Nickel ferrite composite material magnetized cellulose flocculant as well as preparation method and application thereof

Abstract

The invention discloses a nickel ferrite composite material magnetized cellulose flocculant and a preparation method and application thereof.The preparation method comprises the steps that microcrystalline cellulose, nickel ferrite and a silane coupling agent serve as main raw materials, cellulose is subjected to NaIO4 oxidation, ammonia water amination and NaBH3CN reduction modification, and aminated cellulose with the surface modified with-OH and-NH2 is prepared; fe salt and Ni salt are co-precipitated to form NiFe2O4 particles, and the NiFe2O4 particles are coated with a SiO2 layer through a sol-gel method; finally, NiFe2O4 coated SiO2 is grafted to the surface of the aminated cellulose through a silane coupling agent, and the composite flocculant is formed. The preparation process is simple, the reaction condition is mild, the raw material cost is low, the magnetic property of an inorganic material and the adsorbability of an organic material are both achieved, and synergistic interaction is achieved. When the flocculant is applied to printing and dyeing wastewater treatment, the removal effect on COD, total lead and chroma is remarkable, the COD removal rate under the optimal condition reaches 74.56%, the total lead removal rate reaches 91.53%, the chroma removal rate reaches 90.62%, and the flocculant is superior to a traditional flocculant (such as polyferric sulfate) and is wide in applicable pH range and low in dosage (1.5 g / L).

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a nickel-ferrite composite material magnetized cellulose flocculant and a preparation method and application thereof. Background Art

[0002] With the rapid development of the printing and dyeing industry, wastewater discharge in the printing and dyeing process releases many pollutants, such as dyes, auxiliaries, heavy metals and acid-base organic matter. This kind of wastewater has the characteristics of large chromaticity, large organic content, complex composition, difficult biodegradability and unstable treatment effect. In China, the treatment methods of printing and dyeing wastewater are diversified, covering many categories such as biological method, chemical method, physical method, etc. Among them, chemical coagulation stands out and is widely used in the field of printing and dyeing wastewater treatment. This method is highly adaptable. No matter what kind of complex and changeable printing and dyeing wastewater quality it faces, it can respond flexibly and give full play to its role. The operation process is simple and easy, and there is no need for professionals to spend a lot of energy on complex manipulation, which greatly reduces the labor cost and technical threshold. The space it occupies is relatively limited, which can effectively solve the problem of tight site of the enterprise. In terms of treatment effect, the chemical coagulation method performs well, with high removal efficiency of chemical oxygen demand (COD) and chromaticity, which can greatly reduce the pollution level of printing and dyeing wastewater and minimize the pressure of subsequent treatment. It meets the needs of printing and dyeing enterprises from multiple dimensions and helps the sustainable development of the printing and dyeing industry. However, the use of flocculants in the prior art to treat printing and dyeing wastewater faces many technical problems. Dyes (such as reactive dyes, disperse dyes, etc.) in printing and dyeing wastewater usually have complex organic structures and high stability. Traditional flocculants are difficult to effectively destroy their chemical bonds, resulting in low decolorization efficiency, especially for soluble dyes. Most flocculants (such as aluminum salts and iron salts) need to be within a specific pH range to achieve the best effect. The pH of printing and dyeing wastewater fluctuates greatly (strong acid or strong base), and additional pH adjustment is required, which increases the cost and complexity of treatment.

[0003] Cellulose is a renewable raw material with low toxicity, low density, high crystallinity, high surface area, good mechanical strength, insolubility in water and biodegradability. It has a potential application value in the treatment of printing and dyeing wastewater due to its abundant hydroxyl groups, physical stability caused by long-chain molecular structure and chemical stability, as well as abundant adsorption active sites, high adsorption capacity and binding affinity.

[0004] Silane coupling agents can couple organic materials with inorganic materials to improve the mechanical strength of products. Nickel ferrite has an inverse spinel structure and thus has good chemical stability, mechanical toughness and moderate saturation magnetization. It can usually improve its acid resistance by forming a silicon layer. The formed nickel ferrite composite material has good hydrothermal stability and is completely biodegradable, indicating that it has potential adsorption treatment performance in practical applications. Summary of the invention

[0005] The purpose of the present invention is to provide a novel nickel ferrite composite material magnetized cellulose flocculant, a preparation method thereof and an application thereof in removing COD, total lead and chromaticity from printing and dyeing wastewater.

