An organic-inorganic hybrid flocculant, a preparation method and application thereof

Abstract

This invention provides an organic-inorganic hybrid flocculant, its preparation method, and its application, belonging to the field of industrial wastewater treatment technology. The preparation method of the organic-inorganic hybrid flocculant of this invention includes the following steps: mixing acrylamide, an initiator, and an aluminum hydroxide colloidal solution to carry out a polymerization reaction, obtaining a first gel product; mixing the first gel product with water and an aldehyde compound to carry out a Mannich reaction; mixing the resulting product with diethylenetriamine to carry out an amidation reaction, obtaining a second gel product; mixing the second gel product with carbon disulfide and an aqueous solution of sodium hydroxide to carry out a nucleophilic addition reaction; mixing the resulting product with Prussian blue and water to carry out a coordination reaction, obtaining the organic-inorganic hybrid flocculant. The organic-inorganic hybrid flocculant prepared by this invention has excellent adsorption and sedimentation effects on conventional heavy metals such as lead, chromium, and cadmium in wastewater, and also has excellent adsorption and sedimentation effects on thallium.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, specifically relating to an organic-inorganic hybrid flocculant, its preparation method, and its application. Background Technology

[0002] Wastewater containing heavy metals refers to wastewater rich in heavy metals such as lead, chromium, cadmium, and thallium. These heavy metals are stable in the natural environment, difficult to decompose and destroy, and have a certain degree of toxicity. They can enter the human body through the food chain and accumulate in organisms, causing harm to both humans and the environment. Therefore, effectively treating wastewater containing heavy metals to reduce its pollution and harm to the environment has become an urgent problem to be solved in the field of environmental protection.

[0003] Flocculants are chemical substances used to treat water pollution problems. They adsorb and aggregate colloidal particles or metal ions suspended in a liquid, forming larger particles (or flocs), thus promoting the sedimentation of these particles from a stable suspension. Therefore, flocculants have been widely used for water decolorization and turbidity removal, as well as for the coagulation and sedimentation of pollutants in water.

[0004] However, although commonly used flocculants (such as aluminum sulfate, polyacrylamide, and compound Al(OH)3-PAM flocculants) have good effects on coagulation, sedimentation, decolorization and turbidity removal, they are not effective in treating heavy metals in wastewater, especially thallium. Summary of the Invention

[0005] The purpose of this invention is to provide an organic-inorganic hybrid flocculant, its preparation method, and its application. The organic-inorganic hybrid flocculant prepared by this invention not only has excellent adsorption and sedimentation effects on conventional heavy metals such as lead, chromium, and cadmium in wastewater, but also has excellent adsorption and precipitation effects on thallium.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing an organic-inorganic hybrid flocculant, comprising the following steps:

[0008] Provide aluminum hydroxide colloidal solution;

[0009] Acrylamide, an initiator, and the aluminum hydroxide colloidal solution were mixed and subjected to a polymerization reaction to obtain the first gel product.

[0010] The first gel product was mixed with water and an aldehyde compound and subjected to a Mannich reaction. The resulting product was then mixed with diethylenetriamine and subjected to an amidation reaction to obtain the second gel product.

[0011] The second gel product was mixed with an aqueous solution of carbon disulfide and sodium hydroxide to carry out a nucleophilic addition reaction. The resulting product was then mixed with Prussian blue and water to carry out a coordination reaction, thereby obtaining the organic-inorganic hybrid flocculant.

[0012] Preferably, the initiator comprises potassium persulfate and sodium bisulfite; the mass ratio of potassium persulfate to acrylamide is 0.6~0.8:100; the mass ratio of sodium bisulfite to acrylamide is 0.3~0.5:100; the polymerization reaction is carried out in an inert atmosphere; the polymerization reaction temperature is 40~55℃ and the time is 1~2h.

[0013] Preferably, the aldehyde compound includes at least one of formaldehyde, acetaldehyde, propionaldehyde, cinnamaldehyde, and vanillin; the mass ratio of the aldehyde compound to acrylamide is 29~32:100; the Mannich reaction is carried out at a temperature of 45~55℃ for 1~2 hours.

[0014] Preferably, the mass ratio of diethylenetriamine to acrylamide is 31~34:100; the amidation reaction is carried out at a temperature of 45~55℃ for 2~4 hours.

[0015] Preferably, the mass ratio of carbon disulfide to acrylamide is 65~68:100; the mass percentage concentration of the sodium hydroxide aqueous solution is 20~30%; the volume ratio of the sodium hydroxide aqueous solution to carbon disulfide is 2~2.5:0.8~1; and the temperature of the nucleophilic addition reaction is 20~30℃, and the time is 4~6h.

