A coking wastewater purifying agent, a preparation method and application thereof

Abstract

The application discloses a coking wastewater purifying agent and a preparation method and application thereof, and the purifying agent comprises the following raw materials in parts by weight: 20-25 parts of activated carbon, 18-25 parts of a compound, 4-9 parts of polyacrylamide, 1-5 parts of a surfactant and 60-90 parts of water, wherein the compound is prepared by compounding pear residue and modified shell carbon. The application aims at solving the technical problem that coking wastewater cannot reach the discharge standard.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and particularly relates to a coking wastewater purifying agent, its preparation method, and its application. Background Technology

[0002] Coking wastewater is generated during the processes of coal-to-coke production, coal gas purification, and coking product recovery, producing large amounts of aromatic and heterocyclic compounds. It is classified as high-concentration, recalcitrant organic wastewater. In China, coking wastewater is treated biologically before discharge; this technology is currently one of the most common processes in the coking industry.

[0003] Currently, after biochemical treatment, most organic matter in coking wastewater is degraded, but the COD, color, and turbidity indicators still cannot meet the national emission standards and require further treatment. The treatment method often involves adding a single agent or decolorizing agent for purification. This method has the disadvantages of large agent dosage, low removal efficiency, and poor water color, and usually cannot meet the national emission standards. Summary of the Invention

[0004] This invention provides a coking wastewater purification agent, its preparation method, and its application, in order to solve the technical problem that current coking wastewater cannot meet national emission standards.

[0005] In view of this, the present invention provides a coking wastewater purification agent comprising the following raw materials in parts by weight: 20-25 parts activated carbon, 18-25 parts composite material, 4-9 parts polyacrylamide, 1-5 parts surfactant, and 60-90 parts water, wherein the composite material is a mixture of pear pomace and modified fruit shell carbon.

[0006] Optionally, the complex is prepared using the following method:

[0007] A1: Crush the modified nutshell carbon, sieve it, and obtain the crushed modified nutshell carbon;

[0008] A2: Wash the pear pulp, dry it, crush it, sieve it, put it into the ethanol solution, mix it evenly, and obtain a mixture.

[0009] A3: Add the pulverized modified nutshell carbon to the mixture, mix evenly, heat to a higher temperature, react, cool to a lower temperature, centrifuge, wash, and dry to obtain the composite.

[0010] Furthermore, the composite is prepared using the following method:

[0011] A1: Crush the modified nutshell carbon and pass it through an 80-120 mesh sieve to obtain the crushed modified nutshell carbon;

[0012] A2: Wash the pear residue, dry it, crush it, pass it through an 80-120 mesh sieve, put it into the ethanol solution, mix it evenly, and obtain a mixture.

[0013] A3: Add the pulverized modified nutshell carbon to the mixture, mix evenly, heat to 40-60℃, react for 1-2 hours, cool to 22±3℃, centrifuge, wash with water 3-5 times, dry, and obtain the complex.

[0014] In step A2, the amount of ethanol solution added per 1g of pear pomace is 3-5mL, and the mass fraction of the ethanol solution is 40%.

[0015] Optionally, the weight ratio of the pear pomace and modified fruit shell carbon is (0.4-0.7):1.

[0016] Optionally, the shell carbon is a mixture of carbonized apricot shells and walnut shells, and the weight ratio of apricot shells to walnut shells is 1:1.

[0017] Optionally, the modified nutshell carbon is prepared using the following method:

[0018] B1: Wash the apricot shells and walnut shells, crush them, sieve them, mix them evenly, and obtain the fruit shells;

[0019] B2: The fruit shell is heated under the protection of an inert gas to carbonize it, and then cooled to obtain fruit shell carbon.

[0020] B3: Add an activator to the coconut shell carbon, grind and mix, heat again to react, cool down, wash, and dry to obtain modified coconut shell carbon.

[0021] Furthermore, the modified nutshell carbon is prepared using the following method:

[0022] B1: Wash the apricot shells and walnut shells, crush them, pass them through a 100-120 mesh sieve, mix them evenly, and obtain the fruit shells;

[0023] B2: The shells are heated to 450-650℃ under the protection of inert nitrogen gas for 2-3 hours and then cooled to 22±3℃ to obtain shell carbon.

[0024] B3: Add an activator to the coconut shell carbon, grind and mix, reheat to 750-850℃, react for 1-3 hours, cool down to 22±3℃, wash with water 3-5 times, dry, and obtain modified coconut shell carbon.

[0025] The activator is potassium hydroxide, and the weight ratio of nutshell carbon to potassium hydroxide is 1:(0.4-0.6).