[0006] The technical solution adopted by the present invention is:

[0007] A nickel-ferrite composite material magnetized cellulose flocculant, consisting of the following components:

[0008] Amination of cellulose matrix: Cellulose is treated with NaIO 4 Oxidation, ammonia amination and NaBH 3 CN is reduced and modified, and the surface is modified with hydroxyl -OH and amino -NH 2 Functional groups;

[0009] Nickel ferrite composite material NiFe 2 O 4 @SiO 2 : Synthesis of NiFe by coprecipitation of Fe and Ni salts under alkaline conditions 2 O 4 , and coated with SiO by sol-gel method 2 Layer formation;

[0010] Silane coupling agent bridging structure: aminated cellulose matrix and NiFe were bonded by 3-glycidyloxypropyltrimethoxysilane KH560 2 O 4 @SiO 2 The organic-inorganic hybrid network is formed by covalent bonding, which is the flocculant.

[0011] Furthermore, the aminated cellulose and NiFe 2 O 4 @SiO 2 The mass ratio is 2:1 to 1:1.

[0012] Furthermore, the aminated cellulose and NiFe 2 O 4 @SiO 2 The mass ratio is 4:3.

[0013] A method for magnetizing a cellulose flocculant using the nickel-ferrite composite material comprises the following steps:

[0014] (1) Cellulose oxidative amination:

[0015] Disperse cellulose in demineralized water and add NaIO 4The solution is stirred at 50-60°C for 6-8h, filtered and washed to obtain oxidized cellulose;

[0016] Mix oxidized cellulose with 37% ammonia water at a solid-liquid ratio of 1g:10-20mL, add NaBH 3 CN solution, react at 70-95°C for 12-15h, cooling and reflux during the reaction to prevent ammonia evaporation, to obtain aminated cellulose;

[0017] (2)NiFe 2 O 4 @SiO 2 preparation:

[0018] The trivalent Fe salt and the divalent Ni salt are mixed in a molar ratio of 2 to 4:1, stirred in an aqueous solution with a final concentration of NaOH of 0.7-1.0 mol / L at room temperature for coprecipitation reaction, the reaction time is 0.5-2h, and then centrifuged and washed to obtain NiFe 2 O 4 ;

[0019] NiFe 2 O 4 Disperse in ethanol, add ammonia and tetraethyl silicate TEOS, stir at 50-60℃ for 20-24h, hydrolyze TEOS and 2 O 4 Coated with SiO 2 layer, then centrifugally washed and calcined at high temperature to obtain NiFe 2 O 4 @SiO 2 ;

[0020] (3) Flocculant compound:

[0021] Dissolve the aminated cellulose in toluene and add KH560 and NiFe 2 O 4 @SiO 2 , heat to reflux for 10 to 15 hours, filter, wash and dry to obtain the target flocculant.

[0022] Further, in step (1), NaIO 4 The mass ratio of NaBH to cellulose is 0.2-0.4:1. 3 The mass ratio of CN to oxidized cellulose is 0.05-0.1:1.

[0023] Furthermore, in the TEOS hydrolysis reaction system in step (2), the final concentration of ammonia is 4-8%, and NiFe 2 O 4 The feed ratio with TEOS is 8-12g:1mL.

[0024] Furthermore, in step (3), the mass ratio of KH560 to aminated cellulose is 0.8-1.2:1, and the mass ratio of aminated cellulose to NiFe 2 O 4 @SiO 2 The mass ratio is 1 to 2:1, preferably 4:3.

[0025] Furthermore, the calcination temperature in step (2) is 700-800°C, and the heating temperature in step (3) is 70-80°C.

[0026] The invention also discloses the application of the flocculant in the treatment of printing and dyeing wastewater. The pH value of the wastewater is 5-11, the dosage of the flocculant in the wastewater is 1.0-2.0 g / L, the treatment temperature is room temperature, the reaction time is 30-60 min, and the removal rates of COD, total lead and chromaticity are ≥70%, 85% and 85% respectively.

