Preparation method of Fe3O4-CuO loaded chitosan modified active coke catalyst and application of Fe3O4-CuO loaded chitosan modified active coke catalyst in wastewater treatment

Abstract

The invention provides a preparation method of a Fe3O4-CuO loaded chitosan modified active coke catalyst and application of the Fe3O4-CuO loaded chitosan modified active coke catalyst in wastewater treatment, and belongs to the technical field of wastewater treatment.The preparation method comprises the steps that chitosan is used for modifying activated carbon to prepare chitosan modified activated carbon, then FeSO4. 7H2O and CuSO4. 5H2O are used as raw materials to prepare a Fe3O4-CuO loaded chitosan modified active coke catalyst, and the Fe3O4-CuO loaded chitosan modified active coke catalyst is prepared. Loading the Fe3O4-CuO on chitosan modified active carbon to prepare a Fe3O4-CuO loaded chitosan modified active coke catalyst; according to the application, wastewater is treated by utilizing the Fe3O4-CuO loaded chitosan modified active coke catalyst and potassium persulfate. When the Fe3O4-CuO loaded chitosan modified active coke catalyst is used for treating wastewater, potassium persulfate can be effectively promoted to be decomposed to generate free radicals, and the removal rate of COD and the removal rate of total phenols in the wastewater are increased.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a preparation method of a Fe3O4-CuO loaded chitosan modified activated coke catalyst and application thereof in wastewater treatment. Background Art

[0002] The total amount of wastewater discharged in my country has increased year by year, bringing new challenges to wastewater treatment technology. The water quality parameters of wastewater have also gradually changed, with its composition changing from simple to complex, its concentration changing from low to high, and its biodegradability changing from easy to difficult, making it difficult for traditional water treatment technologies to meet the increasingly stringent emission standards. Among them, phenolic compounds are a type of difficult-to-degrade organic pollutants with a phenol structure. They have high biological toxicity and a wide range of pollution, and some new water treatment technologies are needed to remove them.

[0003] As a wastewater catalytic treatment technology, advanced oxidation technology can produce highly oxidizing active substances in situ to treat most of the difficult-to-degrade organic pollutants, so that the wastewater meets the discharge standards.

[0004] Non-metallic catalytic materials such as graphene, activated carbon, molecular sieves, zeolites, carbon nanotubes and biochar have excellent properties such as porous structures and active sites. In the activation of persulfate reaction, non-metallic catalytic materials can not only catalyze by themselves, but also combine with metal elements to serve as carriers of metals. However, due to its low autocatalytic reactivity, it is generally widely used as a carrier material for metal oxides. Combining metal oxides with non-metallic materials to form new materials can not only effectively alleviate the problems of secondary pollution and recycling difficulties caused by metal oxide activation of persulfate, but also improve the catalytic activity of non-metallic materials. Composite materials synthesized by taking advantage of the advantages of metal oxides and non-metals have a huge application market in the activation of persulfate.

[0005] Therefore, how to develop a supported heterogeneous catalyst with high catalytic activity has always been one of the research hotspots in the treatment of phenol-containing wastewater. Summary of the invention

[0006] In view of the above problems, the present invention provides a Fe3O 4 - Preparation method of CuO-loaded chitosan modified activated coke catalyst and its application in wastewater treatment.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is:

[0008] A method for preparing a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst, the preparation method comprising the following specific steps:

[0009] S1, adding chitosan to an acetic acid aqueous solution to obtain a chitosan suspension;

[0010] S2, adding activated coke powder to water and performing ultrasonic dispersion to obtain an activated coke suspension;

[0011] S3, adding the activated coke suspension into the chitosan suspension, and subjecting the mixture to ultrasonication, stirring, centrifugation, washing, and drying to obtain chitosan-modified activated coke;

[0012] S4. Take FeSO4·7H2O and CuSO4·5H2O and add them to water to dissolve, then add chitosan-modified activated coke, stir, and then aerate under stirring. After the aeration is completed, slowly add ammonia water to adjust the pH value, continue stirring, age, centrifuge, wash the obtained solid to neutrality, and treat it at a constant temperature to obtain the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst.

[0013] Furthermore, in step S4, the weight ratio of chitosan-modified activated coke to FeSO4·7H2O and CuSO4·5H2O is 5:5.8-6.2:1.8-2.2.

