Preparation method of a hybrid flocculant, product and application thereof

Abstract

This invention discloses a method for preparing a hybrid flocculant, its product, and its application. The preparation method includes: (1) dissolving inorganic components in deionized water, adding organic additives, and dissolving to obtain solution I; (2) dissolving acrylamide, cationic monomers, and small molecule alcohols in deionized water to obtain solution II; (3) slowly adding solution II from step (2) to solution I from step (1) to obtain a mixture; (4) purging the mixture from step (3) with an inert gas, then adding an initiator, purging again with an inert gas, and then carrying out a polymerization reaction to obtain the hybrid flocculant. The method of this invention achieves efficient in-situ polymerization of organic components on inorganic components with a high content, resulting in a high molecular weight. This allows the flocculant to perform charge neutralization, adsorption bridging, and metal ion removal functions, and the agent maintains excellent oil and metal ion removal capabilities even after long-term storage.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for preparing a hybrid flocculant, its product, and its application. Background Technology

[0002] CN103351047A discloses an organic-inorganic hybrid flocculant and its preparation method. This method involves adding ammonium persulfate as an initiator during the polymerization of dimethyl diallyl ammonium chloride (DMDAAC) to obtain the PAC-PDMDAAC organic-inorganic hybrid ionic bond flocculant through in-situ polymerization. However, because dimethyl diallyl ammonium chloride lacks specific functional groups, directly grafting the organic phase onto the inorganic phase is difficult, resulting in a low grafting rate. Furthermore, the synthesized organic monomer is only the relatively expensive dimethyl diallyl ammonium chloride, leading to high costs when used for water treatment at the same mass concentration. Additionally, its small molecular weight results in weak bridging and adsorption capacity for particles. Moreover, this flocculant has limited performance characteristics and is poorly effective at removing water containing metal ions.

[0003] CN106745624A discloses an inorganic-organic hybrid flocculant and its preparation method. The raw material components of this flocculant include an initiator and inorganic flocculant and organic monomers in a mass ratio of 1:9 to 1:6. The organic monomers include dimethyl diallyl ammonium chloride and acrylamide in a mass ratio of 1:9 to 1:5, and the initiator accounts for 0.02% to 5% of the mass of the organic monomers. This hybrid flocculant is obtained by introducing acrylamide and dimethyl diallyl ammonium chloride into the inorganic flocculant, initiating the in-situ copolymerization of the two monomers in an inorganic system. This flocculant can improve the settling rate of tailings suspension and reduce the turbidity of the supernatant. However, the main effective component of this flocculant is an expensive organic component, while the content of inorganic components is low, resulting in a high cost of the flocculant. The low inorganic component content leads to poor removal effect of this flocculant on turbid and oily wastewater with low zeta potential, especially oily wastewater with a high degree of emulsification. In addition, the partial cross-linking caused by the flocculant synthesis process leads to a deterioration in the performance of the flocculant, and the agent has a single function and no significant effect on the simultaneous removal of metal ions in wastewater.

[0004] In summary, it is essential to develop a low-cost, high-performance, high-charge-neutralization, high-molecular-weight, long-term storage-stable inorganic-organic hybrid flocculant that can synergistically remove metal ions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a hybrid flocculant, along with its product and applications. The method of this invention achieves efficient in-situ polymerization of organic components on inorganic components with a high content, resulting in a high molecular weight flocculant that combines charge neutralization, adsorption bridging, and metal ion removal functions. Furthermore, the flocculant maintains excellent oil and metal ion removal capabilities even after long-term storage, making it a promising candidate for simultaneous oil and metal removal in wastewater treatment.

[0006] The first aspect of this invention provides a method for preparing a hybrid flocculant, comprising:

[0007] (1) Dissolve the inorganic components in deionized water, add organic additives, dissolve, and obtain solution I;

[0008] (2) Dissolve acrylamide, cationic monomer, and small molecule alcohol in deionized water to obtain solution II;

[0009] (3) Slowly add solution II from step (2) to solution I from step (1) to obtain a mixture;

[0010] (4) The mixture from step (3) is first purged with an inert gas, then an initiator is added, and then purged with an inert gas again. Then a polymerization reaction is carried out to obtain a hybrid flocculant.

[0011] In this invention, the inorganic component in step (1) includes at least one of polyaluminum sulfate (PAS), polyaluminum chloride (PAC), polyaluminum chloride sulfate (PACS), polyaluminum silicate chloride (PASiC), polyaluminum silicate sulfate (PSAS), and polyaluminum silicate (PASI), preferably at least one of polyaluminum sulfate (PAS) and polyaluminum chloride (PAC).

