Preparation method and application of Sn-S chelating type organic composite flocculant

Abstract

The invention relates to the technical field of flocculants, and discloses a preparation method and application of a Sn-S chelating type organic composite flocculant. According to the preparation method, dioctyltin dilaurate and dimercaptosuccinic acid are taken as raw materials, organic tin compound chelation is carried out by utilizing a chelation mechanism, and tin and sulfur atoms are combined to form a five-membered ring-shaped organic ring-shaped framework material, namely the Sn-S chelating type organic composite flocculant. The Sn-S chelating type organic composite flocculant provided by the invention is a chelating dominant chemical bond, a stable five-membered ring chelate is formed through a covalent bond, the bond energy is high, the reaction irreversibility is strong, the organic annular skeleton structure is stable, and the spatial position of a sulfur atom can be fixed in advance through the annular skeleton, so that the sulfur atom is coordinated with a heavy metal in a five-membered ring configuration, and the adsorption capacity of the flocculant is improved. Therefore, the affinity to Pb < 2 + > and Hg < 2 + > is particularly good, the removal effect on heavy metal ions such as mercury and lead ions in wastewater is excellent, and the removal rate can reach 90% or above.

Description

Technical Field

[0001] The invention relates to the technical field of flocculants, and in particular to a preparation method and application of a Sn-S chelate type organic composite flocculant. Background Art

[0002] Heavy metal ions (mainly chromium, cadmium, copper, mercury, nickel, zinc, lead and other metal ions) are the main pollutants in water sources and the priority pollutants in water quality, which are extremely harmful. In the smelting of non-ferrous metals and chemical production, especially in the smelting of metals such as copper, lead, zinc and gold, a large amount of wastewater containing mercury (Hg) and lead (Pb) will be generated. In addition, in the chemical production process, such as the production of coatings, drugs and cosmetics, mercury, lead or their compounds may also be used as raw materials or preservatives, thus generating wastewater containing mercury and lead.

[0003] At present, Hg in water 2+ , Pb 2+ Removal methods include adsorption, chemical reduction, chemical precipitation, ion exchange, solvent extraction and reverse osmosis. Among them, adsorption has the characteristics of simple operation, high efficiency and low cost, environmental friendliness and deep treatment, making it a very effective treatment method for mercury and lead-containing wastewater. In the adsorption method, the adsorption material is one of the key factors affecting the adsorption effect. The form, type and existence of the adsorption material determine the material preparation cost, adsorption process and adsorption efficiency.

[0004] The existing adsorption materials have limited adsorption capacity for heavy metal ions such as mercury and lead ions, and the adsorption materials need to be further optimized. Summary of the invention

[0005] In order to solve the problem of Hg in wastewater by existing adsorption materials 2+ , Pb 2+ In order to solve the problem of low adsorption rate, the present invention provides a preparation method and application of a Sn-S chelating organic composite flocculant.

[0006] The specific technical scheme of the present invention is: In a first aspect, the present invention provides a method for preparing a Sn-S chelating organic composite flocculant, comprising the following steps: Step S1: dispersing dioctyltin dilaurate in a solvent to obtain a dioctyltin dilaurate solution; Step S2: pre-hydrolyzing the dimercaptosuccinic acid to obtain a dimercaptosuccinic acid hydrolyzate; Step S3: mixing the dioctyltin dilaurate solution with the dithiosuccinic acid hydrolyzate, subjecting the mixed solution to ultrasonic treatment, and stirring the mixture for reaction to obtain a reaction solution; Step S4: allowing the reaction solution to stand for phase separation, removing the aqueous phase, allowing the solution to stand for aging, purifying, and drying to obtain a Sn-S chelating organic composite flocculant.

[0007] The present invention uses dioctyltin dilaurate and dimercaptosuccinic acid as raw materials, utilizes a chelating mechanism to chelate organic tin compounds, combines tin with sulfur atoms to form a five-membered ring organic cyclic skeleton material, namely the Sn-S chelated organic composite flocculant, which is applied to the removal of heavy metals in wastewater and has an excellent effect.

