A method for preparing a flocculant and its application

Abstract

This invention provides a method for preparing a flocculant and its application. The method includes the following steps: 1) dissolving a first monomer, a second monomer, and a third monomer in water, removing oxygen, to obtain a monomer aqueous solution; 2) adding an initiator to the monomer aqueous solution, reacting to obtain a reactant; 3) washing the reactant to remove any unreacted initiator, drying, and pulverizing to obtain the flocculant; wherein the first monomer is polyaluminum chloride, the second monomer is methacryloyloxyethyltrimethylammonium chloride and / or acrylamidopropyltrimethylammonium chloride, and the third monomer is acrylamide.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and in particular to a method for preparing a flocculant. Background Technology

[0002] With the continuous development of my country's industry, the petroleum industry, as one of its pillar industries, has been developing rapidly in recent years. However, with the continuous extraction of oil and gas, the country's environmental protection requirements are becoming increasingly stringent, and the treatment of oily wastewater has attracted more and more attention. If this oily wastewater is not properly treated, it will result in extremely low water resource utilization efficiency and cause great harm to the environment.

[0003] Conventional water treatment processes require the addition of chemical additives, typically flocculants. Currently, commonly used flocculants are broadly classified into inorganic and organic flocculants. Traditional inorganic coagulants are mainly composed of aluminum and iron salts and their hydrolyzed polymers. They are used in large quantities, resulting in a large amount of sludge, colored effluent, and some corrosivity to equipment, easily causing secondary pollution. Furthermore, their molecular weight and flocculation bridging ability are significantly inferior to organic flocculants. While commonly used organic polymeric flocculants require smaller dosages and settle quickly, they are expensive, have limited applicability and effectiveness when used alone, and possess some biotoxicity, limiting their applicability. Moreover, existing reports on flocculants primarily target oil or suspended solids in oily wastewater, and their overall effectiveness in treating oily wastewater remains unsatisfactory. In water with high mineralization, the treatment effect is even more difficult to meet on-site construction and discharge requirements.

[0004] Therefore, there is still considerable room for improvement and enhancement in the technology and performance of flocculants. Summary of the Invention

[0005] One aspect of the present invention provides a method for preparing a flocculant, comprising the following steps:

[0006] 1) Dissolve the first monomer, the second monomer, and the third monomer in water, remove oxygen, and obtain an aqueous solution of monomers;

[0007] 2) The initiator is added to the aqueous solution of the monomer, and the reactants are obtained after the reaction.

[0008] 3) Wash the unreacted initiator from the reactants, dry, and pulverize to obtain the flocculant;

[0009] Wherein, the first monomer is polyaluminum chloride, the second monomer is methacryloyloxyethyltrimethylammonium chloride and / or acrylamidopropyltrimethylammonium chloride, and the third monomer is acrylamide.

[0010] In one specific embodiment, the mass content of the first monomer is 10% to 40%, the mass content of the second monomer is 10% to 40%, and the mass content of the third monomer is 40% to 50%, with the total monomer mass being 100%.

[0011] In one specific embodiment, in step 2), the reaction temperature is 50 to 60°C.

[0012] In one specific implementation, in step 2), the reaction time is 4 to 8 hours.

[0013] In one specific embodiment, in step 3), the drying temperature is 50 to 60°C.

[0014] In one specific embodiment, in step 3), the drying time is more than 24 hours.

[0015] In one specific implementation, oxygen is removed by introducing nitrogen gas.

[0016] In one specific embodiment, the total monomer concentration in the monomer aqueous solution is 15% to 30% by mass.

[0017] In one specific embodiment, the total monomer concentration in the monomer aqueous solution is 20% by mass.

[0018] In one specific embodiment, the initiator is ammonium persulfate and / or potassium persulfate.

[0019] In one specific embodiment, the initiator is used in an amount of 0.1% to 0.3% of the total monomer mass.

[0020] The second invention provides the application of a flocculant prepared by the method according to any one of the inventions in the treatment of wastewater.

