Method for degrading acid orange 7 by paper mill sludge magnetic biochar supported catalyst

Abstract

The invention discloses a method for degrading acid orange 7 by using a paper mill sludge magnetic biochar supported catalyst, which comprises the following steps: adding the paper mill sludge magnetic biochar supported catalyst into acid orange 7 sewage, adding peroxymonosulfate to start reaction after adsorption equilibrium, and recycling the paper mill sludge magnetic biochar supported catalyst by using a magnet after the reaction is finished; the preparation method of the paper mill sludge magnetic biochar supported catalyst comprises the following steps: directly adding powder obtained by drying paper mill sludge into a Co (NO3) 2 solution, continuously stirring and mixing for 1-25 hours, carrying out solid-liquid separation, taking a solid, drying, pyrolyzing in an argon atmosphere, washing, and drying again to obtain the paper mill sludge magnetic biochar supported catalyst, the paper mill sludge magnetic biochar supported catalyst has the following phases: Fe2O3, Co3O4, CaCO3 and Fe3O4.

Description

Technical Field

[0001] The invention relates to the technical field of resource treatment of papermaking sludge, and in particular to a method for degrading acid orange 7 (AO7) using a papermaking sludge magnetic biochar-loaded catalyst. Background Art

[0002] Azo dyes are the most widely used synthetic dyes in printing and dyeing processes. About 10%-15% of azo dyes are discharged into the water environment without treatment during the production process, destroying the ecological balance and affecting human health. Therefore, wastewater containing azo dyes must be effectively treated before discharge. Among many water treatment technologies, persulfate-based advanced oxidation technology (SRAOPs) is an ideal process for treating refractory dye wastewater. Its principle is mainly to produce highly oxidizing reactive oxygen species (ROSs), such as sulfate radicals (SO4· - ), hydroxyl radical (HO·), singlet oxygen ( 1 O2) and other rapid oxidation and decomposition of organic pollutants to achieve the purpose of water purification. At present, one of the difficulties in the research of this technology is to develop low-cost, highly active and easily recyclable heterogeneous catalytic materials.

[0003] On the other hand, with the rapid development of the papermaking industry, a large amount of papermaking sludge is discharged during production. According to statistics, about 6.5 m3 of paper sludge will be generated for every ton of paper produced. 3 Papermaking sludge. Papermaking sludge has complex components (mainly cellulose, lignin and ferrous sulfate, etc.), and is difficult to recycle. It is currently mainly disposed of by landfill, composting and ocean dumping, which has high disposal costs and will cause environmental pollution and waste of resources to a certain extent. Therefore, how to effectively dispose of papermaking sludge has become a major problem restricting the sustainable development of the papermaking industry.

[0004] The patent specification with publication number CN115041166A discloses a heterogeneous persulfate catalyst and its preparation method and application, which belongs to the field of harmless and resource-based treatment technology of papermaking sludge. The preparation method of the heterogeneous persulfate catalyst includes the following steps: (1) adding ferrous salt and persulfate to the sludge to condition the sludge and then dehydrate it to obtain dehydrated sludge; (2) pyrolyzing the dehydrated sludge to obtain a heterogeneous persulfate catalyst. This patented technical method uses papermaking sludge as the main raw material to prepare a heterogeneous persulfate catalyst, realizing the resource utilization of papermaking sludge solid waste.

[0005] The patent specification with publication number CN119034820A discloses a method for preparing a sludge-derived carbon-supported iron-cobalt oxide catalyst and its application in electro-Fenton degradation of organic pollutants. The specific preparation process is: first, the papermaking sludge is dried and soaked with excess hydrofluoric acid to remove impurities therein, then the residual hydrofluoric acid is removed by centrifugation and filtration, then it is put back into the oven to dry and grind into powder, then added to Co(NO3)2·6H2O solution and Fe(NO3)3·9H2O solution for soaking, then stirred and mixed evenly in a magnetic stirrer and vacuum dried, finally ground into powder and placed in a tubular furnace for calcination to obtain the product sludge-derived carbon-supported iron-cobalt oxide catalyst. The sludge-derived carbon-supported iron-cobalt oxide catalyst can simultaneously and efficiently generate H2O2 and activated persulfate, and can then be used in the electro-Fenton degradation of organic pollutants reaction system. The catalyst prepared by this patented technology is carbon-supported CoO nanoparticles and Fe2O3 polyhedral structures. In addition, the above patented technology first treats the dried papermaking sludge by soaking it in hydrofluoric acid, which will dissolve the elements in the papermaking sludge that originally had the potential to serve as active ingredients. Summary of the invention

[0006] The present invention provides a method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst. Papermaking sludge is used as a cheap raw material. The papermaking sludge is rich in iron and carbon elements, and a new magnetic biochar SRAOPs catalytic material with high catalytic activity is developed. The material is used to activate permonosulfate (PMS) to degrade the typical azo dye Acid Orange 7.