[0016] Preferably, the mass ratio of Prussian blue to acrylamide is 35-40:100; the coordination reaction is carried out at a temperature of 50-60°C for 2-3 hours.

[0017] The present invention provides an organic-inorganic hybrid flocculant prepared by the preparation method described above, comprising an inorganic component and an organic component coated on the surface of the inorganic component; the organic component comprises acrylamide, diethylenetriamine and organic intermediates; the inorganic component comprises aluminum salt and Prussian blue.

[0018] This invention provides the application of the organic-inorganic hybrid flocculant described in the above technical solution in the treatment of wastewater containing heavy metals.

[0019] Preferably, the heavy metal elements in the heavy metal-containing wastewater include at least one of Tl, Pb, Cr, Hg, Cd, Cu, and Zn; in the heavy metal-containing wastewater, the concentration of Tl is 1~2 mg / L; the concentration of Pb is 1~20 mg / L; the concentration of Cr is 1~10 mg / L; the concentration of Hg is 1~2 mg / L; the concentration of Cd is 1~3 mg / L; the concentration of Cu is 1~20 mg / L; and the concentration of Zn is 1~20 mg / L.

[0020] Preferably, the heavy metal-containing wastewater also includes As; the concentration of As in the heavy metal-containing wastewater is 1~3 mg / L.

[0021] This invention provides a method for preparing an organic-inorganic hybrid flocculant, comprising the following steps: providing an aluminum hydroxide colloidal solution; mixing acrylamide, an initiator, and the aluminum hydroxide colloidal solution to perform a polymerization reaction to obtain a first gel product; mixing the first gel product with water and an aldehyde compound to perform a Mannich reaction; mixing the resulting product with diethylenetriamine to perform an amidation reaction to obtain a second gel product; mixing the second gel product with carbon disulfide and an aqueous solution of sodium hydroxide to perform a nucleophilic addition reaction; mixing the resulting product with Prussian blue and water to perform a coordination reaction to obtain the organic-inorganic hybrid flocculant. This invention uses acrylamide and aluminum hydroxide colloid as raw materials, and a polymerization reaction is carried out under the action of an initiator to prepare a first gel. The first gel is an aluminum hydroxide-polyacrylamide flocculant with a hybrid structure and a structure similar to nerve cell fibers. Specifically, it has an inorganic aluminum hydroxide core, and organic molecules are wrapped around the core. This increases the distance between multiple groups, thereby reducing steric hindrance and mismatch effects, and improving the adsorption capacity of the obtained aluminum hydroxide-polyacrylamide flocculant. This invention prepares a dithiocarbamic acid chelating functional group by adding diethylenetriamine and carbon disulfide. The function of this dithiocarbamic acid chelating functional group is to separate heavy metal ions. This invention introduces the dithiocarbamic acid chelating functional group into the intermediate product, aluminum hydroxide-polyacrylamide flocculant. The presence of the aluminum hydroxide-polyacrylamide flocculant gives the organic-inorganic hybrid flocculant excellent flocculation ability. Based on this, the introduced dithiocarbamic acid chelating functional group can achieve efficient separation of heavy metal ions. The organic-inorganic hybrid flocculant prepared by this invention is a novel hybrid material with high molecular weight, effectively improving the flocculation effect. It not only has excellent adsorption and sedimentation effects on conventional heavy metals such as lead, chromium, and cadmium in wastewater, removing conventional heavy metal elements from wastewater to the first-class standard for integrated wastewater discharge (GB8978-1996), but also has excellent adsorption and precipitation effects on thallium.

[0022] Furthermore, this invention employs in-situ polymerization to initiate the polymerization of acrylamide in an inorganic sol, achieving a uniform hybridization of inorganic and organic components. Based on this, an organic-inorganic hybrid flocculant with a uniformly dispersed organic component encapsulating the inorganic component is synthesized, exhibiting a structure similar to nerve cell fibers. The organic-inorganic hybrid flocculant prepared by this invention demonstrates excellent adsorption and sedimentation effects on heavy metals and heavy metal-like elements (such as arsenic), and also exhibits good coagulation and sedimentation effects on suspended solids in wastewater.

[0023] Furthermore, the organic-inorganic hybrid flocculant of the present invention exhibits the characteristics of large flocs and fast sedimentation speed, high reagent utilization rate, and effective cost saving. Detailed Implementation

[0024] This invention provides a method for preparing an organic-inorganic hybrid flocculant, comprising the following steps:

[0025] Provide aluminum hydroxide colloidal solution;

[0026] Acrylamide, an initiator, and the aluminum hydroxide colloidal solution were mixed and subjected to a polymerization reaction to obtain the first gel product.

