Application of amphiphilic modified starch flocculant

Abstract

The invention discloses application of an amphiphilic modified starch flocculant, and belongs to the technical field of environmental protection. As the addition amount of the amphiphilic modified starch flocculant CS-DML is increased to 10.0 mg / g TSS from 0 mg / g TSS, the sludge moisture content FCMC and the sludge specific resistance SRF are both rapidly reduced firstly, after the addition amount is continuously increased to the optimal addition amount 10.0 mg / g TSS, the numerical changes of the FCMC and the SRF do not tend to be stable, in the amphiphilic modified starch flocculant CS-DML, the hydrophobic CS-DML has excellent dehydration performance, and the water content of the hydrophobic CS-DML is greatly reduced. According to the amphiphilic modified starch flocculant CS-DML, the water content FCMC of sludge can be reduced from 97.47% to 79.46% only under the mechanical pressure of 0.05 MPa, the specific resistance SRF of the sludge can be reduced from 10 * 10 < 12 > m / Kg to 1 * 10 < 12 > m / Kg, the numerical values of the water content FCMC of the sludge and the specific resistance SRF of the sludge are low, the optimal dosage is 10.0 mg / g TSS, and the hydrophobic structure of the amphiphilic modified starch flocculant CS-DML is beneficial to sludge dehydration.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to the application of an amphiphilic modified starch flocculant. Background Art

[0002] At present, the treatment and disposal of sludge faces two challenges. On the one hand, as a by-product of sewage treatment, sludge contains toxic and harmful substances, such as pathogens, heavy metals, and some organic matter. If it is directly discharged, it will cause serious pollution to the ecological environment. The sludge needs to be properly treated and disposed to reduce its harm to the environment. On the other hand, the moisture content of untreated sludge is generally above 92%. The sludge needs to be dehydrated to reduce the volume of sludge and reduce its storage and transportation costs. The high moisture content of sludge is due to the fact that the surface of sludge particles will be wrapped with a hydration layer to form a stable colloidal suspension. These particles are negatively charged and repel each other, resulting in poor sedimentation and dewatering performance, and sludge solid-liquid separation is difficult. In addition, the organic components in the sludge, especially the extracellular polymers (EPS), will affect the dewatering performance of the sludge and increase the difficulty of sludge dewatering. Mechanical dewatering is the mainstream process for sludge dewatering. Affected by the composition characteristics of the sludge, it is difficult to achieve a good dewatering effect if mechanical dewatering is performed directly. Therefore, before mechanical dewatering, the sludge needs to be pretreated to facilitate subsequent efficient dewatering.

[0003] Coagulation / flocculation is one of the conventional sludge pretreatment technologies. The coagulation / flocculation process lays an important foundation for the subsequent mechanical dehydration to reduce the sludge volume. Coagulation / flocculation has been widely used in wastewater treatment due to its advantages such as simple operation, low cost, wide application range and good treatment effect, and the selection of coagulants / flocculants has become the key and core of sewage treatment technology. At present, synthetic organic polymer flocculants such as polyacrylamide (PAM) and inorganic coagulants such as iron salts and aluminum salts are widely used in the market. Although inorganic coagulants and organic polymer flocculants have good coagulation / flocculation effects and are the mainstream water treatment agents in the current market, they are actually used in the process of water safety due to the inevitable presence of metal ions and highly toxic organic monomer residues. Therefore, the development of new, efficient and environmentally friendly coagulants / flocculants has always been a hot research topic. Summary of the invention

[0004] In order to solve the technical problem of the present invention, the present invention provides an application of an amphiphilic modified starch flocculant, the hydrophilicity and hydrophobicity of the flocculant are easily adjusted, and the flocculant can better interact with the amphiphilic EPS in the sludge colloid, and the molecular weight and the number of functional groups of the flocculant are increased by the method of graft copolymerization, thereby enhancing the flocculation and sludge dewatering performance. The present invention provides an amphiphilic modified starch flocculant (both hydrophilic and lipophilic) with controllable hydrophobicity, which can more effectively reduce the moisture content of the mud cake and improve the sludge disposal performance. The hydrophobic CS-DML has excellent dewatering performance. Under only a mechanical pressure of 0.05MPa, it can reduce the sludge moisture content FCMC from 97.47% to 79.46%, and can reduce the sludge specific resistance SRF from 10×10 12 m / Kg drops to 1×10 12 m / Kg, not only the sludge moisture content FCMC and sludge specific resistance SRF values ​​are low, but also the optimal dosage is 10.0 mg / g TSS. The hydrophobic structure of the amphiphilic modified starch flocculant CS-DML is conducive to the dehydration of sludge.

