A multi-core organic-inorganic composite flocculant, a preparation method and application thereof

Abstract

The present application relates to the technical field of flocculants, in particular to a kind of multi-core organic-inorganic composite flocculants and its preparation method and application, the multi-core organic-inorganic composite flocculants, by weight parts, include the following raw materials: inorganic polymer 70-90 parts, organic polymer 10-30 parts, polydimethyl diallyl ammonium chloride 1-5 parts, modified nano titanium dioxide 1-3 parts, deionized water 500-800 parts.The multi-core organic-inorganic composite flocculants prepared by the present application have excellent flocculation effect and stability and simple preparation method, wide application range, small dosage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flocculants, in particular to a multi-core organic-inorganic composite flocculant and its preparation method and application. BACKGROUND

[0002] Flocculation technology is an important technology for solid-liquid separation in waste water treatment and sludge dewatering in pulp and papermaking, pharmaceutical, food, cosmetics, metal processing and other industries. In the process of waste water treatment, after adding flocculant, the stability of particles in the aqueous solution is destroyed and collides with each other, forming fine flocs under the action of van der Waals force, and then forming larger flocs to settle. Through sedimentation and filtration, the purpose of solid-liquid separation is achieved. Flocculants are mainly divided into four categories: inorganic, organic, microbial and composite flocculants. Inorganic flocculants are widely used in traditional wastewater treatment, mainly by neutralizing the charge on colloidal particles to make them coagulate. Inorganic flocculants are usually used in excess, resulting in a large amount of metal hydroxide remaining in the sludge, increasing the difficulty of water treatment. Organic flocculants mainly settle particles through adsorption and bridging. Compared with inorganic flocculants, organic high molecular flocculants have a large relative molecular weight and contain more active functional groups on the molecular chain. Therefore, organic flocculants can achieve greater flocculation efficiency at a smaller dosage, and the flocs formed during flocculation are larger, easy to settle and have less sludge production. Microbial flocculants are metabolites produced by microorganisms during metabolism, mainly composed of lipids, polysaccharides, proteins and other high molecular compounds. Composite flocculants are obtained by compounding two or more flocculants, which can effectively improve the flocculation effect by utilizing the synergistic effect of several flocculants, while reducing the amount of flocculant used.

[0003] Patent CN109293928A discloses a composite flocculant for papermaking wastewater treatment and its preparation method. The preparation method uses amphiphilic surfactant molecules to assemble micelles, including the following steps: I preparation of triazine polyamide polycondensate, II preparation of triazine polyamide acrylonitrile copolymer, III modified active silicic acid, IV ionization, and V preparation of composite flocculant. The composite flocculant prepared by the method has good flocculation effect, excellent performance stability, small environmental impact, no secondary pollution, and safety and environmental protection. However, the preparation method of the composite flocculant is relatively complex and may not be suitable for industrialization.

[0004] Patent CN114773547A discloses an inorganic-organic composite flocculant and its preparation method and application. The raw materials for preparing the inorganic-organic composite flocculant include inorganic flocculating body, acrylamide, functional monomer, initiator and water by weight fraction, and also include anionic monomer, structure regulator and surfactant by weight fraction. The inorganic-organic composite flocculant provided by the invention has short flocculation settling time and high flocculation efficiency, simplifies the operation process, and also reduces the treatment cost. However, when the inorganic flocculating body is copolymerized with acrylamide, the inorganic particles are not easy to disperse uniformly, which may cause the instability of the composite flocculant.

[0005] Therefore, there is an urgent need in the market to develop a multi-core organic-inorganic composite flocculant with simple preparation method and excellent stability. SUMMARY

[0006] In view of the problems in the prior art, the purpose of the present application is to obtain a multi-core organic-inorganic composite flocculant with high stability and flocculation effect, simple preparation method, wide application range and small dosage.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0008] The present application provides a multi-core organic-inorganic composite flocculant, which comprises the following raw materials by weight fraction: inorganic polymer 70-90 parts, organic polymer 10-30 parts, polydimethyl diallyl ammonium chloride 1-5 parts, modified nano titanium dioxide 1-3 parts, and deionized water 500-800 parts.

