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

Abstract

The application relates to the technical field of flocculants, and discloses a preparation method of Sn-S chelate type organic composite flocculants and application thereof. The Sn-S chelate type organic composite flocculants are prepared by using di-n-octyltin dilaurate and dimercaptosuccinic acid as raw materials and chelating mechanism to chelate organotin compounds, combine tin and sulfur atoms to form a five-membered ring organic ring skeleton material. The Sn-S chelate type organic composite flocculants provided by the application are chelate-dominant chemical bonds, can form stable five-membered ring chelates through covalent bonds, have high bond energy, strong irreversible reaction, stable organic ring skeleton structure, can fix the spatial position of sulfur atoms in advance through the ring skeleton, can be coordinated with heavy metals in the form of five-membered ring, and can improve reaction kinetics and binding strength. Therefore, the Sn-S chelate type organic composite flocculants have excellent affinity to Pb 2+ and Hg 2+ , and can remove mercury and lead ions in wastewater with a removal rate of more than 90%.

Description

Technical Field

[0001] This invention relates to the field of flocculant technology, and in particular to a method for preparing a Sn-S chelated organic composite flocculant and its application. Background Technology

[0002] Heavy metal ions (mainly referring to chromium, cadmium, copper, mercury, nickel, zinc, lead, etc.) are major pollutants in water sources and priority pollutants for water quality control, posing a significant threat. In non-ferrous metal smelting and chemical production, especially in the smelting of metals such as copper, lead, zinc, and gold, large quantities of wastewater containing mercury (Hg) and lead (Pb) are generated. Furthermore, in chemical production processes, such as the production of coatings, pharmaceuticals, and cosmetics, mercury, lead, or their compounds may be used as raw materials or preservatives, resulting in mercury and lead-containing wastewater.

[0003] Currently, Hg in water bodies 2+ Pb 2+ Methods for removing mercury and lead include adsorption, chemical reduction, chemical precipitation, ion exchange, solvent extraction, and reverse osmosis. Among these, adsorption is a highly effective method for treating mercury- and lead-containing wastewater due to its simplicity, high efficiency, low cost, environmental friendliness, and ability to achieve deep treatment. In adsorption, the adsorbent material is a key factor affecting the adsorption effect; its morphology, type, and form determine the preparation cost, adsorption process, and adsorption efficiency.

[0004] Existing adsorption materials have limited adsorption capacity for heavy metal ions such as mercury and lead ions, and further optimization of adsorption materials is needed. Summary of the Invention

[0005] To address the issue of existing adsorption materials' ineffective handling of Hg in wastewater... 2+ Pb 2+ To address the problem of low adsorption rate, this invention provides a method for preparing a Sn-S chelated organic composite flocculant and its application.

[0006] The specific technical solution of this invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a Sn-S chelated organic composite flocculant, comprising the following steps:

[0008] Step S1: Disperse dioctyltin dilaurate in a solvent to obtain a dioctyltin dilaurate solution;

[0009] Step S2: Pre-hydrolyze dimercaptosuccinic acid to obtain dimercaptosuccinic acid hydrolysate;

[0010] Step S3: Mix the dioctyltin dilaurate solution with the dimercaptosuccinic acid hydrolysate, sonicate the mixture, stir the reaction to obtain the reaction solution;

[0011] Step S4: Allow the reaction solution to stand and separate into phases, remove the aqueous phase, allow it to stand and mature, purify, and dry to obtain a Sn-S chelated organic composite flocculant.

[0012] This invention uses dioctyltin dilaurate and dimercaptosuccinic acid as raw materials, and utilizes a chelation mechanism to chelate organotin compounds, combining tin and sulfur atoms to form a five-membered ring-shaped organic cyclic framework material, namely the Sn-S chelated organic composite flocculant. When applied to the removal of heavy metals from wastewater, it has excellent effects.

[0013] The Sn-S chelating organic composite flocculant provided by this invention utilizes chelation-dominated chemical bonding, forming stable five-membered ring chelates through covalent bonds. These chelates exhibit high bond energy, strong irreversibility, and a stable organic cyclic framework structure. This Sn-S chelating organic composite flocculant can pre-fix the spatial positions of sulfur atoms within the cyclic framework, enabling them to coordinate with heavy metals in a five-membered ring configuration. This enhances reaction kinetics and binding strength, thus improving the effectiveness against Pb. 2+ Hg 2+ Sn-S chelating organic composite flocculant exhibits excellent affinity for mercury and lead ions in wastewater. After adsorbing these ions, Sn atoms can form stable organometallic complexes through coordination reactions, thereby removing heavy metal ions from the solution with a removal rate exceeding 90%.