[0014] Furthermore, in step S3, the weight ratio of the activated coke powder in the activated coke suspension to the chitosan in the chitosan suspension is 10:3.3-3.7.

[0015] Furthermore, in step S4, the volume weight ratio of chitosan-modified activated coke to water is 5 g:450-550 mL.

[0016] Further, in step S1, the concentration of the acetic acid aqueous solution is 4.8-5.2 wt %;

[0017] The weight-to-volume ratio of chitosan to acetic acid aqueous solution is 3.3-3.7 g:200 mL;

[0018] In step S2, the weight volume ratio of activated coke powder to water is 10 g:450-550 mL.

[0019] Furthermore, in step S3, the frequency of ultrasound is above 400W and the time is 20 to 30 minutes;

[0020] The stirring time is 12 to 16 hours;

[0021] In step S4, after adding the chitosan-modified activated carbon and before aeration, the stirring time is 25 to 30 minutes;

[0022] The aeration time is 5 to 6 minutes;

[0023] The pH value after adjustment is 10-11;

[0024] After adjusting the pH and before aging, the stirring time is 1 to 1.5 hours;

[0025] The aging time is 24 to 48 hours;

[0026] The temperature of the constant temperature treatment is 105-110°C and the time is 24-28 hours.

[0027] An application of the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst prepared by the above preparation method in wastewater treatment, wherein the application comprises taking wastewater and adjusting the pH value, adding the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst and potassium persulfate, stirring the reaction, separating the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst, and obtaining a clear liquid;

[0028] The separated Fe3O4-CuO loaded chitosan modified activated coke catalyst was continuously used as a catalyst.

[0029] Furthermore, the addition amount of the Fe3O4-CuO loaded chitosan modified activated coke catalyst is 0.14-0.16 g / L.

[0030] Furthermore, the addition amount of potassium persulfate is 2.4-2.6 mmol / L.

[0031] Further, the pH value of the wastewater is adjusted to 4.8-5.2.

[0032] The beneficial effects of the preparation method of a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst of the present invention and its application in wastewater treatment are as follows:

[0033] The present invention forms a chemical bond connection by chemically reacting the active groups on the chitosan molecular chain with the functional groups on the surface of the activated coke. This chemical bond connection can destroy part of the original pore structure of the activated coke and form new pores in the process, thereby promoting the development of the pore structure of the activated coke during the heat treatment process, further increasing the porosity, thereby increasing the specific surface area, and enhancing its adsorption performance and catalytic activity.

[0034] The Fe3O4-CuO-loaded chitosan-modified activated coke catalyst is prepared by loading a specific amount of metal oxides on chitosan-modified activated coke. The porous structure of the catalyst can provide more active sites for the subsequent catalytic reaction, reduce the mass transfer resistance, and facilitate the adsorption of pollutants so that they can fully contact with the oxidant, thus promoting the rapid reaction.

[0035] At the same time, the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst of the present invention has a well-dispersed state, which is beneficial to the exposure of active sites, and further beneficial to promoting the catalytic reaction;

[0036] The Fe3O4-CuO-loaded chitosan-modified activated coke catalyst of the present invention is used to treat wastewater, which can effectively promote the decomposition of potassium persulfate to generate free radicals, thereby improving the COD removal rate and total phenol removal rate in the wastewater;

[0037] The Fe3O4-CuO-loaded chitosan-modified activated coke catalyst of the invention has strong magnetism, which is beneficial to the recovery and recycling of the catalyst. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0039] Example 1 Preparation method of Fe3O4-CuO loaded chitosan modified activated coke catalyst and its application in wastewater treatment

[0040] This embodiment is a preparation method of a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst and its application in wastewater treatment, as follows:

[0041] 1. Preparation method of Fe3O4-CuO loaded chitosan modified activated coke catalyst

[0042] S1. Take 3.5 g of chitosan and add it to 200 mL of 5 wt% acetic acid aqueous solution to obtain a chitosan suspension.

[0043] S2, taking the activated coke, crushing, washing and removing impurities, drying, crushing, and passing through a 200-mesh sieve to obtain activated coke powder for standby use;

[0044] Take 10 g of activated coke powder, add it into 500 mL of water, and disperse it by ultrasonic to obtain an activated coke suspension.

[0045] S3. Take the above activated coke suspension and add it into the above chitosan suspension, ultrasonicate it for 20 min at a frequency of 400 W, then stir it for 12 h, centrifuge it, wash it and dry it to obtain chitosan-modified activated coke.