[0027] The first gel product was mixed with water and an aldehyde compound and subjected to a Mannich reaction. The resulting product was then mixed with diethylenetriamine and subjected to an amidation reaction to obtain the second gel product.

[0028] The second gel product was mixed with an aqueous solution of carbon disulfide and sodium hydroxide to carry out a nucleophilic addition reaction. The resulting product was then mixed with Prussian blue and water to carry out a coordination reaction, thereby obtaining the organic-inorganic hybrid flocculant.

[0029] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0030] In this invention, the preparation method of the aluminum hydroxide colloidal solution may include the following steps: mixing a soluble ammonium salt, a soluble aluminum salt, and water, and then reacting them to obtain the aluminum hydroxide colloidal solution. In this invention, the soluble ammonium salt may include ammonium carbonate or ammonium bicarbonate; the soluble aluminum salt may include aluminum chloride or aluminum sulfate. The mass ratio of the soluble ammonium salt to the soluble aluminum salt in this invention may be 80-90:100; in specific embodiments of this invention, the mass ratio of the soluble ammonium salt to the soluble aluminum salt is 80:100, 85:100, or 90:100. The mass ratio of the total mass of the soluble ammonium salt and the soluble aluminum salt to the mass of acrylamide in this invention may be 60-70:100; in specific embodiments of this invention, the mass ratio of the total mass of the soluble ammonium salt and the soluble aluminum salt to the mass of acrylamide is 60:100, 65:100, or 70:100. In this invention, specifically, an aqueous solution of a soluble ammonium salt is added dropwise to an aqueous solution of a soluble aluminum salt, and an aluminum hydroxide colloidal solution is obtained after the reaction. The mass percentage concentration of the aqueous solution of the soluble ammonium salt in this invention can be 10%~20%; in specific embodiments of this invention, the mass percentage concentration of the aqueous solution of the soluble ammonium salt is 10%, 15%, or 20%. The mass percentage concentration of the aqueous solution of the soluble aluminum salt in this invention can be 5%~10%; in specific embodiments of this invention, the mass percentage concentration of the aqueous solution of the soluble aluminum salt is 5%, 8%, or 10%. The volume ratio of the aqueous solution of the soluble ammonium salt to the aqueous solution of the soluble aluminum salt in this invention can be 1:2. In this invention, the reaction temperature can be 25~35℃, and the reaction time can be 0.5~1.5h; in specific embodiments of this invention, the reaction temperature is 25℃, 30℃, or 35℃, and the reaction time is 0.5h, 1h, or 1.5h.

[0031] After obtaining an aluminum hydroxide colloidal solution, the present invention mixes acrylamide, an initiator, and the aluminum hydroxide colloidal solution to carry out a polymerization reaction to obtain a first gel product. In the present invention, the initiator may include potassium persulfate and sodium bisulfite; the mass ratio of potassium persulfate to acrylamide may be 0.6~0.8:100; the mass ratio of sodium bisulfite to acrylamide may be 0.3~0.5:100. In specific embodiments of the present invention, the mass ratio of potassium persulfate to acrylamide is 0.6:100, 0.7:100, or 0.8:100; the mass ratio of sodium bisulfite to acrylamide is 0.3:100, 0.4:100, or 0.5:100. Specifically, in the present invention, acrylamide is mixed with the aluminum hydroxide colloidal solution and pretreated to obtain a mixed solution; an aqueous solution of the initiator is added to the mixed solution to carry out a polymerization reaction. In the present invention, the polymerization reaction can be carried out in an inert atmosphere; the inert atmosphere may include at least one of nitrogen, helium, and argon atmospheres. In this invention, the pretreatment is carried out under water bath conditions; the pretreatment temperature can be 40~55℃, and the time can be 0.5~1.5h. In specific embodiments of this invention, the pretreatment temperature is 40℃, 45℃, 50℃, or 55℃; the time is 0.5h, 1h, or 1.5h. Before carrying out the polymerization reaction, an inert gas is introduced into the system containing the mixed liquid to remove oxygen, facilitating the subsequent reaction. In this invention, the aqueous solution of the initiator may include an aqueous solution of potassium persulfate and an aqueous solution of sodium bisulfite; the mass percentage concentration of the potassium persulfate aqueous solution can be 1.9~2.4%, and the mass percentage concentration of the sodium bisulfite aqueous solution can be 1~1.5%. In specific embodiments of this invention, the mass percentage concentration of the potassium persulfate aqueous solution is 1.9%, 2%, or 2.4%; the mass percentage concentration of the sodium bisulfite aqueous solution is 1%, 1.06%, or 1.5%. The volume ratio of the potassium persulfate aqueous solution and the sodium bisulfite aqueous solution in this invention can be 1:1. The polymerization reaction temperature of this invention can be 40-55℃, and the time can be 1-2 hours. In a specific embodiment of this invention, the polymerization reaction temperature is 40℃, 45℃, 50℃, or 55℃; the time is 1 hour, 1.5 hours, or 2 hours; and the polymerization reaction temperature is the same as the pretreatment temperature. After the polymerization reaction is completed, the resulting reaction solution can be aged to obtain an aged gel; the aged gel is added to acetone for extraction and precipitation to obtain a first gel product. In this invention, the aging is carried out under closed conditions; the aging temperature can be 25-35℃, and the time can be 3-5 hours. In a specific embodiment of this invention, the aging temperature is 25℃, 30℃, or 35℃; and the time is 3 hours, 4 hours, or 5 hours.

