the nano-SiOx with a coupling agent. According to the chemical bond theory of the coupling agent, the coupling agent can improve the compatibility of organic matter and inorganic matter and then make the two well compound, Form a relatively uniform dispersion system to improve related performance; under the action of ultrasonic dispersion, the present invention uses a coupling agent to modify the surface of nanomaterial SiOx to have reactive groups; reactive nanometer SiOx is used in the preparation of polyacrylamide sol With the help of the ultrasonic dispersion in the early stage and the stirring and dispersion of the polymerization process, as well as the interpenetration and inclusion barrier effect of the polymerization of acrylamide into macromolecules, the nano-SiOx is uniformly dispersed in the synthetic polyacrylamide sol to form a stable nano-composite high Molecular system; then, use HCHO, HN(CH ₃ ) ₂ and BrCH ₂ CH ₃ to cationize the obtained sol through Mannich reaction to obtain nano-SiOx composite polyacrylamide cationic flocculant. This is a nano-SiOx composite polyacrylamide flocculant that exists in an aqueous solution state. It does not require dehydration and drying, nor does it need to be stirred and dissolved during application, and it can be stored for a long time without aging and degradation.

specific implementation

Example 1:

A kind of nano-SiOx composite polyacrylamide cationic flocculant, this flocculant is to add the nano-SiOx modified through (γ-epoxypropylene) propyl group-triethoxysilane when the known preparation polyacrylamide technology, In the formula, x is 1.2-1.6, and use ammonium sulfate aqueous solution and N, N, N', N'-tetramethylethylenediamine initiator aqueous solution to initiate radical aqueous solution polymerization to obtain nano-SiOx composite polyacrylamide hydrogel, and then Nano-SiOx composite polyacrylamide hydrogel was modified by Mannich cationic reaction with formaldehyde, dimethylamine and ethyl bromide to obtain nano-SiOx composite polyacrylamide cationic flocculant.

The preparation method of above-mentioned flocculant comprises the steps:

(1) Surface modification and modification of nano-SiOx particles

Take the nano-SiOx of DP1 in the container, add absolute absolute ethanol to the nano-SiOx at a volume ratio of 1:1.5 to soak, and then add (γ-epoxypropylene) propyl-tri Ethoxysilane, ultrasonic vibration reaction for 2 hours, drying in an infrared drying oven, continuous extraction with a certain amount of absolute ethanol in a Soxhlet extractor for 4 hours, dried and stored in a dry bottle .

(2) Preparation of polyacrylamide and compounding with nano-SiOx

a. In a container equipped with electric stirring, nitrogen conduit, thermometer and spherical condenser, add deionized water, add modified nano-SiOx according to the mass ratio of modified nano-SiOx to water 1/9, and ultrasonically oscillate for 30 minutes to obtain white suspension;

b. Add acrylamide to the above-mentioned white suspension according to the mass ratio of modified nano-SiOx to acrylamide 3/97, stir and react at room temperature for 30 minutes; and pass nitrogen gas for 5 minutes to drive away oxygen,

c. Add redox initiator according to 0.3-0.5% of the mass of acrylamide in the dispersion of step b above, and react at room temperature for 1-3 hours; then raise the temperature to 40-55°C, and react for 1-3 hours to obtain the reaction solution; add 0.15-0.3% initiator of acrylamide mass to the reaction solution and continue to react for 0.5-2 hours to obtain nano-SiOx composite polyacrylamide hydrogel;

(3) Cationic modification of nano-SiOx composite polyacrylamide hydrogel

Mix formaldehyde and dimethylamine at a volume ratio of 0.6-1.0, adjust the pH of the mixture to 3-4, add the above-mentioned mixture to nano-SiOx composite polyacrylamide hydrogel at a volume ratio of 0.75:1.0, and then adjust it with NaOH solution The pH of the system is 8; react at 35°C for 2 hours; when the above-reacted sol is diluted to 35% of the original volume concentration, add bromoethane according to the volume ratio of formaldehyde and bromoethane at 1:1, and stir at 30°C After heat preservation and reaction for 24 hours, the nano-SiOx composite polyacrylamide cationic flocculant is obtained.

Example 2:

Storage stability test of nano-SiOx composite polyacrylamide cationic flocculant:

After 2% concentration of nano-SiOx composite polyacrylamide cationic flocculant was placed at room temperature for 4 months, the flocculation performance of kaolin artificial simulated sewage was measured, and the settling time was 11.5 seconds; a certain concentration of SiOx nanocomposite polyacrylamide cationic flocculant After the aqueous solution of the agent was frozen at -12°C for one week, the initial settling time of the flocs was measured to be 11.3 seconds, and the transparency of the water body remained basically unchanged, which was basically the same as the settling of the instant-configured nano-SiOx composite polyacrylamide cationic flocculant Speed (9.8 seconds), while its appearance and viscosity are basically unchanged, showing good anti-aging performance.