[0009] The multi-core inorganic-organic composite flocculant prepared by blending the inorganic polymer with the self-made organic polymer, polydimethyl diallyl ammonium chloride, modified nano titanium dioxide and deionized water has the characteristics of good stability, good flocculation effect, wide application range and small dosage. The inorganic flocculant and the organic flocculant can play the following roles in cooperation: (1) electric neutralization: the multi-core hydroxyl complex produced by the hydrolysis of inorganic polymer can neutralize the electric charge on the surface of suspended particles, reduce the repulsive force between particles, and promote the aggregation of particles. (2) adsorption and bridging: the long chain structure of organic polymer can adsorb multiple particles to form larger flocs, which are convenient for settling or filtering. (3) net capture and sweeping: the flocs formed during the flocculation process can capture small particles in water, further improving the flocculation effect. Compared with single inorganic or organic flocculant, the flocculation effect of the composite flocculant is more significant, and it can handle more complex water quality. Due to the synergistic effect, the dosage of the composite flocculant is less than that of the single flocculant, which reduces the treatment cost, and the flocs formed are dense, with fast settling speed, which is convenient for subsequent treatment.

[0010] In some embodiments, the inorganic polymer is a combination of polyaluminum chloride and polyaluminum ferric silicate, and the mass ratio of the two is 1:(0.2-0.5).

[0011] In some embodiments, the preparation method of the organic polymer comprises the following steps:

[0012] A1, adding nanocellulose into a urea-NaOH aqueous solution, stirring at room temperature for 20-30 min to obtain a cellulose solution;

[0013] A2, adding the cellulose solution obtained in step A1, ammonium persulfate and azobisdimethylaminoformamide hydrochloride into deionized water, stirring at room temperature for 20-30 min, adding acrylamide, N,N'-methylenebisacrylamide and KH-570, heating to 70-80°C for 3-5 h, adding hydroquinone and stirring for 10-20 min, adjusting the pH to 6.8-7.2, washing, filtering and drying to obtain the organic polymer.

[0014] Preferably, the preparation method of the urea-NaOH aqueous solution is: adding urea and NaOH into deionized water, stirring at room temperature for 20-30 min, and the mass ratio of urea, NaOH and deionized water is 1:(1.5-2):(9-13).

[0015] The organic polymer prepared by using nanocellulose to modify polyacrylamide has higher stability, hydrophilicity and flocculation effect, which may be because: on the one hand, the rigid chain structure and hydrogen bond network of cellulose can improve the stability of the organic polymer in high temperature, acid-base or oxidation environment; on the other hand, the abundant hydroxyl and carboxyl functional groups of cellulose can enhance the adsorption capacity of the composite material to heavy metal ions, dyes and the like. It is found in the present application that introducing KH-570 segment on the synthetic organic polymer chain segment can further improve the flocculation effect and stability of the composite flocculant, which may be because: on the one hand, introducing KH-570 segment can increase the content of the hydrophobic segment on the segment, so that the flocculated substances can more easily agglomerate to improve the flocculation effect; on the other hand, the -Si-(OH)3 segment contained in the segment can complex with inorganic particles in the wastewater to further improve the flocculation effect, and the segment can promote the dispersion of titanium dioxide, which is conducive to further improving the flocculation effect of the multi-core organic-inorganic flocculant. It is also found in the present application that adding hydroquinone in the process of synthesizing the organic polymer also has a positive effect on the flocculation effect of the flocculant, which may be because the reaction of the nanocellulose modified polyacrylamide segment and hydroquinone can introduce phenolic hydroxyl groups on the organic polymer chain segment, which can prevent the structure of the organic polymer from being destroyed in high temperature, acid-base or oxidation environment by inhibiting the generation of free radicals, and through the complexation of phenolic hydroxyl groups with heavy metal ions, it is conducive to further improving the flocculation effect of the flocculant.

[0016] In some embodiments, the mass ratio of the nanocellulose and the acrylamide is (0.15-0.25): 1.