[0008] The Sn-S chelate organic composite flocculant provided by the present invention is a chelate-dominated chemical bond, which forms a stable five-membered ring chelate through covalent bonds, has high bond energy, strong reaction irreversibility, and a stable organic ring skeleton structure. The Sn-S chelate organic composite flocculant can pre-fix the spatial position of sulfur atoms through the ring skeleton, so that it coordinates with heavy metals in a five-membered ring configuration, thereby improving the reaction kinetics and binding strength, thereby reducing the Pb 2+ , Hg 2+ In wastewater, Sn-S chelated organic composite flocculants adsorb mercury and lead ions with high affinity to mercury and lead ions. Sn atoms can form stable organic metal complexes through coordination reaction, thereby removing heavy metal ions from the solution, and the removal rate can reach more than 90%.

[0009] Specifically, in the Sn-S chelated organic composite flocculant, the principle of removing mercury and lead ions from wastewater is that the octyl (Oct-) and lauric acid residues on tin are hydrophobic and can form a "protective layer" to reduce the attack of water molecules on the Sn-S bond and reduce the coordination competition of impurity ions; Sn 4+ As a central metal, it preferentially occupies the strong coordination sites of sulfur ligands. However, when encountering heavy metals with stronger affinity, tin can "give way" to the target heavy metal through the ligand replacement mechanism while remaining stable. For example, it is converted into Sn-OOCR complex. Sn-S chelated organic composite flocculant enables the compound to selectively capture the highly toxic heavy metal Pb through dynamic equilibrium. 2+ , Hg 2+ .

[0010] Preferably, in step S1, the solvent is a mixed solvent of tetramethylethylenediamine and tetrahydrofuran.

[0011] Using a mixed solvent of tetramethylethylenediamine and tetrahydrofuran as the reaction environment can make the chelating reaction have higher reaction activity.

[0012] Preferably, in step S2, the pre-hydrolysis method is: dissolving dimercaptosuccinic acid in an ethanol aqueous solution and stirring.

[0013] Preferably, in step S3, the alkalinity of the mixed solution is set to 0.5-2.0.

[0014] Preferably, in step S3, the stirring speed of the stirring reaction is 200-500 rpm, and the time of the stirring reaction is 24-48 hours.

[0015] Preferably, in step S4, the standing and aging time is 20 to 60 hours.

[0016] Preferably, in step S4, the purification method is: adding a mixed solution of anhydrous ethanol and acetone, and ultrasonically shaking for 10 to 30 minutes.

[0017] Preferably, in step S4, the drying temperature is 140-160°C.

[0018] In a second aspect, based on the above preparation method, the present invention provides a Sn-S chelating organic composite flocculant.

[0019] In a third aspect, based on the above preparation method, the present invention provides an application of a Sn-S chelating organic composite flocculant in wastewater treatment.

[0020] Compared with the prior art, the present invention has the following technical effects: The present invention uses dioctyltin dilaurate and dimercaptosuccinic acid as raw materials, utilizes the chelation mechanism to chelate organic tin compounds, combines tin with sulfur atoms to form a five-membered ring organic ring skeleton material, and forms a stable five-membered ring chelate with a chemically bonded covalent bond. The bond energy is high, the reaction irreversibility is strong, the organic ring skeleton structure is stable, and it remains stable even under high salt or acidic (pH ≥ 3) conditions, and the range of wastewater treatment is wide.

[0021] The Sn-S chelate organic composite flocculant prepared by the preparation method of the present invention can pre-fix the spatial position of the sulfur atom through the cyclic skeleton, so that it coordinates with the heavy metal in the configuration of a five-membered ring, thereby improving the reaction kinetics and binding strength, thereby 2+ , Hg 2+ In wastewater, Sn-S chelated organic composite flocculants adsorb mercury and lead ions with high affinity to mercury and lead ions. Sn atoms can form stable organic metal complexes through coordination reaction, thereby removing heavy metal ions from the solution, and the removal rate can reach more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope morphology image of the chelating organic composite flocculant prepared in Example 1; Figure 2The flocculants prepared in Examples 1 to 4 and Comparative Examples 1 to 4 are effective in removing total lead and total mercury from wastewater; Figure 3 This is a diagram showing the removal effect of the chelating organic composite flocculant prepared in Example 1 on total lead and total mercury in wastewater under different pH conditions; Figure 4 This is a diagram showing the removal effect of total lead and total mercury in wastewater under different dosage conditions of the chelating organic composite flocculant prepared in Example 1. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should belong to the scope of protection of the present invention.