[0014] More specifically, in Sn-S chelating organic composite flocculants, the principle behind the removal of mercury and lead ions from wastewater lies in the fact that the octyl (Oct-) and lauric acid residues on tin are hydrophobic, forming a "protective layer" that reduces the attack of water molecules on the Sn-S bond and reduces the coordination competition of impurity ions; Sn 4+ As the central metal, tin preferentially occupies the strong coordination sites of sulfur ligands. However, when encountering heavy metals with stronger affinity, tin can "yield" sulfur atoms to the target heavy metal through ligand substitution mechanisms, while maintaining its own stability. For example, it can be transformed into Sn-OOCR complexes. Sn-S chelating organic composite flocculants can selectively capture the highly toxic heavy metal Pb through dynamic equilibrium. 2+ Hg 2+ .

[0015] Preferably, in step S1, the solvent is a mixture of tetramethylethylenediamine and tetrahydrofuran.

[0016] Using a mixed solvent of tetramethylethylenediamine and tetrahydrofuran as the reaction environment can make the chelation reaction highly reactive.

[0017] Preferably, in step S2, the pre-hydrolysis method is as follows: dissolve dimercaptosuccinic acid in an aqueous ethanol solution and stir.

[0018] Preferably, in step S3, the alkalinity of the mixture is set to 0.5 to 2.0.

[0019] Preferably, in step S3, the stirring speed of the stirring reaction is 200~500 rpm, and the stirring reaction time is 24~48 hours.

[0020] Preferably, in step S4, the settling and ripening time is 20 to 60 hours.

[0021] Preferably, in step S4, the purification method is as follows: add a mixed solution of anhydrous ethanol and acetone, and sonicate for 10-30 minutes.

[0022] Preferably, in step S4, the drying temperature is 140~160℃.

[0023] Secondly, based on the above preparation method, the present invention provides a Sn-S chelated organic composite flocculant.

[0024] Thirdly, based on the above preparation method, this invention provides an application of Sn-S chelated organic composite flocculant in wastewater treatment.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] This invention uses dioctyltin dilaurate and dimercaptosuccinic acid as raw materials, and utilizes a chelation mechanism to chelate organotin compounds, combining tin and sulfur atoms to form a five-membered ring organic cyclic framework material. The chemically bonded covalent bonds form a stable five-membered ring chelate with high bond energy, strong irreversibility of reaction, and stable organic cyclic framework structure, which remains stable even under high salt or acidic conditions (pH≥3), and has a wide range of applications in wastewater treatment.

[0027] The Sn-S chelated organic composite flocculant prepared by the method of this invention can pre-fix the spatial positions of sulfur atoms through a cyclic framework, enabling them to coordinate with heavy metals in a five-membered ring configuration, thereby enhancing reaction kinetics and binding strength, and thus improving the reaction of Pb. 2+ Hg 2+ Sn-S chelating organic composite flocculant exhibits excellent affinity for mercury and lead ions in wastewater. After adsorbing these ions, Sn atoms can form stable organometallic complexes through coordination reactions, thereby removing heavy metal ions from the solution with a removal rate exceeding 90%. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the chelated organic composite flocculant prepared in Example 1.

[0029] Figure 2 The graphs show the removal effects of the flocculants prepared in Examples 1 to 4 and Comparative Examples 1 to 4 on total lead and total mercury in wastewater.

[0030] Figure 3 The graph shows the removal effect of the chelated organic composite flocculant prepared in Example 1 on total lead and total mercury in wastewater under different pH conditions.

[0031] Figure 4 The graph shows the removal effect of the chelated organic composite flocculant prepared in Example 1 on total lead and total mercury in wastewater under different dosage conditions. Detailed Implementation

[0032] The present invention will be further described below with reference to embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0033] This invention provides a method for preparing a Sn-S chelated organic composite flocculant, comprising the following steps:

[0034] Step S1: Disperse dioctyltin dilaurate in a solvent to obtain a dioctyltin dilaurate solution;

[0035] Step S2: Pre-hydrolyze dimercaptosuccinic acid to obtain dimercaptosuccinic acid hydrolysate;

[0036] Step S3: Mix the dioctyltin dilaurate solution with the dimercaptosuccinic acid hydrolysate, sonicate the mixture, stir the reaction to obtain the reaction solution;

[0037] Step S4: Allow the reaction solution to stand and separate into phases, remove the aqueous phase, allow it to stand and mature, purify, and dry to obtain a Sn-S chelated organic composite flocculant.

