Flocculation demulsifier special for oily wastewater and use method of flocculation demulsifier

Abstract

The invention belongs to the technical field of flocculation demulsifiers, and provides a flocculation demulsifier special for oil-containing wastewater and a use method of the flocculation demulsifier. The special flocculation demulsifier for the oily wastewater comprises the following components in parts by mass: 2-6 parts of gemini quaternary ammonium salt, 2-6 parts of polyquaternary ammonium salt and 1-5 parts of polyaluminum chloride. The flocculation demulsifier is used for a complex oil-containing wastewater system containing heavy and light suspended particles such as silt and oil drum wall residues, the dosage in the treatment process is small, oil stains and impurities can be rapidly gathered into flocculates to float on the liquid level, the oil stain separation speed is high, the demulsification efficiency is high, and the treatment effect is good. And the oil drum cleaning wastewater is purified and can be repeatedly utilized.

Description

Technical Field

[0001] This invention relates to the field of flocculant and demulsifier technology, and in particular to a flocculant and demulsifier specifically for oily wastewater and its application method. Background Technology

[0002] The process of circulating and cleaning oil drums generates oily wastewater containing high concentrations of heavy crude oil, asphalt, and other oils. The COD is 5000-20000 mg / L, the petroleum content is >1000 mg / L, and the salinity reaches 3000-8000 mg / L, exceeding the limits in GB31571-2015 "Emission Standard for Pollutants from Petrochemical Industry" by more than 50 times. Direct discharge will have a significant impact on the environment. The harmful effects of oily wastewater on soil are as follows: When it seeps into soil pores, it forms a hydrophobic oil film up to the micrometer level, hindering the penetration of air and moisture, leading to a severe decrease in soil permeability and water retention. This hydrophobic oil film also inhibits the activity of microorganisms in the soil, reducing the efficiency of organic matter decomposition, causing soil impoverishment, and hindering crop root development, which can lead to crop death in severe cases. The harmful effects of oily wastewater on water bodies are manifested in the following ways: direct discharge forms a floating oil layer, blocking atmospheric flow, reducing dissolved oxygen concentration in the water, and preventing some aquatic organisms from surviving normally; benzene compounds and sulfides in oil can directly poison aquatic organisms, and polycyclic aromatic hydrocarbons can accumulate in organisms, inducing malformations in marine organisms and gene mutations in shellfish, and can also enter the human body through aquatic products. The harmful effects of oily wastewater on the atmospheric environment are manifested in the presence of light hydrocarbons (such as benzene and toluene) and hydrogen sulfide (…). S) volatilizes, producing a foul odor; under anaerobic conditions, oils degrade to produce methane (C) Its greenhouse effect is C This is 28 times greater than the rate of natural disasters, exacerbating climate change.

[0003] The treatment of oily wastewater has become a key aspect of environmental governance. Oily wastewater contains heavy crude oil, asphalt, and cleaning aids (such as nonionic alkylphenol polyoxyethylene ethers) adhering to barrel walls, forming a highly stable oil-in-water (O / W) emulsion system. The core challenge in treating oily wastewater lies in disrupting its triple synergistic stabilization mechanism: Interface film strengthening: The surfactant used in cleaning oil drums forms a dense molecular film (2~5nm thick) on the surface of oil droplets, which significantly improves the mechanical strength of the oil droplets; Electrostatic repulsion dominates: Surfactant components such as anionic sulfonates enable oil droplets to repel each other through the electric double layer, effectively inhibiting the aggregation of oil droplets (Zeta potential reaches -35~-50mV). Kinetic hindrance: High shear cleaning results in oil droplet size <10μm and uniform distribution, with a settling velocity of less than 0.1cm / h.

[0004] Currently, the main methods for treating wastewater from oil drum washing are chemical and physical methods. Chemical methods use flocculants and demulsifiers for demulsification. General-purpose flocculants and demulsifiers (such as polyether-based flocculant and demulsifier SP169) have an oil removal rate of <80% for heavy oil and struggle to penetrate the asphaltene-colloid composite barrier. While strong acid / high-salt demulsification processes (pH≤3) can improve the demulsification effect, they also lead to a rebound in effluent COD (up to 30%) and increase the amount of hazardous sludge (sludge oil content >15%), ultimately failing to meet discharge requirements. Physical methods often involve ultrafiltration membrane treatment. Although deep separation can be achieved, the equipment investment is 5-8 times that of chemical methods, and the membrane flux decay rate is >70% / month, making it economically inefficient.