[0032] After obtaining the first gel product, the present invention mixes the first gel product with water and an aldehyde compound, and performs a Mannich reaction to obtain a gel intermediate. In a specific embodiment of the present invention, the first gel product is mixed with water to obtain an aqueous solution of the first gel product; the aqueous solution of the first gel product is then mixed with an aldehyde compound to perform a Mannich reaction to obtain a solution containing the gel intermediate. In the present invention, the mass percentage concentration of the aqueous solution of the first gel product can be 0.5% to 1.5%; in a specific embodiment of the present invention, the mass percentage concentration of the aqueous solution of the first gel product is 0.5%, 1%, or 1.5%. Before mixing the aqueous solution of the first gel product with the aldehyde compound, the present invention can adjust the pH value of the aqueous solution of the first gel product to 7 to 9. In a specific embodiment of the present invention, the pH value of the aqueous solution of the first gel product can be adjusted to 7, 8, or 9. In the present invention, the reagent used to adjust the pH value can be an aqueous solution of sodium hydroxide. In the present invention, the aldehyde compound can include at least one of formaldehyde, acetaldehyde, propionaldehyde, cinnamaldehyde, and vanillin; the mass ratio of the aldehyde compound to acrylamide can be 29 to 32:100. In specific embodiments of the present invention, the aldehyde compound can be formaldehyde, acetaldehyde, propionaldehyde, cinnamaldehyde, or vanillin. The mass ratio of the aldehyde compound to acrylamide in the present invention is 29:100, 30:100, 31:100, or 32:100. In specific embodiments of the present invention, the Mannich reaction can be carried out under water bath conditions; the temperature of the Mannich reaction can be 45-55°C, and the time can be 1-2 hours. In specific embodiments of the present invention, the temperature of the Mannich reaction is 45°C, 50°C, or 55°C; and the time is 1 hour, 1.5 hours, or 2 hours. After obtaining the solution containing the gel intermediate, the present invention can proceed with subsequent operations without post-processing.

[0033] After obtaining the gel intermediate, the present invention mixes the gel intermediate with diethylenetriamine and performs an amidation reaction to obtain a second gel product. In a specific embodiment of the present invention, the solution containing the gel intermediate is mixed with diethylenetriamine and subjected to an amidation reaction to obtain a solution containing the second gel product. In the present invention, the mass ratio of diethylenetriamine to acrylamide can be 31~34:100. In a specific embodiment of the present invention, the mass ratio of diethylenetriamine to acrylamide is 31:100, 32:100, 33:100, or 34:100. In the present invention, the amidation reaction can be carried out under water bath conditions; the temperature of the amidation reaction can be 45~55℃, and the time can be 1~2h. In a specific embodiment of the present invention, the temperature of the amidation reaction is 45℃, 50℃, or 55℃; and the time is 1h, 1.5h, or 2h.

[0034] After obtaining the second gel product, the present invention mixes the second gel product with carbon disulfide and an aqueous solution of sodium hydroxide to perform a nucleophilic addition reaction, thereby obtaining a nucleophilic addition gel product. In the present invention, the mass percentage concentration of the aqueous solution of sodium hydroxide can be 20-30%; in a specific embodiment of the present invention, the mass percentage concentration of the aqueous solution of sodium hydroxide is 25%. The volume ratio of the aqueous solution of sodium hydroxide to carbon disulfide in the present invention can be 2-2.5:0.8-1; in a specific embodiment of the present invention, the volume ratio of the aqueous solution of sodium hydroxide to carbon disulfide is 2:1. In a specific embodiment of the present invention, the solution containing the second gel product is mixed with an aqueous solution of sodium hydroxide, and then carbon disulfide is added to the resulting mixture to perform a nucleophilic addition reaction, thereby obtaining a solution containing the nucleophilic addition gel product. In the present invention, the mass ratio of carbon disulfide to acrylamide can be 65-68:100. In a specific embodiment of the present invention, the mass ratio of carbon disulfide to acrylamide is 65:100, 66:100, 67:100, or 68:100. The nucleophilic addition reaction described in this invention can be carried out at a temperature of 20-30°C for 4-6 hours. In specific embodiments of this invention, the temperature of the nucleophilic addition reaction is 20°C, 25°C, or 30°C; and the time is 4 hours, 5 hours, or 6 hours. In this invention, the sodium hydroxide aqueous solution can create an alkaline environment, promoting the breaking of NH bonds and providing substitution sites for the subsequently added CS2.