[0038] This invention uses dioctyltin dilaurate and dimercaptosuccinic acid as raw materials, and utilizes a chelation mechanism to chelate organotin compounds, combining tin and sulfur atoms to form a five-membered ring-shaped organic cyclic framework material, namely the Sn-S chelated organic composite flocculant. When applied to the removal of heavy metals from wastewater, it has excellent effects.

[0039] The Sn-S chelating organic composite flocculant provided by this invention utilizes chelation-dominated chemical bonding, forming stable five-membered ring chelates through covalent bonds. These chelates exhibit high bond energy, strong irreversibility, and a stable organic cyclic framework structure. This Sn-S chelating organic composite flocculant can pre-fix the spatial positions of sulfur atoms within the cyclic framework, enabling them to coordinate with heavy metals in a five-membered ring configuration. This enhances reaction kinetics and binding strength, thus improving the effectiveness against Pb. 2+ Hg 2+ Sn-S chelating organic composite flocculant exhibits excellent affinity for mercury and lead ions in wastewater. After adsorbing these ions, Sn atoms can form stable organometallic complexes through coordination reactions, thereby removing heavy metal ions from the solution with a removal rate exceeding 90%.

[0040] More specifically, in Sn-S chelating organic composite flocculants, the principle behind the removal of mercury and lead ions from wastewater lies in the fact that the octyl (Oct-) and lauric acid residues on tin are hydrophobic, forming a "protective layer" that reduces the attack of water molecules on the Sn-S bond and reduces the coordination competition of impurity ions; Sn 4+ As the central metal, tin preferentially occupies the strong coordination sites of sulfur ligands. However, when encountering heavy metals with stronger affinity, tin can "yield" sulfur atoms to the target heavy metal through ligand substitution mechanisms, while maintaining its own stability. For example, it can be transformed into Sn-OOCR complexes. Sn-S chelating organic composite flocculants can selectively capture the highly toxic heavy metal Pb through dynamic equilibrium. 2+ Hg 2+ .

[0041] In one embodiment, in step S1, the solvent is a mixed solvent of tetramethylethylenediamine and tetrahydrofuran.

[0042] Using a mixed solvent of tetramethylethylenediamine and tetrahydrofuran as the reaction environment can make the chelation reaction highly reactive.

[0043] In one embodiment, in step S2, the pre-hydrolysis method is as follows: dissolve dimercaptosuccinic acid in an aqueous ethanol solution and stir.

[0044] In one embodiment, in step S3, the alkalinity of the mixture is set to 0.5 to 2.0.

[0045] In one embodiment, in step S3, the stirring speed of the stirring reaction is 200~500 rpm, and the stirring reaction time is 24~48 hours.

[0046] In one embodiment, in step S4, the settling and ripening time is 20 to 60 hours.

[0047] In one embodiment, in step S4, the purification method is as follows: add a mixed solution of anhydrous ethanol and acetone, and sonicate for 10-30 minutes.

[0048] In one embodiment, in step S4, the drying temperature is 140~160°C.

[0049] The present invention will now be further described in conjunction with more specific embodiments.

[0050] Example 1

[0051] A chelating organic composite flocculant is provided, which is prepared according to the following steps:

[0052] (1) Mix 0.21g TMEDA and 0.225g THF, then disperse 15g dioctyltin dilaurate in it and stir to obtain a mixed solution of dioctyltin dilaurate.

[0053] (2) Mix 50 mL of water and 100 mL of anhydrous ethanol to obtain a solvent, then dissolve 1.5 g of dimercaptosuccinic acid in the solvent and stir for 1 hour to fully hydrolyze the dimercaptosuccinic acid to obtain a dimercaptosuccinic acid hydrolysate.

[0054] (3) Mix the dioctyltin dilaurate solution from step (1) with the dimercaptosuccinic acid hydrolysate from step (2), and then subject the mixture to ultrasonic treatment for 1 hour. During the ultrasonic treatment, a 1 mg / L NaOH solution is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixture reaches 1.0. The ultrasonic power for the ultrasonic treatment is 150 W. After ultrasonic treatment, the mixture is stirred at 300 rpm at 25°C for 30 hours to ensure complete reaction of the dioctyltin dilaurate and mercapto groups, thus obtaining the reaction solution.