[0046] S4. Take 6g of FeSO4·7H2O and 2g of CuSO4·5H2O and add them to 500mL of deionized water, stir and dissolve at 50℃, then add 5g of chitosan-modified activated coke, continue stirring for 25min, and then aerate for 5min under stirring. Stop aeration, slowly add 20wt% ammonia water, adjust the pH value to 10.5, stir again for 1h, age for 24h, centrifuge, wash the obtained solid to neutrality, and treat at a constant temperature of 110℃ for 24h to obtain Fe3O4-CuO-loaded chitosan-modified activated coke catalyst.

[0047] 2. Application of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst in wastewater treatment

[0048] Take the secondary sedimentation water and adjust the pH value to 5. Turn on the stirrer and add 0.15 g / L Fe3O4-CuO-loaded chitosan-modified activated coke catalyst and 2.5 mmol / L potassium persulfate. Stir the reaction for 2 hours. Separate the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst (reusable) by magnetic absorption to obtain a clear liquid, and test the water quality of the clear liquid.

[0049] Among them, the COD value of the secondary sedimentation water is 425 mg / L and the total phenol content is 83.09 mg / L; the COD value of the clear liquid is 21.7 mg / L and the total phenol content is 1.75 mg / L, that is, the COD removal rate is 94.89% and the total phenol removal rate is 97.89%.

[0050] The separated Fe3O4-CuO loaded chitosan modified activated coke catalyst is continued to be used as a catalyst for the next wastewater treatment.

[0051] Example 2-5 Preparation method of Fe3O4-CuO loaded chitosan modified activated coke catalyst and its application in wastewater treatment

[0052] Examples 2 to 5 are respectively a preparation method of a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst and its application in wastewater treatment. According to the optimized formula given in Example 1, the preparation method of the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst that can achieve better COD and total phenol removal effects and the scope of its application in wastewater treatment are further explored to obtain the formulas and preparation methods in Examples 2 to 5, wherein Examples 2 to 5 are basically the same as Example 1, and the only difference is that some process parameters are different, as shown in Table 1 for details:

[0053] Table 1 List of process parameters in Examples 2 to 5

[0054]

[0055]

[0056] The contents and results of other parts of Examples 2 to 5 are the same as those of Example 1 and will not be repeated here.

[0057] Example 6 Investigation of process parameters in the preparation of Fe3O4-CuO loaded chitosan modified activated coke catalyst

[0058] In this example, various process conditions in the preparation process of the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst in Example 1 are investigated. During the investigation, the preparation method of the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst is basically the same as the preparation method in Example 1, and the application process of the above-mentioned Fe3O4-CuO-loaded chitosan-modified activated coke catalyst in wastewater treatment is also the same as the method in Example 1.

[0059] 1. Chitosan Investigation

[0060] The effects of adding chitosan and not adding chitosan on the catalyst performance were investigated respectively, wherein the process of preparing the catalyst by adding chitosan was the same as that in Example 1 (the obtained catalyst was a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst).

[0061] The method for directly preparing the catalyst without adding chitosan is as follows:

[0062] Take 6g of FeSO4·7H2O and 2g of CuSO4·5H2O and add them to 500mL of deionized water, stir and dissolve at 50℃, then add 5g of activated coke, continue stirring for 25min, aerate for 5min under stirring, stop aeration, slowly add 20wt% ammonia water, adjust the pH value to 10.5, continue stirring for 1h, age for 24h, centrifuge, wash the obtained solid to neutrality, and treat at a constant temperature of 110℃ for 24h to obtain Fe3O4-CuO loaded activated coke catalyst.

[0063] The same batch of secondary sedimentation effluent was treated with Fe3O4-CuO-loaded chitosan modified activated coke catalyst and Fe3O4-CuO-loaded activated coke catalyst according to the method in Example 1. The treatment results are shown in Table 2.

[0064] Table 2 Chitosan investigation results list

[0065]

[0066] It can be seen from Table 2 that the catalyst prepared without adding chitosan has a significantly lower removal effect on COD and total phenol in wastewater than the catalyst prepared with adding chitosan. Therefore, the Fe3O4-CuO loaded chitosan modified activated coke catalyst prepared by the present invention has good catalytic performance.

