An oil-removing material, its preparation method and application

Abstract

An embodiment of the present invention discloses an oil removal material, a preparation method thereof and an application. The method includes: tetraethyl orthosilicate, iron acetate, and magnesium acetate are subjected to hydrolysis and condensation reactions in the presence of a solvent and hydrochloric acid to form a transparent sol, and the sol is subjected to vacuum freeze-drying and grinding treatments to obtain a powder; the powder, water, and cetyltrimethylammonium chloride are subjected to a hydrothermal reaction in a high-pressure reaction kettle to obtain a hydrothermal product; the hydrothermal product is subjected to centrifugal separation and washing, and then calcined at 500-600 °C to obtain the oil removal material. The material provided by the present invention has good thermal stability, a large specific surface area, a high adsorption capacity, can be regenerated and recycled multiple times, is particularly suitable for oil removal and purification of recovered ammonia water in the coal chemical industry, and has potential industrial application prospects.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of coal chemical industry ammonia water recovery and oil removal, and particularly to an oil removal material, a preparation method thereof and an application thereof. Background Art

[0002] In the coal chemical industry, the recovery of ammonia water is of great significance because ammonia water is not only a valuable chemical, but also pollutes the environment if not properly treated. Common ammonia water recovery technologies include ammonia stripping method, distillation method, absorption method, membrane separation method, ion exchange method, etc. The ammonia water generated in the coal chemical process usually comes from the gasification of coal, the production of synthetic ammonia, and the processing of other by-products. Some oil substances may be mixed in these processes, resulting in the chromaticity, slag content, etc. of the ammonia water not meeting the recovery standards, significantly affecting the quality of the recovered ammonia water. If the ammonia water cannot be effectively reused, it will not only cause waste of resources, but also increase the cost of backend hazardous waste treatment. At present, the main oil removal materials on the market, such as resins, are mostly used for oil removal under acidic conditions, and the adsorption capacity will be significantly reduced under alkaline conditions. Therefore, it is of great application value to develop an oil removal adsorption material suitable for high pH conditions in the ammonia water medium system.

[0003] The patent "Oil Removal Material for Treating Coking Surplus Ammonia Water and Its Preparation and Use Method" published in CN117244515A prepares sulfide by directly reacting sulfur and edible oil, and further stirs it with coke powder and asphalt at 140 - 180 °C for preparation. This material has the characteristics of high surface area and low specific gravity, has an affinity for tar in coking surplus ammonia water, meets the use requirements of factories for treating coking surplus ammonia water, and can be regenerated and reused. However, the oil removal rate of this material generally does not exceed 80%, and the effect of deep oil removal for ammonia water is still limited.

[0004] The patent "Preparation Method of a Carboxylated Ferric Tetroxide - Polyamidine Composite Oil Removal Material" in CN109364895B discloses a preparation method of a carboxylated ferric tetroxide - polyamidine composite oil removal material. This material is a composite of carboxylated ferric tetroxide - polyamidine, and mainly self - assembles through electrostatic attraction and hydrogen bonding between the large amount of positive charges carried by polyamidine and carboxylated ferric tetroxide, has a good adsorption effect on negatively charged petroleum particles in petroleum wastewater, and can achieve rapid oil - water separation through an external magnetic field. Since this adsorption and oil removal process utilizes electrostatic adsorption, this material is only applicable to negatively charged petroleum particles, and the range of removal of oil - containing substances will be limited.