[0017] The present application can make the flocculant have better flocculation effect while having better stability by limiting the ratio of acrylamide and nanocellulose, which may be because limiting the ratio of acrylamide and nanocellulose can solve the problem of poor flocculation effect and stability of organic macromolecules caused by the capture of free radicals by nanocellulose affecting the polymerization reaction of acrylamide.

[0018] In some embodiments, the mass ratio of the acrylamide, KH-570 and hydroquinone is 1:(0.05-0.15):(0.05-0.15).

[0019] The present application can make the flocculant have better flocculation effect while having better stability by limiting the ratio of acrylamide, KH-570 and hydroquinone, which may be because limiting the ratio of the two can solve the problem of the influence of the siloxane hydrophobic segment on the dispersibility and flocculation effect of organic macromolecules and the problem of the reducing property of hydroquinone interfering with the electric neutralization of inorganic macromolecules, resulting in the inability of colloidal particles to effectively destabilize and reducing the flocculation efficiency.

[0020] In some embodiments, the preparation method of the modified nanometer titanium dioxide comprises the following steps: adding nanometer titanium dioxide into deionized water, obtaining a suspension after high-speed dispersion at 5000-7000 rpm, adding Tris-HCl and dopamine hydrochloride, stirring at 7000-9000 rpm at room temperature for 3-5 h, washing, suction filtration, drying and grinding to obtain the modified nanometer titanium dioxide.

[0021] In some embodiments, the average particle size of the nanometer titanium dioxide is 10-50 nm.

[0022] The nano-titanium dioxide has photocatalytic antibacterial performance and can generate strong oxidizing free radicals under light to kill or inhibit the growth of microorganisms. The flocculants are prone to microbial contamination during storage, and the antibacterial properties of the nano-titanium dioxide can effectively prolong the shelf life of the flocculants. However, the dispersibility of the nano-titanium dioxide in the flocculants is poor. To solve the above problems, the application uses dopamine hydrochloride to modify the titanium dioxide to form a polydopamine segment on the nano-titanium dioxide, which can not only improve the dispersibility of the nano-titanium dioxide but also further improve the flocculation effect of the composite flocculant. This may be because the polydopamine segment is rich in polar groups such as catechol, amino and imino groups, which strongly interact with water molecules through hydrogen bonds to form a hydration layer, thereby inhibiting the van der Waals force between nano-titanium dioxide particles and inhibiting agglomeration. Moreover, the polydopamine forms a coating layer on the surface of the nano-titanium dioxide, which can prevent direct contact of the nanoparticles by physical isolation. At the same time, the modified nano-titanium dioxide particles can act as a physical support material to prevent the entanglement or sedimentation of organic flocculant chains, thereby improving the suspension stability of the flocculant and preventing the occurrence of delamination or precipitation. The polar groups in the polydopamine segment can chemically bond with the amide and carboxyl groups in the polyacrylamide to form hydrogen bonds or covalent bonds, which enhances the network structure of the flocculant and enables it to more effectively adsorb and bridge suspended particles during water treatment. The aromatic ring structure of the polydopamine segment can interact with organic polymers through π-π stacking, which not only improves the hydrophilicity of the titanium dioxide but also further enhances the stability of the flocculant.

[0023] In some embodiments, the mass ratio of the nano-titanium dioxide and dopamine hydrochloride is 1:(0.13-0.28).

[0024] By limiting the ratio of nano-titanium dioxide and dopamine hydrochloride, the composite flocculant has better flocculation effect and stability, which may be because the limitation of the ratio of the two can make the nano-titanium dioxide have better dispersibility while avoiding the problem of abnormal flocculation caused by the strong interaction between the substances in the flocculant.

[0025] The second aspect of the application provides a preparation method of a multi-core organic-inorganic composite flocculant, comprising the following steps:

[0026] S1, adding inorganic polymers, organic polymers and polydimethyl diallyl ammonium chloride into deionized water, stirring at room temperature for 20-30 min to obtain a premix;

[0027] S2, adding the modified nano-titanium dioxide into the premix obtained in step S1, stirring at room temperature for 30-60 min to obtain a multi-core organic-inorganic composite flocculant.