Example 3:

Coagulation performance test of nano-SiOx composite polyacrylamide cationic flocculant:

Coagulation experiments were carried out in the laboratory by collecting urban domestic sewage, catalyst wastewater from petroleum refining companies, and metal smelting production wastewater. The results show that the SiOx nanocomposite polyacrylamide cationic flocculant has a fast flocculation speed, a good removal rate of SS in the three kinds of wastewater, and can partially remove COD and NH ₄ ⁺ -N in the aforementioned wastewater, showing good performance Coagulation properties. The results are shown in the data listed in Table 1, Table 2 and Table 3.

1) Urban domestic sewage Appearance: light yellow, with black suspended matter, water temperature: 19°C. There is a pungent stench, and the whole water body has a certain viscosity, pH: around 7.6.

Table 1 Results of urban domestic sewage treatment

indicators raw water Treated water Removal rate (%) COD (mg/L) 295.96 228.34 22.85 SS(mg/L) 1596 63.34 96.00

2) Catalyst wastewater from petroleum refining companies Appearance: white suspension with a large amount of suspended matter, mixed wastewater for catalyst production and treatment, mainly catalyst carrier silica, and various catalyst metal ions, with a strong ammonia smell, Water temperature: 39°C, pH: around 8.35.

Table 2 Catalyst Wastewater Treatment Results of Petroleum Refining and Chemical Company

indicators COD(mg/L) NH ₄ ⁺ -N (mg/L) SS(mg/L) raw water   1249.01   28096.5 3120 treated water 464.01 25063.5 110 removal rate 62.87% 10.57% 96.47%

3) Metal smelting production wastewater Appearance: No odor, with a light smell of petroleum hydrocarbons. There are very small white particles present. The main components are some rare earth element oxides and metal ion complexes. pH: around 1.32. Water temperature: 21°C.

Table 3 Metal smelting wastewater treatment results

indicators COD(mg/L) NH ₄ ⁺ -N (mg/L) SS(mg/L) raw water 344.54 27169. 2120 treated water 344.1   23252.31 1525 removal rate 0% 14.42% 28.07%

Example 4:

Sludge flocculation and dewatering performance test of nano-SiOx composite polyacrylamide cationic flocculant:

The sludge flocculation and dehydration test of nano-SiOx composite polyacrylamide cationic flocculant is divided into two parts: laboratory test and productive test, and all tests are carried out on-site at a certain urban sewage treatment plant in Lanzhou.

1) In the laboratory test, the SiOx composite polyacrylamide cationic flocculant with a concentration of 5% was stored indoors for 4 weeks, and then diluted and prepared into dilute solutions with a concentration of 0.1%, 0.2%, 0.3%, and 0.4%. The type flocculant dissolves quickly and evenly. Take 50mL of concentrated residual activated sludge (not nitrified, water content 96.7%) as a test mud sample, add it to a 250mL beaker, then add 50mL of a flocculant solution with a concentration of 0.4% and add water to 100mL, use a glass rod to Stir evenly, and the observed reaction results are: flocculation agglomerates are formed instantaneously, the agglomerates are large in size, the flocs are dense, and the boundary line of mud-water layering is obvious. There is no suspended matter in the water layer and it is only slightly yellow, but there is a certain degree of turbidity. Record the dosage of flocculant solution used for the best flocculation effect. At the same time, add 0.3%, 0.2%, and 0.1% flocculant solutions to the same mud sample in turn, observe and record the dosage of the flocculant solution used for the best flocculation effect. See Table 4 for the chemical consumption calculated according to the dosage of flocculant solution of each concentration when the best flocculation effect of each group of tests is obtained.

Table 4 The dosage and consumption of different concentrations of flocculant solutions

 Flocculant Concentration (%) Optimum dosage (mL) Drug consumption‰(dry medicine/dry mud) 0.6 1.5 2.7 0.5 2.0 3.0 0.4 2.0 2.4 0.3 3.0 2.7 0.2 5.0 3.0 0.1 12.0 3.6

2) Productive sludge dewatering test The model of sludge dewatering machine is HD-2000, which is produced in Yixing, Jiangsu Province. The filter width is 2 meters, the belt speed is 4 meters per minute, the pressure of the upper filter cloth is 0.3 MPa, the pressure of the lower filter cloth is 0.2 Mpa, and the concentration stirring speed is 80%. The dehydrated sludge is unnitrated sludge after the concentration of residual sludge in the secondary settling tank, and its water content is 96.5%-96.7%. The dissolving and dosing process of the flocculant solution is completed by an automatic dosing machine, and the use concentration is adjusted continuously with the test process between 1-5‰. The observed results of the obtained sludge dewatering test are as follows:

(1) The used flocculant dissolves quickly and evenly during the dissolving process, and there is no floc residue in the solution, while other solid PAM flocculants have floc residue during dissolution.

(2) In the machine test of the flocculant used, the agent and the sludge flocculate evenly, the particles of the flocculation group are large, the filter cake is easy to peel off, the mud cake is large in size and elastic, and the filtrate is relatively clear and slightly yellow. The nano-SiOx composite polyacrylamide cationic flocculant can overcome the problems of other flocculant products in the high-load sludge dewatering operation, the flocculation performance is reduced or the normal operation needs to be increased, showing the high-load sludge dewatering operation. The use concentration is low and stable and remarkable. The data of productive sludge dewatering test are listed in Table 5, and the amount of flocculant is basically the same as when it is used as coagulant, reflecting good operation stability.

