A deep fluorine removal agent for coking wastewater treatment and a preparation method thereof

Abstract

The present application relates to a kind of deep fluorine removal agent for coking wastewater treatment and its preparation method, belong to fluorine removal agent technical field, the fluorine removal agent is according to the following mass fraction of component composition: polymeric ferric sulfate 20%-30%, polyaluminum chloride 20%-30%, oxalic acid modified montmorillonite load aluminium sulfide 26%-48%, cerium dioxide modified ethylenediaminetetraacetic acid disodium hydrogel 3%-5%, carbon powder 3%-10%, calcium chloride 2%-5%, dimethyl diallyl ammonium chloride 1%-4%.In the application of coking wastewater fluorine removal, the concentration of fluoride in water can be efficiently reduced.

Description

Technical Field

[0001] This invention belongs to the field of defluorinating agent technology, specifically, it relates to a deep defluorinating agent for coking wastewater treatment and its preparation method. Background Technology

[0002] Coking wastewater primarily originates from residual ammonia water from coke ovens and from coal gas refining processes and subsequent deep processing. This wastewater is characterized by high organic content, deep color, and a high concentration of harmful and recalcitrant substances, classifying it as high-concentration, recalcitrant organic wastewater. After biological treatment, the fluoride levels do not meet discharge standards, necessitating further treatment. Defluoridation processes are incorporated into both advanced coking wastewater treatment and zero-discharge projects. During zero-discharge wastewater treatment, fluoride significantly contributes to scaling on reverse osmosis membranes. Therefore, developing highly efficient defluoridating agents is crucial. Summary of the Invention

[0003] The purpose of this invention is to provide a deep defluorinating agent for treating coking wastewater.

[0004] The technical problem to be solved by this invention is that the defluorination performance of traditional deep defluorinating agents used for coking wastewater treatment is poor.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides a deep defluoridation agent for treating coking wastewater, comprising the following components by weight: 20%-30% polyferric sulfate, 20%-30% polyaluminum chloride, 26%-48% oxalic acid-modified montmorillonite-supported aluminum sulfide, 3%-5% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 3%-10% charcoal powder, 2%-5% calcium chloride, and 1%-4% dimethyl diallyl ammonium chloride.

[0007] The preparation method of the deep defluorination agent for coking wastewater treatment specifically includes the following steps:

[0008] (1) Add montmorillonite to deionized water, disperse it by ultrasonication, then add anhydrous oxalic acid to the suspension, stir the suspension on a magnetic stirrer, modify montmorillonite by acid etching, dry and grind the solid obtained from the suspension by filtration, and obtain oxalic acid modified montmorillonite.

[0009] (2) Aluminum sulfide was placed in oxygen-free deionized water, sealed, and magnetically stirred in a 60°C water bath for 60 min to obtain a suspension. Oxalic acid-modified montmorillonite was added to the suspension under a nitrogen atmosphere, and the mixture was sealed and stirred for further reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain oxalic acid-modified montmorillonite-supported aluminum sulfide.

[0010] (3) Add cerium dioxide powder to an aqueous solution of disodium ethylenediaminetetraacetate and sonicate it to disperse it evenly to obtain a mixed solution. Add the solution to a quartz reaction bottle, seal it, and place it in a microwave reactor to react at a certain temperature to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel.

[0011] (4) Weigh out the polyferric sulfate, polyaluminum chloride, oxalic acid-modified montmorillonite-supported aluminum sulfide, cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, carbon powder, calcium chloride, and dimethyl diallyl ammonium chloride according to the corresponding mass proportions, and mix them together in a mixer to obtain a deep defluorination agent.

[0012] Further, in step (1), the mass ratio of montmorillonite, deionized water, and anhydrous oxalic acid is 2-4:200-250:0.09-0.12g, the ultrasonic dispersion time is 30-45min, and the stirring time is 30-40min.