[0005] Therefore, there is an urgent need to develop a special flocculant demulsifier that targets and breaks down the emulsification barrier of heavy oil to meet the industrial upgrading needs of "high efficiency, low carbon, and resource utilization". Summary of the Invention

[0006] The purpose of this invention is to provide a flocculant and demulsifier specifically for oily wastewater and its application method, addressing the shortcomings of existing technologies.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a flocculant and demulsifier specifically for oily wastewater, comprising the following components by weight: Gemini quaternary ammonium salt 2-6 parts, polyquaternary ammonium salt 2-6 parts, polyaluminum chloride 1-5 parts.

[0008] Preferably, the gemini quaternary ammonium salt comprises gemini quaternary ammonium salt I or gemini quaternary ammonium salt II; The general structural formula of the gemini quaternary ammonium salt I is: ; The general structural formula of the gemini quaternary ammonium salt II is: ; Where R is a straight-chain alkyl group, and X is a group containing Cl, Br, NO3, HCOO, CH3COO, CH3CH2COO or CH3C6H4SO3.

[0009] Preferably, the number of carbon atoms in the straight-chain alkyl group is any integer from 6 to 20.

[0010] Preferably, the polyquaternary ammonium salt comprises polyquaternary ammonium salt I and / or polyquaternary ammonium salt II; The general structural formula of the polyquaternium salt I is: ; The general structural formula of the polyquaternium salt II is: ; Where Y is either Cl or Br, and n is any integer from 5 to 100.

[0011] Preferably, the preparation method of the polyquaternary ammonium salt I includes the following steps: 1) Mix N,N,N',N'-tetramethylethylenediamine and water to obtain a mixture; 2) Slowly add haloethyl ether to the mixture to carry out the reaction, and polyquaternary ammonium salt I is obtained.

[0012] Preferably, the mass ratio of N,N,N',N'-tetramethylethylenediamine, haloethyl ether and water is 35~55:35~55:70; Step 2) The slow addition rate is 1~10 mL / s; Step 2) The reaction temperature is 70~150℃ and the reaction time is 5~20h.

[0013] Preferably, the preparation method of the polyquaternary ammonium salt II includes the following steps: ② Mix 1,3-bis[3-(dimethylamino)propyl]urea and water to obtain a mixture; ② Slowly add haloethyl ether to the mixture to carry out the reaction, and polyquaternary ammonium salt II is obtained.

[0014] Preferably, the mass ratio of the 1,3-bis[3-(dimethylamino)propyl]urea, haloethyl ether and water is 35~55:35~55:70; The slow addition rate described in step ② is 1~10 mL / s; The reaction temperature in step ② is 80~160℃, and the reaction time is 6~20h.

[0015] The present invention also provides a method for using the flocculant and demulsifier specifically for oily wastewater, wherein gemini quaternary ammonium salt, polyquaternary ammonium salt and polyaluminum chloride are added sequentially to the oily wastewater.

[0016] Preferably, the mass of the gemini quaternary ammonium salt is 0.2 to 1.0% of the mass of the oily wastewater.

[0017] The beneficial effects of this invention are: The flocculant and demulsifier of this invention is designed for complex oily wastewater systems containing heavy and light suspended particles such as mud, sand, and oil drum wall residue. It treats oily wastewater with low dosage, fast oil-stain separation speed, and high demulsification efficiency, and has excellent oil-stain removal performance for oil drum cleaning wastewater. Detailed Implementation

[0018] This invention provides a flocculant and demulsifier specifically for oily wastewater, comprising the following components by weight: Gemini quaternary ammonium salt 2-6 parts, polyquaternary ammonium salt 2-6 parts, polyaluminum chloride 1-5 parts.

[0019] In this invention, the flocculant and demulsifier specifically for oily wastewater comprises, by weight, the following components: Gemini quaternary ammonium salt 2-6 parts, preferably 3-5 parts, more preferably 4 parts; polyquaternary ammonium salt 2-6 parts, preferably 3-5 parts, more preferably 4 parts; polyaluminum chloride 1-5 parts, preferably 2-4 parts, more preferably 3 parts.

[0020] In this invention, the gemini quaternary ammonium salt preferably comprises gemini quaternary ammonium salt I or gemini quaternary ammonium salt II; The general structural formula of the gemini quaternary ammonium salt I is: ; The general structural formula of the gemini quaternary ammonium salt II is: ; Wherein, R is independent and preferably a straight-chain alkyl group, and X is independent and preferably contains Cl, Br, NO3, HCOO, CH3COO, CH3CH2COO or CH3C6H4SO3.