[0012] In this invention, in step (1), the organic additive is at least one of the following: 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), 2-hydroxyphosphonoacetic acid (HPAA), hexamethylenediaminetetramethylenephosphonic acid (HDTMPA), sodium polyaspartate (PASP), nitrotriacetic acid (NTA), iminodiacetic acid (IDA), sodium gluconate, and potassium sodium tartrate, preferably at least one of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), iminodiacetic acid (IDA), and potassium sodium tartrate.

[0013] In this invention, in step (1), when the inorganic component is dissolved in deionized water, the mass fraction of the inorganic component is controlled to be 15%~50%, preferably 30%~40%.

[0014] In this invention, in step (1), the mass fraction of the additive is 1-5%, preferably 2-3%, based on the mass of the inorganic component.

[0015] In this invention, in step (1), the dissolution is performed by ultrasound, with an ultrasound frequency of 30 kHz to 60 kHz and an ultrasound time of 30 to 60 min.

[0016] In this invention, in step (2), the cationic monomer includes at least one of dimethyl diallyl ammonium chloride (DMDAAC), N,N,N-trimethyl-3-allylamino-1-chloropropylamine (APTAC), methacryloyloxyethyltrimethylammonium chloride (DMC), acryloyloxyethylmethylammonium chloride (DAC), NN-dimethylamine ethyl methacrylate (DMAEMA), and [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC), preferably at least one of dimethyl diallyl ammonium chloride (DMDAAC), N,N,N-trimethyl-3-allylamino-1-chloropropylamine (APTAC), NN-dimethylamine ethyl methacrylate (DMAEMA), and acryloyloxyethylmethylammonium chloride (DAC).

[0017] In this invention, in step (2), the small molecule alcohol includes at least one of methanol, ethanol, propanol, and butanol.

[0018] In this invention, in step (2), the mass ratio of the sum of acrylamide and cationic monomer to the inorganic component in step (1) is (1:1) to (1:6), preferably (1:2) to (1:4).

[0019] In this invention, in step (2), the total mass fraction of acrylamide and cationic monomer in the aqueous solution is controlled to be 6%~20%, preferably 10%~15%.

[0020] In this invention, in step (2), the mass ratio of the cationic monomer to the acrylamide monomer is (1:1) to (4:1), preferably (2:1) to (3:1).

[0021] In this invention, in step (2), the small molecule alcohol is 1‰ to 5‰ of the mass of deionized water, preferably 2‰ to 4‰.

[0022] In this invention, the slow addition method in step (3) is to add the ingredients slowly under stirring conditions.

[0023] In this invention, in step (4), the mass fraction of the initiator is 0.5‰~4.0‰, preferably 1.0‰~2.5‰, based on the sum of the masses of acrylamide and cationic monomer in step (2).

[0024] In this invention, in step (4), the time for purging with an inert gas (such as nitrogen or argon) is 20-60 min, and the time for purging with an inert gas (such as nitrogen or argon) is 10-30 min.

[0025] In this invention, the polymerization reaction conditions in step (4) are: placed in a water bath at 40~90℃, with a stirring rate of 100~500 r / min and a reaction time of 1~6 h.

[0026] In this invention, the initiator in step (4) is persulfate.

[0027] In this invention, in step (4), the persulfate is at least one of its sodium salt, ammonium salt, and potassium salt.

[0028] A second aspect of the present invention provides a hybrid flocculant prepared by the above method.

[0029] In this invention, the intrinsic viscosity of the hybrid flocculant is 1000~5000 mL g. -1 .

[0030] The third aspect of this invention provides the application of the above-mentioned hybrid flocculant in the simultaneous removal of oil and metal ions from wastewater.

[0031] In this invention, the oil content of the wastewater is 1000~10000 mg / L. -1 Metal ions: 50-500 mg / L -1 .

[0032] In this invention, the dosage of the hybrid flocculant is 10~400 mg / L. -1 Preferred dosage: 20-100 mg / L -1 .

[0033] In this invention, the hybrid flocculant is suitable for removing metal ions when the pH value of the wastewater is adjusted to 5-11, preferably 6-9.

[0034] In this invention, the metal ions include at least one of the following: calcium, magnesium, iron, copper, lead, zinc, nickel, chromium, cadmium, etc.