[0005] "A System and Method for Treating Wastewater Containing Complex Organic Pollutants and Ammonia Nitrogen" disclosed in Patent CN112047550A uses an adsorption reaction and high-efficiency separation unit, a phenol recovery unit, and an ammonia recovery unit connected in sequence to remove oils and suspended solids in the wastewater. The oil-removing powder adsorbent used is powdered activated carbon or diatomaceous earth with a particle size of 100 mesh to 300 mesh, and resin is used at the back end to deeply remove phenolic substances therein. However, since the powdered activated carbon or diatomaceous earth used does not have specific adsorption for oil, it may cause a decrease in the ammonia water concentration, resulting in the loss of ammonia water, and the depth of oil adsorption by such adsorbents is limited. Summary of the Invention

[0006] To this end, an embodiment of the present invention provides an oil-removing material, its preparation method and application. This material uses tetraethyl orthosilicate, iron acetate, and magnesium acetate as precursors, and undergoes hydrolysis and condensation reactions in a solvent and hydrochloric acid (as a catalyst) medium system, and then undergoes hydrothermal modification under the action of cetyltrimethylammonium chloride (as a template agent) in a high-pressure reaction kettle, and finally is calcined and formed. This material has good thermal stability, a large specific surface area, a high adsorption capacity, and can be regenerated and recycled multiple times. It is particularly suitable for the oil removal and purification of ammonia water recovery in the coal chemical industry and has potential industrial application prospects.

[0007] To achieve the above object, the embodiment of the present invention provides the following technical solutions:

[0008] According to the first aspect of the embodiment of the present invention, the present invention provides a preparation method of an oil-removing material, and the method includes the following steps:

[0009] (1) Tetraethyl orthosilicate, iron acetate, and magnesium acetate undergo hydrolysis and condensation reactions in the presence of a solvent and hydrochloric acid to form a transparent sol, and the sol is subjected to vacuum freeze-drying and grinding to obtain a powder;

[0010] (2) The powder, water, and cetyltrimethylammonium chloride are subjected to hydrothermal reaction in a high-pressure reaction kettle to obtain a hydrothermal product;

[0011] (3) The hydrothermal product is centrifuged, washed, and then calcined at 500 - 600 °C to obtain the oil-removing material.

[0012] Further, in step (1), the molar ratio of tetraethyl orthosilicate, iron acetate, and magnesium acetate is 10:1 - 2:0.5 - 1;

[0013] The solvent is ethanol, and the volume ratio of the solvent to tetraethyl orthosilicate is 20 - 100:1;

[0014] The concentration of the hydrochloric acid is 0.5 - 3 mol / L, and the volume ratio of the hydrochloric acid to the solvent is 1:15 - 30;

[0015] The temperature of the hydrolysis and condensation reaction is 10~50 °C, and the time is 1~3 h;

[0016] The conditions of the vacuum freeze-drying are: temperature -30 °C~-20 °C, vacuum degree 5~10 Pa, and time 12~24 h;

[0017] The particle size of the powder is 30~150 μm.

[0018] Furthermore, in step (2), the solid-liquid ratio of the powder to water is 1~4:10, and the solid-liquid ratio of cetyltrimethylammonium chloride to water is 2~5:100;

[0019] The temperature of the hydrothermal reaction is 180~220 °C, and the time is 2~4 h.

[0020] Furthermore, in step (3), the solvents used for washing are deionized water and ethanol;

[0021] The calcination time is 2~5 h.

[0022] According to the second aspect of the embodiments of the present invention, the present invention provides an oil removal material which is made by the method described in any one of the above.

[0023] According to the third aspect of the embodiments of the present invention, the present invention provides the application of the above-mentioned oil removal material in the oil removal treatment of ammonia water recovery in the coal chemical industry.

[0024] According to the fourth aspect of the embodiments of the present invention, the present invention provides an oil removal method for ammonia water recovery in the coal chemical industry, and the method includes:

[0025] The oil-containing ammonia water and the above-mentioned oil removal material enter the oil removal reaction unit for an adsorption reaction to obtain a mixed liquid;

[0026] The mixed liquid enters the solid-liquid separation unit for solid-liquid separation to obtain the oil-absorbed material and the oil-removed ammonia water;

[0027] The oil-absorbed material enters the regeneration unit to carry out a desorption reaction with the regeneration liquid, and the obtained regenerated material returns to the oil removal reaction unit for reuse.

[0028] Furthermore, the mass ratio of the oil content in the oil-containing ammonia water to the oil removal material is 1:10~50, and the hydraulic retention time of the oil removal reaction unit is 1~3 h.