[0005] In order to solve the technical problem of the present invention, the present invention provides the following technical solutions: an application of an amphiphilic modified starch flocculant, the application of the amphiphilic modified starch flocculant CS-DML in sludge dewatering, the preparation method of the amphiphilic modified starch flocculant is simple and low in cost; as the dosage of the amphiphilic modified starch flocculant CS-DML increases from 0 mg / g TSS to 10.0 mg / g TSS, the sludge moisture content FCMC and the sludge specific resistance SRF both decrease rapidly first, and after continuing to increase the dosage to the optimal dosage of 10.0 mg / g TSS, the FCMC and SRF values ​​do not change much and tend to be stable, and the hydrophobic CS-DML has excellent dehydration performance. Only under a mechanical pressure of 0.05 MPa, the sludge moisture content FCMC can be reduced from 97.47% to 79.46%, and the sludge specific resistance SRF can be reduced from 10×10 12 m / Kg drops to 1×10 12 m / Kg, not only the FCMC and SRF values ​​of sludge water content were low, but also the optimal dosage was 10.0mg / g TSS. The hydrophobic structure of the amphiphilic modified starch flocculant CS-DML was beneficial to the dehydration of sludge.

[0006] The structural formula of the amphiphilic modified starch flocculant is as follows:

[0007]

[0008] Where n,m=50-1000;

[0009] The preparation method of the amphiphilic modified starch flocculant is as follows:

[0010] Step 1: Preparation of etherified modified starch: 10 g starch and 3 g NaOH were added into water, alkalized and gelatinized at 75° C. for 1.5 h, 4 g 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution was added dropwise, and the reaction was continued for 2.5 h, and 0.05 mol / L sodium hydroxide aqueous solution was added dropwise to adjust the pH to 9, thereby obtaining etherified modified starch;

[0011] Step 2: Preparation of amphiphilic modified starch flocculant: fully dissolve the obtained etherified modified starch in 150 mL aqueous solution to make the mass fraction of etherified modified starch 30%, stir at 45 ° C for 40 minutes, and introduce nitrogen, add freshly prepared ammonium persulfate solution, react for 10 minutes, so that the ammonium persulfate solution and the etherified modified starch are fully reacted, wherein the molar ratio of ammonium persulfate to the etherified modified starch is 1:10; add acryloyloxyethyl dimethylbenzyl ammonium chloride DML and acrylamide comonomer to the system at a rate of 4 drops / s, and the molar ratio is 1:4, stir and react at 50 ° C for 4 hours to ensure that the entire reaction is carried out under anaerobic conditions, after the reaction is completed, add precipitant ethanol, wherein the volume ratio of ethanol to the product solution is 4:1, precipitate, dry, and crush the product, Soxhlet extract in 105 ° C acetone solution for 48 hours, and dry to obtain a powdered amphiphilic modified starch flocculant CS-DML.

[0012] Preferably, the amphiphilic modified starch flocculant CS-DML not only has efficient sludge dehydration performance, which can reduce the sludge moisture content to below 80% under the action of only 0.05MPa low pressure, but also can reduce the hydrophobic organic matter and COD value in the water body, and also has antibacterial and deodorizing effects.

[0013] Preferably, the contact angle of the amphiphilic modified starch flocculant CS-DML is 43.4° and its solubility is good.

[0014] An amphiphilic modified starch flocculant, the structural formula of the amphiphilic modified starch flocculant is as follows:

[0015]

[0016] Where n,m=50-1000.

[0017] Preferably, the preparation method of the amphiphilic modified starch flocculant comprises the following steps:

[0018] Step 1: adding sodium hydroxide to starch for alkalization and gelatinization reaction, then adding 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution to continue the reaction, adjusting the pH, and obtaining etherified modified starch;

[0019] Step 2: Under a nitrogen atmosphere, add ammonium persulfate to the etherified modified starch, then add acrylamide and acryloyloxyethyl dimethylbenzyl ammonium chloride, stir, add a precipitant to precipitate after the reaction is completed, filter, dry, crush, then Soxhlet extract with acetone solution, and dry to obtain an amphiphilic modified starch flocculant.