[0028] The third aspect of the present application provides a use of a multi-core organic-inorganic composite flocculant in the field of water treatment, and the addition amount of the multi-core organic-inorganic composite flocculant is 20-40 mg / L.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) The multi-core inorganic-organic composite flocculant prepared by blending inorganic polymers, self-made organic polymers, polydimethyl diallyl ammonium chloride, modified nano titanium dioxide and deionized water has the characteristics of good stability, good flocculation effect, wide application range and small dosage.

[0031] (2) The organic polymer prepared by using nano cellulose modified polyacrylamide has higher stability, hydrophilicity and flocculation effect, and the present application further improves the flocculation effect and stability of the composite flocculant by introducing KH-570 and hydroquinone segments on the synthetic organic polymer chain segment.

[0032] (3) The present application can effectively prolong the shelf life of the composite flocculant by adding modified nano titanium dioxide in the composite flocculant, and the nano titanium dioxide particles can be used as physical support material to prevent the entanglement or sedimentation of the organic flocculant chain, thereby improving the suspension stability of the flocculant and avoiding the occurrence of stratification or precipitation. And the present application uses dopamine hydrochloride modified nano titanium dioxide to make it have more active sites, which can form interaction between the organic polymer in the flocculation process, thereby improving the flocculation effect and stability of the flocculant. DETAILED DESCRIPTION

[0033] The present application will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the present application and are only used to illustrate the present application, but not to limit the present application. Other combinations and various modifications within the concept of the present application can be made without departing from the spirit or scope of the present application.

[0034] In the following examples and comparative examples, except for modified nano titanium dioxide and organic polymer, the remaining compounds and related reagents used can be purchased from the market, wherein the effective substance content in polyaluminum chloride is 24wt%, purchased from Hongyuan Environmental Protection Technology Co., Ltd. in Gongyi; the effective substance content in polyaluminum silicate iron is 36wt%, purchased from Henan Haiyun Environmental Protection Technology Co., Ltd.; the item number of nano cellulose is 623, purchased from Zibo Daoqin New Material Co., Ltd.; the average particle size of nano titanium dioxide is 20nm, the item number is JL-TA18, purchased from Hangzhou Jule Biological Material Co., Ltd.; the model of polyacrylamide is HK-5351, purchased from Chongqing Haixuan Environmental Protection Technology Co., Ltd.; the number average molecular weight of polydimethyl diallyl ammonium chloride is 491.065, purchased from Shandong Wochier Environmental Protection Technology Co., Ltd.

[0035] Preparation Example 1

[0036] The preparation method of the urea-NaOH aqueous solution used in Preparation Examples 2-8 is as follows: 10 g of urea and 17 g of NaOH are added to 110 g of deionized water and stirred at room temperature for 25 min to obtain the solution.

[0037] Preparation Example 2

[0038] The preparation method of the organic polymer-1 comprises the following steps:

[0039] A1, 2 g of nanocellulose is added to 20 g of urea-NaOH aqueous solution, stirred at room temperature for 25 min to obtain a cellulose solution;

[0040] A2, all the cellulose solution obtained in step A1 and 0.5 g of ammonium persulfate, 0.1 g of azobisdimethylaminoformamide hydrochloride are added to 50 g of deionized water, stirred at room temperature for 25 min, 10 g of acrylamide, 1 g of N,N'-methylenebisacrylamide and 1 g of KH-570 are added, and the temperature is raised to 75°C under nitrogen protection for 4 h, 1 g of hydroquinone is added and stirred for 15 min, the pH is adjusted to 7, and the organic polymer-1 is obtained by washing, filtering and drying.

[0041] Preparation Example 3

[0042] The preparation method of the organic polymer-2 is the same as that of Preparation Example 2, except that the amount of nanocellulose added is 3.5 g.

[0043] Preparation Example 4

[0044] The preparation method of the organic polymer-3 is the same as that of Preparation Example 2, except that the amount of KH-570 added is 2.5 g.