[0035] In existing technologies, due to the dispersion effect of inorganic components in the dispersed phase of inorganic component systems, it is difficult to achieve chain growth and in-situ polymerization of organic components. This results in low molecular weight of hybrid agents, or even grafting failure and monomer residues. In addition, if acrylamide monomers are used for this type of polymerization, the catalytic effect of impurities contained in the inorganic components will cause explosive polymerization and cross-linking, leading to a decrease in agent solubility and the encapsulation and covering of inorganic components, weakening or even eliminating the charge neutralization effect of inorganic components. Therefore, in practice, the in-situ polymerization of organic monomers in inorganic components can only be achieved by controlling the content of inorganic components to a low level. The resulting flocculant exhibits poor turbidity and oil removal effects for turbid and oily wastewater with low zeta potential, especially oily wastewater with a high degree of emulsification.

[0036] Through extensive research, the inventors of this invention discovered that by introducing organic additives and alcohols, in-situ polymerization of organic components in an inorganic dispersed phase can be achieved even when the inorganic component is significantly higher than the organic component. Furthermore, the prepared flocculant exhibits excellent charge neutralization and adsorption bridging properties.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The method of preparing multifunctional hybrid flocculant of the present invention realizes the efficient in-situ polymerization of organic components on inorganic components in inorganic polymer dispersion system; and breaks through the conventional method to realize the efficient in-situ polymerization of inorganic components with high content using acrylamide monomer as raw material, which greatly improves the charge neutralization and adsorption bridging performance of flocculant, and shows excellent oil removal effect for oily wastewater with high emulsification degree.

[0039] (2) The multifunctional hybrid flocculant of the present invention has the functions of charge neutralization and adsorption bridging, and also has the advantages of removing metal ions and oil removal.

[0040] (3) The multifunctional flocculant of the present invention is an organic-inorganic hybrid flocculant, which is stable for a long time and will not exhibit phase separation, and has a synergistic effect.

[0041] (4) The flocculant prepared by the present invention is mainly composed of inexpensive inorganic components, resulting in low reagent cost. Attached Figure Description

[0042] Figure 1 Microscopic image of flocs after oil removal using flocculant prepared in Comparative Example 4;

[0043] Figure 2 Microscopic image of flocs after oil removal from the flocculant prepared in Example 1. Detailed Implementation

[0044] The method of the present invention will be further described in detail below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0045] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0046] In this embodiment, the oil content of the water sample was measured using an infrared oil analyzer.

[0047] In this embodiment, the metal ions in the water sample were measured using a Hach EZ6000 trace metal analyzer.

[0048] In the embodiments, the viscosity of the flocculant was measured using an Ubbelohde viscometer. Example 1

[0049] (1) Preparation of inorganic component solution: Take an appropriate amount of polyaluminum chloride and dissolve it in deionized water to make its mass fraction 35%. Add 2.5% potassium sodium tartrate additive based on the mass of polyaluminum chloride, and sonicate at 30KHz for 30 min.

[0050] (2) Preparation of organic component solution: Dissolve propanol, acrylamide and N,N,N-trimethyl-3-allylamino-1-chloropropane (APTAC) in deionized water so that the total mass fraction of organic monomers, i.e., cationic monomers and acrylamide monomers, is 15%, and the mass fraction of methanol is 3‰ of the mass of deionized water. The mass ratio of cationic monomers to acrylamide monomers is 2:1, and the mass ratio of the sum of acrylamide and cationic monomers to the inorganic components in step (1) is 3:7.

[0051] (3) Inorganic-organic solution mixing: The solution from step (2) is slowly added to the solution from step (1) under stirring conditions to obtain a mixture.

[0052] (4) Polymerization reaction: The mixture from step (3) was first purged with nitrogen for 20 min. Based on the mass of acrylamide and cationic monomer from step (2), 2‰ potassium persulfate was added, and then purged with nitrogen for 20 min. The mixture was placed in a water bath at 50°C and reacted for 4 h at a stirring rate of 300 r / min to obtain the hybrid flocculant.

[0053] The intrinsic viscosity of the hybrid flocculant, measured by an Ubbelohde viscometer, was 1390 mL g. -1 .

[0054] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L.-1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 96.6% of the oil was removed, and the calcium ion removal rate was 74.3%. Example 2

[0055] Same as Example 1, except that the mass fraction of polyaluminum chloride is 30%, 2% iminodiacetic acid is added, and the mass ratio of the sum of acrylamide and cationic monomer to the inorganic components in step (1) is 1:2.

[0056] The intrinsic viscosity of the obtained multifunctional hybrid flocculant, measured by an Ubbelohde viscometer, was 1460 mL g. -1 .

[0057] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 95.8% of the oil was removed, and the calcium ion removal rate was 72.9%. Example 3

[0058] Same as Example 1, except that the additive is 2.5% 2-hydroxyphosphonic acid.

[0059] The intrinsic viscosity of the obtained multifunctional hybrid flocculant, measured by an Ubbelohde viscometer, was 1270 mL g. -1 .

