A demulsifier for low oil content coal coking wastewater and its preparation method

Abstract

The present invention discloses a demulsifier for low oil content coal coking wastewater and its preparation method, belonging to the chemical engineering field. The composite demulsifier components include demulsifier A, n-alkane, and polyaluminum chloride. The demulsifier A is mainly composed of octadeceneamine polyoxyethylene ether. The polysiloxane chain segment formed by the reaction of silicone oil and glacial acetic acid is embedded into the demulsifier A, and then polyaluminum chloride, n-pentane, and cetyltrimethylammonium bromide are added for compounding to obtain a block-modified high-efficiency and multi-purpose demulsifier. The present invention utilizes the multi-branched demulsifier. The low-content coal tar forms clusters and flocs in the n-alkane solvent. The polyaluminum chloride changes the oil droplets from a dispersed state to a coalesced state, and the demulsifier makes the coalesced demulsifier form a complete oil phase, significantly reducing the water content of the tar and improving the separation of tar and ammonia water.

Description

Technical Field

[0001] The present invention relates to the chemical industry field, and more specifically, to a highly efficient demulsifier for wastewater treatment applicable to various wastewater mixtures such as coking wastewater, semi-coke production wastewater, coal gasification wastewater, and coal liquefaction wastewater, especially a highly efficient demulsifier for low oil content. Background Art

[0002] The oil content in the organic wastewater formed during the pyrolysis of coal can usually reach 2,000 - 3,000 mg / L. If the oil content is not reduced through pretreatment, it will damage the natural environment and severely inhibit the activity of microorganisms in biochemical treatment. Therefore, the removal of oil substances is the primary problem to be solved.

[0003] The dispersed state of oil in water can be divided into floating oil, dispersed oil, emulsified oil, and dissolved oil. Currently, in engineering, gravity oil separation and air flotation processes are generally used to remove floating oil and a small amount of dispersed oil, and most of the dissolved oil can be effectively recovered through the extraction method. Therefore, how to convert emulsified oil into floating oil or dissolved oil is the key to selecting a demulsifier.

[0004] The separation of tar and ammonia water is a very important link in the coking production process, and the separation effect will affect the washing of the primary cooler, tar dehydration, and the quality of chemical products. In coking enterprises, there is generally a partial emulsification phenomenon between tar and ammonia water, resulting in problems such as difficult tar dehydration, frequent blockage and cleaning of the trays of the ammonia distillation tower, attachment of tar slag on the tubes of the primary cooler, and excessive resistance.

[0005] After retrieval, the patent number is CN105540738B, and the invention creation name is: A Highly Efficient Demulsifier and Its Preparation Method and Application. This application discloses a demulsifier for wastewater in the iron and steel industry, coking industry, oilfield exploitation, and machining industry. The demulsifier of this application is prepared by mixing diallyl terephthalate, formalin, ethylene glycol monobutyl ether, and polygala root extract. The prepared demulsifier has a relatively low molecular weight, has good demulsification performance at high temperatures, but has poor demulsification performance at normal temperatures, and also has poor demulsification performance for the low oil content water quality in the coking industry. Summary of the Invention

[0006] 1. Technical Problems to be Solved by the Invention

[0007] In view of the deficiencies of the above-mentioned existing technologies, the present invention provides a demulsifier for low oil content coal coking wastewater and a preparation method thereof; the present invention provides a polyamine polyamine-based polymer composite demulsifier, which has been structurally designed for specific wastewater in the coking industry, so that the demulsifier forms an unstable film at the interface between tar and ammonia water, causing tiny tar droplets to aggregate into large beads, and finally settling and stratifying. It has high demulsification ability in the temperature range of 0°C - 90°C for coking wastewater, and can adapt to the fluctuations in the quality of wastewater in the coking industry, maintaining stable removal rates of oil content, COD and other indicators.

[0008] 2. Technical Solution

[0009] To achieve the above object, the technical solution provided by the present invention is as follows:

[0010] A preparation method of a demulsifier for low oil content coal coking wastewater of the present invention comprises the following steps:

[0011] Step 1: Take octadecene amine and sodium hydroxide and add them into reaction kettle A. Slowly introduce ethylene oxide into reaction kettle A with nitrogen. After the reaction is completed, add acetic acid to neutralize the basic catalyst to obtain a two-segment block "octadecene amine polyoxyethylene ether".

[0012] Step 2: Add dimethyl silicone oil and acetic acid into reaction kettle B, evacuate to carry out a polymerization reaction, add the "octadecene amine polyoxyethylene ether" prepared in reaction kettle A, and neutralize acetic acid with sodium hydroxide after the block polymerization reaction is completed to obtain an organosilicon-modified octadecene amine polyoxyethylene ether demulsifier.