[0026] Optionally, the pear pomace is further modified before use by: placing the pear pomace in an ethylene glycol solution, adding α-hydroxyferric oxide, mixing evenly, heating to a higher temperature, reacting, and after the reaction is complete, removing the solid, cooling, washing, and drying to obtain modified pear pomace.

[0027] Furthermore, the pear pomace undergoes the following modification treatment before use: the pear pomace is placed in an ethylene glycol solution, α-hydroxyferric oxide is added, mixed evenly, heated to 100-140℃, and reacted for 5-7 hours. After the reaction is completed, the solid is removed, cooled to 22±3℃, washed with ethanol 3-5 times, and dried to obtain modified pear pomace.

[0028] The amount of ethylene glycol solution added to each 1g of pear pomace is 5-7mL, the mass fraction of the ethylene glycol solution is 12.5%, and the weight ratio of pear pomace to α-hydroxy iron oxide is 1:(0.1-0.2).

[0029] Optionally, the pear pomace is pretreated by the following method before use: the pear pomace is washed, placed in hydrochloric acid solution, mixed evenly, reacted in a water bath, and after the reaction is completed, the solid is removed, washed, and dried to obtain the pretreated pear pomace.

[0030] Furthermore, the pear residue is pretreated by the following method before use: the pear residue is washed, placed in hydrochloric acid solution, mixed evenly, and reacted in a water bath at 40-60℃ for 1-2 hours. After the reaction is completed, the solid is taken out, washed with water 3-5 times, and dried to obtain the pretreated pear residue.

[0031] The amount of hydrochloric acid solution added to each 1g of pear pomace is 2-4mL, and the mass fraction of the hydrochloric acid solution is 40%.

[0032] A method for preparing a coking wastewater purifier includes the following steps: adding activated carbon, a composite material, polyacrylamide, and a surfactant into water and mixing them evenly to obtain the purifier.

[0033] An application of a coking wastewater purifying agent includes the following steps: adding the purifying agent to the coking wastewater to be treated, mixing evenly, aerating, allowing to stand, filtering, and obtaining the treated coking wastewater.

[0034] Optionally, the amount of the purifying agent added is 0.4-0.7 wt% of the coking wastewater to be treated.

[0035] As can be seen from the above technical solutions, the embodiments of the present invention have the following advantages:

[0036] 1. In this application, activated carbon, composite material and polyacrylamide are used as the main raw materials of the purifying agent. Activated carbon is loose and porous and has better adsorption properties. It can adsorb COD and pigments in coking wastewater. Polyacrylamide can be used as a flocculant. It can form precipitates with pollutants and pigments in coking wastewater and remove them by settling.

[0037] The composite material is a mixture of pear pomace and modified fruit shell carbon. Using pear pomace not only achieves waste utilization and resource conservation, but also provides numerous adsorption sites due to its porous surface, enabling the adsorption of COD, pigments, and pollutants from coking wastewater. Using modified fruit shell carbon also achieves waste utilization and resource conservation. Furthermore, fruit shell carbon possesses a high specific surface area and well-developed pore structure, exhibiting superior adsorption capacity. Modification of the fruit shell carbon further enhances its adsorption performance. The composite material, made from pear pomace, benefits from the pore structure suitable for adsorbing large organic molecules, while the modified fruit shell carbon is suitable for adsorbing small organic molecules. The increased total specific surface area and pore structure of the composite material further enhance its adsorption performance, making it more effective in removing COD, color, and turbidity.

[0038] 2. This application also uses α-hydroxy iron oxide to modify pear pomace. α-hydroxy iron oxide is a material with high adsorption performance. After introducing α-hydroxy iron oxide onto the surface of pear pomace, the specific surface area and surface active sites of pear pomace can be increased. Through the synergistic effect between the two, the adsorption capacity for substances such as COD, pigments and pollutants is further enhanced, and the treatment effect of coking wastewater is improved.

[0039] 3. This application also uses hydrochloric acid solution to pretreat pear pomace, which changes the chemical properties of the pear pomace surface, increases the active sites on its surface, and can also introduce acidic functional groups on the pear pomace surface, thereby further improving the adsorption of pear pomace, improving the treatment effect on coking wastewater, and making it easier for coking wastewater to meet the discharge standards. Detailed Implementation

[0040] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in the present invention can be purchased on the market or prepared by existing methods.