[0020] Among them, AM stands for acrylamide; DML stands for acryloyloxyethyl dimethylbenzyl ammonium chloride; CS-DML stands for amphiphilic modified starch flocculant; APS stands for ammonium persulfate.

[0021] The invention also provides application of the amphiphilic modified starch flocculant in sludge dewatering.

[0022] In order to solve the technical problem of the present invention, another technical solution is proposed: the structural formula of the amphiphilic modified starch flocculant is as follows:

[0023]

[0024] Where n,m=50-1000.

[0025] Beneficial effects:

[0026] (1) Compared with the hydrophobically modified cationic starch flocculant CS-DMRs previously prepared by our research group, the amphiphilic modified starch flocculant CS-DML of the present invention has a higher preparation yield; CS-DMRs require three steps to synthesize, while the present invention only requires two steps to synthesize, and the preparation steps are simpler; and the monomer DML is cheaper than DMR, and is more economical and practical. Compared with the hydrophobically modified cationic starch flocculant CS-DMRs, the amphiphilic modified starch flocculant CS-DML of the present invention has better dehydration performance, and lower sludge moisture content and sludge specific resistance.

[0027] (2) As the dosage of amphiphilic modified starch flocculant CS-DML increased from 0 mg / g TSS to 10.0 mg / g TSS, the sludge moisture content FCMC and sludge specific resistance SRF first decreased rapidly. After the dosage continued to increase to the optimal dosage of 10.0 mg / g TSS, the FCMC and SRF values ​​did not change much and tended to be stable. Among the amphiphilic modified starch flocculants CS-DML flocculants, the hydrophobic CS-DML has excellent dehydration performance. Under only 0.05 MPa mechanical pressure, it can reduce the sludge moisture content FCMC from 97.47% to 79.46%, and can reduce the sludge specific resistance SRF from 10×10 12 m / Kg drops to 1×10 12 m / Kg, not only the sludge moisture content FCMC and sludge specific resistance SRF values ​​are low, but also the optimal dosage is 10.0 mg / g TSS. The hydrophobic structure of the amphiphilic modified starch flocculant CS-DML is conducive to the dehydration of sludge.

[0028] (3) Starch, a natural polymer flocculant, has the characteristics of low cost, environmental protection, and wide sources. Its molecular structure usually contains a large number of active groups such as hydroxyl and amine. Through modification methods such as etherification, amination, esterification, oxidation, and graft copolymerization, different functional monomers can be introduced into the natural polymer to improve its own shortcomings such as poor solubility, low charge, and low molecular weight, thereby producing a wide variety of high-efficiency water treatment agents.

[0029] (4) The raw material used in the present invention is a natural polymer: starch, which is widely available, non-toxic, biodegradable, and has no secondary pollution risk. Since the starch structure is rich in a large number of functional groups such as hydroxyl groups, it can not only serve as a substrate to graft hydrophobic chains, but also assist in the synergistic adsorption of pollutants in water bodies, effectively enhancing the application range of natural polymer flocculants.

[0030] (5) The amphiphilic modified starch flocculant of the present invention not only has high efficiency in sludge dehydration performance, but can also reduce the sludge moisture content to below 80% under the action of a low pressure of 0.05 MPa, and can also reduce the hydrophobic organic matter and COD value in the water body, and also has the effects of antibacterial and deodorization. The preparation method and operation process of the product of the present invention are simple, the synthesis time is short, the raw material source is wide, the cost is low, and the product has a wide range of use. The product is an economical, green, and environmentally friendly water treatment agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 The hydrogen nuclear magnetic resonance spectra of the flocculants prepared in Example 1 and Comparative Example 1;

[0033] Figure 2 The Fourier transform infrared spectra of the flocculants prepared in Example 1 and Comparative Example 1;

[0034] Figure 3 The contact angle diagrams of the flocculants prepared in Example 1 and Comparative Example 1;

[0035] Figure 4 The relationship diagram between the flocculant dosage and the moisture content of the mud cake prepared in Example 1 and Comparative Example 1;

[0036] Figure 5 This is a relationship diagram between the flocculants prepared in Example 1 and Comparative Example 1 and the sludge specific resistance. DETAILED DESCRIPTION