[0067] 2. Investigation on the amount of ferrous sulfate heptahydrate added

[0068] The same batch of chitosan-modified activated coke was taken, and different amounts of ferrous sulfate heptahydrate were used to prepare the corresponding Fe3O4-CuO-loaded chitosan-modified activated coke catalysts (i.e., only the amount of ferrous sulfate heptahydrate added in Example 1 was changed, and other conditions remained unchanged). Among them, the amounts of different ferrous sulfate heptahydrates added were 0, 2, 4, 6, 8, and 10 g, respectively. Then, the same batch of secondary sedimentation effluent was treated with the above-mentioned Fe3O4-CuO-loaded chitosan-modified activated coke catalyst according to the method in Example 1, and the treatment results are shown in Table 3.

[0069] Table 3 Summary of investigation results of different addition amounts of ferrous sulfate heptahydrate

[0070]

[0071]

[0072] As can be seen from Table 3, the catalyst prepared by adding an appropriate amount of ferrous sulfate heptahydrate can effectively remove COD and total phenols in wastewater, but adding an excessive amount of ferrous sulfate heptahydrate or a small amount of ferrous sulfate heptahydrate will lead to a decrease in the COD removal rate and the total phenol removal rate in wastewater. Therefore, the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst prepared by adding an appropriate amount of ferrous sulfate heptahydrate in the present invention has better catalytic performance.

[0073] 3. Investigation on the amount of copper sulfate pentahydrate added

[0074] The same batch of chitosan-modified activated coke was taken, and different amounts of copper sulfate pentahydrate were added to prepare the corresponding Fe3O4-CuO-loaded chitosan-modified activated coke catalysts (i.e., only the amount of copper sulfate pentahydrate added in Example 1 was changed, and other conditions remained unchanged). Among them, the amounts of different copper sulfate pentahydrates added were 0, 1, 2, 3, and 4 g, respectively. Then, the same batch of secondary sedimentation effluent was treated with the above Fe3O4-CuO-loaded chitosan-modified activated coke catalyst according to the method in Example 1, and the treatment results are shown in Table 3.

[0075] Table 4 Summary of investigation results of different addition amounts of copper sulfate pentahydrate

[0076]

[0077] As can be seen from Table 4, the catalyst prepared by adding an appropriate amount of copper sulfate pentahydrate can effectively remove COD and total phenol in wastewater, but adding an excessive amount of copper sulfate pentahydrate or a small amount of copper sulfate pentahydrate will lead to a decrease in the COD removal rate and the total phenol removal rate in wastewater. Therefore, the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst prepared by adding an appropriate amount of copper sulfate pentahydrate in the present invention has better catalytic performance.

[0078] Example 7 Investigation of process parameters during application of Fe3O4-CuO loaded chitosan modified activated coke catalyst

[0079] This example uses the Fe3O4-CuO loaded chitosan modified activated coke catalyst prepared in Example 1 to investigate various process conditions during its application. During the investigation, the same batch of secondary sedimentation water as in Example 1 was used, and the application process of the Fe3O4-CuO loaded chitosan modified activated coke catalyst in wastewater treatment was basically the same as the method in Example 1.

[0080] 1. Investigation of catalyst addition amount

[0081] The same batch of secondary sedimentation effluent was treated by adding different amounts of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst prepared in Example 1 (i.e., only the amount of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst added in Example 1 was changed, and other conditions remained unchanged). Among them, the amounts of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst added in different Examples 1 were 0.05, 0.10, 0.15, 0.20, and 0.25 g / L, respectively. The treatment results are shown in Table 5.

[0082] Table 5 Summary of investigation results of different catalyst addition amounts

[0083]

[0084] It can be seen from Table 5 that when the addition amount of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst is increased from 0.05 g / L to 0.15 g / L, the COD removal rate and total phenol removal rate in the wastewater are significantly improved, however, when the addition amount of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst is increased from 0.15 g / L to 0.25 g / L, the COD removal rate and total phenol removal rate in the wastewater are significantly decreased. Therefore, the present invention adds a suitable amount of Fe3O4-CuO-loaded chitosan-modified activated coke catalyst, which can effectively remove COD and total phenol in the wastewater.