[0041] Preparation Example

[0042] Preparation Example 1

[0043] A modified coconut shell carbon, prepared by the following method:

[0044] B1: Wash 2kg of apricot shells and 2kg of walnut shells, crush them, pass them through a 110-mesh sieve, mix them evenly, and obtain the fruit shells;

[0045] B2: The shells are heated to 550°C under the protection of inert nitrogen gas for 2.5 hours and then cooled to 25°C to obtain shell carbon.

[0046] B3: Add 2 kg of potassium hydroxide to the nutshell carbon, grind and mix, heat again to 800℃, react for 2 h, cool down to 25℃, and dry to obtain modified nutshell carbon.

[0047] Preparation Example 2

[0048] A complex prepared by the following method:

[0049] A1: 2 kg of the modified nutshell carbon prepared in Preparation Example 1 was pulverized and passed through a 100-mesh sieve to obtain the pulverized modified nutshell carbon.

[0050] A2: Wash 0.8 kg of pear pomace, dry it, crush it, pass it through a 100-mesh sieve, and put it into a 40% ethanol solution. Mix it evenly to obtain a mixture; the amount of ethanol solution added to each 1 g of pear pomace is 4 mL.

[0051] A3: Add the pulverized modified nutshell carbon to the mixture, mix evenly, heat to 50℃, react for 1.5h, cool to 25℃, centrifuge, wash with water 5 times, and dry to obtain the composite.

[0052] Preparation Example 3

[0053] A compound, which differs from Preparation Example 2 in that the amount of pear pomace added is different; in Preparation Example 3, the amount of pear pomace added is 1.1 kg.

[0054] Preparation Example 4

[0055] A compound, which differs from Preparation Example 2 in that the amount of pear pomace added is different; in Preparation Example 4, the amount of pear pomace added is 1.4 kg.

[0056] Preparation Example 5

[0057] A compound, which differs from Preparation Example 2 in that the amount of pear pomace added is different; in Preparation Example 5, the amount of pear pomace added is 0.5 kg.

[0058] Preparation Example 6

[0059] A compound, which differs from Preparation Example 2 in that the amount of pear pomace added is different; in Preparation Example 6, the amount of pear pomace added is 3 kg.

[0060] Example

[0061] Example 1

[0062] A coking wastewater purification agent, the raw material ratio of which is shown in Table 1.

[0063] A method for preparing a coking wastewater purification agent includes the following steps:

[0064] Activated carbon, the composite prepared using Preparation Example 2, polyacrylamide, and surfactant were placed in water and mixed evenly to obtain a purifying agent.

[0065] Examples 2-8

[0066] A coking wastewater purification agent differs from Example 1 in that the raw material ratio of the purification agent is different, as shown in Table 1.

[0067] Table 1. Weight of each raw material in the purifying agent (kg)

[0068]

[0069]

[0070] Examples 9-12

[0071] A coking wastewater purification agent, which differs from Example 8 in that the source of the complex is different. The complexes in Examples 9-12 were prepared using Preparation Examples 3-6, respectively.

[0072] Example 13

[0073] A coking wastewater purifying agent, which differs from Example 9 in that the pear pomace in the composite undergoes the following modification treatment before use: the pear pomace is placed in a 12.5% ​​ethylene glycol solution, α-hydroxyferric oxide is added, mixed evenly, heated to 120°C, and reacted for 6 hours. After the reaction is completed, the solid is removed, cooled to 25°C, washed 5 times with ethanol, and dried to obtain modified pear pomace; wherein, the amount of ethylene glycol solution added per 1g of pear pomace is 6mL, and the weight ratio of pear pomace to α-hydroxyferric oxide is 1:0.15.

[0074] Example 14

[0075] A coking wastewater purification agent, which differs from Example 13 in that the pear residue in the complex undergoes the following pretreatment before use: the pear residue is washed, placed in a 40% hydrochloric acid solution, mixed evenly, and subjected to a water bath reaction at 50°C for 1.5 hours. After the reaction is completed, the solid is removed, washed with water 5 times, and dried to obtain the pretreated pear residue; wherein, the amount of hydrochloric acid solution added to each 1g of pear residue is 3mL.

[0076] Comparative Example

[0077] Comparative Example 1

[0078] A coking wastewater purifier differs from Example 1 in that no complex is added to the raw materials of the purifier.

[0079] Comparative Example 2

[0080] A coking wastewater purifier, which differs from Example 1 in that the modified nutshell carbon in the composite is replaced with an equal amount of nutshell carbon.

[0081] Comparative Example 3

[0082] A coking wastewater purifier differs from Example 1 in that the modified fruit shell carbon in the composite is replaced by pear pomace in equal amounts.