[0007] The specific technical solutions are as follows: A method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, comprising: adding the papermaking sludge magnetic biochar-loaded catalyst to Acid Orange 7 wastewater, adding peroxymonosulfate to start the reaction after adsorption equilibrium, and recovering the papermaking sludge magnetic biochar-loaded catalyst using a magnet after the reaction is completed; The preparation method of the papermaking sludge magnetic biochar-loaded catalyst comprises: drying the papermaking sludge after passing it through a 100-300 mesh screen, directly adding the dried powder into a Co(NO3)2 solution, stirring and mixing continuously for 1-25 hours, performing solid-liquid separation (such as centrifugation, etc.), drying the solid, and pyrolyzing it in an argon atmosphere, then washing it, and drying it again to obtain the papermaking sludge magnetic biochar-loaded catalyst; The papermaking sludge magnetic biochar-loaded catalyst has the following phases: Fe2O3, Co3O4, CaCO3 and Fe3O4.

[0008] In the preparation method of the papermaking sludge magnetic biochar-loaded catalyst described in the present invention, the operation of hydrofluoric acid pickling of papermaking sludge is not performed as in the patent specification with publication number CN119034820A, but the original calcium carbonate, ferrous sulfate, ferric oxide and other components of the papermaking sludge are retained. On this basis, unlike the impregnation method in the patent specification with publication number CN119034820A, the preparation method of the papermaking sludge magnetic biochar-loaded catalyst described in the present invention is to directly add the powder obtained by drying the papermaking sludge into the Co(NO3)2 solution and soak it for a period of time before taking it out. This process relies on ion exchange and adsorption of papermaking sludge to capture Co 2+ , Co 2+ The paper sludge magnetic biochar-loaded catalyst is loaded into the paper sludge, and then pyrolyzed in an argon atmosphere, impurities are washed away, and the catalyst is dried to obtain the paper sludge magnetic biochar-loaded catalyst. The paper sludge magnetic biochar-loaded catalyst finally obtained in this way has the characteristics of coexistence of Fe2O3, Co3O4, CaCO3 and Fe3O4, which is conducive to the conduction of SRAOPs. In short, the paper sludge magnetic biochar-loaded catalyst of the present invention can efficiently activate peroxymonosulfate to generate singlet oxygen active oxygen species, and thus can efficiently degrade acid orange 7.

[0009] In some embodiments, in the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the papermaking sludge needs to be dried before passing through a 100-300 mesh sieve, such as a 200 mesh sieve.

[0010] In some embodiments, in the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the ratio of the added mass of the papermaking sludge magnetic biochar-loaded catalyst to the mass of Acid Orange 7 in the Acid Orange 7 wastewater can be 1~25:10.

[0011] In some embodiments, in the method for degrading Acid Orange 7 using a paper sludge magnetic biochar-loaded catalyst, the content of Acid Orange 7 in the Acid Orange 7 wastewater may be 1-200 mg / L.

[0012] In some embodiments, in the method for degrading Acid Orange 7 using a paper sludge magnetic biochar-loaded catalyst, the ratio of the added mass of permonosulfate to the added mass of the paper sludge magnetic biochar-loaded catalyst can be 1 to 2:1, for example, 1.5:1.

[0013] In some embodiments, in the method for degrading Acid Orange 7 using paper sludge magnetic biochar-loaded catalyst, the reaction temperature may be 10-30°C, such as 25°C.

[0014] In some embodiments, in the method for degrading Acid Orange 7 using paper sludge magnetic biochar-loaded catalyst, the pH of the reaction system may be 4 to 12, such as 4.24, 7.16, 10.19, 11.86, etc.

[0015] In some embodiments, in the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, stirring may be performed during the reaction process. Further, the stirring speed may be 200-300 rpm, such as 250 rpm.