[0021] In this invention, the gemini quaternary ammonium salt contains two hydrophilic quaternary ammonium groups, has a more compact molecular structure, can be efficiently adsorbed at the interface of oily wastewater, and significantly reduce interfacial tension; the hydrophobic chains in the gemini quaternary ammonium salt can penetrate deep into the oil phase, replace natural components such as asphaltenes and colloids, and disrupt the stability of the interfacial film.

[0022] In this invention, the number of carbon atoms in the straight-chain alkyl group is preferably any integer from 6 to 20, and more preferably any integer from 10 to 15.

[0023] In this invention, the polyquaternary ammonium salt preferably comprises polyquaternary ammonium salt I and / or polyquaternary ammonium salt II; The general structural formula of the polyquaternium salt I is: ; The general structural formula of the polyquaternium salt II is: ; Wherein, Y is independent and preferably Cl or Br, n is independent and preferably any integer from 5 to 100, more preferably any integer from 20 to 60, and more preferably 40.

[0024] In this invention, the polyquaternary ammonium salt has a relatively long molecular chain, which can promote the coalescence of oil droplets through a "bridging-flocculation" effect; the polyquaternary ammonium salt has a dense charge characteristic, which can neutralize the charge at the oil-water interface and weaken the electrostatic repulsion force; using polyquaternary ammonium salt alone may result in incomplete interface coverage due to insufficient flexibility of the molecular chain.

[0025] In this invention, the gemini quaternary ammonium salt rapidly reduces interfacial tension, providing a lower surface energy interface for the polyquaternary ammonium salt to act more easily. The polyquaternary ammonium salt bridges the oil droplets loosened by the gemini quaternary ammonium salt through long chains, accelerating aggregation and sedimentation, forming a synergistic demulsification path of "loosening first and then agglomerating".

[0026] In this invention, the preparation method of the polyquaternary ammonium salt I preferably includes the following steps: 1) Mix N,N,N',N'-tetramethylethylenediamine and water to obtain a mixture; 2) Slowly add haloethyl ether to the mixture to carry out the reaction, and polyquaternary ammonium salt I is obtained.

[0027] In this invention, the mass ratio of N,N,N',N'-tetramethylethylenediamine, haloethyl ether and water is preferably 35~55:35~55:70, more preferably 37~52:37~52:70, and even more preferably 50:50:70; The slow addition rate in step 2) is preferably 1~10 mL / s, more preferably 3~7 mL / s, and even more preferably 5 mL / s; The reaction temperature in step 2) is preferably 70~150℃, more preferably 90~140℃, and even more preferably 120℃; the reaction time is preferably 5~20h, more preferably 8~16h, and even more preferably 14h.

[0028] In this invention, step 2) preferably involves heating the mixture and then slowly adding the haloethyl ether; preferably, the mixture is heated to 25~55°C, and more preferably to 40°C.

[0029] In this invention, the preparation method of the polyquaternary ammonium salt II preferably includes the following steps: ① Mix 1,3-bis[3-(dimethylamino)propyl]urea and water to obtain a mixture; ② Slowly add haloethyl ether to the mixture to carry out the reaction, and polyquaternary ammonium salt II is obtained.

[0030] In this invention, the mass ratio of 1,3-bis[3-(dimethylamino)propyl]urea, haloethyl ether and water is preferably 35~55:35~55:70, more preferably 42~52:42~52:70, and even more preferably 50:50:70; The slow addition rate in step ② is preferably 1~10 mL / s, more preferably 3~7 mL / s, and even more preferably 5 mL / s; The reaction temperature in step ② is preferably 80~160℃, more preferably 92~140℃, and even more preferably 120℃; the reaction time is preferably 6~20h, more preferably 8~16h, and even more preferably 14h.

[0031] In this invention, step ② preferably involves heating the mixture and then slowly adding the haloethyl ether; preferably, the mixture is heated to 25~55°C, and more preferably to 40°C.

[0032] In this invention, the oily wastewater preferably includes wastewater from cleaning oil drums.

[0033] The present invention also provides a method for using the flocculant and demulsifier specifically for oily wastewater, wherein gemini quaternary ammonium salt, polyquaternary ammonium salt and polyaluminum chloride are added sequentially to the oily wastewater.

[0034] In this invention, the mass of the gemini quaternary ammonium salt is preferably 0.2-1.0% of the mass of the oily wastewater, more preferably 0.4-0.8%, and even more preferably 0.6%.

[0035] In this invention, it is preferable to add the gemini quaternary ammonium salt, stir, then add the polyquaternary ammonium salt, stir again, and finally add the polyaluminum chloride, stir, and let stand. The stirring speed is preferably 300-500 r / min, more preferably 400 r / min; the stirring time is preferably 0.5-3 min, more preferably 1 min.

