Preparation method and application of flocculant

Abstract

The invention provides a preparation method and application of a flocculating agent. The method comprises the following steps: 1) dissolving a first monomer, a second monomer and a third monomer in water, and removing oxygen to obtain a monomer aqueous solution; 2) adding an initiator into the monomer aqueous solution, and reacting to obtain a reactant; and 3) washing the incompletely reacted initiator in the reactant, drying, and crushing to obtain the flocculant, wherein the first monomer is polyaluminum chloride, the second monomer is methacryloyloxyethyl trimethyl ammonium chloride and / or acrylamide propyl trimethyl ammonium chloride, and the third monomer is acrylamide.

Description

Technical Field

[0001] The invention relates to the field of sewage treatment, and in particular to a method for preparing a flocculant. Background Art

[0002] With the continuous development of my country's industry, the petroleum industry, as one of the pillar industries, has continued to develop in recent years. However, with the continuous exploitation of oil and gas, the country's environmental protection requirements have become more stringent, and the treatment of oily wastewater has received more and more attention. If these oily wastewaters cannot be properly treated, the utilization efficiency of water resources will be extremely low, and the harm to the environment will be extremely great.

[0003] Conventional water treatment processes require the addition of chemical additives, generally flocculants. The flocculants commonly used now are roughly divided into inorganic flocculants and organic flocculants. Traditional inorganic coagulants are mainly aluminum salts, iron salts and their hydrolyzed polymers. They are used in large quantities, and the amount of sludge formed in the treated water is large, the effluent is colored, and they are also corrosive to the equipment, which is easy to cause secondary pollution. At the same time, the molecular weight and flocculation bridging ability are much worse than those of organic flocculants. Although the commonly used organic polymer flocculants have a small dosage and fast sedimentation, they are expensive, and the scope of application and effect are limited when used alone. They also have certain biological toxicity, and their scope of application is relatively small. Moreover, the flocculants reported so far are mainly used to treat oil or suspended matter in oily wastewater, and the overall effect of oily wastewater treatment is still unsatisfactory. In the case of water quality with a high degree of mineralization, the treatment effect is even more difficult to meet the construction and discharge requirements on site.

[0004] Therefore, there is still much room for improvement and enhancement in flocculant technology and performance. Summary of the invention

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

[0006] 1) dissolving the first monomer, the second monomer and the third monomer in water, removing oxygen, and obtaining a monomer aqueous solution;

[0007] 2) adding an initiator to the monomer aqueous solution to obtain a reactant after reaction;

[0008] 3) washing the incompletely reacted initiator in the reactant, drying, and crushing to obtain the flocculant;

[0009] Wherein, the first monomer is polyaluminium chloride, the second monomer is methacryloyloxyethyl trimethylammonium chloride and / or acrylamidopropyl trimethylammonium chloride, and the third monomer is acrylamide.

[0010] In a specific embodiment, based on the mass of the total monomers 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%.

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

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

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

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

[0015] In one embodiment, oxygen is removed by passing nitrogen.

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

[0017] In a specific embodiment, the mass concentration of total monomers in the monomer aqueous solution is 20%.

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

[0019] In a specific embodiment, the amount of the initiator is 0.1% to 0.3% by weight of the total monomers.

[0020] The second aspect of the present invention provides the use of a flocculant prepared by the method described in any one of the first aspects of the present invention in treating sewage.

[0021] Beneficial effects of the present invention:

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

[0023] (2) The raw materials required by the present invention are widely available and have good universality;

[0024] (3) The flocculant synthesized by the present invention has the advantages of both inorganic flocculants and organic flocculants and has good flocculation ability. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with examples, but the examples of the present invention are only exemplary descriptions, and the implementation methods do not constitute limitations of the present invention under any circumstances.

[0026] Example 1

[0027] Preparation of flocculant 1:

[0028] The monomers are polyaluminium chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide, and the mass ratio of the three is 1:2:2.

[0029] (1) adding polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer (polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide, wherein the mass ratio of the three is 1:2:2) with a mass concentration of 20%, and passing nitrogen gas for 30 minutes to remove oxygen in the flask;

[0030] (2) under the protection of continuous nitrogen flow, adding potassium persulfate initiator with a mass fraction of 0.1% of the total monomer while stirring, and then placing in a constant temperature water bath at 50° C. for reaction for 4 hours to obtain a reactant;

[0031] (3) The unreacted initiator in the reactant is washed with anhydrous ethanol and then placed in a 60°C constant temperature drying oven for thorough drying for 24 hours. The dried product is crushed with a pulverizer.

[0032] Example 2

[0033] Preparation of flocculant 2:

[0034] The monomers are polyaluminium chloride, acrylamidopropyltrimethylammonium chloride and acrylamide, and the mass ratio of the three is 2:3:5.

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

[0036] (2) under the protection of continuous nitrogen flow, adding potassium persulfate initiator with a mass fraction of 0.2% of the total monomer while stirring, and then placing in a constant temperature water bath at 50° C. for reaction for 6 hours to obtain a reactant;

[0037] (3) The unreacted initiator in the reactant is washed with anhydrous ethanol and then placed in a 60°C constant temperature drying oven for thorough drying for 24 hours. The dried product is crushed with a pulverizer.