[0024] The present invention provides a method for preparing a Sn-S chelating organic composite flocculant, comprising the following steps: Step S1: dispersing dioctyltin dilaurate in a solvent to obtain a dioctyltin dilaurate solution; Step S2: pre-hydrolyzing the dimercaptosuccinic acid to obtain a dimercaptosuccinic acid hydrolyzate; Step S3: mixing the dioctyltin dilaurate solution with the dithiosuccinic acid hydrolyzate, subjecting the mixed solution to ultrasonic treatment, and stirring the mixture for reaction to obtain a reaction solution; Step S4: allowing the reaction solution to stand for phase separation, removing the aqueous phase, allowing the solution to stand for aging, purifying, and drying to obtain a Sn-S chelating organic composite flocculant.

[0025] The present invention uses dioctyltin dilaurate and dimercaptosuccinic acid as raw materials, utilizes a chelating mechanism to chelate organic tin compounds, combines tin with sulfur atoms to form a five-membered ring organic cyclic skeleton material, namely the Sn-S chelated organic composite flocculant, which is applied to the removal of heavy metals in wastewater and has an excellent effect.

[0026] The Sn-S chelate organic composite flocculant provided by the present invention is a chelate-dominated chemical bond, which forms a stable five-membered ring chelate through covalent bonds, has high bond energy, strong reaction irreversibility, and a stable organic ring skeleton structure. The Sn-S chelate organic composite flocculant can pre-fix the spatial position of sulfur atoms through the ring skeleton, so that it coordinates with heavy metals in a five-membered ring configuration, thereby improving the reaction kinetics and binding strength, thereby reducing the Pb 2+ , Hg 2+In wastewater, Sn-S chelated organic composite flocculants adsorb mercury and lead ions with high affinity to mercury and lead ions. Sn atoms can form stable organic metal complexes through coordination reaction, thereby removing heavy metal ions from the solution, and the removal rate can reach more than 90%.

[0027] Specifically, in the Sn-S chelated organic composite flocculant, the principle of removing mercury and lead ions from wastewater is that the octyl (Oct-) and lauric acid residues on tin are hydrophobic and can form a "protective layer" to reduce the attack of water molecules on the Sn-S bond and reduce the coordination competition of impurity ions; Sn 4+ As a central metal, it preferentially occupies the strong coordination sites of sulfur ligands. However, when encountering heavy metals with stronger affinity, tin can "give way" to the target heavy metal through the ligand replacement mechanism while remaining stable. For example, it is converted into Sn-OOCR complex. Sn-S chelated organic composite flocculant enables the compound to selectively capture the highly toxic heavy metal Pb through dynamic equilibrium. 2+ , Hg 2+ .

[0028] In one embodiment, in step S1, the solvent is a mixed solvent of tetramethylethylenediamine and tetrahydrofuran.

[0029] Using a mixed solvent of tetramethylethylenediamine and tetrahydrofuran as the reaction environment can make the chelating reaction have higher reaction activity.

[0030] In one embodiment, in step S2, the pre-hydrolysis method is: dissolving dimercaptosuccinic acid in an ethanol aqueous solution and stirring.

[0031] In one embodiment, in step S3, the alkalinity of the mixed solution is set to 0.5-2.0.

[0032] In one embodiment, in step S3, the stirring speed of the stirring reaction is 200-500 rpm, and the time of the stirring reaction is 24-48 hours.

[0033] In one embodiment, in step S4, the standing and aging time is 20 to 60 hours.

[0034] In one embodiment, in step S4, the purification method is: adding a mixed solution of anhydrous ethanol and acetone, and ultrasonically shaking for 10 to 30 minutes.