[0027] Furthermore, the printing and dyeing wastewater has an initial COD of ≤3000 mg / L, a chromaticity of ≤2000 times, and a total lead concentration of ≤2.0 mg / L.

[0028] The surface of cellulose contains a large number of hydrogen bonds and hydroxyl groups. The hydrogen bond network on the surface makes cellulose have high strength and toughness and makes cellulose highly hydrophilic, making it easy to adsorb polar pollutants. The surface hydroxyl groups can form hydrogen bonds with the polar groups in the dye molecules and organic additives. This intermolecular force can make the active dye molecules firmly bind to the cellulose surface, thereby removing the color in the wastewater; a large number of hydroxyl groups can be modified with functional groups to introduce more other materials to improve its adsorption performance. After acidification, the hydrogen bond between the two adjacent aldehyde groups of cellulose breaks the ring to form two aldehyde groups, and then after amination treatment, the two adjacent aldehyde functional groups are converted into -OH and -NH 2 Due to the nucleophilic electrons on the amino group of the nucleophilic reaction attacking the epoxy group on the added 3-glycidyloxypropyltrimethoxysilane, the epoxy group opens to form -NH-C and is grafted onto the cellulose. The introduced -NH- group can be protonated in the printing and dyeing wastewater, thereby carrying a positive charge, neutralizing the negatively charged colloidal particles in the printing and dyeing wastewater through electrostatic action, reducing the repulsive force between particles, promoting aggregation and improving the flocculant treatment efficiency. Under alkaline conditions, Ni 2+ and Fe 3+ Ion coprecipitation to form NiFe 2 O 4 The sol-gel method is used to hydrolyze and polycondense tetraethyl silicate to form a Si-O-Si skeleton structure, which can be wrapped in NiFe 2 O 4 The Si-OH generated on the particle surface can form Si-O-Si bonds with the methoxy groups on 3-glycidyloxypropyltrimethoxysilane, thereby converting NiFe2 O 4 @SiO 2 Connected to cellulose, the hydroxyl groups on its surface can form hydrogen bonds with the polar groups in the dye to achieve adsorption effect, and NiFe 2 O 4 @SiO 2 The metal sites on the surface adsorb heavy metal ions through coordination. A nickel ferrite composite material magnetized cellulose flocculant is obtained. Tests show that the present invention has a very good treatment effect in removing COD, total lead and chromaticity from printing and dyeing wastewater.

[0029] The beneficial effects of the present invention are mainly reflected in:

[0030] (1) The main raw materials of the nickel-ferrite composite magnetized cellulose flocculant provided by the present invention, cellulose, silane coupling agent, ferric chloride hexahydrate and nickel chloride hexahydrate, are widely available and inexpensive;

[0031] (2) The method for preparing the nickel-ferrite composite magnetized cellulose flocculant provided by the present invention is simple to operate, has mild reaction conditions and low energy consumption;

[0032] (3) The nickel ferrite composite magnetized cellulose flocculant provided by the present invention combines inorganic and organic components by grafting, giving full play to the synergistic effect of inorganic and organic flocculants, and has higher stability and a wider pH value application range.

[0033] (4) The quaternary amine introduced into the cellulose surface provided by the present invention can be protonated to carry positive charge, and the negatively charged pollutants in the wastewater can be neutralized by electrostatic action; at the same time, hydroxyl groups are introduced to form hydrogen bonds with dye molecules to enhance chromaticity removal.

[0034] (5) The nickel-ferrite composite magnetized cellulose flocculant provided by the present invention modifies the cellulose functional groups to introduce a large number of hydroxyl functional groups and NiFe 2 O 4 @SiO 2 Materials improve the removal effect of cellulose on COD, total lead and color in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The scanning electron microscope (SEM) image of the nickel ferrite composite magnetized cellulose flocculant obtained in Example 1;

[0036] Figure 2 This is a graph showing the effect of flocculant dosage and COD, total lead and chromaticity removal in printing and dyeing wastewater in Example 1 of the present invention;

[0037] Figure 3This is a graph showing the reaction time and the removal effects of COD, total lead and chroma in wastewater in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] The cellulose in the examples of the present invention was purchased from Shanghai Haohong Biopharmaceutical Technology Co., Ltd., and the particle size was 20 to 80 μm.