[0013] Furthermore, in step (2), the mass ratio of aluminum sulfide, oxygen-free deionized water, and oxalic acid-modified montmorillonite is 1.5-3.0:100-150:1.5-3.0g, and the stirring reaction time is 30-40min.

[0014] Furthermore, in step (3), the mass ratio of cerium dioxide powder to disodium ethylenediaminetetraacetate aqueous solution is 1-10:40-80g, the microwave reaction temperature is 90-100℃, and the microwave reaction time is 10-30min.

[0015] Furthermore, in step (4), the mixer is a three-dimensional motion mixer with a rotation speed of 10-20 rpm and a mixing time of 3-18 h.

[0016] The beneficial effects of this invention are:

[0017] 1. In the technical solution of this invention, montmorillonite is modified with oxalic acid to make it have a rougher surface, increasing its specific surface area and pore volume. Montmorillonite's unique layered structure can serve as a good loading material. Pure aluminum sulfide tends to aggregate and oxidize, which reduces its specific surface area and ability to react with pollutants. Loading aluminum sulfide onto oxalic acid-modified montmorillonite can avoid agglomeration and low reactivity, and can efficiently remove fluorides. The preparation process of this defluorinating agent is simple and quick.

[0018] 2. In the technical solution of this invention, when the pH is 6.5-7, it is a weakly acidic environment. The surface of the oxalic acid-modified montmorillonite loaded with aluminum sulfide carries a positive charge, which is conducive to the electrostatic adsorption of fluoride ions. Some free aluminum ions can react with fluoride ions to form a complex, which is a chemical adsorption. In summary, the oxalic acid-modified montmorillonite loaded with aluminum sulfide can simultaneously achieve chemical adsorption and electrostatic adsorption, thus accelerating the defluorination rate.

[0019] 3. In the technical solution of this invention, the disodium ethylenediaminetetraacetate hydrogel, after being modified with cerium dioxide, has a high adsorption capacity and selectivity for fluoride ions, thus significantly improving the adsorption effect on fluoride ions. Some of the aluminum ions from the oxalic acid-modified montmorillonite loaded with aluminum sulfide can complex with the cerium dioxide-modified disodium ethylenediaminetetraacetate to form a complex, promoting the complexation of fluoride ions by polyferric sulfate and polyaluminum chloride, accelerating the fluoride removal rate. Another part of the free aluminum ions directly reacts and complexes with fluoride ions, increasing the fluoride removal rate. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0023] (1) Add 2g of montmorillonite to 200g of deionized water and ultrasonically disperse for 30min. Then add 0.09g of anhydrous oxalic acid to the suspension and stir the suspension on a magnetic stirrer for 30min. Modify the montmorillonite by acid etching. Dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite.

[0024] (2) 1.5g of aluminum sulfide was placed in 100g of oxygen-free deionized water, sealed, and magnetically stirred in a 60℃ water bath for 60min to obtain a suspension. Under a nitrogen atmosphere, 1.5g of oxalic acid-modified montmorillonite was added to the suspension, and the mixture was sealed and stirred to continue the reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain oxalic acid-modified montmorillonite-supported aluminum sulfide.

[0025] (3) Add 1g of cerium dioxide powder to 40g of disodium ethylenediaminetetraacetate aqueous solution, sonicate to disperse it evenly, and add the mixed solution to a quartz reaction bottle, seal it, put it into a microwave reactor, and react at 90℃ for 10min to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel.

[0026] (4) Weigh out 20% polyferric sulfate, 20% polyaluminum chloride, 26% oxalic acid-modified montmorillonite-supported aluminum sulfide, 3% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 3% carbon powder, 2% calcium chloride, and 1% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, and use a three-dimensional motion mixer with the mixer speed set to 10 rpm and the mixing time to 3 hours to obtain a deep defluorination agent.

[0027] Example 2

[0028] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0029] (1) Add 2.5g of montmorillonite to 210g of deionized water and ultrasonically disperse for 32min. Then add 0.095g of anhydrous oxalic acid to the suspension and stir the suspension on a magnetic stirrer for 32min to modify the montmorillonite by acid etching. Dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite.