[0035] After obtaining the nucleophilic addition reaction gel product, the present invention mixes the nucleophilic addition reaction gel product with Prussian blue and water to carry out a coordination reaction to obtain the organic-inorganic hybrid flocculant. In the present invention, the mass ratio of Prussian blue to acrylamide can be 35-40:100; in specific embodiments of the present invention, the mass ratio of Prussian blue to acrylamide is 35:100, 38:100, or 40:100. In specific embodiments of the present invention, the solution containing the nucleophilic addition reaction gel product is mixed with an aqueous solution of Prussian blue to carry out a coordination reaction. In the present invention, the mass percentage concentration of the aqueous solution of Prussian blue can be 20%. The temperature of the coordination reaction in the present invention can be 50-60°C, and the time can be 2-3 hours. In specific embodiments of the present invention, the temperature of the coordination reaction is 50°C, 55°C, or 60°C; and the time is 2 hours, 2.5 hours, or 3 hours. After the coordination reaction is completed, the resulting reaction solution can be added to acetone for extraction and precipitation to obtain a flocculant colloid. The flocculant colloid is then dried and ground sequentially to obtain the organic-inorganic hybrid flocculant. In this invention, Prussian blue can be dispersed in a gel for the adsorption of thallium.

[0036] This invention also provides an organic-inorganic hybrid flocculant prepared by the method described above, comprising an inorganic component and an organic component coated on the surface of the inorganic component; the organic component includes acrylamide, diethylenetriamine, and organic intermediates; the inorganic component includes aluminum salts and Prussian blue. The organic-inorganic hybrid flocculant of this invention is a light blue solid powder.

[0037] This invention also provides the application of the organic-inorganic hybrid flocculant described in the above-mentioned technical solution in the treatment of heavy metal-containing wastewater. In this invention, the heavy metal elements in the heavy metal-containing wastewater may include at least one selected from Tl, Pb, Cr, Hg, Cd, Cu, and Zn. In this invention, the concentration of Tl in the heavy metal-containing wastewater can be 1-2 mg / L; in a specific embodiment of this invention, the concentration of Tl in the heavy metal-containing wastewater is 1.05 mg / L. In this invention, the concentration of Pb in the heavy metal-containing wastewater can be 1-20 mg / L; in a specific embodiment of this invention, the concentration of Pb in the heavy metal-containing wastewater is 11.50 mg / L. In this invention, the concentration of Cr in the heavy metal-containing wastewater can be 1-10 mg / L; in a specific embodiment of this invention, the concentration of Cr in the heavy metal-containing wastewater is 6.70 mg / L. In the wastewater containing heavy metals, the concentration of Hg can be 1-2 mg / L; in a specific embodiment of the invention, the concentration of Hg in the wastewater containing heavy metals is 1.25 mg / L. In the wastewater containing heavy metals, the concentration of Cd can be 1-3 mg / L; in a specific embodiment of the invention, the concentration of Cd in the wastewater containing heavy metals is 2.50 mg / L. In the wastewater containing heavy metals, the concentration of Cu can be 1-20 mg / L; in a specific embodiment of the invention, the concentration of Cu in the wastewater containing heavy metals is 15.00 mg / L. In the wastewater containing heavy metals, the concentration of Zn can be 1-20 mg / L; in a specific embodiment of the invention, the concentration of Zn in the wastewater containing heavy metals is 14.62 mg / L. In this invention, the wastewater containing heavy metals may also include heavy metal-like elements, which may include As. In the heavy metal-containing wastewater described in this invention, the concentration of As can be 1~3 mg / L; in a specific embodiment of this invention, the concentration of As in the heavy metal-containing wastewater is 2.10 mg / L. The organic-inorganic hybrid flocculant prepared by this invention has good adsorption and sedimentation effects on heavy metal elements (such as thallium, lead, chromium, cadmium, etc.) and heavy metal-like elements (such as As), and also has good coagulation and sedimentation effects on suspended solids in wastewater.

