Preparation method and application of coking wastewater flocculant

Abstract

This invention provides a method for preparing a coking wastewater flocculant and its application, belonging to the field of coking wastewater treatment technology. The preparation method utilizes aluminum chloride and ferric chloride as inorganic metal salts and APTES as a silicon source to prepare a coking wastewater flocculant with both ionic and covalent bonds. The coking wastewater flocculant, when used in conjunction with a micro-vortex flocculation reactor, can effectively remove components such as COD, thiocyanate, color, and turbidity from coking wastewater.

Description

Technical Field

[0001] This invention relates to the field of coking wastewater treatment technology, and in particular to a method for preparing and applying a coking wastewater flocculant. Background Technology

[0002] Coking wastewater is the wastewater generated during the coal coking process. It contains pollutants including phenols, polycyclic aromatic compounds, and heterocyclic compounds containing nitrogen, oxygen, and sulfur, making it a typical complex, highly toxic, and recalcitrant industrial wastewater. Flocculation and sedimentation are crucial steps in coking wastewater treatment, typically employing simple inorganic or organic flocculants such as polyaluminum chloride, polyaluminum sulfate, polyaluminum ferric chloride, and polyacrylamide. However, existing flocculants are not ideal for treating coking wastewater and cannot adequately meet the various requirements for denitrification, carbon reduction, color reduction, and turbidity reduction. Therefore, it is necessary to develop a novel coking wastewater flocculant. Summary of the Invention

[0003] To address the above problems, this invention provides a method for preparing a flocculant for coking wastewater and its application.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a flocculant for coking wastewater, the method comprising the following steps:

[0006] S1. Add aluminum chloride and ferric chloride in a molar ratio of 3:1.8 to 2.2 to anhydrous ethanol, mix well, and obtain mixed solution A;

[0007] After mixing anhydrous ethanol, water and hydrochloric acid thoroughly, add APTES to obtain mixed solution B;

[0008] S2. Slowly add mixed solution A to mixed solution B. After the addition is complete, continue the reaction and add sodium hydroxide to alkalize. The resulting system continues to react to obtain a homogeneous sol.

[0009] S3. Take the sol and age it until the sol becomes a dry gel. Then continue to dry the dry gel and crush it to obtain the coking wastewater flocculant.

[0010] Furthermore, in step S1, the molar ratio of silicon in the added APTES to aluminum in the mixed solution A is 1:0.05 to 0.06 (i.e., the molar ratio of Si / Al is 1:0.05 to 0.06).

[0011] Furthermore, in step S2, sodium hydroxide is added until the pH of the resulting system is 9.0 to 10.0.

[0012] Furthermore, in step S2, mixed solution B is added dropwise with mixed solution A under vigorous stirring.

[0013] Furthermore, in step S2, after the mixed solution B is completely added, the reaction time is 30-40 minutes;

[0014] After adding sodium hydroxide for alkalization, the resulting system continued to react for more than 60 minutes.

[0015] Furthermore, in step S2, after the mixed solution B is completely added, the reaction temperature is room temperature (generally, room temperature refers to 15-40℃).

[0016] After adding sodium hydroxide for alkalization, the temperature at which the resulting system continues to react is room temperature (generally, room temperature refers to 15–40°C).

[0017] In step S3, the aging and drying temperatures are both room temperature (generally, room temperature refers to 15–40°C).

[0018] An application of a coking wastewater flocculant, wherein the coking wastewater flocculant prepared by the above preparation method is used in conjunction with a micro vortex flocculation reactor to treat coking wastewater.

[0019] Furthermore, the specific process of the application involves taking coking wastewater directly into a micro-vortex flocculation reactor, adding coking wastewater flocculant to carry out flocculation reaction, then adding polyacrylamide to continue flocculation, sedimentation, and effluent supernatant.

[0020] Furthermore, the amount of flocculant added to the coking wastewater is 2000–5000 ppm.

[0021] Furthermore, after adding the coking wastewater flocculant, the flocculation reaction time is 15-20 minutes.

[0022] The beneficial effects of the preparation method and application of the coking wastewater flocculant of the present invention are as follows:

[0023] This invention utilizes aluminum chloride and ferric chloride as inorganic metal salts and APTES as a silicon source to prepare a coking wastewater flocculant with both ionic and covalent bonds. When used in conjunction with a micro vortex flocculation reactor, it can simultaneously remove components such as COD, thiocyanate, color, and turbidity from coking wastewater, thereby effectively improving the treatment effect.

[0024] This invention, by changing the silicon source and selecting appropriate proportions of aluminum and iron, produces an inorganic-organic hybrid flocculant with both ionic and covalent bonds. Simultaneously, the inorganic and organic components are linked through the combination of ionic and covalent bonds, resulting in a coking wastewater flocculant with a dense pore morphology and a three-dimensional spatial network structure. The synergistic effect of the silicon-aluminum polymer macromolecules, silicon-iron polymer macromolecules, amino groups, carbon chains, and dense spatial structure in the coking wastewater flocculant effectively increases the particulate matter concentration in the system, promotes the formation of nucleated flocs, adsorbs organic matter, and enhances flocculation, accelerating the coagulation process and improving the coagulation effect.