[0030] (2) 1.8g of aluminum sulfide was placed in 105g of oxygen-free deionized water, sealed, and magnetically stirred in a 60℃ water bath for 60min to obtain a suspension. Under a nitrogen atmosphere, 1.8g of oxalic acid-modified montmorillonite was added to the suspension, and the mixture was sealed and stirred to continue the reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain oxalic acid-modified montmorillonite-supported aluminum sulfide.

[0031] (3) Add 2g of cerium dioxide powder to 45g of disodium ethylenediaminetetraacetate aqueous solution, sonicate to disperse it evenly, and add the mixed solution to a quartz reaction bottle, seal it, put it into a microwave reactor, and react at 95℃ for 12min to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel.

[0032] (4) Weigh out 22% polyferric sulfate, 25% polyaluminum chloride, 28% oxalic acid-modified montmorillonite-supported aluminum sulfide, 3.5% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 3.5% carbon powder, 2.5% calcium chloride, and 2% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, and use a three-dimensional motion mixer with the speed of the mixer set to 12 rpm and the mixing time to 5 hours to obtain a deep defluorination agent.

[0033] Example 3

[0034] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0035] (1) Add 3g of montmorillonite to 230g of deionized water and ultrasonically disperse for 38min. Then add 0.1g of anhydrous oxalic acid to the suspension and stir the suspension on a magnetic stirrer for 35min. Modify the montmorillonite by acid etching. Dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite.

[0036] (2) 2.0g of aluminum sulfide was placed in 140g of oxygen-free deionized water, sealed, and magnetically stirred in a 60℃ water bath for 60min to obtain a suspension. Under a nitrogen atmosphere, 2.0g of oxalic acid modified montmorillonite was added to the suspension, and the mixture was sealed and stirred to continue the reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain oxalic acid modified montmorillonite-supported aluminum sulfide.

[0037] (3) Add 8g of cerium dioxide powder to 60g of ethylenediaminetetraacetic acid disodium aqueous solution, sonicate to disperse it evenly, and add the mixed solution to a quartz reaction bottle, seal it, put it into a microwave reactor, and react at 95℃ for 25min to obtain cerium dioxide modified ethylenediaminetetraacetic acid disodium hydrogel.

[0038] (4) Weigh out 28% polyferric sulfate, 28% polyaluminum chloride, 38% oxalic acid-modified montmorillonite-supported aluminum sulfide, 4% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 8% carbon powder, 4% calcium chloride, and 3% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, and use a three-dimensional motion mixer with the mixer speed set to 18 rpm and the mixing time to 15 h to obtain a deep defluorination agent.

[0039] Example 4

[0040] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0041] (1) Add 4g of montmorillonite to 250g of deionized water and ultrasonically disperse for 45min. Then add 0.12g of anhydrous oxalic acid to the suspension and stir the suspension on a magnetic stirrer for 40min. Modify the montmorillonite by acid etching. Dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite.

[0042] (2) 3.0g of aluminum sulfide was placed in 150g of oxygen-free deionized water, sealed, and magnetically stirred in a 60℃ water bath for 60min to obtain a suspension. Under a nitrogen atmosphere, 3.0g of oxalic acid-modified montmorillonite was added to the suspension, and the mixture was sealed and stirred to continue the reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain oxalic acid-modified montmorillonite-supported aluminum sulfide.

[0043] (3) Add 10g of cerium dioxide powder to 80g of disodium ethylenediaminetetraacetate aqueous solution, sonicate to disperse it evenly, and add the mixed solution to a quartz reaction bottle, seal it, put it into a microwave reactor, and react at 100℃ for 30min to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel.

[0044] (4) Weigh out 30% polyferric sulfate, 30% polyaluminum chloride, 48% oxalic acid-modified montmorillonite-supported aluminum sulfide, 5% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 10% carbon powder, 5% calcium chloride, and 4% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, and use a three-dimensional motion mixer with the mixer speed set to 20 rpm and the mixing time to 18 hours to obtain a deep defluorination agent.