[0045] Preparation Example 5

[0046] The preparation method of the organic polymer-4 is the same as that of Preparation Example 2, except that the amount of hydroquinone added is 2.5 g.

[0047] Preparation Example 6

[0048] The preparation method of the organic polymer-5 comprises the following steps:

[0049] A1, 2 g of nanocellulose is added to 20 g of urea-NaOH aqueous solution, stirred at room temperature for 25 min to obtain a cellulose solution;

[0050] A2, all the cellulose solution obtained in step A1 and 0.5 g ammonium persulfate, 0.1 g azobisdimethylvaleronitrile hydrochloride were added into 50 g deionized water, stirred at room temperature for 25 min, 10 g acrylamide, 1 g N,N'-methylene bisacrylamide were added, and the temperature was raised to 75°C under nitrogen protection for 4 h, 1 g hydroquinone was added and stirred for 15 min, the pH was adjusted to 7, and then washed, filtered and dried to obtain organic polymer-5.

[0051] Preparation Example 7

[0052] The preparation method of organic polymer-6 comprises the following steps:

[0053] A1, 2 g nanocellulose was added into 20 g urea-NaOH aqueous solution, stirred at room temperature for 25 min to obtain a cellulose solution;

[0054] A2, all the cellulose solution obtained in step A1 and 0.5 g ammonium persulfate, 0.1 g azobisdimethylvaleronitrile hydrochloride were added into 50 g deionized water, stirred at room temperature for 25 min, 10 g acrylamide, 1 g N,N'-methylene bisacrylamide and 1 g KH-570 were added, and the temperature was raised to 75°C under nitrogen protection for 4 h, the pH was adjusted to 7, and then washed, filtered and dried to obtain organic polymer-6.

[0055] Preparation Example 8

[0056] The preparation method of modified nanometer titanium dioxide-1 comprises the following steps: 10 g nanometer titanium dioxide was added into 50 g deionized water, and after high-speed dispersion at 6000 rpm, a suspension was obtained, 4 g Tris-HCl and 2 g dopamine hydrochloride were added, and stirred at room temperature at 8000 rpm for 4 h, and then washed, suction filtered, dried and ground to obtain modified nanometer titanium dioxide-1.

[0057] Preparation Example 9

[0058] The preparation method of modified nanometer titanium dioxide-2 is the same as that of preparation example 8, except that the amount of dopamine hydrochloride added is 3.5 g.

[0059] Example 1

[0060] A multi-core organic-inorganic composite flocculant comprises, by weight, the following raw materials: inorganic polymer 80 parts, organic polymer-1 20 parts, polydimethyl diallyl ammonium chloride 3 parts, modified nanometer titanium dioxide-1 2 parts, and deionized water 650 parts.

[0061] The inorganic polymer is a combination of polyaluminum chloride and polyaluminum ferric silicate, and the mass ratio of the two is 1:0.35.

[0062] The preparation method of the multi-core organic-inorganic composite flocculant of the embodiment comprises the following steps:

[0063] S1, the inorganic polymer, organic polymer-1, and polydimethyl diallyl ammonium chloride are added to deionized water, stirred at room temperature for 25 min, and a premix is obtained;

[0064] S2, the modified nano titanium dioxide-1 is added to the premix obtained in step S1, stirred at room temperature for 45 min, and a multi-core organic-inorganic composite flocculant is obtained.

[0065] Embodiment 2

[0066] A multi-core organic-inorganic composite flocculant comprises the following raw materials in parts by weight: inorganic polymer 70 parts, organic polymer-1 10 parts, polydimethyl diallyl ammonium chloride 1 part, modified nano titanium dioxide-1 1 part, and deionized water 500 parts.

[0067] The inorganic polymer is a combination of polyaluminum chloride and polyaluminum ferric silicate, and the mass ratio of the two is 1:0.2.

[0068] The preparation method of the multi-core organic-inorganic composite flocculant of the embodiment comprises the following steps:

[0069] S1, the inorganic polymer, organic polymer-1, and polydimethyl diallyl ammonium chloride are added to deionized water, stirred at room temperature for 20 min, and a premix is obtained;

[0070] S2, the modified nano titanium dioxide-1 is added to the premix obtained in step S1, stirred at room temperature for 30 min, and a multi-core organic-inorganic composite flocculant is obtained.