[0013] Step 3: Dissolve polyaluminum chloride and cetyltrimethylammonium bromide in ethylene glycol, stir until completely dissolved, and add it to the organosilicon-modified octadecene amine polyoxyethylene ether demulsifier synthesized in Step 2, and stir evenly.

[0014] Step 4: Add n-pentane to the mixture in Step 3 and stir evenly to complete the preparation.

[0015] Furthermore, in the "octadecene amine polyoxyethylene ether" obtained in Step 1, m(octadecene amine):m(sodium hydroxide):m(ethylene oxide) = (90 - 100):0.7:16.

[0016] Furthermore, in the organosilicon-modified octadecene amine polyoxyethylene ether demulsifier obtained in Step 2, m(octadecene amine polyoxyethylene ether):m(dimethyl silicone oil):m(acetic acid) = (100 - 120):64:0.9.

[0017] Furthermore, in the mixture obtained in Step 3, m(organosilicon-modified octadecene amine polyoxyethylene ether):m(ethylene glycol):m(polyaluminum chloride):m(cetyltrimethylammonium bromide) = (160 - 180):64:0.5:0.7.

[0018] Furthermore, in the product obtained in Step 4, m (mixed solution): m (n-pentane) = (200 - 240): 110.

[0019] Furthermore, in Step 1, octadeceneamine and sodium hydroxide are added to Reactor A. First, vacuum is pumped and replaced with dry nitrogen twice; it is stirred and heated to 125 - 135 °C, and ethylene oxide is slowly introduced into the reactor with nitrogen, controlling the polymerization pressure at 0.20 ± 0.01 MPa; it is maintained for 2 h, and then ethylene oxide is slowly introduced into the reactor with nitrogen for the second time; controlling the polymerization pressure at 0.31 ± 0.01 MPa, maintaining for 2 h, and after the reaction is completed, acetic acid is added to neutralize the basic catalyst.

[0020] Furthermore, in Step 2, dimethyl silicone oil and acetic acid are mixed and added to Reactor B, and the temperature is controlled at 100 - 120 °C; vacuum is pumped for the polymerization reaction, maintained for 2 h, and the "octadeceneamine polyoxyethylene ether" prepared in Reactor A is added and maintained for 2 h.

[0021] A demulsifier for low oil content coal coking wastewater of the present invention is prepared by using the said method.

[0022] 3. Beneficial effects

[0023] Adopting the technical solution provided by the present invention, compared with the existing well-known technologies, it has the following remarkable effects:

[0024] (1) In view of the characteristics of low coal tar sewage, the present invention prepares a modified silicone octadeceneamine polyoxyethylene ether demulsifier. This demulsifier uses octadeceneamine as the initiator, with octadeceneamine polyoxyethylene ether as the main chain and silicon dioxide as the side chain. The demulsifier molecules have both hydrophobic groups and hydrophilic groups, so that it has good demulsification performance and good dispersibility at the same time.

[0025] (2) In the present invention, n-pentane plays a super strong auxiliary role in low content coal tar. Low content coal tar forms clusters and flocs in the n-alkane solvent, and asphaltenes form micelle nuclei and are solubilized by the n-pentane solute to form micelles. There is a strong association between asphaltenes, and asphaltene molecules form association nuclei (2 nm) through π-π stacking; secondly, the association nuclei undergo re-association through the interaction with n-pentane to form intermediate-sized associations (5 - 50 nm); furthermore, the association nuclei themselves can re-associate to form associations with irregular sizes (>100 nm). After dilution with the solvent, they associate to form larger aggregates. When the asphaltene concentration is lower than 1 - 2 mg·L -1 When, asphaltene molecules do not associate, and the critical concentration for asphaltene monomers to associate is 10 mg·L -1 . The association form is from molecular association - micelle - association - cluster.

[0026] (3) In the present invention, polyaluminum chloride plays a super auxiliary role in low-content coal tar. Polyaluminum chloride can be mixed in oily sewage in a short time, dissolved in ethylene glycol and compounded into the system, which can quickly reduce the interfacial tension between oil and water. Through the adsorption bridging effect, oil droplets are flocculated, and the aggregates have high strength and are not easily redispersed. When used in combination with a demulsifier, the oil droplets change from a dispersed state to a coalesced state, and the demulsifier makes the coalesced demulsifier form a complete oil phase, significantly reducing the water content of the tar and improving the separation of tar and ammonia water.