[0040] Example 1

[0041] A method for preparing a novel nickel ferrite composite material magnetized cellulose flocculant comprises the following steps:

[0042] Step 1: weigh 10 g of cellulose with a particle size of 20 to 80 μm, add it to 130 mL of demineralized water and mix, then add 20 mL of 0.8 mol / L NaIO 4 The solution was maintained at 50°C, with a stirring speed of 400 rpm and magnetic stirring for 6 hours; then stirred at room temperature for 2 hours; the mixed solution was evacuated and filtered, and the obtained filter cake was washed with deionized water and then vacuum filtered and dried to obtain oxidized cellulose.

[0043] Step 2: 10 g of oxidized cellulose was added into 37% ammonia water at a solid-liquid ratio of 1 g:10 mL, the heating temperature was maintained at 75 °C, and stirred for 3 h. During the process, cooling and reflux were set to prevent ammonia evaporation, and 50 mL of 0.2 mol / L NaBH was added. 3 The CN / ethanol mixed solution was heated to maintain the temperature at 95° C., heated and stirred for 15 h and cooled to reflux, with a stirring speed of 280 rpm, and then the solvent was removed by rotary evaporation to obtain aminated cellulose.

[0044] Step 3: Add 1 mol / L FeCl 3 6H 2 O aqueous solution 160mL and NiCl 2 6H 2 O aqueous solution, stirred at room temperature for 0.5 h, added the mixture into 500 mL of 1 mol / L sodium hydroxide aqueous solution, stirred at room temperature for 1 h, washed with deionized water and centrifuged to obtain NiFe 2 O 4 .

[0045] Step 4: 9gNiFe 2 O 4The precipitate was dispersed in 25 mL of ethanol, the ultrasonic frequency was 20 kHz, the temperature was 60 ° C, the ultrasonic treatment was carried out for 2 h, 10 mL of 25% ammonia water was added, 1 mL of 98% tetraethyl silicate reagent was added, the stirring temperature was 60 ° C, the stirring speed was 400 rpm, the magnetic stirring was carried out for 20 h, and then centrifuged, washed 3 times with 15 mL of methanol, vacuum dried for 48 h, and calcined at 800 ° C for 2 h to obtain NiFe 2 O 4 @SiO 2 Particles.

[0046] Step 5: Dissolve 10 g of aminated cellulose material in 50 mL of toluene solution, add 10 ml of 98% 3-glycidyloxypropyltrimethoxysilane, and mix the aminated cellulose material with NiFe 2 O 4 @SiO 2 The mass ratio of the particles is 2:1 with NiFe added 2 O 4 @SiO 2 The particles were heated to reflux at 80°C for 13 h.

[0047] Step 6, filter the product obtained in step (5), wash with 50 mL of toluene, and dry in vacuum to obtain the nickel ferrite composite material magnetized cellulose flocculant Y1. The SEM image of flocculant Y1 is shown in Figure 1 .

[0048] Example 2

[0049] A method for preparing a novel nickel ferrite composite material magnetized cellulose flocculant, wherein the preparation steps are repeated in Example 1, except that in step 5, NiFe is changed 2 O 4 @SiO 2 The amount of particles added is such that the aminated cellulose material and NiFe 2 O 4 @SiO 2 The mass ratio of the particles was adjusted to 4:3”, and the other conditions remained unchanged, and finally the nickel-ferrite composite magnetized cellulose flocculant Y2 was obtained.

[0050] Example 3

[0051] A method for preparing a novel nickel ferrite composite material magnetized cellulose flocculant, wherein the preparation steps are repeated in Example 1, except that in step 5, NiFe is changed 2 O 4 @SiO 2 The amount of particles added is such that the aminated cellulose material and NiFe 2 O 4 @SiO 2The mass ratio of the particles was adjusted to 1:1”, and the other conditions remained unchanged, and finally the nickel-ferrite composite magnetized cellulose flocculant Y3 was obtained.