[0035] In one embodiment, in step S4, the drying temperature is 140-160°C.

[0036] The present invention will be further described below in conjunction with more specific embodiments.

[0037] Example 1 A chelating organic composite flocculant is provided, which is prepared according to the following steps: (1) 0.21 g of TMEDA and 0.225 g of THF were mixed, and then 15 g of dioctyltin dilaurate was dispersed therein and stirred to obtain a dioctyltin dilaurate mixed solution.

[0038] (2) 50 mL of water and 100 mL of anhydrous ethanol were mixed to obtain a solvent, and then 1.5 g of dimercaptosuccinic acid was dissolved in the solvent. The mixture was stirred for 1 hour to fully hydrolyze the dimercaptosuccinic acid, thereby obtaining a dimercaptosuccinic acid hydrolyzate.

[0039] (3) The dioctyltin dilaurate solution in step (1) is mixed with the dithiosuccinic acid hydrolyzate in step (2), and then the mixed solution is subjected to ultrasonic treatment for 1 hour. During the ultrasonic treatment, a NaOH solution with a concentration of 1 mg / L is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixed solution is 1.0. The ultrasonic power of the ultrasonic treatment is 150 W. After the ultrasonic treatment, the mixed solution is stirred at a speed of 300 rpm at 25° C. for 30 hours to complete the reaction between dioctyltin dilaurate and the thiol group to obtain a reaction solution.

[0040] (4) The reaction solution was allowed to stand for phase separation, the aqueous phase was removed, the organic phase was allowed to stand for 30 hours, and 150 mL of a mixed solution of anhydrous ethanol and acetone was added, wherein the volume ratio of anhydrous ethanol to acetone in the mixed solution was 2:1. After ultrasonic vibration for 25 minutes, the mixture was dried at 150°C and ground to obtain a solid powder, which was a Sn-S chelating organic composite flocculant, denoted as D1. The sample was taken and the morphology was observed by scanning electron microscopy. The results are shown in Figure 1 .

[0041] Example 2 Provided is a chelating organic composite flocculant, the preparation steps of which are different from those of Example 1, except that: in step (3), during the ultrasonic treatment, a NaOH solution with a concentration of 1 mg / L is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixed solution is 0.5. The other steps are the same as those of Example 1.

[0042] The Sn—S chelating organic composite flocculant powder prepared in this example is recorded as D2.

[0043] Example 3 Provided is a chelating organic composite flocculant, the preparation steps of which are different from those of Example 1, except that: in step (3), during the ultrasonic treatment, a NaOH solution with a concentration of 1 mg / L is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixed solution is 1.5. The other steps are the same as those of Example 1.

[0044] The Sn—S chelating organic composite flocculant powder prepared in this example is recorded as D3.

[0045] Example 4 Provided is a chelating organic composite flocculant, the preparation steps of which are different from those of Example 1, except that: in step (3), during the ultrasonic treatment, a NaOH solution with a concentration of 1 mg / L is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixed solution is 2.0. The other steps are the same as those of Example 1.

[0046] The Sn—S chelating organic composite flocculant powder prepared in this example is recorded as D4.

[0047] Comparative Example 1 Provided is a flocculant, the preparation steps of which are different from those of Example 1, except that in step (3), ultrasonic treatment is not performed. The other steps are the same as those of Example 1.

[0048] Step (3) of this comparative example is specifically as follows: the dioctyltin dilaurate solution in step (1) and the dithiothiosuccinic acid hydrolyzate in step (2) are mixed and dispersed uniformly, and then a NaOH solution with a concentration of 1 mg / L is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixed solution is 1.0, and then the mixed solution is stirred at a rate of 300 rpm at 25° C. for 30 hours to allow the dioctyltin dilaurate and the thiol group to react completely, thereby obtaining a reaction solution.

[0049] The flocculant powder prepared in this comparative example is recorded as P1.