[0029] Furthermore, the solid-liquid separation includes centrifugal separation or ceramic membrane filtration, wherein the rotation speed of the centrifugal separation is 1000~3000 rpm / min, and the pore size of the ceramic membrane is 0.5~5 μm.

[0030] Further, the solid-liquid ratio of the oil-absorbed material to the regeneration liquid is 1:5 to 20;

[0031] The regeneration liquid is ethanol with a volume fraction of more than 98%, and the temperature of the desorption reaction is 20 to 40 °C; or, the regeneration liquid is an aqueous sodium hydroxide solution with a mass fraction of 3% to 5%, and the temperature of the desorption reaction is 60 to 80 °C.

[0032] The embodiments of the present invention have the following advantages:

[0033] (1) The material provided by the present invention has a relatively high specific surface area, which can reach 32 to 45 m 2 / g. In the oil adsorption and removal reaction, it can provide more active sites for adsorption reaction, and the adsorption capacity > 20 mg / g (oil / material).

[0034] (2) The material provided by the present invention can effectively remove oil from ammonia water under high pH conditions, and the oil content in ammonia water can be reduced to less than 2 ppm, overcoming the disadvantage that general oil removal materials are only suitable for oil removal under lower pH conditions.

[0035] (3) The material provided by the present invention has good chemical stability, does not react with ammonia water, does not introduce impurities during the adsorption process, and will not cause a decrease in the concentration of ammonia water. It is a specific adsorption and oil removal process, avoiding the problem of secondary pollution of ammonia water during the oil removal process.

[0036] (4) The material provided by the present invention can be regenerated using ethanol or a hot sodium hydroxide solution, can be used multiple times, has a low cost, and is suitable for engineering applications. Description of the Drawings

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only exemplary, and for those of ordinary skill in the art, other implementation drawings can be obtained based on the provided drawings without creative efforts.

[0038] Figure 1 It is the process flow diagram of oil removal for ammonia water recovery in the coal chemical industry provided by the present invention. Detailed Embodiments

[0039] The following specific embodiments illustrate the implementation manners of the present invention. Those familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] Example 1

[0041] This example provides an oil removal material, and its preparation method includes the following steps:

[0042] (1) Add 10 ml of tetraethyl orthosilicate, 0.86 g of iron acetate, and 0.64 g of magnesium acetate (the molar ratio of Si, Fe, and Mg is 10:1:1) to 1 L of ethanol. Subsequently, slowly add 50 ml of 1 mol / L hydrochloric acid, stir at 40 °C for 2 h, transfer the formed transparent sol to a vacuum freeze dryer, and dry it at -20 °C and 5 Pa for 24 h. Grind it thoroughly to obtain a powder with a particle size of 30 - 150 μm.

[0043] (2) Transfer 30 g of the powder obtained in step (1) to a high-pressure reactor with an effective volume of 200 ml, add 150 ml of water for mixing, and then add 4.5 g of cetyltrimethylammonium chloride (CTAC). After the reactor reacts at 200 °C for 2 h, it is naturally cooled.

[0044] (3) Centrifuge the product after the hydrothermal reaction, wash it three times with deionized water and ethanol respectively, with a dosage of 100 ml each time, and then calcine it in a muffle furnace at 550 °C for 4 hours to obtain the oil removal material.

[0045] Example 2

[0046] This example provides an oil removal material, and its preparation method includes the following steps:

[0047] (1) Add 10 ml of tetraethyl orthosilicate, 0.86 g of iron acetate, and 0.32 g of magnesium acetate according to (the molar ratio of Si, Fe, and Mg is 10:1:0.5) to 1 L of ethanol. Subsequently, slowly add 65 ml of 1.5 mol / L hydrochloric acid, stir thoroughly at 40 °C for 3 h, transfer the formed transparent sol to a vacuum freeze dryer, and dry it at -20 °C and 5 Pa for 24 h. Grind it thoroughly to obtain a powder with a particle size of 30 - 150 μm.