[0085] 2. Investigation on the dosage of potassium persulfate

[0086] The same batch of secondary sedimentation water was treated by adding different amounts of potassium persulfate (i.e., only the amount of potassium persulfate added in Example 1 was changed, and other conditions remained unchanged). The amounts of potassium persulfate added were 0.5, 1.5, 2.5, 3.5, and 4.5 mmol / L, respectively. The treatment results are shown in Table 6.

[0087] Table 6 Summary of investigation results of different potassium persulfate addition amounts

[0088]

[0089] It can be seen from Table 6 that when the addition amount of potassium persulfate is increased from 0.5mmol / L to 2.5mmol / L, the COD removal rate and the total phenol removal rate in the wastewater are significantly improved, however, when the addition amount of potassium persulfate is increased from 2.5mmol / L to 4.5mmol / L, the COD removal rate and the total phenol removal rate in the wastewater are significantly decreased. Therefore, the addition of an appropriate amount of potassium persulfate in the present invention can effectively remove COD and total phenol in wastewater.

[0090] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst, characterized in that: The preparation method comprises the following specific steps: S1, adding chitosan to an acetic acid aqueous solution to obtain a chitosan suspension; S2, adding activated coke powder to water and performing ultrasonic dispersion to obtain an activated coke suspension; S3, adding the activated coke suspension into the chitosan suspension, and subjecting the mixture to ultrasonication, stirring, centrifugation, washing, and drying to obtain chitosan-modified activated coke; S4. Take FeSO4·7H2O and CuSO4·5H2O and add them to water to dissolve, then add chitosan-modified activated coke, stir, and then aerate under stirring. After the aeration is completed, slowly add ammonia water to adjust the pH value, continue stirring, age, centrifuge, wash the obtained solid to neutrality, and treat it at a constant temperature to obtain the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst.

2. The method for preparing the Fe3O4-CuO-loaded chitosan-modified activated coke catalyst according to claim 1, characterized in that: In step S4, the weight ratio of chitosan-modified activated coke to FeSO4·7H2O and CuSO4·5H2O is 5:5.8-6.2:1.8-2.

2.

3. The method for preparing the Fe3O4-CuO-loaded chitosan modified activated coke catalyst according to claim 1 or 2, characterized in that: In step S3, the weight ratio of the activated coke powder in the activated coke suspension to the chitosan in the chitosan suspension is 10:3.3-3.

7.

4. The method for preparing the Fe3O4-CuO-loaded chitosan modified activated coke catalyst according to claim 1 or 2, characterized in that: In step S4, the volume weight ratio of chitosan-modified activated coke to water is 5 g:450-550 mL.

5. The method for preparing the Fe3O4-CuO-loaded chitosan modified activated coke catalyst according to claim 1 or 2, characterized in that: In step S1, the concentration of the acetic acid aqueous solution is 4.8-5.2 wt %; The weight-to-volume ratio of chitosan to acetic acid aqueous solution is 3.3-3.7 g:200 mL; In step S2, the weight volume ratio of activated coke powder to water is 10 g:450-550 mL.

6. The method for preparing the Fe3O4-CuO-loaded chitosan modified activated coke catalyst according to claim 1 or 2, characterized in that: In step S3, the frequency of ultrasound is above 400W and the time is 20 to 30 minutes; The stirring time is 12 to 16 hours; In step S4, after adding the chitosan-modified activated carbon and before aeration, the stirring time is 25 to 30 minutes; The aeration time is 5 to 6 minutes; The pH value after adjustment is 10-11; After adjusting the pH and before aging, the stirring time is 1 to 1.5 hours; The aging time is 24 to 48 hours; The temperature of the constant temperature treatment is 105-110°C and the time is 24-28 hours.

7. Use of a Fe3O4-CuO-loaded chitosan-modified activated coke catalyst prepared by the preparation method according to any one of claims 1 to 6 in wastewater treatment, characterized in that: The application is to adjust the pH value of wastewater, add Fe3O4-CuO loaded chitosan modified activated coke catalyst and potassium persulfate, stir for reaction, separate Fe3O4-CuO loaded chitosan modified activated coke catalyst, and obtain clear liquid.

8. The use according to claim 7, characterized in that: The addition amount of Fe3O4-CuO loaded chitosan modified activated coke catalyst is 0.14-0.16 g / L.

9. The use according to claim 7, characterized in that: The amount of potassium persulfate added is 2.4-2.6 mmol / L.

10. The use according to claim 7, characterized in that: The pH value of wastewater is adjusted to 4.8-5.2.

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