[0016] In some preferred examples, in the method for preparing the paper sludge magnetic biochar-loaded catalyst, the ratio of the mass of the powder obtained by drying the paper sludge to the molar number of Co(NO3)2 in the Co(NO3)2 solution is 1 g:10~20 mmol, for example, 1 g:15 mmol, etc.

[0017] In some preferred examples, in the method for preparing the paper sludge magnetic biochar-loaded catalyst, the concentration of Co(NO3)2 in the Co(NO3)2 solution is 0.1~0.5 mol / L.

[0018] In some preferred examples, in the method for preparing the papermaking sludge magnetic biochar-loaded catalyst, the pyrolysis temperature is 540-560° C., such as 550° C., and the pyrolysis time is 2-3 h.

[0019] The papermaking sludge magnetic biochar-loaded catalyst of the present invention is used as a novel magnetic biochar material to construct a magnetic biochar+PMS system, promotes the generation of singlet active oxygen species in the magnetic biochar+PMS system, and can completely degrade acid orange 7. The papermaking sludge magnetic biochar-loaded catalyst+PMS system of the present invention has a wide pH application range (applicable to pH=4.2~11.9). When the catalyst dosage is 0.2 g / L and the PMS concentration is 0.3 g / L, the system can remove more than 97% of 100 mg / L AO7 within 60 minutes.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses papermaking sludge as a carrier and adopts the strategy of "treating waste with waste" to provide a new idea for the development of wastewater / solid waste coordinated treatment technology.

[0021] 2. The present invention uses papermaking sludge as raw material, which not only solves the sludge disposal problem, but also has environmental friendliness. At the same time, biochar itself is easy to degrade and will not cause long-term negative impact on the environment.

[0022] 3. The present invention adopts a thermal modification method to prepare a magnetic biochar metal oxide catalyst, and constructs a magnetic biochar + PMS system, which promotes the production of singlet reactive oxygen species in the magnetic biochar + PMS system, explores the optimal performance of the magnetic biochar + PMS system in degrading Acid Orange 7, and provides a new and effective way for the degradation of Acid Orange 7.

[0023] 4. The catalyst prepared by the present invention has phases such as Fe2O3, Co3O4, CaCO3, Fe3O4, etc., which can be magnetically recovered. The catalyst has a rich mesoporous structure (average mesopore diameter is 5-6 nm) and a large specific surface area (over 43 m 2 / g), and has good catalytic activity and stability, promoting the degradation of acid orange 7.

[0024] 5. The papermaking sludge magnetic biochar metal oxide catalyst prepared by the present invention has higher cost-effectiveness. The preparation process of the papermaking sludge magnetic biochar metal oxide catalyst is relatively simple, and it can be processed using existing pyrolysis equipment. Its raw material sources are wide and the price is relatively low. Therefore, the preparation and application of sludge biochar catalyst not only helps to solve the problem of papermaking sludge disposal, but also can reduce the cost of pollution control. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The catalytic activity comparison diagram is shown in Figure 1, where (a) is a catalytic activity comparison diagram of dry papermaking sludge powder raw material, raw sludge biochar and Co-containing biochar (i.e., Co / PSB catalyst), and (b) is a catalytic activity comparison diagram of cobalt-containing biochar (i.e., Co / PSB catalyst), copper-containing biochar (i.e., Cu / PSB catalyst) and aluminum-containing biochar (i.e., Al / PSB catalyst).

[0026] Figure 2 X-ray diffraction (XRD) patterns of dried paper sludge powder raw material, raw sludge biochar, Co-loaded paper sludge, Co / PSB catalyst, Cu / PSB catalyst and Al / PSB catalyst.

[0027] Figure 3 High-resolution X-ray photoelectron spectroscopy (XPS) spectra of the catalysts, where (a) is the XPS spectra of Fe on the surface of the Co / PSB catalyst before and after the reaction, and (b) is the XPS spectra of Co on the surface of the Co / PSB catalyst before and after the reaction.

[0028] Figure 4 Hysteresis loop diagram of raw mud biochar and Co / PSB catalyst.

[0029] Figure 5 This is the result graph of the effect of pH on the activation of PMS and degradation of AO7 by Co / PSB catalyst.