[0021] The beneficial effects of this invention are:

[0022] (1) The production process of this invention is simple, low in cost, fast in action time, short in settling time, and free from secondary pollution;

[0023] (2) The raw materials required for this invention are widely available and have good universality;

[0024] (3) The flocculant synthesized in this invention has the advantages of both inorganic and organic flocculants and has good flocculation ability. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0026] Example 1

[0027] Preparation of flocculant 1:

[0028] The monomers are polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride, and acrylamide, with a mass ratio of 1:2:2.

[0029] (1) Add polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer concentration of 20% (polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide, wherein the mass ratio of the three is 1:2:2). Purge the oxygen in the flask with nitrogen for 30 minutes.

[0030] (2) Under the protection of continuous nitrogen gas, potassium persulfate initiator with a total monomer mass fraction of 0.1% was added while stirring, and then placed in a constant temperature water bath at 50℃ for 4 hours to obtain the reactants;

[0031] (3) After washing away the initiator that has not been fully reacted in the reactants with anhydrous ethanol, place them in a constant temperature drying oven at 60°C for 24 hours to dry thoroughly. Then, pulverize the dried product with a pulverizer.

[0032] Example 2

[0033] Preparation of flocculant 2:

[0034] The monomers are polyaluminum chloride, acrylamidopropyltrimethylammonium chloride, and acrylamide, with a mass ratio of 2:3:5.

[0035] (1) Add polyaluminum chloride, acrylamidopropyltrimethylammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer concentration of 20% (polyaluminum chloride, acrylamidopropyltrimethylammonium chloride and acrylamide, wherein the mass ratio of the three is 2:3:5). Purge the flask with nitrogen for 30 minutes to remove oxygen.

[0036] (2) Under the protection of continuous nitrogen gas, potassium persulfate initiator with a total monomer mass fraction of 0.2% was added while stirring, and then placed in a constant temperature water bath at 50℃ for 6 hours to obtain the reactants;

[0037] (3) After washing away the initiator that has not been fully reacted in the reactants with anhydrous ethanol, place them in a constant temperature drying oven at 60°C for 24 hours to dry thoroughly. Then, pulverize the dried product with a pulverizer.

[0038] Example 3

[0039] Preparation of flocculant 3:

[0040] The monomers are polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride, and acrylamide, with a mass ratio of 3:2:5.

[0041] (1) Add polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer concentration of 20% (polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide, wherein the mass ratio of the three is 3:2:5). Purge the oxygen in the flask with nitrogen for 30 minutes.

[0042] (2) Under the protection of continuous nitrogen gas, 0.1% of ammonium persulfate initiator with total monomer mass fraction was added while stirring, and then placed in a 50℃ constant temperature water bath for 4 hours to obtain the reactants;

[0043] (3) After washing away the initiator that has not been fully reacted in the reactants with anhydrous ethanol, place them in a constant temperature drying oven at 60°C for 24 hours to dry thoroughly. Then, pulverize the dried product with a pulverizer.

[0044] Example 4

[0045] Preparation of flocculant 4:

[0046] The monomers are polyaluminum chloride, acrylamidopropyltrimethylammonium chloride, and acrylamide, in a mass ratio of 1:4:5.

[0047] (1) Add polyaluminum chloride, acrylamidopropyltrimethylammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer concentration of 20% (polyaluminum chloride, acrylamidopropyltrimethylammonium chloride and acrylamide, wherein the mass ratio of the three is 1:4:5). Purge the flask with nitrogen for 30 minutes to remove oxygen.

[0048] (2) Under the protection of continuous nitrogen gas, 0.3% of ammonium persulfate initiator with total monomer mass fraction was added while stirring, and then placed in a 60℃ constant temperature water bath for 4 hours to obtain the reactant;

[0049] (3) After washing away the initiator that has not been fully reacted in the reactants with anhydrous ethanol, place them in a constant temperature drying oven at 60°C for 24 hours to dry thoroughly. Then, pulverize the dried product with a pulverizer.

[0050] Example 5

[0051] Preparation of flocculant 5:

[0052] The monomers are polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride, and acrylamide, with a mass ratio of 4:1:5.

[0053] (1) Add polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer concentration of 20% (polyaluminum chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide, wherein the mass ratio of the three is 4:1:5). Purge the flask with nitrogen for 30 minutes to remove oxygen.