[0083] Comparative Example 4

[0084] A coking wastewater purifier, which differs from Example 1 in that the pear pomace in the compound is replaced in equal amounts with modified fruit shell carbon.

[0085] Application examples

[0086] Application Example 1

[0087] The application of a coking wastewater purification agent includes the following steps:

[0088] The purifying agent prepared in Example 1 was added to the coking wastewater to be treated, mixed evenly, aerated, and allowed to stand to obtain the treated coking wastewater; wherein, the amount of purifying agent added was 0.5 wt% of the coking wastewater to be treated.

[0089] Application Example 2-14

[0090] The difference between Application Example 2-14 and Application Example 1 is that the source of the purifying agent is different. The purifying agent in Application Example 2-14 was prepared in Example 2-14.

[0091] Application Comparative Examples 1-4

[0092] The difference between Comparative Examples 1-4 and Application Example 1 is that the source of the purifying agent is different. The purifying agents in Comparative Examples 1-4 were prepared using the methods described in Comparative Examples 1-4.

[0093] Performance testing

[0094] The coking wastewater treated in corresponding use cases 1-14 and application comparison examples 1-4 was measured:

[0095] COD: The COD in the treated coking wastewater was determined according to HJ828-2017 "Determination of Chemical Oxygen Demand in Water - Dichromate Method". The test results are shown in Table 2.

[0096] Color: The color of the treated coking wastewater was measured according to GB / T11903-89 "Determination of Color in Water". The test results are shown in Table 2.

[0097] Turbidity: The turbidity of the treated coking wastewater was measured in accordance with GB / T13200-91 "Determination of Turbidity in Water". The test results are shown in Table 2.

[0098] The COD content in the coking wastewater before treatment was 2300 mg / L, the color was 120 times, and the turbidity was 150 NTU.

[0099] Table 2 Detection Results

[0100]

[0101]

[0102] As can be seen from Table 2, the coking wastewater purifier of this application significantly reduces COD, color and turbidity in coking wastewater through the combined action of various raw materials. The removal rate of COD is 95.9-99.5%, the removal rate of color is 80.7-85.4%, and the removal rate of turbidity is 86.7-91.6%.

[0103] Combining Application Example 1 and Comparative Examples 1-4, it can be seen that the COD removal rate in the treated coking wastewater in Application Example 1 was 96.1%, the color removal rate was 81.1%, and the turbidity removal rate was 87.6%, which is better than that in Comparative Examples 1-4. This indicates that the composite material made from pear pomace and modified fruit shell carbon is more suitable. It not only realizes waste utilization and saves resources, but also shows that both pear pomace and modified fruit shell carbon have certain adsorption properties. When pear pomace and modified fruit shell carbon are used to form a composite material, the pore structure of pear pomace is suitable for adsorbing large molecular organic matter, while the pore structure of modified fruit shell carbon is suitable for adsorbing small molecular organic matter. Moreover, the total specific surface area and pore structure of the composite material are increased, which further enhances the adsorption performance and is more conducive to the removal of COD, color, and turbidity.

[0104] As can be seen from Application Examples 1-3, the COD removal rate of the treated coking wastewater in Application Example 2 was 96.6%, the color removal rate was 81.8%, and the turbidity removal rate was 88.2%, which is better than other application examples. This indicates that the amount of compound added in Application Example 2 is more appropriate and can better improve the removal of COD, color, and turbidity. When the amount of compound added is too small, it will not play a good adsorption role and the purification effect on coking wastewater will not reach the best level. When the amount of compound added is too large, it will lead to the saturation of the compound adsorption sites, causing the excess compound to be unable to effectively adsorb pollutants, which will increase the difficulty of treating coking wastewater. Moreover, excessive compound may release some other substances, which will affect the water quality of coking wastewater.

[0105] Combining Application Examples 2 and 4-5, it can be seen that the COD removal rate in the treated coking wastewater in Application Example 4 was 97.3%, the color removal rate was 82.3%, and the turbidity removal rate was 88.8%, which is better than other application examples. This indicates that the amount of activated carbon added in Application Example 4 is more suitable and can better improve the purification effect on coking wastewater. When the amount of activated carbon added is too small, it cannot play a good adsorption role; when the amount of activated carbon added is too large, the adsorption sites of the activated carbon reach saturation, and the excess activated carbon will not play an adsorption role, which will also lead to the waste of raw materials.

[0106] Combining Application Examples 4 and 6-7, it can be seen that the COD removal rate in the treated coking wastewater in Application Example 7 was 97.8%, the color removal rate was 82.9%, and the turbidity removal rate was 89.6%, which is better than other application examples. This indicates that the amount of polyacrylamide added in Application Example 7 is more appropriate and has a better flocculation effect.