[0048] (2) Transfer 30 g of the powder obtained in step (1) to a high-pressure reactor with an effective volume of 200 ml, add 150 ml of water for mixing, and then add 3.2 g of cetyltrimethylammonium chloride (CTAC). After the reactor reacts at 220 °C for 2 h, it is naturally cooled.

[0049] (3) Centrifuge the product after the hydrothermal reaction, wash it three times with deionized water and ethanol respectively, with a dosage of 100 ml each time, and then calcine it in a muffle furnace at 550 °C for 4 hours to obtain the oil removal material.

[0050] Example 3

[0051] This embodiment provides an oil removal material, and its preparation method includes the following steps:

[0052] (1) Add 10 ml of tetraethyl orthosilicate, 1.29 g of iron acetate, and 0.32 g of magnesium acetate (with a molar ratio of Si, Ca, and Mg of 10:1.5:0.5) to 1 L of ethanol. Subsequently, slowly add 50 ml of 1 mol / L hydrochloric acid, and stir thoroughly at 40 °C for 2 h. Transfer the formed transparent sol to a vacuum freeze dryer, and dry it at -20 °C and 5 Pa for 24 h. Grind it thoroughly to obtain a powder with a particle size of 30 - 150 μm.

[0053] (2) Transfer 30 g of the powder obtained in step (1) to a high-pressure reactor with an effective volume of 200 ml, add 150 ml of water for mixing, and then add 6.0 g of cetyltrimethylammonium chloride (CTAC). After the reactor reacts at 200 °C for 2 h, cool it naturally.

[0054] (3) Centrifuge the product after the hydrothermal reaction, wash it three times with deionized water and ethanol respectively, with a dosage of 100 ml each time, and then calcine it in a muffle furnace at 550 °C for 4 h to obtain the oil removal material.

[0055] Comparative Example 1

[0056] This comparative example provides an oil removal material, and the difference in its preparation method from that of Example 1 is only that in step (1), 50 ml of 1 mol / L nitric acid is used to replace 50 ml of 1 mol / L hydrochloric acid.

[0057] Comparative Example 2

[0058] This comparative example provides an oil removal material, and the difference in its preparation method from that of Example 1 is only that in step (2), an equal amount of dodecyltrimethylammonium bromide (DTAB) is used to replace cetyltrimethylammonium chloride (CTAC).

[0059] Comparative Example 3

[0060] This comparative example provides an oil removal material, and the difference in its preparation method from that of Example 1 is only that in step (3), it is calcined in a muffle furnace at 300 °C for 4 h.

[0061] Test Example 1

[0062] Test the specific surface area (BET) and adsorption effect of the oil removal materials of Examples 1 - 3 and Comparative Examples 1 - 3.

[0063] Among them, the specific surface area is tested using a BET analyzer (Autosorb-iQ from Quantachrome).

[0064] Calculation formula:

[0065]

[0066] Where:

[0067] S represents the specific surface area of the substance, with the unit of m 2 / g;

[0068] V m represents the monolayer adsorption gas capacity, which represents the amount of gas that can be adsorbed on the surface of the substance under specific conditions;

[0069] A m represents the cross-sectional area of nitrogen molecules in liquid hexagonal close packing at 77K temperature, with a value of 16.2×10 -20 m 2 ;

[0070] NA represents Avogadro's constant, which represents the number of particles contained in each mole of substance, with a value of 6.022×10 23 .

[0071] Based on the multi-molecular layer adsorption theory, the BET analyzer can calculate the monolayer adsorption gas capacity V m by measuring the amount of adsorbed gas at different pressures, and then calculate the specific surface area S using the above formula.

[0072] The test conditions for the oil removal adsorption capacity (mg / g) are as follows: Using n-hexadecane dissolved in concentrated ammonia water as the simulated solution (oil content 100 mg / L, ammonia water concentration 25%, pH 12) as the experimental medium, the dosage of the oil removal material is 1 g / L, and the adsorption reaction is carried out at room temperature (25°C) for 2h.