[0027] (4) In the present invention, cetyltrimethylammonium bromide is introduced. Cetyltrimethylammonium bromide will undergo a hydrolysis reaction to generate an electrostatic attraction effect, causing droplets to aggregate and collide with each other; displace the surfactant originally adsorbed on the interface, forming a new interfacial film structure with a loose arrangement and easy to break, thereby increasing the water separation rate and having a relatively fast water separation rate. At the same time, cetyltrimethylammonium bromide also plays a role in inhibiting the reproduction of microorganisms in the system, extending the service life of the product to a certain extent.

[0028] (5) Due to the excellent demulsification performance and various auxiliary components introduced in the demulsifier of the present invention, it can effectively reduce indicators such as ammonia nitrogen, COD, and suspended solids in coking wastewater. The oil content can be reduced to below 100 ppm, ammonia nitrogen can be reduced to 40%, COD can be reduced to 40%, and suspended solids can be reduced to 60%. The wastewater after oil separation by adding this demulsifier can greatly reduce the subsequent water treatment load. Specific embodiments

[0029] To further understand the content of the present invention, the present invention will be further described below in conjunction with embodiments.

[0030] Example 1

[0031] Take 188 g of octadecylamine and 1.4 g of sodium hydroxide (AR) and add them to reaction kettle A. First, evacuate and replace with dry nitrogen 2 times; turn on the stirrer and heat up to 125 - 135 °C, and slowly introduce ethylene oxide into the reaction kettle with nitrogen, controlling the polymerization pressure at 0.20 ± 0.01 MPa; keep for about 2 h, and then slowly introduce ethylene oxide into the reaction kettle with nitrogen for the second time; control the polymerization pressure at 0.31 ± 0.01 MPa and keep for about 2 h. After the reaction is completed, add 2.5 g of acetic acid (AR) to neutralize the basic catalyst to obtain a two-segment block "octadecylamine polyoxyethylene ether";

[0032] Mix 128 g of dimethyl silicone oil and 1.8 g of acetic acid and add them to reaction kettle B, controlling the temperature at 100 - 120 °C; evacuate for polymerization reaction, keep for about 2 h, add the "octadecylamine polyoxyethylene ether" prepared in reaction kettle A, and keep for about 2 h. After the block polymerization reaction is completed, add 1.2 g of sodium hydroxide to neutralize acetic acid to obtain an organosilicon-modified octadecylamine polyoxyethylene ether product;

[0033] Dissolve 1 g of polyaluminum chloride and 1.4 g of cetyltrimethylammonium bromide in 128 g of ethylene glycol, stir until completely dissolved, add it to the organosilicon-modified octadeceneamine polyether demulsifier synthesized in Step 2, and stir evenly;

[0034] Add 220 g of n-pentane to the mixture in Step (3), stir evenly, and the preparation is completed.

[0035] Comparative Example 1

[0036] Take 188 g of ethylenediamine and 1.4 g of sodium hydroxide (AR) and add them to Reactor A. First, evacuate and replace with dry nitrogen twice; turn on the stirrer and heat up to 125 - 135 °C, slowly introduce ethylene oxide into the reactor with nitrogen, and control the polymerization pressure at 0.20 ± 0.01 MPa; keep for about 2 h, and then slowly introduce ethylene oxide into the reactor with nitrogen for the second time; control the polymerization pressure at 0.31 ± 0.01 MPa and keep for about 2 h. After the reaction is completed, add 2.5 g of acetic acid (AR) to neutralize the basic catalyst to obtain the two-block "ethylenediamine polyoxyethylene ether";

[0037] Mix 128 g of dimethyl silicone oil and 1.8 g of acetic acid and add them to Reactor B, control the temperature at 100 - 120 °C; evacuate for polymerization reaction, keep for about 2 h, add the "ethylenediamine polyoxyethylene ether" prepared in Reactor A, keep for about 2 h, and after the block polymerization reaction is completed, add 1.2 g of sodium hydroxide to neutralize acetic acid to obtain the organosilicon-modified ethylenediamine polyoxyethylene ether product;

[0038] Dissolve 1 g of polyaluminum chloride and 1.4 g of cetyltrimethylammonium bromide in 128 g of ethylene glycol, stir until completely dissolved, add it to the organosilicon-modified ethylenediamine polyether demulsifier synthesized in Step 2, and stir evenly;

[0039] Add 220 g of n-pentane to the mixture in Step (3), stir evenly, and the preparation is completed.