[0107] As can be seen from Application Examples 7 and 8, variations in the amount of surfactant and water added within a certain range do not have a significant impact on coking wastewater.

[0108] Combining Application Examples 7 and 9-12, it can be seen that the COD removal rate in the treated coking wastewater in Application Example 9 was 98.3%, the color removal rate was 83.8%, and the turbidity removal rate was 90.5%, which is better than other application examples. This indicates that the composite prepared by Preparation Example 3 is more suitable. Too much or too little pear residue cannot achieve a better synergistic effect with the modified fruit shell carbon. The amount of pear residue added in Preparation Example 3 is better, which enables the composite to play a better adsorption role.

[0109] Combining Application Examples 9 and 13, it can be seen that the COD removal rate in the treated coking wastewater in Application Example 13 was 99.2%, the color removal rate was 84.9%, and the turbidity removal rate was 91.0%, which is better than Application Example 9. This indicates that the pear pomace is more suitable after modification treatment. After introducing α-hydroxy iron oxide on the surface of the pear pomace, the specific surface area and surface active sites of the pear pomace can be increased. Through the synergistic effect between the two, the adsorption capacity for substances such as COD and pigments is further enhanced, thereby improving the treatment effect of coking wastewater.

[0110] Combining Application Examples 13 and 14, it can be seen that the COD removal rate of the treated coking wastewater in Application Example 14 is 99.5%, the color removal rate is 85.4%, and the turbidity removal rate is 91.6%, which is better than Application Example 13. This indicates that pretreatment of pear pomace before use is more appropriate. Pretreatment of pear pomace with hydrochloric acid solution can change the chemical properties of the pear pomace surface, increase its surface active sites, and introduce acidic functional groups on the pear pomace surface, thereby further improving the adsorption capacity of the pear pomace, improving the treatment effect on coking wastewater, and making it easier for the coking wastewater to meet the discharge standards.

[0111] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coking wastewater purification agent, characterized in that: The raw materials include the following parts by weight: 20-25 parts activated carbon, 18-25 parts compound, 4-9 parts polyacrylamide, 1-5 parts surfactant, and 60-90 parts water, wherein the compound is a mixture of pear pomace and modified fruit shell carbon. The complex was prepared using the following method: A1: Crush the modified nutshell carbon, sieve it, and obtain the crushed modified nutshell carbon; A2: Wash the pear pulp, dry it, crush it, sieve it, put it into the ethanol solution, mix it evenly, and obtain a mixture. A3: Add the pulverized modified nutshell carbon to the mixture, mix evenly, heat to a higher temperature, react, cool to a lower temperature, centrifuge, wash, and dry to obtain the composite. The weight ratio of the pear pomace and modified fruit shell carbon is (0.4-0.7):1; The modified nutshell carbon was prepared using the following method: B1: Wash the apricot shells and walnut shells, crush them, sieve them, mix them evenly to obtain fruit shells, and the weight ratio of apricot shells to walnut shells is 1:

1. B2: The fruit shell is heated and cooled under the protection of an inert gas to carbonize it, thus obtaining fruit shell carbon. B3: Add an activator to the coconut shell carbon, grind and mix, heat again to react, cool down, wash, and dry to obtain modified coconut shell carbon; The pear pomace undergoes the following modification treatment before use: the pear pomace is placed in an ethylene glycol solution, α-hydroxyferric oxide is added, mixed evenly, heated to a higher temperature, and reacted. After the reaction is completed, the solid is removed, cooled, washed, and dried to obtain the modified pear pomace. The pear pomace is pretreated by the following method before use: the pear pomace is washed, placed in hydrochloric acid solution, mixed evenly, reacted in a water bath, and after the reaction is completed, the solid is removed, washed, and dried to obtain the pretreated pear pomace.

2. A method for preparing a coking wastewater purifying agent as described in any one of claims 1, characterized in that: The process includes the following steps: adding activated carbon, a complex, polyacrylamide, and a surfactant to water, mixing them thoroughly, and obtaining a purifying agent.

3. The application of the coking wastewater purifying agent according to claim 2, characterized in that: The process includes the following steps: adding the purifying agent to the coking wastewater to be treated, mixing evenly, aerating, allowing to stand, filtering, and obtaining the treated coking wastewater.

4. The application of the coking wastewater purifying agent according to claim 3, characterized in that: The amount of the purifying agent added is 0.4-0.7 wt% of the coking wastewater to be treated.

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