[0038] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] Example 1

[0040] 10 mL of ammonium carbonate aqueous solution (15% by mass) was added dropwise to 20 mL of aluminum chloride aqueous solution (8% by mass), and the mixture was reacted at 30 °C for 1 h to obtain an aluminum hydroxide colloidal solution.

[0041] 5g of acrylamide was added to the aluminum hydroxide colloidal solution, and the mixture was incubated in a constant temperature water bath at 45°C for 0.5h to obtain a mixed solution. Nitrogen gas was bubbled into the mixed solution to remove oxygen, and under nitrogen protection, 1.5mL of potassium persulfate aqueous solution (2% by mass) and 1.5mL of sodium bisulfite aqueous solution (1% by mass) were added. The polymerization reaction was carried out in a constant temperature water bath at 45°C for 1h. After the reaction, the resulting reaction solution was sealed and aged at 25°C for 3h to obtain an aged gel. The aged gel was added dropwise to acetone for extraction and precipitation to obtain the first gel product.

[0042] The first gel product was mixed with pure water to prepare an aqueous solution with a mass percentage concentration of 0.5%. Sodium hydroxide was added to the aqueous solution to adjust the pH to 7, and then 1.45 mL of formaldehyde was added dropwise. The reaction was carried out in a constant temperature water bath at 45°C for 1 hour. After the reaction was completed, a solution containing the gel intermediate was obtained.

[0043] 1.55 mL of diethylenetriamine was added to the solution containing the gel intermediate, and the reaction was carried out in a constant temperature water bath at 45 °C for 2 h. After the reaction was completed, a solution containing the second gel product was obtained.

[0044] Add 6.5 mL of sodium hydroxide aqueous solution (25% by mass) to the solution containing the second gel product, then add 3.25 mL of carbon disulfide to the resulting mixture, and carry out a nucleophilic addition reaction for 4 h in a constant temperature water bath at 20 °C to obtain a solution containing the nucleophilic addition reaction gel product.

[0045] 8.75 mL of Prussian blue aqueous solution (20% by mass) was added to the solution containing the nucleophilic addition reaction gel product. The mixture was reacted in a constant temperature water bath at 50 °C for 2 hours. After the reaction, the resulting solution was added dropwise to acetone for extraction and precipitation to obtain a flocculant colloid. The flocculant colloid was then dried and ground sequentially to obtain an organic-inorganic hybrid flocculant (pale blue solid powder).

[0046] Test Example 1

[0047] The wastewater used in the test case was thallium-containing heavy metal wastewater from a smelter, and the water quality is shown in Table 1.

[0048] Table 1. Component content of thallium-containing heavy metal wastewater

[0049]

[0050] Take 1000 mL of thallium-containing wastewater and add 500 mg of the organic-inorganic hybrid flocculant prepared in Example 1. Stir for 15 min and then let stand for 0.5 h. After standing, the water body can be clearly divided into layers, with the upper layer of water being significantly clear and the lower layer containing flocculated sediment. The upper layer of water was tested, and the results are shown in Table 2.

[0051] Example 2

[0052] 10 mL of ammonium carbonate aqueous solution (15% by mass) was added dropwise to 20 mL of aluminum chloride aqueous solution (8% by mass), and the mixture was reacted at 30 °C for 1 h to obtain an aluminum hydroxide colloidal solution.

[0053] 4.77 g of acrylamide was added to the aluminum hydroxide colloidal solution, and the mixture was kept in a constant temperature water bath at 50 °C for 1 h to obtain a mixed solution. Helium gas was bubbled into the mixed solution to remove oxygen, and under helium protection, 1.8 mL of potassium persulfate aqueous solution (1.9% by mass) and 1.8 mL of sodium bisulfite aqueous solution (1.06% by mass) were added to the mixed solution. The polymerization reaction was carried out in a constant temperature water bath at 50 °C for 1.5 h. After the reaction, the resulting reaction solution was sealed and aged at 30 °C for 4 h to obtain an aged gel. The aged gel was added dropwise to acetone for extraction and precipitation to obtain the first gel product.

[0054] The first gel product was mixed with pure water to prepare an aqueous solution with a mass percentage concentration of 1%. Sodium hydroxide was added to the aqueous solution to adjust the pH to 8, and then 1.43 mL of formaldehyde was added dropwise. The reaction was carried out in a constant temperature water bath at 50°C for 1.5 h. After the reaction was completed, a solution containing the gel intermediate was obtained.