[0040] Comparative Example 2 (without adding PAC)

[0041] Take 188 g of octadeceneamine and 1.4 g of sodium hydroxide (AR) and add them to Reactor A. First, evacuate and replace with dry nitrogen twice; turn on the stirrer and heat up to 125 - 135 °C, slowly introduce ethylene oxide into the reactor with nitrogen, and control the polymerization pressure at 0.20 ± 0.01 MPa; keep for about 2 h, and then slowly introduce ethylene oxide into the reactor with nitrogen for the second time; control the polymerization pressure at 0.31 ± 0.01 MPa and keep for about 2 h. After the reaction is completed, add 2.5 g of acetic acid (AR) to neutralize the basic catalyst to obtain the two-block "octadeceneamine polyoxyethylene ether";

[0042] 128 g of dimethyl silicone oil and 1.8 g of acetic acid are mixed and added to reactor B, and the temperature is controlled at 100 - 120 °C; vacuum is pumped for polymerization reaction for about 2 h, then the "octadeceneamine polyoxyethylene ether" prepared in reactor A is added and kept for about 2 h. After the block polymerization reaction is completed, 1.2 g of sodium hydroxide is added to neutralize acetic acid, and the organosilicon-modified octadeceneamine polyoxyethylene ether product is obtained;

[0043] Dissolve 1.4 g of cetyltrimethylammonium bromide in 128 g of ethylene glycol, stir until completely dissolved, and add it to the organosilicon-modified octadeceneamine polyether demulsifier synthesized in step 2, and stir evenly;

[0044] Add 220 g of n-pentane to the mixture in step (3) and stir evenly to complete the preparation.

[0045] Comparative Example 3 (without adding n-pentane)

[0046] Take 188 g of octadeceneamine and 1.4 g of sodium hydroxide (AR) and add them to reactor A. First, pump vacuum and displace with dry nitrogen 2 times; turn on the stirrer and heat up to 125 - 135 °C, and slowly introduce ethylene oxide into the reactor with nitrogen, controlling the polymerization pressure at 0.20 ± 0.01 MPa; keep for about 2 h, and then slowly introduce ethylene oxide into the reactor with nitrogen for the second time; control the polymerization pressure at 0.31 ± 0.01 MPa and keep for about 2 h. After the reaction is completed, add 2.5 g of acetic acid (AR) to neutralize the basic catalyst to obtain the two-block "octadeceneamine polyoxyethylene ether";

[0047] 128 g of dimethyl silicone oil and 1.8 g of acetic acid are mixed and added to reactor B, and the temperature is controlled at 100 - 120 °C; vacuum is pumped for polymerization reaction for about 2 h, then the "octadeceneamine polyoxyethylene ether" prepared in reactor A is added and kept for about 2 h. After the block polymerization reaction is completed, 1.2 g of sodium hydroxide is added to neutralize acetic acid, and the organosilicon-modified octadeceneamine polyoxyethylene ether product is obtained;

[0048] Dissolve 1 g of polyaluminum chloride and 1.4 g of cetyltrimethylammonium bromide in 128 g of ethylene glycol, stir until completely dissolved, and add it to the organosilicon-modified octadeceneamine polyether demulsifier synthesized in step 2, and stir evenly;

[0049] Add 220 g of methanol to the mixture in step (3) and stir evenly to complete the preparation.

[0050] Comparative Example 4 (without adding cetyltrimethylammonium bromide)

[0051] 188 g of octadecylamine and 1.4 g of sodium hydroxide (AR) were added to reactor A. First, the reactor was evacuated and purged with dry nitrogen twice. The stirring was turned on and the temperature was raised to 125 - 135 °C. Ethylene oxide was slowly introduced into the reactor with nitrogen, and the polymerization pressure was controlled at 0.20 ± 0.01 MPa. This was maintained for about 2 h. Then, ethylene oxide was slowly introduced into the reactor again with nitrogen for the second time. The polymerization pressure was controlled at 0.31 ± 0.01 MPa and maintained for about 2 h. After the reaction was completed, 2.5 g of acetic acid (AR) was added to neutralize the basic catalyst, and the two-block "octadecylamine polyoxyethylene ether" was obtained.

[0052] 128 g of dimethyl silicone oil and 1.8 g of acetic acid were mixed and added to reactor B. The temperature was controlled at 100 - 120 °C. The reactor was evacuated for polymerization reaction and maintained for about 2 h. Then, the "octadecylamine polyoxyethylene ether" prepared in reactor A was added and maintained for about 2 h. After the block polymerization reaction was completed, 1.2 g of sodium hydroxide was added to neutralize acetic acid, and the organosilicon-modified octadecylamine polyoxyethylene ether product was obtained.