[0052] Example 4

[0053] A method for preparing a novel nickel-ferrite composite material magnetized cellulose flocculant. The preparation steps are repeated in Example 1, with the only difference being that "in step 2, the solid-liquid ratio of oxidized cellulose to 37% ammonia water is adjusted to 1g:15mL", and the other conditions remain unchanged, and finally a nickel-ferrite composite material magnetized cellulose flocculant Y4 is obtained.

[0054] Example 5

[0055] A method for preparing a novel nickel-ferrite composite material magnetized cellulose flocculant. The preparation steps are repeated in Example 2, with the only difference being that "in step 2, the solid-liquid ratio of oxidized cellulose to 37% ammonia water is adjusted to 1g:15mL", and the other conditions remain unchanged, and finally a nickel-ferrite composite material magnetized cellulose flocculant Y5 is obtained.

[0056] Example 6

[0057] A method for preparing a novel nickel-ferrite composite material magnetized cellulose flocculant. The preparation steps are repeated in Example 3, with the only difference being that "in step 2, the solid-liquid ratio of oxidized cellulose to 37% ammonia water is adjusted to 1g:15mL", and the other conditions remain unchanged, and finally a nickel-ferrite composite material magnetized cellulose flocculant Y6 is obtained.

[0058] Example 7

[0059] A method for preparing a novel nickel-ferrite composite material magnetized cellulose flocculant. The preparation steps are repeated in Example 1, with the only difference being that "in step 2, the solid-liquid ratio of oxidized cellulose to 37% ammonia water is adjusted to 1g:20mL", and the other conditions remain unchanged, and finally a nickel-ferrite composite material magnetized cellulose flocculant Y7 is obtained.

[0060] Example 8

[0061] A method for preparing a novel nickel-ferrite composite material magnetized cellulose flocculant. The preparation steps are repeated in Example 2, with the only difference being that "in step 2, the solid-liquid ratio of oxidized cellulose to 37% ammonia water is adjusted to 1g:20mL", and the other conditions remain unchanged, and finally a nickel-ferrite composite material magnetized cellulose flocculant Y8 is obtained.

[0062] Example 9

[0063] A method for preparing a novel nickel-ferrite composite material magnetized cellulose flocculant. The preparation steps are repeated in Example 3, with the only difference being that "in step 2, the solid-liquid ratio of oxidized cellulose to 37% ammonia water is adjusted to 1g:20mL", and the other conditions remain unchanged, and finally a nickel-ferrite composite material magnetized cellulose flocculant Y9 is obtained.

[0064] Comparative Example 1

[0065] The flocculant was cellulose, which was purchased from Shanghai Haohong Biopharmaceutical Technology Co., Ltd.

[0066] Comparative Example 2

[0067] The flocculant is NiFe prepared in step 4 of Example 1 2 O 4 @SiO 2 .

[0068] Comparative Example 3

[0069] Comparative Example 3 The preparation method of flocculant is repeated in Example 1, except that "NaIO 4 The solution was replaced by HCl solution of the same molar concentration, and the other conditions remained unchanged to obtain a flocculant.

[0070] Comparative Example 4

[0071] The flocculant was polyferric sulfate, which was purchased from Henan Zhongbang Environmental Protection Technology Co., Ltd.

[0072] Comparative Example 5

[0073] The flocculant was polyaluminium ferric silicate, purchased from Zibo Guangzheng Aluminium Salt Chemical Co., Ltd.

[0074] Comparative Example 6

[0075] The flocculant was polyaluminium chloride, purchased from Zhengzhou Daqian Environmental Protection Technology Co., Ltd.

[0076] Comparative Example 7

[0077] The flocculant was polyacrylamide, which was purchased from Sichuan Shuiyuanqing Environmental Protection Technology Co., Ltd.

[0078] Application Example 1:

[0079] The wastewater from a printing and dyeing factory in Zhejiang was used. The pH value of the printing and dyeing wastewater in the production process was 6.5, the COD content was about 2800 mg / L, the total lead content was about 1.12 mg / L, and the chromaticity was about 1500.