[0037] Example 1

[0038] Step 1: Preparation of etherified modified starch: 10 g starch and 3 g NaOH were added into water, alkalized and gelatinized at 75° C. for 1.5 h, 4 g 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution was added dropwise, and the reaction was continued for 2.5 h, and 0.05 mol / L sodium hydroxide aqueous solution was added dropwise to adjust the pH to 9, thereby obtaining etherified modified starch;

[0039] Step 2: Preparation of amphiphilic modified starch flocculant: fully dissolve the obtained etherified modified starch in 150 mL aqueous solution to make the mass fraction of etherified modified starch 30%, stir at 45 ° C for 40 minutes, and introduce nitrogen, add freshly prepared ammonium persulfate solution, react for 10 minutes, so that the ammonium persulfate solution and the etherified modified starch are fully reacted, wherein the molar ratio of ammonium persulfate to the etherified modified starch is 1:10; add acryloyloxyethyl dimethylbenzyl ammonium chloride DML and acrylamide comonomer to the system at a rate of 4 drops / s, and the molar ratio is 1:4, stir and react at 50 ° C for 4 hours to ensure that the entire reaction is carried out under anaerobic conditions, after the reaction is completed, add precipitant ethanol, wherein the volume ratio of ethanol to the product solution is 4:1, precipitate, dry, and crush the product, Soxhlet extract in 105 ° C acetone solution for 48 hours, and dry to obtain a powdered amphiphilic modified starch flocculant CS-DML.

[0040] The structural formula of the amphiphilic modified starch flocculant is as follows:

[0041]

[0042] Where n,m=50-1000.

[0043] Example 2

[0044] Step 1: Preparation of etherified modified starch: 5 g of starch was dispersed in an aqueous solution, and then 0.5 g of NaOH was added, alkalized and gelatinized at 80°C for 3 h, 2 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution was added dropwise, and the reaction was continued for 4 h, and 0.1 mol / L of sodium hydroxide aqueous solution was added dropwise to adjust the pH to 5 to obtain etherified modified starch.

[0045] Step 2: Preparation of amphiphilic modified starch flocculant: fully dissolve the obtained etherified modified starch in 100mL aqueous solution to make the mass fraction of etherified modified starch 15%, and introduce nitrogen, stir in a water bath at 40°C to fully dissolve it, add freshly prepared ammonium persulfate solution, react for 30min, so that the ammonium persulfate solution and etherified modified starch fully react, wherein the molar ratio of ammonium persulfate to etherified modified starch is 1:20. DML and acrylamide comonomer are added to the system at a rate of 2 drops / s, and the molar ratio is 5:2, and the reaction is stirred at 45°C for 6h, ensuring that the entire reaction is carried out under nitrogen conditions. After the reaction is completed, precipitant acetone is added, wherein the volume ratio of acetone to product solution is 2:1, the product is precipitated, dried, and crushed, and Soxhlet extraction is performed in 85°C acetone solution for 2 days, and drying is performed to obtain a powdered amphiphilic modified starch flocculant CS-DML.

[0046] After testing, the prepared CS-DML has Figure 1-3 Similar 1 H NMR and FTIR spectra as well as contact angles indicate that CS-DML has been successfully prepared.

[0047] Example 3

[0048] Step 1: Preparation of etherified modified starch: 5 g of starch was added to 1.0 g of NaOH and gelatinized in an alkaline water bath at 60° C. for 1 h, 1.5 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution was added dropwise, and the reaction was continued at 60° C. for 4 h. At this time, the solution was brown, and 0.1 mol / L of sodium hydroxide aqueous solution was added dropwise to adjust the pH to 6 to obtain etherified modified starch;

[0049] Step 2: Preparation of amphiphilic modified starch flocculant: fully dissolve the obtained etherified modified starch in 100mL aqueous solution, make the mass fraction of etherified modified starch 10%, stir at 60℃ for 1 hour, and introduce nitrogen, add freshly prepared ammonium persulfate solution, react for 15min, so that the ammonium persulfate solution and etherified modified starch fully react, wherein the molar ratio of ammonium persulfate to etherified modified starch is 1:25. DML and acrylamide comonomer are added to the system at a rate of 2 drops / s, and the molar ratio is 2:5, and the reaction is stirred at 25℃ for 3h to ensure that the entire reaction is carried out under anaerobic conditions. After the reaction is completed, precipitant ethanol is added, wherein the volume ratio of ethanol to product solution is 2:1, the product is precipitated, dried, and crushed, and Soxhlet extraction is performed in 100℃ acetone solution for 2 days, and drying is performed to obtain powdered amphiphilic modified starch flocculant CS-DML.