[0053] 1 g of polyaluminum chloride was dissolved in 128 g of ethylene glycol. After stirring until completely dissolved, it was added to the organosilicon-modified octadecylamine polyether demulsifier synthesized in step 2 and stirred evenly.

[0054] 220 g of n-pentane was added to the mixture in step (3) and stirred evenly to complete the preparation.

[0055] For the detection of the demulsification performance of the examples and comparative examples in this patent, the petroleum and natural gas industry standard SY / T5281 - 2000 (bottle test method) was adopted. The oily wastewater selected for the test was the wastewater from the coal chemical industry (wastewater source: Xinjiang Tianyu Coal Chemical Group Co., Ltd.). The comparative data of the demulsification performance detection are shown in the following table:

[0056]

[0057]

[0058] As can be seen from the above table, the demulsification performance of Example 1 is excellent compared with Comparative Examples 1, 2, 3, and 4. The oil content can reach 41 ppm at 90 min. The separation effects of the ammonia nitrogen, total phenol, suspension, and COD indexes of Example 1 are also significantly better than those of the comparative examples. Therefore, the special demulsifier for coal chemical industry wastewater of the present invention has high and significant demulsification performance and can greatly reduce the indexes such as COD and ammonia nitrogen.

Claims

1. A preparation method of a demulsifier for low oil content coal coking wastewater, characterized in that, The steps are as follows: Step 1: Take octadecene amine and sodium hydroxide and add them into reactor A. Slowly introduce ethylene oxide into reactor A with nitrogen. After the reaction is completed, add acetic acid to neutralize the basic catalyst to obtain a two-block "octadecene amine polyoxyethylene ether". Step 2: Add dimethyl silicone oil and acetic acid into reactor B, evacuate to carry out a polymerization reaction, add the "octadecene amine polyoxyethylene ether" prepared in reactor A, and neutralize acetic acid with sodium hydroxide after the block polymerization reaction is completed to obtain a demulsifier of organosilicon-modified octadecene amine polyoxyethylene ether. Step 3: Dissolve polyaluminum chloride and cetyltrimethylammonium bromide in ethylene glycol, stir until completely dissolved, and add it to the demulsifier of organosilicon-modified octadecene amine polyoxyethylene ether synthesized in Step 2, and stir evenly. Step 4: Add n-pentane to the mixture in Step 3 and stir evenly to complete the preparation.

2. The preparation method of a demulsifier for low oil content coal coking wastewater according to claim 1, characterized in that: In the "octadecene amine polyoxyethylene ether" obtained in Step 1, m(octadecene amine):m(sodium hydroxide):m(ethylene oxide)=(90 - 100):0.7:

16.

3. The preparation method of a demulsifier for low oil content coal coking wastewater according to claim 2, characterized in that: In the demulsifier of organosilicon-modified octadecene amine polyoxyethylene ether obtained in Step 2, m(octadecene amine polyoxyethylene ether):m(dimethyl silicone oil):m(acetic acid)=(100 - 120):64:0.

9.

4. The preparation method of a demulsifier for low oil content coal coking wastewater according to claim 3, characterized in that: In the mixture obtained in Step 3, m(organosilicon-modified octadecene amine polyoxyethylene ether):m(ethylene glycol):m(polyaluminum chloride):m(cetyltrimethylammonium bromide)=(160 - 180):64:0.5:0.

7.

5. The preparation method of a demulsifier for low oil-content coal coking wastewater according to claim 4, characterized in that: In the product obtained in Step 4, m(mixture):m(n-pentane)=(200 - 240):

110.

6. The preparation method of a demulsifier for low oil-content coking wastewater according to any one of claims 1-5, characterized in that: In Step 1, take octadecene amine and sodium hydroxide and add them into reactor A. First, evacuate and displace with dry nitrogen 2 times; stir and heat up to 125 - 135 °C, slowly introduce ethylene oxide into the reactor with nitrogen, control the polymerization pressure at 0.20 ± 0.01 MPa; hold for 2 h, and then slowly introduce ethylene oxide into the reactor with nitrogen for the second time; control the polymerization pressure at 0.31 ± 0.01 MPa and hold for 2 h. After the reaction is completed, add acetic acid to neutralize the basic catalyst.

7. The preparation method of a demulsifier for low oil content coal coking wastewater according to claim 6, characterized in that: In Step 2, add dimethyl silicone oil and acetic acid into reactor B, control the temperature at 100 - 120 °C; evacuate to carry out a polymerization reaction and hold for 2 h, add the "octadecene amine polyoxyethylene ether" prepared in reactor A and hold for 2 h.

8. A demulsifier for low oil content coal coking wastewater, characterized in that: Prepared by the method according to any one of claims 1 - 7.

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