Table 5 Test data of productive sludge dewatering

Moisture content of raw mud (%) Moisture content of mud cake (%) Mud cake thickness (mm) Filtrate sedimentation ratio (SV%) The amount of medicine used (L/h) Amount of flocculant (dry medicine/dry mud, ‰) 96.7 76.8 5 3 300-330 2.8-3.0

Claims (10)

1, a kind of nanometer SiOx composite polyacrylamide cationic flocculant, this flocculation agent is to add modified Nano SiOx when preparation polyacrylamide technology, x is 1.2-1.6 in the formula, and cause the free yl solution polymerization reaction with redox initiator and obtain nanometer SiOx composite polyacrylamide hydrogel, then nanometer SiOx composite polyacrylamide hydrogel is carried out reaction kinetic and obtain nanometer SiOx composite polyacrylamide cationic flocculant.

2, nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 1 is characterized in that described modified Nano SiOx carries out modification at nanometer SiOx with coupling agent; Described coupling agent is (γ-propylene oxide base) propyl group-triethoxyl silane.

3, nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 1, it is characterized in that described redox initiator is oxygenant ammonium persulphate and reductive agent N, N, N ', the N '-Tetramethyl Ethylene Diamine aqueous solution, its redox initiator of adding are oxygenant ammonium persulphate and reductive agent sodium sulfite aqueous solution; Oxygenant is identical with the equivalence ratio of reductive agent.

4, nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 1 is characterized in that described nanometer SiOx composite polyacrylamide hydrogel is carried out reaction kinetic is that nanometer SiOx composite polyacrylamide hydrogel is carried out Mannich cation modifying reaction with formaldehyde, dimethylamine and monobromethane.

5, a kind of preparation method of nanometer SiOx composite polyacrylamide cationic flocculant comprises the steps:

(1) carries out surface modification and the modification of nanometer SiOx earlier;

(2) Preparation of Polyacrylamide and compound with nanometer SiOx;

A, be 1 by mass ratio: after (6-10) in modified Nano SiOx, adding water white suspension liquid;

B, in the above-mentioned a white suspension liquid in step, add acrylamide react acrylamide and nanometer SiOx dispersion liquid; Wherein modified Nano SiOx and acrylamide mass ratio (2-6): 100;

0.3-0.5% by quality in the dispersion liquid in c, above-mentioned b step adds redox initiator, at room temperature reacts 1-3 after individual hour; Be warming up to 40-55 ℃, reaction got reaction solution in 1-3 hour; The 0.15-0.3% initiator of adding the acrylamide quality again in reaction solution continues reaction and promptly gets white nanometer SiOx composite polyacrylamide hydrogel after 0.5-2 hour; Described redox initiator is oxygenant ammonium persulphate and reductive agent N, N, and N ', the N '-Tetramethyl Ethylene Diamine aqueous solution, its redox initiator of adding are oxygenant ammonium persulphate and reductive agent sodium sulfite aqueous solution; Oxygenant is identical with the equivalence ratio of reductive agent;

(3) nanometer SiOx composite polyacrylamide hydrogel is carried out cation modifying.

6, the preparation method of nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 5 is characterized in that in above-mentioned (2) a step also being included between the step with b and feeds nitrogen in acrylamide and the nanometer SiOx dispersion liquid with removal oxygen.

7, the preparation method of nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 5, it is characterized in that the surface modification of described nanometer SiOx and modification comprise the steps: by volume 1: (1-3) add the absolute alcohol kind solvent and soak at nanometer SiOx, be 1 then by volume in the alcoholic solution of above-mentioned SiOx: (1-3) add coupling agent, sonic oscillation reaction 1-4 hour gets the nanometer SiOx of modification again with ethanol-extracted; X among the SiOx is 1.2-1.6.

8, the preparation method of nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 5 is characterized in that the coupling agent in above-mentioned (1) step is (γ-propylene oxide base) propyl group-triethoxyl silane.

9, the preparation method of nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 5 is characterized in that in above-mentioned (2) a step that SiOx adds and also comprises behind the water and adopt the sonic oscillation reaction.

10, the preparation method of nanometer SiOx composite polyacrylamide cationic flocculant as claimed in claim 5, it is characterized in that the nanometer SiOx composite polyacrylamide hydrogel described in above-mentioned (3) step carry out cation modifying comprise the steps: with formaldehyde and dimethylamine by volume 0.4-1.0 mix, the pH that regulates mixture is 3-4, (0.5-0.8) by volume: 1.0 join said mixture in the nanometer SiOx composite polyacrylamide hydrogel, and re-adjustment reaction system pH is 8-9; Reacted 1-3 hour down at 30-45 ℃; Above-mentioned reacted colloidal sol is diluted to 35% o'clock of original volume concentration, press formaldehyde and monobromethane volume ratio 1: (0.5-2), add monobromethane in the thin liquid above-mentioned releasing, after at room temperature stirring reaction 12-30 hour, promptly get nanometer SiOx composite polyacrylamide cationic flocculant.