[0050] The prepared CS-DML has Figure 1-3 Similar 1H NMR and FTIR spectra as well as contact angles indicate that CS-DML has been successfully prepared.

[0051] Example 4

[0052] Step 1: Preparation of etherified modified starch: add 1.5 g NaOH to an aqueous solution of 5 g starch, alkalize and gelatinize at 40°C for 1.5 h, add dropwise 2 g 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution, continue the reaction for 2.5 h, then add dropwise 0.1 mol / L sodium hydroxide aqueous solution to adjust the pH to 8 to obtain etherified modified starch.

[0053] Step 2: Preparation of amphiphilic modified starch flocculant: fully dissolve the obtained etherified modified starch in 100mL aqueous solution to make the mass fraction of etherified modified starch 10%, and introduce nitrogen, stir for 1 hour in a 40℃ water bath, add freshly prepared ammonium persulfate solution, react for 10min, so that the ammonium persulfate solution and etherified modified starch fully react, wherein the molar ratio of ammonium persulfate to etherified modified starch is 1:30. DML and acrylamide comonomer are added to the system at a rate of 2 drops / s, and the molar ratio is 4:3, and the reaction is stirred at 30℃ for 10h to ensure that the entire reaction is carried out under anaerobic conditions. After the reaction is completed, precipitant ethanol is added, wherein the volume ratio of ethanol to product solution is 2:1, the product is precipitated, dried, and crushed, and Soxhlet extraction is performed in 80℃ acetone solution for 2 days, and drying is performed to obtain powdered amphiphilic modified starch flocculant CS-DML.

[0054] The prepared CS-DML has Figure 1-3 Similar 1 H NMR and FTIR spectra as well as contact angles indicate that CS-DML has been successfully prepared.

[0055] Comparative Example 1

[0056] The same as Example 1, except that methacryloyloxyethyl trimethylammonium chloride (DMC) is used as the active functional monomer to prepare a hydrophilic modified cationic starch flocculant (CS-DMC).

[0057] summary:

[0058] Figure 1 The hydrogen nuclear magnetic resonance spectra of CS-DML prepared in Example 1 and CS-DMC prepared in Comparative Example 1 are shown in FIG. Figure 2 The Fourier transform infrared spectra of CS-DML prepared in Example 1 and CS-DMC prepared in Comparative Example 1 are shown in the figure. 1 In the HNMR spectrum, the chemical shift of the methylene and methyl protons is 2.10 ppm. In the FTIR spectrum, at 1664 cm -1The characteristic peaks of C=O stretching vibration of CONH2 group on AM were observed at 1720, 1475 and 950 cm-1 in the FTIR spectrum of monomer DMC. -1 The infrared characteristic peaks at correspond to the characteristic peaks of DML carbonyl and methyl groups. 1 In the HNMR spectrum, the chemical shift of the methyl proton vibration of the quaternary ammonium salt is 3.20 ppm.

[0059] According to the above 1 HNMR and FTIR information showed that monomers AM and DML were successfully grafted onto CS.

[0060] Figure 3 The contact angles of CS-DML prepared in Example 1 and CS-DMC prepared in Comparative Example 1. The contact angle is an important parameter for measuring the hydrophobicity of a material, and the contact angle of the sample is positively correlated with the hydrophobicity. During the synthesis process, CS-DML with the same charge density but different hydrophobicity was obtained by adjusting the ratio of the reaction monomers DML and AM and keeping the total molar amount unchanged. Figure 3 As shown, the hydrophilicity and hydrophobicity of the flocculant CS-DML are characterized: CS-DML>CS-DMC, and the contact angles of CS-DML are all less than 90°, indicating that its solubility is relatively good.