[0050] Comparative Example 2 Provided is a flocculant, the preparation steps of which are different from those of Example 1, except that the dimercaptosuccinic acid pre-hydrolysis step is not performed. The other steps are the same as those of Example 1.

[0051] The specific steps of this comparative example are: (1) 0.21 g of TMEDA and 0.225 g of THF were mixed, and then 15 g of dioctyltin dilaurate was dispersed therein and stirred to obtain a dioctyltin dilaurate mixed solution.

[0052] (2) Add 1.5 g of dithiosuccinic acid to the dioctyltin dilaurate solution obtained in step (1), disperse evenly, and obtain a mixed solution. Then, the mixed solution is subjected to ultrasonic treatment for 1 hour, and the ultrasonic power of the ultrasonic treatment is 150 W. During the ultrasonic treatment, a NaOH solution with a concentration of 1 mg / L is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixed solution is 1.0. After the ultrasonic treatment, the mixed solution is stirred at a rate of 300 rpm at 25° C. for 30 hours to allow the dioctyltin dilaurate and the thiol group to react completely, thereby obtaining a reaction solution.

[0053] (3) The reaction solution was allowed to stand for phase separation, the aqueous phase was removed, the organic phase was allowed to stand for 30 hours, and 150 mL of a mixed solution of anhydrous ethanol and acetone was added, wherein the volume ratio of anhydrous ethanol to acetone in the mixed solution was 2:1. After ultrasonic vibration for 25 minutes, the mixture was dried at 150°C and ground to obtain a solid powder, which was a flocculant and was recorded as P2.

[0054] Comparative Example 3 Provided is a flocculant, the preparation steps of which are the same as those of Example 1, except that in step (2), no dimercaptosuccinic acid is added, and 1.5 g of mercaptosuccinic acid is used instead of 1.5 g of dimercaptosuccinic acid. The other steps are the same as those of Example 1.

[0055] The flocculant powder prepared in this comparative example is recorded as P3.

[0056] Comparative Example 4 Provided is a flocculant: cationic polyacrylamide (PAM-DMC). PAM-DMC is a common composite coagulant in the art and is purchased from Jiangsu Hengfeng Fine Chemical Co., Ltd.

[0057] The flocculant powder provided in this comparative example is recorded as P4.

[0058] Performance Testing

Test 1

[0059] Table 1 As can be seen from Table 1, the Sn-S chelated organic composite flocculant prepared in the embodiment has excellent removal effect on mercury and lead in wastewater, and the removal rate can reach more than 90%, especially the flocculant prepared in Example 1, the removal rate of total lead and total mercury reached 98.03% and 98.77% respectively. This shows that the present invention uses the chelation mechanism to chelate organic tin compounds, combines tin with sulfur atoms to form a five-membered ring organic cyclic skeleton material, and applies it to the removal of heavy metals in wastewater, which has excellent effect.

[0060] By comparing the embodiment of the present invention with comparative example 4, it can be seen that the removal rate of total lead and total mercury by the Sn-S chelating organic composite flocculant provided by the present invention is much higher than that of the composite coagulant PDM-DMC. The reasons are as follows: ① Conventional composite coagulant PDM-DMC removes heavy metal ions in wastewater by physical adsorption and charge neutralization mechanism, and the adsorption efficiency is low. The Sn-S chelate organic composite flocculant provided by the present invention is a chelation-dominated chemical bond, which forms a stable five-membered ring chelate through covalent bonds, has high bond energy, strong reaction irreversibility, and a stable organic cyclic skeleton structure. The cyclic skeleton pre-fixes the spatial position of the sulfur atom, so that it coordinates with the heavy metal in a five-membered ring configuration, thereby improving the reaction kinetics and binding strength, thereby improving the Pb 2+ , Hg 2+ The affinity of DM-DMC is much higher than that of coagulant PDM-DMC.

[0061] ② In the Sn-S chelate organic composite flocculant provided by the present invention, sulfur atoms are 2+ , Hg 2+ The affinity is high, and each molecule provides two sulfur coordination sites, which can bind more heavy metal ions per unit mass.