[0071] Embodiment 3

[0072] A multi-core organic-inorganic composite flocculant comprises the following raw materials in parts by weight: inorganic polymer 90 parts, organic polymer-1 30 parts, polydimethyl diallyl ammonium chloride 5 parts, modified nano titanium dioxide-1 3 parts, and deionized water 800 parts.

[0073] The inorganic polymer is a combination of polyaluminum chloride and polyaluminum ferric silicate, and the mass ratio of the two is 1:0.5.

[0074] The preparation method of the multi-core organic-inorganic composite flocculant of the embodiment comprises the following steps:

[0075] S1, the inorganic polymer, organic polymer-1, and polydimethyl diallyl ammonium chloride are added to deionized water, stirred at room temperature for 30 min, and a premix is obtained;

[0076] S2, add modified nano-titanium dioxide-1 into the premix obtained in step S1, stir at room temperature for 60 min, to obtain a multi-core organic-inorganic composite flocculant.

[0077] Example 4

[0078] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the organic polymer-1 is replaced by an equal amount of organic polymer-2.

[0079] Example 5

[0080] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the organic polymer-1 is replaced by an equal amount of organic polymer-3.

[0081] Example 6

[0082] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the organic polymer-1 is replaced by an equal amount of organic polymer-4.

[0083] Example 7

[0084] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the organic polymer-1 is replaced by an equal amount of organic polymer-5.

[0085] Example 8

[0086] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the organic polymer-1 is replaced by an equal amount of organic polymer-6.

[0087] Example 9

[0088] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the modified nano-titanium dioxide-1 is replaced by an equal amount of modified nano-titanium dioxide-2.

[0089] Example 10

[0090] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the organic polymer-1 is replaced by an equal amount of polyacrylamide.

[0091] Comparative Example 1

[0092] A multi-core organic-inorganic composite flocculant and a preparation method thereof, the specific implementation manner is the same as that of example 1, and the difference lies in that the modified nano-titanium dioxide-1 is replaced by an equal amount of nano-titanium dioxide.

[0093] Performance test

[0094] The multi-core organic-inorganic composite flocculants obtained in the above examples and comparative examples were tested for heavy metal ion absorption performance:

[0095] (1) Preparation of simulated wastewater: heavy metal ions were dissolved in deionized water to prepare simulated wastewater with Cd 2+ , As 3+ , Cr 6+ ion concentrations of 3 mg / L, 4 mg / L, and 3 mg / L, respectively.

[0096] (2) Test process: each multi-core organic-inorganic composite flocculant was added to the simulated wastewater after being stored at 25°C for 0 days and 30 days, respectively, and placed on a coagulation stirrer. The pH of the solution was controlled at 4, the reaction temperature was 25°C, and the solution was first stirred at a speed of 250 r / min for 1 min, then slowly stirred at a speed of 50 r / min for 10 min. After standing for 30 min, the content of heavy metal ions in the solution was tested and the removal rate was calculated.

[0097] The concentration of residual metal ions in the solution was determined by inductively coupled plasma optical emission spectrometer ICP-OES, and the heavy metal ion removal rate of the flocculant was calculated according to the following formula:

[0098] Heavy metal ion removal rate = [(C e -C0) / C0] x 100%

[0099] In the formula, C0 represents the initial concentration of heavy metal ions, and C e represents the residual heavy metal concentration.