[0060] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 89.2% of the oil was removed, and the calcium ion removal rate was 62.5%. Example 4

[0061] Same as Example 1, except that the organic additive is selected as 1.5% potassium sodium tartrate.

[0062] The intrinsic viscosity of the obtained multifunctional hybrid flocculant, measured by an Ubbelohde viscometer, was 1230 mL g. -1 .

[0063] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 88.3% of the oil was removed, and the calcium ion removal rate was 57.6%. Example 5

[0064] Same as Example 1, except that the mass ratio of the added cationic monomer to the acrylamide monomer is 4:1.

[0065] The intrinsic viscosity of the obtained multifunctional hybrid flocculant, measured by an Ubbelohde viscometer, was 1190 mL g. -1 .

[0066] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 86.4% of the oil was removed, and the calcium ion removal rate was 65.1%. Example 6

[0067] Same as Example 1, except that the cationic monomer is NN-dimethylaminoethyl methacrylate (DMAEMA).

[0068] The intrinsic viscosity of the obtained multifunctional hybrid flocculant, measured by an Ubbelohde viscometer, was 2640 mL g. -1 .

[0069] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 99.2% of the oil was removed, and the calcium ion removal rate was 74.9%.

[0070] For an oil content of 5000 mg / L -1 Calcium ions 123 mg / L -1 The wastewater was treated with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 93.5% of the oil was removed. Example 7

[0071] Same as Example 1, except that the inorganic component is replaced with polyaluminum sulfate.

[0072] The intrinsic viscosity of the hybrid flocculant, measured by an Ubbelohde viscometer, was 1470 mL g. -1 .

[0073] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 97.5% of the oil was removed, and the calcium ion removal rate was 76.2%. Example 8

[0074] The flocculant prepared in Example 1 simultaneously removes oil and metal ions, and is effective for oil content of 3000 mg / L. -1 Magnesium ions 206 mg / L -1 The wastewater was treated to a pH of 8, and the flocculant dosage was 150 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 94.3% of the oil was removed, and the magnesium ion removal rate was 51.5%. Comparative Example 1

[0075] Same as Example 1, except that potassium sodium tartrate additive was not added during the preparation of the inorganic component solution.

[0076] The intrinsic viscosity of the hybrid flocculant, measured by an Ubbelohde viscometer, was 210 mL g. -1 .

[0077] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 52.8% of the oil was removed, and the calcium ion removal rate was 42.6%. Comparative Example 2

[0078] Same as Example 4, except that methanol was not added during the preparation of the organic component solution to obtain the flocculant.

[0079] The intrinsic viscosity of the obtained multifunctional hybrid flocculant, measured by an Ubbelohde viscometer, was 760 mL g. -1 .

[0080] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 64.2% of the oil was removed, and the calcium ion removal rate was 46.8%. Comparative Example 3

[0081] For comparison, a flocculant with the highest inorganic component content was prepared according to CN106745624A, with an inorganic component to organic component ratio of 1:6. This prepared flocculant was used for simultaneous oil and metal ion removal. For an oil content of 2000 mg / L... -1 Calcium ions 123 mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after flocculant addition. Testing revealed only 46.2% oil removal, with calcium ion concentration remaining essentially unchanged. The flocculant dosage was increased to 200 mg / L. -1 It can achieve 87.35% oil removal while the calcium ion concentration remains essentially unchanged. This is because the demulsification effect of flocculants is particularly important for heavily emulsified oily wastewater, requiring a high inorganic component content in the inorganic-organic hybrid agent. However, the agent prepared by the method provided in CN106745624A is mainly composed of organic components with a low inorganic component content. Such agents can be used to remove turbid wastewater (sedimented suspended solids) with low zeta potential, but their removal effect on heavily emulsified oily wastewater is poor. Comparative Example 4

[0082] Similar to Example 1, except that no acrylamide monomer was introduced, resulting in a hybrid flocculant. The intrinsic viscosity of the obtained hybrid flocculant, measured by an Ubbelohde viscometer, was only 460 mL g. -1 .

[0083] The prepared flocculant was used for simultaneous oil and metal ion removal, effective for oil content of 2000 mg / L. -1 Calcium ions 123mg / L -1 The wastewater was treated to a pH of 8, with a flocculant dosage of 100 mg / L. -1 Measurements were taken one hour after addition. Testing showed that 69.8% of the oil was removed, and the calcium ion removal rate was 47.6%.