[0080] The dosage of flocculant Y1 prepared in Example 1 in wastewater was 0.5 g / L, 1.0 g / L, 1.5 g / L, 2.0 g / L and 2.5 g / L respectively. 1 L of wastewater was treated according to different dosages of flocculant. The temperature was 25° C. and the reaction time was 60 min. The treatment effects on COD, total lead and chromaticity in the water are shown in Table 1. Figure 2 shown.

[0081] Table 1

[0082]

[0083] The flocculant Y1 prepared in Example 1 was added to the wastewater at an amount of 1.5 g / L to treat 1 L of the wastewater at a temperature of 25°C. The treatment effects on COD, total lead and chromaticity in the water at different reaction times (10 min, 20 min, 30 min, 40 min, 50 min, 60 min) are shown in Table 2. Figure 3 shown.

[0084] Table 2

[0085]

[0086]

[0087] It can be seen from Table 2 that with the increase of treatment time, the treatment effect of the flocculant first increases and then decreases. This is because the long-term stillness causes the flocs to loosen, and some fine particles are re-suspended, and then tend to stabilize.

[0088] The flocculant prepared in Example 1 and the flocculants of Comparative Examples 1, 2, 3, 4, 5, 6, and 7 were added to the wastewater at a dosage of 1.5 g / L. 1 L of the wastewater was treated at a temperature of 25° C. for a reaction time of 40 min. When the pH value of the wastewater was adjusted to 5, 7, 9, and 11, respectively, the treatment of COD, total lead, and chromaticity in the wastewater was as shown in Tables 3, 4, and 5.

[0089] Table 3 Removal effect of wastewater COD

[0090]

[0091]

[0092] Table 4 Removal effect of total lead in wastewater

[0093]

[0094]

[0095] Table 5 Removal effect of wastewater chroma

[0096]

[0097] 1.5 g / L of the flocculants prepared in Examples 1 to 9 and Comparative Examples 1, 2, 3, 4, 5, 6, and 7 were added to 1 L of wastewater at a temperature of 25°C and a reaction time of 40 min. The treatment of COD, total lead and chromaticity in the wastewater is shown in Table 6.

[0098] Table 6

[0099]

[0100]

[0101] according to Figure 1 and Figure 2 It can be seen that the flocculant prepared in Example 1 has a COD content of about 2800 mg / L, a total lead content of about 1.12 mg / L, and a chromaticity of about 1500 at pH = 6.5. The optimal dosage of the flocculant in the printing and dyeing wastewater is 1.5 g / L, and the optimal reaction time is 40 min. Through orthogonal experimental data analysis, it is obtained that the nickel ferrite composite magnetized cellulose flocculant is not better for COD, total lead and chromaticity removal as the proportion of nickel ferrite composite material is higher, the optimal ratio is 4:3, and the solid-liquid ratio of cellulose to ammonia water can be fully aminated at 1:15.

[0102] Comparing the examples and comparative examples, the nickel-ferrite composite material magnetized cellulose flocculant prepared in the examples is obtained by aminating cellulose and using a silane coupling agent to form a graft with nickel-ferrite iron using organic silicon covalent bonds, modifying the cellulose surface to produce a large number of hydroxyl groups and introducing nickel-ferrite iron composite materials, which has good effects of removing COD, total lead and chromaticity from wastewater. The nickel-ferrite composite material magnetized cellulose flocculant prepared in the examples is better than conventional flocculants such as polyaluminum silicate iron and polyferric sulfate in treating wastewater alone. And the acidified solution NaIO 4 The effect of post-treatment after replacing with HCl is poor, which may be because HCl does not completely acidify the cellulose. Under the optimal conditions (Example 5), the removal rates of COD, total lead and chroma can reach 74.56%, 91.53% and 90.62% respectively.

[0103] from Figure 1 The SEM scanning electron microscope image shows that the particles form tight aggregates through flocculation, indicating that the material has high structural strength and stability, which is beneficial to improving the overall performance; the surface of the material presents a uniform porous morphology and has strong adsorption capacity; the high surface roughness increases the interface contact area, promotes flocculation efficiency, and has high mechanical stability.

[0104] It can be seen from this that the nickel-ferrite composite magnetized cellulose flocculant provided by the present invention has mild reaction conditions, low cost, simple preparation, excellent flocculation effect, and has a good market application prospect.