[0100] The test results are shown in Table 1:

[0101] Table 1

[0102]

[0103] From the data in Table 1, it can be seen that the multi-core organic-inorganic composite flocculants of Examples 1-3 have excellent flocculation effect and stability, and from the comparison of Example 4 and Example 1, it can be seen that changing the ratio of nanocellulose and acrylamide will make nanocellulose capture free radicals and affect the polymerization of acrylamide, resulting in poor organic polymer flocculation effect and stability; from the comparison of Example 5 and Example 1, it can be seen that changing the ratio of acrylamide and KH-570 will make the siloxane hydrophobic segment affect the dispersibility of the organic polymer, resulting in poor flocculation effect and stability of the composite flocculant; from the comparison of Example 6 and Example 1, it can be seen that changing the ratio of acrylamide and hydroquinone will make the reducing property of hydroquinone interfere with the electric neutralization of inorganic polymer, resulting in poor flocculation effect and stability of the flocculant; from the comparison of Examples 7, 8 and Example 1, it can be seen that not adding KH-570 or hydroquinone during the preparation of the organic polymer will make the flocculation effect and stability of the composite flocculant poor; from the comparison of Example 9 and Example 1, it can be seen that changing the ratio of dopamine hydrochloride and nanometer titanium dioxide will make the interaction between the substances strong, resulting in the problem of abnormal flocculation, which leads to poor stability and flocculation effect of the composite flocculant; from the comparison of Example 10 and Example 1, it can be seen that directly using polyacrylamide as the organic polymer will result in poor stability and flocculation effect of the composite flocculant; from the comparison of Comparative Example 1 and Example 1, it can be seen that without modifying the nanometer titanium dioxide, the stability and flocculation effect of the composite flocculant are general.

[0104] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A polynuclear organic-inorganic composite flocculant, characterized by, The raw materials include, by weight, 70-90 parts of inorganic polymer, 10-30 parts of organic polymer, 1-5 parts of polydimethyl diallyl ammonium chloride, 1-3 parts of modified nano titanium dioxide, and 500-800 parts of deionized water. The preparation method of the organic polymer comprises the following steps: A1, adding nano cellulose into urea-NaOH aqueous solution, stirring at room temperature for 20-30 min to obtain a cellulose solution; A2, adding the cellulose solution obtained in step A1, ammonium persulfate and azobisdimethylaminoformamide hydrochloride into deionized water, stirring at room temperature for 20-30 min, adding acrylamide, N,N'-methylene bisacrylamide and KH-570, heating to 70-80℃ for 3-5 h, adding hydroquinone and stirring for 10-20 min, adjusting pH to 6.8-7.2, washing, filtering and drying to obtain an organic polymer; The mass ratio of the nano cellulose and acrylamide is (0.15-0.25):1; The mass ratio of the acrylamide, KH-570 and hydroquinone is 1:(0.05-0.15):(0.05-0.15); The preparation method of the modified nano titanium dioxide comprises the following steps: adding nano titanium dioxide into deionized water, dispersing at a high speed of 5000-7000 rpm to obtain a suspension, adding Tris-HCl and dopamine hydrochloride, stirring at a speed of 7000-9000 rpm at room temperature for 3-5 h, washing, suction filtering, drying and grinding to obtain modified nano titanium dioxide.

2. The polynuclear organic-inorganic complex flocculant according to claim 1, characterized by, The inorganic polymer is a combination of polyaluminum chloride and polyaluminum ferric silicate, and the mass ratio of the two is 1:(0.2-0.5).

3. The polynuclear organic-inorganic complex flocculant according to claim 1, characterized by The average particle size of the nano titanium dioxide is 10-50 nm.

4. The polynuclear organic-inorganic complex flocculants according to claim 1, characterized by, The mass ratio of the nano titanium dioxide and dopamine hydrochloride is 1:(0.13-0.28).

5. A method for preparing the polynuclear organic-inorganic complex flocculant according to any one of claims 1 to 4, characterized by, The method comprises the following steps: S1, adding inorganic polymer, organic polymer and polydimethyl diallyl ammonium chloride into deionized water, stirring at room temperature for 20-30 min to obtain a premix; S2, adding modified nano titanium dioxide into the premix obtained in step S1, stirring at room temperature for 30-60 min to obtain a multi-core organic-inorganic composite flocculant.

6. Use of the polynuclear organic-inorganic complex flocculant according to any one of claims 1 to 4 or prepared according to claim 5 in the field of water treatment, characterized in that, The addition amount of the multi-core organic-inorganic composite flocculant is 20-40 mg / L.

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