[0036] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0037] In the embodiments and comparative examples of the present invention, the structural formula of Gemini Quaternary Ammonium Salt I is as follows: Where R is a saturated straight-chain alkyl group with 15 carbon atoms, and X is Br; The structural formula of Gemini Quaternary Ammonium Salt II is Where R is a saturated straight-chain alkyl group with 16 carbon atoms, and X is Br; The structural formula of polyquaternary ammonium salt I is Where Y is Cl and n is 40; The preparation method of polyquaternary ammonium salt I is as follows: 50g of N,N,N',N'-tetramethylethylenediamine and 50g of water are added sequentially to a flask and stirred until homogeneous to obtain a mixture. The mixture is heated to 40℃, and 50g of dichloroethyl ether is slowly added to the mixture at a rate of 2mL / s to obtain a reaction solution. The reaction solution is heated to 120℃ and reacted at 120℃ for 14 hours to obtain polyquaternary ammonium salt I.

[0038] The structural formula of polyquaternium salt II is Where Y is Cl and n is 50; The preparation method of polyquaternium salt II is as follows: 50g of 1,3-bis[3-(dimethylamino)propyl]urea and 50g of water are added sequentially to a flask and stirred until homogeneous to obtain a mixture. The mixture is heated to 40℃, and 50g of dichloroethyl ether is slowly added to the mixture at a rate of 2mL / s to obtain a reaction solution. The reaction solution is heated to 120℃ and reacted at 120℃ for 14 hours to obtain polyquaternium salt II.

[0039] The oily wastewater used in the embodiments and comparative examples of this invention is the wastewater from the cleaning of oil drums at the factory of Shanxi Wanche Environmental Protection Technology Co., Ltd.

[0040] Example 1

[0041] Take 80g of oily wastewater, add 0.16g of Gemini Quaternary Ammonium Salt I to the wastewater, and stir at 400 r / min for 1 min; then add 0.24g of Polyquaternary Ammonium Salt I, and stir at 400 r / min for 1 min; finally add 0.08g of Polyaluminum Chloride, and stir at 400 r / min for 1 min. After stopping stirring, let it stand, and record the demulsification time and the state of the wastewater after demulsification.

[0042] Example 2

[0043] The amount of Gemini Quaternary Ammonium Salt I in Example 1 was modified to 0.32g, and the rest was the same as in Example 1.

[0044] Example 3

[0045] The amount of Gemini Quaternary Ammonium Salt I in Example 1 was modified to 0.48g, and the rest was the same as in Example 1.

[0046] Example 4

[0047] The amount of polyquaternary ammonium salt I in Example 1 was modified to 0.32g, and the rest was the same as in Example 1.

[0048] Example 5

[0049] The amount of polyquaternary ammonium salt I in Example 1 was modified to 0.48g, and the rest was the same as in Example 1.

[0050] Example 6

[0051] The amount of polyquaternary ammonium salt I in Example 1 was modified to 0.16g, and Gemini quaternary ammonium salt I was replaced with Gemini quaternary ammonium salt II. The amount of Gemini quaternary ammonium salt II was 0.48g, and the rest was the same as in Example 1.

[0052] Example 7

[0053] The amount of polyquaternary ammonium salt I in Example 6 was modified to 0.32g, and the rest was the same as in Example 6.

[0054] Example 8

[0055] The amount of polyquaternary ammonium salt I in Example 6 was modified to 0.48g, and the rest was the same as in Example 6.

[0056] Example 9

[0057] In Example 7, polyquaternium salt I was replaced with polyquaternium salt II, and everything else was the same as in Example 7.

[0058] Example 10

[0059] In Example 8, polyquaternium salt I was replaced with polyquaternium salt II, and everything else was the same as in Example 8.

[0060] Comparative Example 1

[0061] The polyquaternary ammonium salt I in Example 3 is omitted, and everything else is the same as in Example 1.

[0062] Comparative Example 2

[0063] The polyquaternary ammonium salt I in Example 6 is omitted, and everything else is the same as in Example 6.

[0064] Comparative Example 3

[0065] Gemini quaternary ammonium salt I in Example 10 is omitted; otherwise, it is the same as in Example 1.

[0066] Comparative Example 4

[0067] Take 80g of oily wastewater, add 0.48g of commercially available SP169 flocculant and demulsifier to the oily wastewater, and stir at 400 r / min for 1 min; after stopping stirring, let it stand and record the demulsification time.