[0105] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A nickel-ferrite composite material magnetized cellulose flocculant, characterized in that: It is composed of the following components: Aminated cellulose matrix: prepared by cellulose oxidation with NaIO4, amination with ammonia and reduction with NaBH3CN, with the surface modified with hydroxyl-OH and amino-NH2 functional groups; Nickel ferrite composite material NiFe2O4@SiO2: NiFe2O4 is synthesized by co-precipitation of Fe salt and Ni salt under alkaline conditions, and then coated with SiO2 layer by sol-gel method; Silane coupling agent bridging structure: The aminated cellulose matrix and NiFe2O4@SiO2 are covalently linked by 3-glycidyloxypropyltrimethoxysilane KH560 to form an organic-inorganic hybrid network, which is the flocculant.

2. The flocculant according to claim 1, characterized in that: The mass ratio of the aminated cellulose to NiFe2O4@SiO2 is 2:1 to 1:

1.

3. The flocculant according to claim 2, characterized in that: The mass ratio of the aminated cellulose to NiFe2O4@SiO2 is 4:

3.

4. A method for preparing the nickel-ferrite composite magnetized cellulose flocculant according to claim 1, characterized in that: The following steps are involved: (1) Cellulose oxidative amination: Disperse cellulose in softened water, add NaIO4 solution, stir at 50-60°C for 6-8h, filter and wash to obtain oxidized cellulose; The oxidized cellulose is mixed with 37% ammonia water at a solid-liquid ratio of 1 g: 10-20 mL, and a NaBH3CN solution is added, and the mixture is reacted at 70-95°C for 12-15 hours. During the reaction, the mixture is cooled and refluxed to prevent evaporation of ammonia gas, thereby obtaining aminated cellulose. (2) Preparation of NiFe2O4@SiO2: The trivalent Fe salt and the divalent Ni salt are mixed in a molar ratio of 2 to 4:1, stirred in an aqueous solution with a final concentration of NaOH of 0.7 to 1.0 mol / L at room temperature for a coprecipitation reaction, the reaction time is 0.5 to 2 hours, and then centrifuged and washed to obtain NiFe2O4; Disperse NiFe2O4 in ethanol, add ammonia water and tetraethyl silicate TEOS, stir at 50-60℃ for 20-24h, hydrolyze TEOS and coat NiFe2O4 with SiO2 layer, then centrifuge and wash, and calcine at high temperature to obtain NiFe2O4@SiO2; (3) Flocculant compound: The aminated cellulose was dissolved in toluene, KH560 and NiFe2O4@SiO2 were added, and the mixture was heated under reflux for 10-15 hours. The target flocculant was obtained after filtering, washing and drying.

5. The method according to claim 4, characterized in that: In step (1), the mass ratio of NaIO4 to cellulose is 0.2-0.4:1, and the mass ratio of NaBH3CN to oxidized cellulose is 0.05-0.1:1; In the TEOS hydrolysis reaction system in step (2), the final concentration of ammonia water is 4-8%, and the feed ratio of NiFe2O4 to TEOS is 8-12 g:1 mL; In step (3), the mass ratio of KH560 to aminated cellulose is 0.8-1.2:1, and the mass ratio of aminated cellulose to NiFe2O4@SiO2 is 1-2:1, preferably 4:

3.

6. The method according to claim 4, characterized in that: The calcination temperature in step (2) is 700-800°C, and the heating temperature in step (3) is 70-80°C.

7. Use of the flocculant according to any one of claims 1 to 3 in the treatment of printing and dyeing wastewater.

8. The use according to claim 7, characterized in that The pH value of the wastewater is 5-11, the dosage of the flocculant in the wastewater is 1.0-2.0 g / L, the treatment temperature is room temperature, the reaction time is 30-60 min, and the removal rates of COD, total lead and chromaticity are ≥70%, 85% and 85% respectively.

9. The use according to claim 7, characterized in that The printing and dyeing wastewater has an initial COD of ≤3000 mg / L, a chromaticity of ≤2000 times, and a total lead concentration of ≤2.0 mg / L.

Images