[0073] Calculate according to Q = V(C0 - C) / m, where Q: adsorption capacity (mg / g); V: volume of the reaction solution (L); C0: initial oil concentration in the solution (mg / L); C: oil concentration in the solution after the reaction (mg / L); m: dosage of the oil removal material (g).

[0074] The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] The results show that the oil removal materials provided in Examples 1-3 of the present invention have a more excellent specific surface area and oil removal adsorption capacity, indicating that during the preparation process of the composite material, hydrochloric acid is selected as the catalyst, CTAC is used as the template agent, and calcination is carried out at a certain temperature, which can provide more effective oil removal active sites on the material surface, facilitating the improvement of the binding effect between the material surface and oil, and further enhancing the lipophilic property of the material surface.

[0078] Test Example 2

[0079] The recycled ammonia water provided by a coal chemical enterprise was subjected to oil removal. The ammonia mass fraction of this water sample was 22%, the pH was 12.4, and the oil content was 55.2 mg / L.

[0080] The following steps were taken to conduct an ammonia water oil removal test using the oil removal material of Example 1: Pump 10 L of oil-containing ammonia water into the oil removal reaction tank, add 20 g of the oil removal material, so that the concentration of the oil removal material reaches 2 g / L. After mechanical stirring for 3 h, solid-liquid separation was carried out using a centrifuge at a centrifugal speed of 1500 rpm / min for 10 min. The liquid obtained after centrifugation was the ammonia water after oil removal. The ammonia mass fraction was 22%, the oil content was reduced to 0.9 ppm, and the oil removal rate was 98.4%. The separated solid material entered the regeneration reaction tank, 0.25 L of ethanol (volume fraction 99%, temperature 25°C) was introduced for mixing and stirring for desorption for 1 h, and then solid-liquid separation was carried out again. The adsorption material was regenerated and could enter the adsorption material storage tank for reuse. The regeneration liquid was recycled 3 times and then discharged as wastewater.

[0081] Test Example 3

[0082] The recycled ammonia water provided by a coal chemical enterprise was subjected to oil removal. The ammonia mass fraction of this water sample was 20%, the pH was 12, and the oil content was 104.8 mg / L.

[0083] The following steps were taken to conduct an ammonia water oil removal test using the oil removal material of Example 2: Pump 10 L of oil-containing ammonia water into the oil removal reaction tank, add 40 g of the oil removal material, so that the concentration of the oil removal material reaches 4 g / L. After mechanical stirring for 2 h, solid-liquid separation was carried out using a ceramic membrane (pore size 2 μm). The produced water after separation was the ammonia water after oil removal. The ammonia mass fraction was 20%, the oil content was reduced to 1.5 ppm, and the oil removal rate was 98.6%. The separated solid material entered the regeneration reaction tank, 0.8 L of sodium hydroxide solution (mass fraction 5%, temperature 70°C) was introduced for mixing and stirring for desorption for 1 h, and then solid-liquid separation was carried out again. The adsorption material was regenerated and could enter the adsorption material storage tank for reuse. The alkali solution was recycled 3 times and then discharged as wastewater.

[0084] Test Example 4

[0085] The recovered ammonia water provided by a coal chemical enterprise is degreased. The ammonia mass fraction of this water sample is 20.5%, the pH is 12.2, and the oil content is 170.5 mg / L.

[0086] The degreasing material of Example 3 is used for the ammonia water degreasing test. The steps are as follows: 20 L of oil-containing ammonia water is pumped into the degreasing reaction tank, and 160 g of degreasing material is added. The concentration of the degreasing material reaches 8 g / L. After mechanical stirring for 3 h, solid-liquid separation is carried out by a centrifuge at a centrifugal speed of 1000 rpm / min for 10 min. The liquid obtained after centrifugation is the degreased ammonia water. The ammonia mass fraction is 20.5%, the oil content is reduced to 1.8 ppm, and the degreasing rate is 98.9%. The separated solid material enters the regeneration reaction tank, and 2 L of ethanol (volume fraction 99%, temperature 25°C) is introduced for mixing and stirring for desorption. The desorption time is 1 h, and solid-liquid separation is carried out again. The adsorption material is regenerated and can enter the adsorption material storage tank for reuse. The regeneration liquid is recycled 3 times and then discharged as wastewater.