[0055] (4) The reaction solution was allowed to stand and separate into phases. The aqueous phase was removed, and the organic phase was allowed to stand and mature for 30 hours. 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, it was dried at 150℃ and ground to obtain a solid powder, which is a Sn-S chelated organic composite flocculant, denoted as D1. The morphology of the sample was observed by scanning electron microscopy, and the results are shown in the figure. Figure 1 .

[0056] Example 2

[0057] A chelating organic composite flocculant is provided. The preparation steps are the same as in Example 1, except that in step (3), during the ultrasonic treatment, a 1 mg / L NaOH solution is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixture is 0.5. The other steps are the same as in Example 1.

[0058] The Sn-S chelated organic composite flocculant powder prepared in this embodiment is denoted as D2.

[0059] Example 3

[0060] A chelating organic composite flocculant is provided. The preparation steps are the same as those in Example 1, except that in step (3), during the ultrasonic treatment, a 1 mg / L NaOH solution is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixture is 1.5. The other steps are the same as in Example 1.

[0061] The Sn-S chelated organic composite flocculant powder prepared in this embodiment is designated as D3.

[0062] Example 4

[0063] A chelating organic composite flocculant is provided. The preparation steps are the same as in Example 1, except that in step (3), during the ultrasonic treatment, a 1 mg / L NaOH solution is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixture is 2.0. The other steps are the same as in Example 1.

[0064] The Sn-S chelated organic composite flocculant powder prepared in this embodiment is designated as D4.

[0065] Comparative Example 1

[0066] A flocculant is provided, and the preparation steps are the same as those in Example 1, except that ultrasonic treatment is not performed in step (3). The other steps are the same as those in Example 1.

[0067] Step (3) of this comparative example is as follows: the dioctyltin dilaurate solution in step (1) is mixed with the dimercaptosuccinic acid hydrolysate in step (2) and dispersed evenly. Then, a 1 mg / L NaOH solution is added dropwise at a rate of 0.3 mL / min using a constant flow pump until the alkalinity of the mixture is 1.0. The mixture is then stirred at 300 rpm at 25 °C for 30 hours to ensure that the dioctyltin dilaurate and mercapto groups react completely, thus obtaining the reaction solution.

[0068] The flocculant powder prepared in this comparative example is denoted as P1.

[0069] Comparative Example 2

[0070] A flocculant is provided, the preparation steps of which differ from those in Example 1 in that the pre-hydrolysis step of dimercaptosuccinic acid is omitted. All other steps are the same as in Example 1.

[0071] The specific steps for this comparative example are as follows:

[0072] (1) Mix 0.21g TMEDA and 0.225g THF, then disperse 15g dioctyltin dilaurate in it and stir to obtain a mixed solution of dioctyltin dilaurate.

[0073] (2) Add 1.5g of dimercaptosuccinic acid to the dioctyltin dilaurate solution obtained in step (1), disperse evenly to obtain a mixture, and then subject the mixture to ultrasonic treatment for 1 hour at an ultrasonic power of 150W. During the ultrasonic treatment, a 1mg / L NaOH solution is added dropwise at a rate of 0.3mL / min using a constant flow pump until the alkalinity of the mixture reaches 1.0. After ultrasonic treatment, the mixture is stirred at 300rpm at 25°C for 30 hours to ensure complete reaction of the dioctyltin dilaurate and mercapto groups, resulting in a reaction solution.

[0074] (3) The reaction solution was allowed to stand and separate into phases. The aqueous phase was removed, and the organic phase was allowed to stand and mature for 30 hours. 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, it was dried at 150 °C and ground to obtain a solid powder, which is a flocculant, denoted as P2.

[0075] Comparative Example 3

[0076] A flocculant is provided, the preparation steps of which differ from those of Example 1 in that: in step (2), dimercaptosuccinic acid is not added, and 1.5g of mercaptosuccinic acid is added instead of 1.5g of dimercaptosuccinic acid. The other steps are the same as those of Example 1.

[0077] The flocculant powder prepared in this comparative example is denoted as P3.

[0078] Comparative Example 4

[0079] A flocculant is provided: cationic polyacrylamide (PAM-DMC). PAM-DMC is a common composite coagulant in the art and was purchased from Jiangsu Hengfeng Fine Chemical Co., Ltd.

[0080] The flocculant powder provided in this comparative example is designated as P4.