[0061] Figure 4-5 The relationship diagram of the dosage of CS-DML prepared in Example 1 and CS-DMC prepared in Comparative Example 1, the moisture content of the mud cake and the sludge specific resistance. It can be seen from the figure that as the dosage of CS-DML increases to 10.0 mg / g TSS, the moisture content of the mud cake FCMC and the sludge specific resistance SRF both decrease rapidly first. After continuing to increase the dosage to the optimal dosage, the values ​​of FCMC and SRF do not change much and tend to be stable. Among this CS-DML flocculant, the hydrophobic CS-DML has a more excellent dehydration performance. Only under a mechanical pressure of 0.05 MPa, it can reduce FCMC from 97.47% to 79.46%. It can reduce the sludge specific resistance SRF from 10×10 12 m / Kg drops to 1×10 12 m / Kg, not only the FCMC and SRF values ​​are low, but also the optimal dosage is relatively low, which further shows that the hydrophobic structure of the flocculant is conducive to the dewatering of sludge. In other words, the organic polymer flocculant with a hydrophilic and hydrophobic structure is superior to the hydrophilic organic polymer flocculant in improving the sludge dewatering performance due to the synergistic effect of hydrophobic association, electrical neutralization and bonding bridging effect.

[0062] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement are within the protection scope required by the present invention.

Claims

1. An application of an amphiphilic modified starch flocculant, characterized in that: The application of the amphiphilic modified starch flocculant CS-DML in sludge dewatering, the preparation method of the amphiphilic modified starch flocculant is simple and low in cost; as the dosage of the amphiphilic modified starch flocculant CS-DML increases from 0 mg / g TSS to 10.0 mg / g TSS, the sludge moisture content FCMC and the sludge specific resistance SRF both decrease rapidly first, and after the dosage continues to increase to the optimal dosage of 10.0 mg / g TSS, the FCMC and SRF values ​​do not change much and tend to be stable. The hydrophobic CS-DML has excellent dewatering performance. Only under a mechanical pressure of 0.05 MPa, the sludge moisture content FCMC can be reduced from 97.47% to 79.46%, and the sludge specific resistance SRF can be reduced from 10×10 12 m / Kg drops to 1×10 12 m / Kg, not only the FCMC and SRF values ​​of sludge water content were low, but also the optimal dosage was 10.0mg / g TSS. The hydrophobic structure of the amphiphilic modified starch flocculant CS-DML was beneficial to the dehydration of sludge. The structural formula of the amphiphilic modified starch flocculant is as follows: Where n,m=50-1000.

2. The use of the amphiphilic modified starch flocculant according to claim 1, characterized in that: The preparation method of the amphiphilic modified starch flocculant is as follows: Step 1: Preparation of etherified modified starch: 10 g starch and 3 g NaOH were added into water, alkalized and gelatinized at 75° C. for 1.5 h, 4 g 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution was added dropwise, and the reaction was continued for 2.5 h, and 0.05 mol / L sodium hydroxide aqueous solution was added dropwise to adjust the pH to 9, thereby obtaining etherified modified starch; Step 2: Preparation of amphiphilic modified starch flocculant: fully dissolve the obtained etherified modified starch in 150 mL aqueous solution to make the mass fraction of etherified modified starch 30%, stir at 45 ° C for 40 minutes, and introduce nitrogen, add freshly prepared ammonium persulfate solution, react for 10 minutes, so that the ammonium persulfate solution and the etherified modified starch are fully reacted, wherein the molar ratio of ammonium persulfate to the etherified modified starch is 1:10; add acryloyloxyethyl dimethylbenzyl ammonium chloride DML and acrylamide comonomer to the system at a rate of 4 drops / s, and the molar ratio is 1:4, stir and react at 50 ° C for 4 hours to ensure that the entire reaction is carried out under anaerobic conditions, after the reaction is completed, add precipitant ethanol, wherein the volume ratio of ethanol to the product solution is 4:1, precipitate, dry, and crush the product, Soxhlet extract in 105 ° C acetone solution for 48 hours, and dry to obtain a powdered amphiphilic modified starch flocculant CS-DML.

3. The use of the amphiphilic modified starch flocculant according to claim 1, characterized in that: The amphiphilic modified starch flocculant CS-DML not only has high efficiency in sludge dehydration performance, and can reduce the sludge moisture content to below 80% under the action of only 0.05MPa low pressure, but also can reduce the hydrophobic organic matter and COD value in the water body, and also has antibacterial and deodorizing effects.

4. The use of the amphiphilic modified starch flocculant according to claim 1, characterized in that: The contact angle of the amphiphilic modified starch flocculant CS-DML is 43.4°, and its solubility is good.

5. The amphiphilic modified starch flocculant for use according to claim 1, characterized in that: The structural formula of the amphiphilic modified starch flocculant is as follows: Where n,m=50-1000.

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