[0055] 1.53 mL of diethylenetriamine was added to the solution containing the gel intermediate, and the reaction was carried out in a constant temperature water bath at 50 °C for 3 h. After the reaction was completed, a solution containing the second gel product was obtained.

[0056] Add 6.3 mL of sodium hydroxide aqueous solution (25% by mass) to the solution containing the second gel product, then add 3.15 mL of carbon disulfide to the resulting mixture, and carry out a nucleophilic addition reaction for 5 h in a constant temperature water bath at 25 °C to obtain a solution containing the nucleophilic addition reaction gel product.

[0057] 8.85 mL of Prussian blue aqueous solution (20% by mass) was added to the solution containing the nucleophilic addition reaction product gel. The mixture was reacted in a constant temperature water bath at 55 °C for 2.5 h. After the reaction, the resulting solution was added dropwise to acetone for extraction and precipitation to obtain a flocculant colloid. The flocculant colloid was then dried and ground sequentially to obtain an organic-inorganic hybrid flocculant (pale blue solid powder).

[0058] Test Example 2

[0059] The organic-inorganic hybrid flocculant prepared in Example 1 was replaced with the organic-inorganic hybrid flocculant prepared in Example 2, and the performance of the organic-inorganic hybrid flocculant was tested according to the conditions of Test Example 1. The results are shown in Table 2.

[0060] Example 3

[0061] 10 mL of ammonium carbonate aqueous solution (20% by mass) was added dropwise to 20 mL of aluminum chloride aqueous solution (10% by mass), and the reaction was carried out at 30 °C for 1 h to obtain aluminum hydroxide colloidal solution.

[0062] 5.4 g of acrylamide was added to the aluminum hydroxide colloidal solution, and the mixture was incubated in a constant temperature water bath at 55°C for 1.5 h to obtain a mixed solution. Helium gas was bubbled into the mixed solution to remove oxygen, and under helium protection, 1.8 mL of potassium persulfate aqueous solution (2.4% by mass) and 1.8 mL of sodium bisulfite aqueous solution (1.5% by mass) were added to the mixed solution. The polymerization reaction was carried out in a constant temperature water bath at 55°C for 2 h. After the reaction, the resulting reaction solution was sealed and aged at 35°C for 5 h to obtain an aged gel. The aged gel was added dropwise to acetone for extraction and precipitation to obtain the first gel product.

[0063] The first gel product was mixed with pure water to prepare an aqueous solution with a mass percentage concentration of 1.5%. Sodium hydroxide was added to the aqueous solution to adjust the pH to 9, and then 1.72 mL of formaldehyde was added dropwise. The reaction was carried out in a constant temperature water bath at 55°C for 2 hours. After the reaction was completed, a solution containing the gel intermediate was obtained.

[0064] 1.83 mL of diethylenetriamine was added to the solution containing the gel intermediate, and the reaction was carried out in a constant temperature water bath at 55 °C for 4 h. After the reaction was completed, a solution containing the second gel product was obtained.

[0065] 7.3 mL of sodium hydroxide aqueous solution (25% by mass) was added to the solution containing the second gel product, and then 3.67 mL of carbon disulfide was added to the resulting mixture. The nucleophilic addition reaction was carried out for 6 hours under constant temperature water bath at 30°C to obtain a solution containing the nucleophilic addition reaction gel product.

[0066] 10.8 mL of Prussian blue aqueous solution (20% by mass) was added to the solution containing the nucleophilic addition reaction gel product. The mixture was reacted in a constant temperature water bath at 60°C for 3 hours. After the reaction, the resulting solution was added dropwise to acetone for extraction and precipitation to obtain a flocculant colloid. The flocculant colloid was then dried and ground sequentially to obtain an organic-inorganic hybrid flocculant (pale blue solid powder).

[0067] Test Example 3

[0068] The organic-inorganic hybrid flocculant prepared in Example 1 was replaced with the organic-inorganic hybrid flocculant prepared in Example 3, and the performance of the organic-inorganic hybrid flocculant was tested according to the conditions of Test Example 1. The results are shown in Table 2.

[0069] Comparative Example 1

[0070] An organic-inorganic hybrid flocculant was prepared according to the method and conditions of Example 1, except that Prussian blue was not added.

[0071] Comparative Test Example 1

[0072] The organic-inorganic hybrid flocculant prepared in Example 1 was replaced with the organic-inorganic hybrid flocculant prepared in Comparative Example 1, and the performance of the organic-inorganic hybrid flocculant was tested according to the conditions of Test Example 1. The results are shown in Table 2.