[0025] This invention utilizes coking wastewater flocculants in conjunction with micro-vortex flocculation, making it easier for the colloidal particles in the coking wastewater flocculants to destabilize and form micro-clumps. Furthermore, the coking wastewater forms vortices of varying sizes within the micro-vortex flocculation reactor, creating a significant velocity difference between different flow layers. This increases the relative motion between the micro-clumps and the coking wastewater, raising the collision probability and promoting accelerated coagulation to form flocs. Simultaneously, the vortex motion generates centrifugal force, causing the micro-clumps to generate radial velocity, further increasing the collision probability between the micro-clumps and the coking wastewater, leading to their coagulation and floc formation. When the flocs grow to a certain size, under the shear force of the vortex, the less dense flocs break down, and the broken flocs then undergo further flocculation to form denser flocs, thus benefiting subsequent processing.

[0026] The coking wastewater flocculant of the present invention has a simple preparation process, good treatment effect on coking wastewater, and is suitable for industrial promotion. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] Example 1: A method for preparing a flocculant for coking wastewater

[0029] S1. Take 0.03 mol (4.00 g) aluminum chloride and 0.02 mol (3.25 g) ferric chloride and add them to 10 mL of anhydrous ethanol. Mix them evenly with a magnetic stirrer at room temperature (generally room temperature refers to 15-40℃, and in this example the room temperature is 25℃) to obtain mixed solution A.

[0030] At room temperature (generally, room temperature refers to 15-40℃, and in this example, the room temperature is 25℃), take 200mL of anhydrous ethanol, 50mL of water and 10mL of hydrochloric acid (concentration of 2mol / L) and mix them evenly. Then add APTES until the molar amount of Si in the solution is 0.5mol (at this time, the molar ratio of Si / Al is 1:0.06, and the amount of APTES used is 110.65g), to obtain mixed solution B;

[0031] S2. Under room temperature (generally, room temperature refers to 15-40℃, and in this example, room temperature is 25℃) and vigorous stirring conditions, mixed solution A is slowly added dropwise to mixed solution B. After the addition is complete, stirring is continued for 30 minutes (marked as the first stirring time). Then, an appropriate amount of sodium hydroxide aqueous solution (concentration of 5 mol / L) is added for alkalization. The sodium hydroxide aqueous solution is added until the pH value of the system is 9.5, and then the addition is stopped. The resulting system is stirred for another 60 minutes (marked as the second stirring time) to obtain a uniform sol.

[0032] S3. Take the sol and age it at room temperature (generally room temperature refers to 15-40℃, and in this embodiment the room temperature is 25℃) until the sol becomes a dry gel. Finally, place the dry gel at room temperature (generally room temperature refers to 15-40℃, and in this embodiment the room temperature is 25℃) to continue drying and crushing. The solid powder obtained is the coking wastewater flocculant, labeled as M1.

[0033] Preparation methods of flocculants for coking wastewater in Examples 2-5

[0034] Examples 2-5 are methods for preparing flocculants for coking wastewater. Their steps are basically the same as in Example 1, differing only in some parameters, as detailed in Table 1.

[0035] Table 1. Summary of parameters in Examples 2-5

[0036]

[0037] The contents of other parts of Examples 2 to 5 are the same as those of Example 1, and will not be repeated here.

[0038] Preparation methods of flocculants for coking wastewater (Comparative Examples 1-5)

[0039] Comparative Examples 1-5 are comparative experiments on the preparation process of the coking wastewater flocculant in Example 1, with the only difference being:

[0040] In Comparative Example 1, the amount of ferric chloride used was 0.01 mol, while the amounts of other raw materials and process parameters remained unchanged. The resulting coking wastewater flocculant was labeled DM1.

[0041] In Comparative Example 2, the amount of ferric chloride used was 0.04 mol, while the amounts of other raw materials and process parameters remained unchanged. The resulting coking wastewater flocculant was labeled as DM2.

[0042] In Comparative Example 3, sodium silicate was used instead of APTES as the silicon source, and the molar ratio of Si / Al in sodium silicate was also 1:0.06. The amounts of other raw materials and process parameters remained unchanged, and the resulting coking wastewater flocculant was labeled as DM3.

[0043] In Comparative Example 4, APTES was added to mixed solution B until the molar amount of Si in the solution was 0.2 mol (at which point the molar ratio of Si / Al was 1:0.15). The amounts of other raw materials and process parameters remained unchanged. The resulting coking wastewater flocculant was labeled as DM4.

[0044] In Comparative Example 5, APTES was added to mixed solution B until the molar amount of Si in the solution was 1 mol (at which point the molar ratio of Si / Al was 1:0.01). The amounts of other raw materials and process parameters remained unchanged. The resulting coking wastewater flocculant was labeled as DM5.