[0054] (2) Under the protection of continuous nitrogen gas, potassium persulfate with a total monomer mass fraction of 0.2% and ammonium persulfate initiator with a mass fraction of 0.1% were added while stirring, and then the mixture was placed in a constant temperature water bath at 50°C for 8 hours to obtain the reactants.

[0055] (3) After washing away the initiator that has not been fully reacted in the reactants with anhydrous ethanol, place them in a constant temperature drying oven at 60°C for 24 hours to dry thoroughly. Then, pulverize the dried product with a pulverizer.

[0056] Performance testing

[0057] The evaluation of flocculant flocculation effect refers to the People's Republic of China Petroleum and Natural Gas Industry Standard "SY / T 5796-93 Flocculant Evaluation Method". The specific procedures are as follows:

[0058] (1) Add 1000 mL of wastewater with an oil content of 526 mg / L into 5 beakers respectively, and place them under the stirring paddle, so that the stirring paddle is off the center of the beaker but about 6 mm away from the beaker wall;

[0059] (2) The flocculants prepared in Examples 1 to 5 were dissolved in ultrapure water, and then flocculant aqueous solutions with the concentrations shown in Table 1 were prepared.

[0060] (3) Using a multi-stage stirrer, stir rapidly at 120 r / min for 10 min, then quickly pour each flocculant solution into each beaker containing the wastewater from step (1). After adding, stir rapidly for 1 min.

[0061] (4) Reduce the speed to 20 to 60 r / min and stir slowly for 20 min to allow the flocs to settle evenly;

[0062] (5) Use a pipette to take a sufficient volume of supernatant from half the depth of the water sample in the beaker;

[0063] (6) The obtained supernatant was subjected to water quality analysis to determine the turbidity of the wastewater;

[0064] (7) Measure the turbidity of the clear water;

[0065] (8) The turbidity removal rate was calculated, and the results are shown in Table 1.

[0066] Wherein, turbidity removal rate = (turbidity of wastewater - turbidity of clean water) / turbidity of wastewater.

[0067] Table 1. Effect of flocculant dosage on turbidity removal rate

[0068]

[0069] Experiments have shown that the flocculant of the present invention has a good flocculation effect on oily wastewater, and the turbidity removal rate reaches more than 90% at dosages of 6 to 14 mg / L.

[0070] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A method for preparing a flocculant, comprising the following steps: 1) Dissolve the first monomer, the second monomer, and the third monomer in water, remove oxygen, and obtain an aqueous solution of the monomers; 2) The initiator is added to the aqueous solution of the monomer, and the reactants are obtained after the reaction. 3) Wash the unreacted initiator from the reactants, dry, and pulverize to obtain the flocculant; in, The first monomer is polyaluminum chloride, the second monomer is methacryloyloxyethyltrimethylammonium chloride and / or acrylamidopropyltrimethylammonium chloride, and the third monomer is acrylamide; The total mass of the monomers is taken as 100%, the mass content of the first monomer is 10% to 40%, the mass content of the second monomer is 10% to 40%, and the mass content of the third monomer is 40% to 50%.

2. The method according to claim 1, characterized in that, In step 2), the reaction temperature is 50 to 60°C.

3. The method according to claim 1, characterized in that, In step 2), the reaction time is 4 to 8 hours.

4. The method according to claim 1, characterized in that, In step 3), the drying temperature is 50 to 60°C.

5. The method according to claim 1, characterized in that, In step 3), the drying time is more than 24 hours.

6. The method according to claim 1, characterized in that, Oxygen is removed by introducing nitrogen gas.

7. The method according to claim 1, characterized in that, The total monomer concentration in the monomer aqueous solution is 15% to 30% by mass.

8. The method according to claim 1, characterized in that, The total monomer concentration in the monomer aqueous solution is 20%.

9. The method according to claim 1, characterized in that, The initiator is ammonium persulfate and / or potassium persulfate; The amount of the initiator is 0.1% to 0.3% of the total monomer mass.

10. The use of the flocculant prepared by the method according to any one of claims 1 to 9 in the treatment of wastewater.

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