[0062] ③ The cyclic chelate formed by the Sn-S chelate organic composite flocculant provided by the present invention has a compact structure and high stability; and can resist Cl - 、SO4 2- At the same time, due to its stable structure and wide pH adaptability, it remains stable in the range of pH=3-10, and is particularly suitable for acidic mercury-containing wastewater.

[0063] ④ Since the Sn-S chelate organic composite flocculant of the present invention is a five-membered ring chelate with high bond energy and strong reaction irreversibility, desorption can be inhibited by strong bonding and will not cause secondary release of heavy metals due to pH fluctuation, water shear force or oxidation rupture.

[0064] By comparing Example 1 of the present invention with Comparative Examples 1, 2 and 3, it can be seen that the Sn-S chelated organic composite flocculant provided by the present invention can be prepared by dioctyltin dilaurate and dimercaptosuccinic acid in a suitable environment, among which ultrasonic treatment, pre-hydrolysis of dimercaptosuccinic acid and thiol raw materials have a greater influence on the performance of the product.

[0065]

Test 2

[0066] The test method is as follows: 300 mL of wastewater No. 1-8 is added to a 500 mL measuring cylinder, followed by adding 60 mg of the chelating organic composite flocculant prepared in Example 1, stirring at 300 rpm for 6 minutes, then stirring at 35 rpm for 2 minutes, standing for 15 minutes, taking the supernatant, and determining the total lead and total mercury content in the supernatant.

[0067] Table 2 It can be seen from Table 2 that the optimal pH range for the Sn-S chelating organic composite flocculant provided by the present invention is 3.25-9.76.

[0068]

Test 3

[0069] The test method is as follows: 300 mL of the above wastewater is added into a 500 mL measuring cylinder, and then 15 mg, 30 mg, 45 mg, 60 mg, 75 mg, 90 mg, 105 mg, and 120 mg of the chelating organic composite flocculant prepared in Example 1 are added respectively, stirred at 300 rpm for 6 minutes, then stirred at 35 rpm for 2 minutes, allowed to stand for 15 minutes, the supernatant is taken, and the total lead and total mercury contents of the supernatant are determined.

[0070] Table 3 It can be seen from Table 3 that the optimal dosage of the Sn-S chelating organic composite flocculant provided by the present invention is 30-105 mg per 300 ml of wastewater, that is, the dosage is: 10-35 mg per 100 mL of wastewater.

[0071] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a Sn-S chelating organic composite flocculant, characterized in that: The following steps are involved: Step S1: dispersing dioctyltin dilaurate in a solvent to obtain a dioctyltin dilaurate solution; Step S2: pre-hydrolyzing the dimercaptosuccinic acid to obtain a dimercaptosuccinic acid hydrolyzate; Step S3: mixing the dioctyltin dilaurate solution with the dithiosuccinic acid hydrolyzate, subjecting the mixed solution to ultrasonic treatment, and stirring the mixture for reaction to obtain a reaction solution; Step S4: allowing the reaction solution to stand for phase separation, removing the aqueous phase, allowing the solution to stand for aging, purifying, and drying to obtain a Sn-S chelating organic composite flocculant.

2. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S1, the solvent is a mixed solvent of tetramethylethylenediamine and tetrahydrofuran.

3. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S2, the pre-hydrolysis method is: dissolving dimercaptosuccinic acid in an ethanol aqueous solution and stirring.

4. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S3, the alkalinity of the mixed solution is set to 0.5-2.

0.

5. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S3, the stirring speed of the stirring reaction is 200-500 rpm, and the time of the stirring reaction is 24-48 hours.

6. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S4, the standing and aging time is 20 to 60 hours.

7. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S4, the purification method is: adding a mixed solution of anhydrous ethanol and acetone, and ultrasonically shaking for 10 to 30 minutes.

8. The method for preparing a Sn-S chelating organic composite flocculant according to claim 1, characterized in that: In step S4, the drying temperature is 140-160°C.

9. The Sn-S chelate type organic composite flocculant obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the Sn-S chelated organic composite flocculant obtained by the preparation method according to any one of claims 1 to 8 in wastewater treatment.

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