[0045] Comparative Example 1

[0046] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0047] (1) 1.5g of aluminum sulfide was placed in 100g of oxygen-free deionized water, sealed, and magnetically stirred in a 60℃ water bath for 60min to obtain a suspension. Under a nitrogen atmosphere, 1.5g of montmorillonite was added to the suspension, and the mixture was sealed and stirred to continue the reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain montmorillonite-supported aluminum sulfide.

[0048] (2) Add 1g of cerium dioxide powder to 40g of disodium ethylenediaminetetraacetate aqueous solution, sonicate to disperse it evenly, and add the mixed solution to a quartz reaction bottle, seal it, put it into a microwave reactor, and react at 90℃ for 10min to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel.

[0049] (3) Weigh out 20% polyferric sulfate, 20% polyaluminum chloride, 26% montmorillonite-supported aluminum sulfide, 3% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 3% carbon powder, 2% calcium chloride, and 1% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, use a three-dimensional motion mixer, set the speed of the mixer to 10 rpm, and the mixing time is 3 hours to obtain a deep defluorination agent.

[0050] Comparative Example 2

[0051] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0052] (1) Add 2g of montmorillonite to 200g of deionized water and ultrasonically disperse for 30min. Then add 0.09g of anhydrous oxalic acid to the suspension and stir the suspension on a magnetic stirrer for 30min. Modify the montmorillonite by acid etching. Dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite.

[0053] (2) Add 1g of cerium dioxide powder to 40g of disodium ethylenediaminetetraacetate aqueous solution, sonicate to disperse it evenly, and add the mixed solution to a quartz reaction bottle, seal it, put it into a microwave reactor, and react at 90℃ for 10min to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel.

[0054] (3) Weigh out 20% polyferric sulfate, 20% polyaluminum chloride, 26% oxalic acid modified montmorillonite, 3% cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel, 3% carbon powder, 2% calcium chloride, and 1% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, and use a three-dimensional motion mixer with the speed of the mixer set to 10 rpm and the mixing time to 3 hours to obtain a deep defluorination agent.

[0055] Comparative Example 3

[0056] A method for preparing a deep defluoridation agent for coking wastewater treatment includes the following steps:

[0057] (1) Add 2g of montmorillonite to 200g of deionized water and ultrasonically disperse for 30min. Then add 0.09g of anhydrous oxalic acid to the suspension and stir the suspension on a magnetic stirrer for 30min. Modify the montmorillonite by acid etching. Dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite.

[0058] (2) Weigh out 20% polyferric sulfate, 20% polyaluminum chloride, 26% oxalic acid modified montmorillonite, 3% disodium ethylenediaminetetraacetate, 3% carbon powder, 2% calcium chloride, and 1% dimethyl diallyl ammonium chloride according to the corresponding mass proportions, mix them together, use a three-dimensional motion mixer, set the speed of the mixer to 10 rpm, and the mixing time is 3 hours to obtain a deep defluorination agent.

[0059] The coking wastewater was selected from the secondary effluent of the biochemical treatment plant at X Coking Plant. Defluoridating agents prepared in Examples 1-4 and Comparative Examples 1-3 were added to the wastewater for experiments. Experimental procedure: 3g of defluoridating agent was dissolved in 50ml of deionized water to prepare a solution. This solution was then added to 1L of coking wastewater to be treated, stirred for 20min, and the pH was measured. If the pH was below 6, the pH was adjusted to 6.5-7 with liquid alkali, and then polyacrylamide aqueous solution was added for flocculation and sedimentation for 2h. The experimental results are shown in Table 1.

[0060] Table 1. Fluoride removal status of secondary sedimentation effluent from the wastewater treatment plant of X coking plant.