[0081] Performance testing

[0082] [Test 1]

[0083] The combined wastewater (pH=5, total lead 2.73 mg / L, total mercury 2.56 mg / L) generated during the operation of a metal smelter in Quzhou City, Zhejiang Province, was used to test the heavy metal ion removal efficiency of the flocculants provided in Examples 1 to 4 and Comparative Examples 1 to 4. The results are shown in Table 1 and... Figure 2 The test method is as follows: Take 8 portions of 300mL wastewater and add them to a 500mL graduated cylinder. Then add 60mg of the flocculant provided in Examples 1 to 4 and Comparative Examples 1 to 4. Stir at 300rpm for 6 minutes, then stir at 35rpm for 2 minutes. Let stand for 15 minutes, take the supernatant, and determine the total lead and total mercury content.

[0084] Table 1

[0085]

[0086] As shown in Table 1, the Sn-S chelated organic composite flocculant prepared in the examples exhibits excellent removal effects on mercury and lead in wastewater, with removal rates exceeding 90%. In particular, the flocculant prepared in Example 1 achieves removal rates of 98.03% for total lead and 98.77% for total mercury. This demonstrates that the present invention utilizes a chelation mechanism to chelate organotin compounds, combining tin with sulfur atoms to form a five-membered ring-shaped organic cyclic framework material. Applying this to the removal of heavy metals from wastewater demonstrates excellent performance.

[0087] A comparison of the embodiments of the present invention with Comparative Example 4 shows that the Sn-S chelating organic composite flocculant provided by the present invention has a much higher removal rate of total lead and total mercury than the composite coagulant PAM-DMC. The reasons for this are as follows:

[0088] ① Conventional composite coagulant PAM-DMC removes heavy metal ions from wastewater through physical adsorption and charge neutralization mechanisms, resulting in low adsorption efficiency. The Sn-S chelating organic composite flocculant provided by this invention utilizes chelation-dominated chemical bonding, forming stable five-membered ring chelates through covalent bonds. These chelates exhibit high bond energy, strong irreversibility, and a stable organic cyclic framework. The pre-fixed spatial positions of sulfur atoms within the cyclic framework allow them to coordinate with heavy metals in a five-membered ring configuration, thereby enhancing reaction kinetics and binding strength. Therefore, it is highly effective against Pb. 2+ Hg 2+ Its affinity is much higher than that of the coagulant PAM-DMC.

[0089] ② In the Sn-S chelated organic composite flocculant provided by this invention, the sulfur atom pairs with Pb 2+ Hg 2+ It has a high affinity, with each molecule providing two sulfur coordination sites, allowing it to bind more heavy metal ions per unit mass.

[0090] ③ The Sn-S chelating organic composite flocculant provided by this invention forms a dense cyclic chelate structure with high stability; and resists competitive interference through chelation, thus resisting Cl... - SO4 2- It exhibits coordination competition with coexisting ions; at the same time, due to its stable structure, it has a wide pH adaptability, remaining stable in the pH range of 3-10, and is particularly suitable for acidic mercury-containing wastewater.

[0091] ④ Since the Sn-S chelated organic composite flocculant of this invention is a five-membered ring chelate with high bond energy and strong irreversibility of reaction, it can inhibit desorption through strong bonding and will not cause secondary release of heavy metals due to pH fluctuations, water flow shear force or oxidation.

[0092] As can be seen from the comparison between Example 1 of the present invention and Comparative Examples 1, 2 and 3, the Sn-S chelated organic composite flocculant provided by the present invention can only be prepared by dioctyltin dilaurate and dimercaptosuccinic acid in a suitable environment. Among them, ultrasonic treatment, pre-hydrolysis of dimercaptosuccinic acid and thiol raw materials have a significant impact on the performance of the product.

[0093] [Test 2]

[0094] Wastewater from Mining Plants No. 1-8 in Quzhou City, Zhejiang Province, was used to remove heavy metal ions from the wastewater under different pH conditions using the Sn-S chelating organic composite flocculant D1 obtained in Example 1. The heavy metal ion removal efficiency of the Sn-S chelating organic composite flocculant was characterized, and the results are shown in Table 2. Figure 3 The pH, total lead, and total mercury information for wastewater samples 1-8 are as follows: Wastewater 1: pH = 2.33, total lead 2.54 mg / L, total mercury 2.76 mg / L; Wastewater 2: pH = 3.25, total lead 2.48 mg / L, total mercury 2.59 mg / L; Wastewater 3: pH = 4.29, total lead 2.64 mg / L, total mercury 2.81 mg / L; Wastewater 4: pH = 5.18, total lead 3.09 mg / L... Total mercury 2.88 mg / L; Wastewater No. 5 pH=6.42, total lead 2.49 mg / L, total mercury 2.47 mg / L; Wastewater No. 6 pH=7.80, total lead 2.66 mg / L, total mercury 2.70 mg / L; Wastewater No. 7 pH=9.76, total lead 2.76 mg / L, total mercury 2.23 mg / L; Wastewater No. 8 pH=10.59, total lead 1.98 mg / L, total mercury 1.90 mg / L.