[0084] In addition, by Figure 1It can be seen that the floc particles obtained by this flocculant for oil removal are relatively small, affecting the floc flotation rate and increasing the residence time during actual operation. In contrast, the flocculant prepared in Example 1 of this invention, used for oil removal, achieves excellent oil removal results due to its superior charge neutralization effect. Furthermore, this flocculant has good adsorption bridging properties; as shown in Figure 2, it can produce larger, interconnected floc particles with a faster flotation rate, facilitating the separation of scum from water.

Claims

1. A method for preparing a hybrid flocculant, comprising: (1) Dissolve the inorganic components in deionized water, add organic additives, dissolve, and obtain solution I; (2) Dissolve acrylamide, cationic monomer, and small molecule alcohol in deionized water to obtain solution II; (3) Slowly add solution II from step (2) to solution I from step (1) to obtain a mixture; (4) The mixture from step (3) is first purged with an inert gas, then an initiator is added, and then purged with an inert gas again. Then a polymerization reaction is carried out to obtain a hybrid flocculant. In step (1), the organic additive is at least one of 2-phosphonobutane-1,2,4-tricarboxylic acid, 2-hydroxyphosphonoacetic acid, hexamethylenediaminetetramethylenephosphonic acid, sodium polyaspartate, hyponitrotriacetic acid, iminodiacetic acid, sodium gluconate, and potassium sodium tartrate. In step (2), the mass ratio of the sum of acrylamide and cationic monomer to the inorganic component in step (1) is (1:1) to (1:6).

2. The preparation method according to claim 1, characterized in that, The inorganic component includes at least one of polyaluminum sulfate, polyaluminum chloride, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate, and polyaluminum silicate.

3. The preparation method according to claim 1, characterized in that, In step (1), the organic additive is at least one of 2-phosphonobutane-1,2,4-tricarboxylic acid, iminodiacetic acid, and potassium sodium tartrate.

4. The preparation method according to claim 1, characterized in that, In step (1), when the inorganic component is dissolved in deionized water, the mass fraction of the inorganic component is controlled to be 15%~50%.

5. The preparation method according to claim 1, characterized in that, In step (1), the mass fraction of the organic additive is 1-5%, based on the mass of the inorganic component.

6. The preparation method according to claim 1, characterized in that, In step (1), the dissolution is performed by ultrasound, with an ultrasound frequency of 30 KHz to 60 KHz and an ultrasound time of 30 to 60 min.

7. The preparation method according to claim 1, characterized in that, In step (2), the cationic monomer includes at least one of dimethyl diallyl ammonium chloride, N,N,N-trimethyl-3-allylamino-1-chloropropylamine, methacryloyloxyethyltrimethylammonium chloride, NN-dimethylamine ethyl methacrylate, and [2-(acryloyloxy)ethyl]trimethylammonium chloride.

8. The preparation method according to claim 1, characterized in that, In step (2), the small molecule alcohol includes at least one of methanol, ethanol, propanol, and butanol.

9. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the sum of acrylamide and cationic monomer to the inorganic component in step (1) is (1:2) to (1:4).

10. The preparation method according to claim 1, characterized in that, In step (2), the sum of the mass fractions of acrylamide and cationic monomer in the aqueous solution is controlled to be 6%~20%.

11. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the cationic monomer to the acrylamide monomer is (1:1) to (4:1).

12. The preparation method according to claim 1, characterized in that, In step (2), the small molecule alcohol is 1‰ to 5‰ of the mass of deionized water.

13. The preparation method according to claim 1, characterized in that, In step (4), the mass fraction of the initiator is 0.5‰ to 4.0‰, based on the sum of the masses of acrylamide and cationic monomer in step (2).

14. The preparation method according to claim 1, characterized in that, In step (4), the polymerization reaction conditions are: reaction temperature of 40~90℃, stirring rate of 100~500 r / min, and reaction time of 1~6 h.

15. The preparation method according to claim 1, characterized in that, In step (4), the initiator is persulfate, which is at least one of its sodium, ammonium, and potassium salts.

16. The hybrid flocculant prepared by any of the preparation methods described in claims 1-15.

17. The hybrid flocculant according to claim 16, characterized in that, The intrinsic viscosity of the hybrid flocculant is 1000~5000 mL g. -1 .

18. The application of the hybrid flocculant according to claim 16 or 17 in the simultaneous removal of oil and metal ions from wastewater.

19. The application according to claim 18, characterized in that, The wastewater contains 1000~10000 mg / L of oil. -1 Metal ions: 50-500 mg / L -1 The dosage of the multifunctional hybrid flocculant is 10~400 mg / L. -1 .

20. The application according to claim 19, characterized in that, The applicable conditions for the multifunctional hybrid flocculant to remove metal ions are that the pH value of the wastewater is adjusted to 5-11.

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