[0068] Comparative Example 5

[0069] No flocculants or demulsifiers were added.

[0070] The wastewater conditions after treatment in the examples and comparative examples were observed, and the oil removal rate and the solid content of the clarified liquid were tested. The test results are shown in Table 1. The oil removal rate test procedure is as follows: Remove the upper layer of flocculents, take 10 mL of the lower layer solution with a dropper, extract the lower layer solution with n-hexane, and test the absorbance of the oil phase after extraction using a UV spectrophotometer. The oil removal rate is calculated based on the initial oily wastewater. The clarified liquid solid content test procedure is as follows: Remove the upper layer of flocculents, take 2 g of the lower layer solution with a dropper, dry it at 120℃ to constant weight, and calculate the solid content.

[0071] Table 1 Results of oily wastewater treatment

[0072] As shown in Table 1, the oily wastewater remained emulsified even after 5 days without the addition of any demulsifying agents. Using gemini quaternary ammonium salt alone did not have a significant demulsifying effect. The demulsifying effect of using polyquaternary ammonium salt or commercially available flocculants alone was limited. The demulsification treatment using the combination of ingredients according to Examples 1-10 could achieve demulsification within 2 minutes, and the oil and particulate flocs agglomerated and floated to the liquid surface, resulting in rapid demulsification and a good flocculation and demulsification effect.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flocculating demulsifier specific to oil-containing wastewater, characterized by, By mass fraction, comprising the following components: Gemini quaternary ammonium salt 2~6 parts, polyquaternary ammonium salt 2~6 parts, polyaluminum chloride 1~5 parts.

2. The flocculating demulsifier specific to oil-containing wastewater according to claim 1, characterized by, The Gemini quaternary ammonium salt comprises Gemini quaternary ammonium salt I or Gemini quaternary ammonium salt II; The structural general formula of the gemini quaternary ammonium salt I is ; The general structure of the gemini quaternary ammonium salt II is ; Wherein, R is independently a linear alkyl, X independently comprises Cl, Br, NO3, HCOO, CH3COO, CH3CH2COO or CH3C6H4SO3.

3. The flocculating demulsifier specific to oil-containing wastewater according to claim 2, characterized by, The number of carbon atoms of the linear alkyl is any integer in 6~20.

4. The flocculating demulsifier for oil-containing wastewater according to any one of claims 1 to 3, characterized by, The polyquaternary ammonium salt comprises polyquaternary ammonium salt I and / or polyquaternary ammonium salt II; The polyquaternary ammonium salt I has the general structure ; The polyquaternary ammonium salt II has the general structure ; Wherein, Y is independently Cl or Br, n is independently any integer in 5-100.

5. The flocculating demulsifier specific to oil-containing wastewater according to claim 4, characterized by, The preparation method of the polyquaternary ammonium salt I comprises the following steps: 1) mixing N,N,N',N'-tetramethyl ethylenediamine and water to obtain a mixed solution; 2) slowly adding halogen ether to the mixed solution to react, thereby obtaining the polyquaternary ammonium salt I.

6. The flocculating demulsifier specific to oil-containing wastewater according to claim 5, characterized by, The mass ratio of the N,N,N',N'-tetramethyl ethylenediamine, halogen ether and water is 35~55: 35~55: 70; The speed of the slow addition in step 2) is 1~10 mL / s; The temperature of the reaction in step 2) is 70~150℃, and the reaction time is 5~20h.

7. The flocculating demulsifier specific for oil-containing wastewater according to claim 5 or 6, characterized in that, The preparation method of the polyquaternary ammonium salt II comprises the following steps: ① mixing 1,3-bis[3-(dimethylamino) propyl] urea and water to obtain a mixed solution; ② slowly adding halogen ether to the mixed solution to react, thereby obtaining the polyquaternary ammonium salt II.

8. The flocculating demulsifier specific to oil-containing wastewater according to claim 7, characterized by, The mass ratio of the 1,3-bis[3-(dimethylamino) propyl] urea, halogen ether and water is 35~55: 35~55: 70; The speed of the slow addition in step ② is 1~10 mL / s; The temperature of the reaction in step ② is 80~160℃, and the reaction time is 6~20h.

9. The use of the flocculating demulsifier specific for oily waste water according to any one of claims 1 to 8, characterized in that, The Gemini quaternary ammonium salt, the polyquaternary ammonium salt and the polyaluminum chloride are sequentially added to the oily wastewater.

10. The method of use of claim 9, wherein, The mass of the Gemini quaternary ammonium salt is 0.2~1.0% of the mass of the oily wastewater.

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