[0095] The test method is as follows: Take 300 mL of wastewater No. 1-8 and add it into a 500 mL graduated cylinder. Then add 60 mg of the chelated organic composite flocculant prepared in Example 1. Stir at 300 rpm for 6 minutes, then stir at 35 rpm for 2 minutes. Let it stand for 15 minutes, take the supernatant, and determine the total lead and total mercury content in the supernatant.

[0096] Table 2

[0097]

[0098] As can be seen from Table 2, the optimal pH range for the Sn-S chelated organic composite flocculant provided by this invention is 3.25~9.76.

[0099] [Test 3]

[0100] Wastewater from a metal smelting plant in Quzhou City, Zhejiang Province, was used to remove heavy metal ions from the wastewater using Sn-S chelating organic composite flocculant D1 obtained in Example 1 under different dosage conditions. The heavy metal ion removal efficiency of the Sn-S chelating organic composite flocculant was characterized, and the results are shown in Table 3. Figure 4 The wastewater had a pH of 7.36, total lead of 2.74 mg / L, and total mercury of 2.61 mg / L.

[0101] The test method is as follows: 300 mL of the above wastewater is added to a 500 mL graduated cylinder, and then 15 mg, 30 mg, 45 mg, 60 mg, 75 mg, 90 mg, 105 mg and 120 mg of the chelated organic composite flocculant prepared in Example 1 are added respectively. The mixture is stirred at 300 rpm for 6 minutes, then stirred at 35 rpm for 2 minutes, and allowed to stand for 15 minutes. The supernatant is then taken and the total lead and total mercury content of the supernatant is determined.

[0102] Table 3

[0103]

[0104] As can be seen from Table 3, the optimal dosage of the Sn-S chelated organic composite flocculant provided by this invention is 30-105 mg per 300 mL of wastewater, that is, 10-35 mg per 100 mL of wastewater.

[0105] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a Sn-S chelated organic composite flocculant, characterized in that: Includes the following steps: Step S1: Disperse dioctyltin dilaurate in a solvent to obtain a dioctyltin dilaurate solution; Step S2: Pre-hydrolyze dimercaptosuccinic acid to obtain dimercaptosuccinic acid hydrolysate; Step S3: Mix the dioctyltin dilaurate solution with the dimercaptosuccinic acid hydrolysate, and adjust the alkalinity of the mixture to 0.5~2.

0. Sonicate the mixture and stir the reaction to obtain the reaction solution. Step S4: Allow the reaction solution to stand and separate into phases, remove the aqueous phase, allow it to stand and mature, purify, and dry to obtain a Sn-S chelated organic composite flocculant.

2. The preparation method of the Sn-S chelated organic composite flocculant as described in claim 1, characterized in that: In step S1, the solvent is a mixture of tetramethylethylenediamine and tetrahydrofuran.

3. The preparation method of the Sn-S chelated organic composite flocculant as described in claim 1, characterized in that: In step S2, the pre-hydrolysis method is as follows: dissolve dimercaptosuccinic acid in an aqueous ethanol solution and stir.

4. The preparation method of the Sn-S chelated organic composite flocculant as described in claim 1, characterized in that: In step S3, the stirring speed of the stirring reaction is 200~500 rpm, and the stirring reaction time is 24~48 hours.

5. The preparation method of the Sn-S chelated organic composite flocculant as described in claim 1, characterized in that: In step S4, the settling and ripening time is 20 to 60 hours.

6. The preparation method of the Sn-S chelated organic composite flocculant as described in claim 1, characterized in that: In step S4, the purification method is as follows: add a mixed solution of anhydrous ethanol and acetone, and sonicate for 10-30 minutes.

7. The preparation method of the Sn-S chelated organic composite flocculant as described in claim 1, characterized in that: In step S4, the drying temperature is 140~160℃.

8. The Sn-S chelated organic composite flocculant obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the Sn-S chelated organic composite flocculant obtained by the preparation method according to any one of claims 1 to 7 in wastewater treatment.

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