[0073] Comparative Test Example 2

[0074] The organic-inorganic hybrid flocculant prepared in Example 1 was replaced with a compound Al(OH)3-PAM flocculant (laboratory compounding), and the performance of the organic-inorganic hybrid flocculant was tested according to the conditions of Test Example 1. The results are shown in Table 2.

[0075] Table 2. Removal effects of different organic-inorganic hybrid flocculants on heavy metals and heavy metal elements in wastewater.

[0076]

[0077] Table 2 shows that the Prussian blue-free organic-inorganic hybrid flocculant prepared in Comparative Example 1 did not selectively adsorb thallium in wastewater. The compound Al(OH)3-PAM flocculant had a good coagulation and sedimentation effect on suspended solids in wastewater, but its removal effect on heavy metals and heavy metal-like substances was poor. In contrast, the organic-inorganic hybrid flocculants prepared in Examples 1-3 of this invention showed excellent treatment effects on both heavy metals and heavy metal-like substances in wastewater, while also exhibiting good coagulation and sedimentation effects. They effectively removed suspended solids from wastewater, and all elements in the wastewater met the Class I discharge standard of the "Integrated Wastewater Discharge Standard" (GB 8978-1996), with thallium meeting the "Industrial Wastewater Thallium Pollutant Discharge Standard" (DB36T1149-2019).

[0078] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing an organic-inorganic hybrid flocculant, characterized in that, Includes the following steps: Provide aluminum hydroxide colloidal solution; Acrylamide, an initiator, and the aluminum hydroxide colloidal solution were mixed and subjected to a polymerization reaction to obtain the first gel product. The first gel was mixed with water and an aldehyde compound and subjected to a Mannich reaction. The resulting product was then mixed with diethylenetriamine and subjected to an amidation reaction to obtain the second gel product. The second gel product was mixed with an aqueous solution of carbon disulfide and sodium hydroxide to carry out a nucleophilic addition reaction. The resulting product was then mixed with Prussian blue and water to carry out a coordination reaction, thereby obtaining the organic-inorganic hybrid flocculant.

2. The preparation method according to claim 1, characterized in that, The initiator includes potassium persulfate and sodium bisulfite; the mass ratio of potassium persulfate to acrylamide is 0.6~0.8:100; the mass ratio of sodium bisulfite to acrylamide is 0.3~0.5:100; the polymerization reaction is carried out in an inert atmosphere; the polymerization reaction temperature is 40~55℃ and the time is 1~2h.

3. The preparation method according to claim 1, characterized in that, The aldehyde compound includes at least one of formaldehyde, acetaldehyde, propionaldehyde, cinnamaldehyde, and vanillin; the mass ratio of the aldehyde compound to acrylamide is 29~32:100; the Mannich reaction is carried out at a temperature of 45~55℃ for 1~2 hours.

4. The preparation method according to claim 1, characterized in that, The mass ratio of diethylenetriamine to acrylamide is 31~34:100; the amidation reaction is carried out at a temperature of 45~55℃ for 2~4 hours.

5. The preparation method according to claim 1, characterized in that, The mass ratio of carbon disulfide to acrylamide is 65~68:100; the mass percentage concentration of the sodium hydroxide aqueous solution is 20~30%, and the volume ratio of the sodium hydroxide aqueous solution to carbon disulfide is 2~2.5:0.8~1; the temperature of the nucleophilic addition reaction is 20~30℃, and the time is 4~6h.

6. The preparation method according to claim 1, characterized in that, The mass ratio of Prussian blue to acrylamide is 35-40:100; the coordination reaction is carried out at a temperature of 50-60°C for 2-3 hours.

7. The organic-inorganic hybrid flocculant obtained by the preparation method according to any one of claims 1 to 6 comprises an inorganic component and an organic component coated on the surface of the inorganic component; the organic component comprises acrylamide, diethylenetriamine and organic intermediates; the inorganic component comprises aluminum salt and Prussian blue.

8. The application of the organic-inorganic hybrid flocculant of claim 7 in the treatment of wastewater containing heavy metals.

9. The application according to claim 8, characterized in that, The heavy metal elements in the heavy metal-containing wastewater include at least one of Tl, Pb, Cr, Hg, Cd, Cu, and Zn; the concentration of Tl in the heavy metal-containing wastewater is 1~2 mg / L; the concentration of Pb is 1~20 mg / L; the concentration of Cr is 1~10 mg / L; the concentration of Hg is 1~2 mg / L; the concentration of Cd is 1~3 mg / L; the concentration of Cu is 1~20 mg / L; and the concentration of Zn is 1~20 mg / L.

10. The application according to claim 8 or 9, wherein the heavy metal-containing wastewater further includes As; and the concentration of As in the heavy metal-containing wastewater is 1~3 mg / L.

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