[0045] Example 6: Application of flocculants in coking wastewater

[0046] The coking wastewater flocculants M1-M5 and DM1-DM11 prepared in Examples 1-5 and Comparative Examples 1-5, respectively, were used to treat the secondary biochemical sedimentation effluent (i.e., the coking wastewater to be treated) from the wastewater treatment plant. The specific steps are as follows:

[0047] After biochemical secondary sedimentation, the effluent is 10m 3 The flow rate of wastewater is directly fed into the micro-vortex flocculation reactor (a conventional micro-vortex flocculation reactor can be used). 5000 ppm of coking wastewater flocculant is added, and after 15 minutes of flocculation, 1 ppm of polyacrylamide is added, followed by 10 minutes of flocculation. After sedimentation, the supernatant is discharged. Specific treatment results are shown in Table 2.

[0048] Table 2. Summary of Flocculant Effects in Coking Wastewater

[0049]

[0050] As can be seen from Table 2, the coking wastewater flocculant of the present invention can effectively remove components such as COD, thiocyanate, color, and turbidity from coking wastewater, with good treatment effect. The supernatant after treatment can directly meet the discharge standards.

[0051] Application of flocculants in coking wastewater in Examples 7-9

[0052] In Example 7, the effluent from the biochemical secondary sedimentation was 10m 3The flow rate of / h directly enters the micro vortex flocculation reactor, and 2000ppm coking wastewater flocculant M1 is added. After flocculation reaction for 20min, 5ppm polyacrylamide is added, and flocculation is carried out for 20min. After sedimentation, the supernatant flows out.

[0053] In Example 8, the effluent from the biochemical secondary sedimentation was 10m 3 The flow rate of / h directly enters the micro vortex flocculation reactor, and 4000ppm coking wastewater flocculant M1 is added. After flocculation reaction for 18min, 2ppm polyacrylamide is added, and flocculation is carried out for 15min. After sedimentation, the supernatant flows out.

[0054] In Example 9, the effluent from the biochemical secondary sedimentation was 10m 3 The flow rate of / h is directly fed into the traditional coagulation reactor. 5000ppm coking wastewater flocculant M1 is added. After flocculation reaction for 15min, 1ppm polyacrylamide is added and flocculation is carried out for 10min. After sedimentation, the supernatant flows out.

[0055] The specific processing results of Examples 7 to 9 are shown in Table 3:

[0056] Table 3. Summary of Flocculant Effects in Coking Wastewater

[0057]

[0058] As shown in Table 3, reducing the dosage of the coking wastewater flocculant of this invention slightly affects the removal efficiency of components such as COD, thiocyanate, color, and turbidity in the coking wastewater, but it still maintains a good treatment effect, and the treated supernatant can directly meet the discharge standards. However, when using a conventional coagulation reactor instead of a micro-vortex flocculation reactor, the treatment effect will decrease. Therefore, in practical applications, the coking wastewater flocculant of this invention needs to be used in conjunction with a micro-vortex flocculation reactor.

[0059] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a flocculant for coking wastewater, characterized in that, The preparation method of the coking wastewater flocculant includes the following steps: S1. Add aluminum chloride and ferric chloride in a molar ratio of 3:1.8~2.2 to anhydrous ethanol, mix well, and obtain mixed solution A; Anhydrous ethanol, water, and hydrochloric acid were mixed thoroughly, and then APTES was added to obtain mixed solution B. The molar ratio of silicon in the added APTES to aluminum in mixed solution A was 1:0.05~0.

06. S2. Slowly add mixed solution A to mixed solution B. After the addition is complete, continue the reaction and add sodium hydroxide to alkalize. The resulting system continues to react to obtain a homogeneous sol. S3. Take the sol and age it until the sol becomes a dry gel. Then continue to dry the dry gel and crush it to obtain the coking wastewater flocculant.

2. The method for preparing the coking wastewater flocculant according to claim 1, characterized in that, In step S2, sodium hydroxide is added until the pH of the resulting system is 9.0~10.

0.

3. The method for preparing the coking wastewater flocculant according to claim 1, characterized in that, In step S2, mixed solution B is added dropwise with mixed solution A under vigorous stirring.

4. The method for preparing the coking wastewater flocculant according to claim 1, characterized in that, In step S2, after the mixed solution B is completely added, the reaction time is 30-40 minutes. After adding sodium hydroxide for alkalization, the resulting system continued to react for more than 60 minutes.

5. The method for preparing the coking wastewater flocculant according to claim 1, characterized in that, In step S2, after the mixed solution B is completely added, the reaction temperature is room temperature; After alkalization with sodium hydroxide, the system continues to react at room temperature. In step S3, both the aging and drying temperatures are at room temperature.

6. An application of a flocculant for coking wastewater, characterized in that, The application involves using the preparation method described in any one of claims 1-5 to prepare a coking wastewater flocculant, which is then used in conjunction with a micro vortex flocculation reactor to treat coking wastewater.

7. The application according to claim 6, characterized in that, The specific process of the application is to take coking wastewater directly into a micro vortex flocculation reactor, add coking wastewater flocculant to carry out flocculation reaction, then add polyacrylamide for flocculation, precipitate, and then discharge the supernatant.

8. The application according to claim 7, characterized in that, The dosage of flocculant added to coking wastewater is 2000~5000ppm.

9. The application according to claim 7 or 8, characterized in that, After adding the coking wastewater flocculant, the flocculation reaction time is 15-20 minutes.

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