[0061]

[0062]

[0063] As shown in Table 1 above, the defluorination rates of the deep defluorinating agents prepared in Examples 1-4 all reached over 95%, indicating that the deep defluorinating agents of the present invention have a high defluorination rate. However, the defluorinating agent of Comparative Example 1 was not modified with oxalic acid, resulting in a poor defluorination rate. The defluorinating agent of Comparative Example 2 was not loaded with aluminum sulfide, leading to a decrease in the defluorination rate. The defluorinating agent in Comparative Example 3 was neither modified with cerium dioxide nor loaded with aluminum sulfide, resulting in a very low defluorination rate.

[0064] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0065] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A deep defluoridation agent for treating coking wastewater, characterized in that, The deep defluorination agent is composed of the following components by mass fraction: 20%-30% polyferric sulfate, 20%-30% polyaluminum chloride, 26%-48% oxalic acid-modified montmorillonite-supported aluminum sulfide, 3%-5% cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, 3%-10% carbon powder, 2%-5% calcium chloride, and 1%-4% dimethyl diallyl ammonium chloride.

2. A method for preparing a deep defluorinating agent for coking wastewater treatment according to claim 1, characterized in that, Includes the following steps: (1) Add montmorillonite to deionized water, disperse it by ultrasonication, then add anhydrous oxalic acid to the suspension, stir the suspension on a magnetic stirrer, modify montmorillonite by acid etching, dry and grind the solid obtained from the suspension to obtain oxalic acid modified montmorillonite. (2) Aluminum sulfide was placed in oxygen-free deionized water, sealed, and magnetically stirred in a 60°C water bath for 60 min to obtain a suspension. Oxalic acid-modified montmorillonite was added to the suspension under a nitrogen atmosphere, and the mixture was sealed and stirred for further reaction. The prepared mixture was centrifuged, and the solid was collected for freeze drying. After drying, the solid was collected and ground, and stored under a nitrogen atmosphere to obtain oxalic acid-modified montmorillonite-supported aluminum sulfide. (3) Add cerium dioxide powder to an aqueous solution of disodium ethylenediaminetetraacetate and sonicate it to disperse it evenly to obtain a mixed solution. Add the solution to a quartz reaction flask, seal it and place it in a microwave reactor. React it at a certain temperature to obtain cerium dioxide modified disodium ethylenediaminetetraacetate hydrogel. (4) Weigh out the corresponding mass fractions of polyferric sulfate, polyaluminum chloride, oxalic acid-modified montmorillonite-supported aluminum sulfide, cerium dioxide-modified disodium ethylenediaminetetraacetate hydrogel, carbon powder, calcium chloride, and dimethyl diallyl ammonium chloride, and mix them together in a mixer to obtain a deep defluorination agent. In step (1), the mass ratio of montmorillonite, deionized water, and anhydrous oxalic acid is 2-4:200-250:0.09-0.

12. In step (2), the mass ratio of aluminum sulfide, oxygen-free deionized water, and oxalic acid-modified montmorillonite is 1.5-3.0:100-150:1.5-3.

0.

3. The method for preparing the deep defluorination agent for coking wastewater treatment according to claim 2, characterized in that, In step (1), the ultrasonic dispersion time is 30-45 min and the stirring time is 30-40 min.

4. The method for preparing the deep defluorination agent for coking wastewater treatment according to claim 2, characterized in that, The stirring reaction time in step (2) is 30-40 min.

5. The method for preparing the deep defluorination agent for coking wastewater treatment according to claim 2, characterized in that, In step (3), the mass ratio of cerium dioxide powder to disodium ethylenediaminetetraacetate aqueous solution is 1-10:40-80.

6. The method for preparing the deep defluorination agent for coking wastewater treatment according to claim 2, characterized in that, In step (3), the microwave reaction temperature is 90-100℃ and the microwave reaction time is 10-30min.

7. The method for preparing the deep defluorination agent for coking wastewater treatment according to claim 2, characterized in that, In step (4), the mixer is a three-dimensional motion mixer with a rotation speed of 10-20 rpm and a mixing time of 3-18 h.

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