[0038] Example 3

[0039] Preparation of flocculant 3:

[0040] The monomers are polyaluminium chloride, methacryloyloxyethyltrimethylammonium chloride and acrylamide, and the mass ratio of the three is 3:2:5.

[0041] (1) adding polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer (polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide, wherein the mass ratio of the three is 3:2:5) with a mass concentration of 20%, and passing nitrogen gas for 30 minutes to remove oxygen in the flask;

[0042] (2) under the protection of continuous nitrogen flow, add 0.1% of the total monomer mass fraction of ammonium persulfate initiator while stirring, and then place in a 50° C. constant temperature water bath for reaction for 4 hours to obtain a reactant;

[0043] (3) The unreacted initiator in the reactant is washed with anhydrous ethanol and then placed in a 60°C constant temperature drying oven for thorough drying for 24 hours. The dried product is crushed with a pulverizer.

[0044] Example 4

[0045] Preparation of flocculant 4:

[0046] The monomers are polyaluminium chloride, acrylamidopropyltrimethylammonium chloride and acrylamide, and the mass ratio of the three is 1:4:5.

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

[0048] (2) under the protection of continuous nitrogen flow, add 0.3% of the total monomer mass fraction of ammonium persulfate initiator while stirring, and then place in a constant temperature water bath at 60° C. for reaction for 4 hours to obtain a reactant;

[0049] (3) The unreacted initiator in the reactant is washed with anhydrous ethanol and then placed in a 60°C constant temperature drying oven for thorough drying for 24 hours. The dried product is crushed with a pulverizer.

[0050] Example 5

[0051] Preparation of flocculant 5:

[0052] The monomers are polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide, and the mass ratio of the three is 4:1:5.

[0053] (1) adding polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide to deionized water to prepare an aqueous solution with a total monomer (polyaluminium chloride, methacryloyloxyethyl trimethyl ammonium chloride and acrylamide, wherein the mass ratio of the three is 4:1:5) with a mass concentration of 20%, and passing nitrogen gas for 30 minutes to remove oxygen in the flask;

[0054] (2) adding 0.2% of potassium persulfate and 0.1% of ammonium persulfate as an initiator in a total monomer mass fraction while stirring under the protection of continuous nitrogen flow, and then placing in a constant temperature water bath at 50° C. for reaction for 8 hours to obtain a reactant;

[0055] (3) The unreacted initiator in the reactant is washed with anhydrous ethanol and then placed in a 60°C constant temperature drying oven for thorough drying for 24 hours. The dried product is crushed with a pulverizer.

[0056] Performance measurement

[0057] The evaluation of the flocculation effect of the flocculant refers to the petroleum and natural gas industry standard of the People's Republic of China "SY / T 5796-93 Flocculant Evaluation Method". The specific operation is as follows:

[0058] (1) 1000 mL of wastewater with an oil content of 526 mg / L was added to five beakers respectively and placed under a stirring paddle so that the stirring paddle was offset from 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 respectively dissolved in ultrapure water, and then prepared to obtain flocculant aqueous solutions with concentrations as shown in Table 1 below;

[0060] (3) Using a multi-joint stirrer, after rapid stirring at a speed of 120 r / min for 10 min, each flocculant solution was rapidly poured into each beaker containing the sewage in step (1), and after addition, rapidly stirred 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) Analyze the water quality of the supernatant to determine the turbidity of the sewage;

[0064] (7) Determination of water turbidity;

[0065] (8) Calculate the turbidity removal rate. The results are shown in Table 1.

[0066] Among them, turbidity removal rate = (wastewater turbidity - clean water turbidity) / sewage turbidity.

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

[0068]

[0069] The test shows that the flocculant of the present invention has a good flocculation effect on oily wastewater. When the addition amount is 6 to 14 mg / L, the turbidity removal rate reaches more than 90%.

[0070] Although the present invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that various changes may be made without departing from the true spirit and scope of the present invention. In addition, the subject matter, spirit and scope of the present invention may be varied to accommodate specific situations, materials, material combinations and methods. All of these changes 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) dissolving the first monomer, the second monomer and the third monomer in water, removing oxygen, and obtaining a monomer aqueous solution; 2) adding an initiator to the monomer aqueous solution to obtain a reactant after reaction; 3) washing the incompletely reacted initiator in the reactant, drying, and crushing to obtain the flocculant; in, The first monomer is polyaluminium chloride, the second monomer is methacryloyloxyethyl trimethylammonium chloride and / or acrylamidopropyl trimethylammonium chloride, and the third monomer is acrylamide.

2. The method according to claim 1, characterized in that Taking the mass of the total monomers 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%.

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

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

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

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

7. The method according to claim 1, characterized in that The oxygen was removed by bubbling nitrogen.

8. The method according to claim 1, characterized in that The mass concentration of total monomers in the monomer aqueous solution is 15% to 30%, preferably 20%.

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

10. Use of the flocculant prepared according to the method according to any one of claims 1 to 9 in treating sewage.

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