[0087] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A method for preparing an oil removal material, characterized in that: The method comprises the following steps: (1) tetraethyl orthosilicate, ferric acetate and magnesium acetate are subjected to hydrolysis and condensation reaction in the presence of a solvent and hydrochloric acid to form a transparent sol, and the sol is subjected to vacuum freeze-drying and grinding to obtain a powder; (2) the powder is subjected to a hydrothermal reaction with water and hexadecyltrimethylammonium chloride in a high-pressure reactor to obtain a hydrothermal product; (3) The hydrothermal product is centrifuged and washed, and then calcined at 500-600° C. to obtain the degreasing material.

2. The method for preparing the oil removal material according to claim 1, characterized in that: In step (1), The molar ratio of tetraethyl orthosilicate, ferrous acetate and magnesium acetate is 10:1-2:0.5-1; The solvent is ethanol, and the volume ratio of the solvent to tetraethyl orthosilicate is 20-100:1; The concentration of the hydrochloric acid is 0.5-3 mol / L, and the volume ratio of the hydrochloric acid to the solvent is 1:15-30; The temperature of the hydrolysis and condensation reaction is 10-50°C and the time is 1-3h; The vacuum freeze drying conditions are: temperature -30°C to -20°C, vacuum degree 5 to 10Pa, and time 12 to 24h; The particle size of the powder is 30-150 μm.

3. The method for preparing the oil removal material according to claim 1, characterized in that: In step (2), The solid-liquid ratio of the powder to water is 1-4 g:10 ml, and the solid-liquid ratio of hexadecyltrimethylammonium chloride to water is 2-5 g:100 ml; The temperature of the hydrothermal reaction is 180-220° C. and the time is 2-4 hours.

4. The method for preparing the oil removal material according to claim 1, characterized in that: In step (3), The solvents used for the washing are deionized water and ethanol; The calcination time is 2 to 5 hours.

5. A degreasing material, characterized in that: It is made by the method according to any one of claims 1-4.

6. Use of the oil removal material according to claim 5 in the oil removal process of ammonia water recovery in the coal chemical industry.

7. A deoiling method for recovering ammonia water in the coal chemical industry, characterized in that: The method comprises: The oil-containing ammonia water and the oil removal material as claimed in claim 5 enter the oil removal reaction unit for adsorption reaction to obtain a mixed liquid; The mixed liquid enters the solid-liquid separation unit for solid-liquid separation to obtain the oil-absorbed material and the oil-removed ammonia water; The oil-absorbed material enters the regeneration unit to undergo a desorption reaction with the regeneration liquid, and the resulting regenerated material returns to the oil removal reaction unit for reuse.

8. The deoiling method for recovering ammonia water in the coal chemical industry according to claim 7, characterized in that: The mass ratio of the oil content in the oil-containing ammonia water to the oil removal material is 1:10-50, and the hydraulic retention time of the oil removal reaction unit is 1-3 hours.

9. The deoiling method for recovering ammonia water in the coal chemical industry according to claim 7, characterized in that: The solid-liquid separation includes centrifugal separation or ceramic membrane filtration, wherein the rotation speed of the centrifugal separation is 1000-3000 rpm and the pore size of the ceramic membrane is 0.5-5 μm.

10. The deoiling method for recovering ammonia water in the coal chemical industry according to claim 7, characterized in that: The solid-to-liquid ratio of the oil-absorbed material to the regenerated liquid is 1:5-20; The regeneration liquid is ethanol with a volume fraction of more than 98%, and the temperature of the desorption reaction is 20-40°C; or, the regeneration liquid is a sodium hydroxide aqueous solution with a mass fraction of 3%-5%, and the temperature of the desorption reaction is 60-80°C.

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