[0030] Figure 6 This is the result of the coexistence ion interference experiment on Co / PSB catalyst. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0032] The typical steps of the preparation scheme of paper sludge magnetic biochar-loaded catalyst Co / PSB are as follows: the paper sludge is passed through a 200-mesh sieve and dried, 1 g of dried paper sludge powder is weighed and added to 30 mL, 0.5 mol / L Co(NO3)2 solution, immersed for 1 h and magnetically stirred for 24 h. After complete mixing, the solid is centrifuged and dried in an oven at 105°C to obtain paper sludge loaded with Co. The paper sludge loaded with Co is ground through a 50-mesh sieve, then pyrolyzed in an argon atmosphere at 550°C for 2 h and cooled to room temperature. The product is washed with ultrapure water until the conductivity remains unchanged, placed in a 60°C oven and dried to constant weight, and the resulting sample is Co / PSB.

[0033] For comparison, the preparation methods of Al and Cu modified biochar catalysts Al / PSB and Cu / PSB were the same as above, the only difference being that the Co(NO3)2 solution was replaced by Al(NO3)3 solution and Cu(NO3)2 solution, respectively.

[0034] In addition, the present invention also uses dried papermaking sludge powder raw material and raw mud biochar as comparison. The preparation process of raw mud biochar refers to the preparation scheme of the above catalyst Co / PSB, the only difference is that the Co(NO3)2 solution is replaced by pure water, and the rest are the same.

[0035] The typical operation process of the degradation experiment is as follows: add 20 mg of catalyst or dried paper sludge powder or raw mud biochar to 99 mL of 100 mg / L AO7 solution for 1 min of ultrasonication, let it stand for 30 min for adsorption equilibrium, and then add 1 mL of 30g / L PMS solution to start the reaction. The reaction process was carried out in a constant temperature shaker with a temperature set at 25°C and a speed set at 250 r / min. After the reaction started, 1 mL of water sample was taken at different time points, and the residual active substances were immediately quenched with 0.5 mL of methanol, and then filtered with a 0.22 μm filter membrane and placed in a 2 mL chromatographic bottle for testing. After the experiment, the magnetic catalyst in the reaction solution was recovered using a magnet.

[0036] See also Figure 1 In (a), compared with the dry paper sludge powder raw material and the raw mud biochar, the cobalt-containing biochar (Co / PSB) has a faster rate of catalytic degradation of AO7; the activity comparison results of paper sludge biochar modified with different metals are Figure 1 As shown in (b), the Co-containing biochar has a higher efficiency in activating PMS and a more thorough effect in degrading AO7, indicating that compared with Al and Cu, the incorporation of Co ions can make paper sludge biochar have better PMS activation performance.

[0037] From the XRD results, Figure 2 It can be seen that the dried paper sludge powder raw material has diffraction peaks at 29.6°, 40.1°, 43.7°, 47.04°, and 50.73°, which belong to the typical calcite (CaCO3) crystal structure, while the diffraction peaks at 35.6° and 23.8° are attributed to Fe2O3 and ferrous sulfate containing crystal water, respectively. The above results show that the dried paper sludge powder raw material contains calcium carbonate and iron compounds in different forms. The diffraction peak position of the raw mud biochar is basically consistent with that of the dried paper sludge powder raw material, and the signal intensity is enhanced to varying degrees. For the paper sludge loaded with Co, the diffraction peak position is basically consistent with that of the dried paper sludge powder, but the difference is that the signal intensity is weakened to varying degrees, which may be due to the surface loading of Co. For the final sample Co / PSB catalyst, obvious Co3O4 diffraction peaks appeared at 45.1°, 59.4°, and 65.4°, indicating that the loaded Co salt was converted into Co3O4 after pyrolysis; in addition, the diffraction peak of Fe3O4 appeared at 62.8°. The appearance of the Co3O4 diffraction peak confirmed the successful loading of the Co element, which can play a positive role as an active site in the activation of PMS. In addition, Fe2O3 and Fe3O4 can also participate in the catalytic reaction as active sites.

[0038] Depend on Figure 3 In (a), Fe 3+ 2p 1 / 2, Fe 2+ 2p 1 / 2, Fe 3+ 2p 3 / 2 and Fe 2+ The characteristic peaks of the four Fe elements 2p 3 / 2 are Figure 3 In (b), Co can be observed 3+ 2p 1 / 2, Co 2+ 2p 1 / 2, Co 3+ 2p 3 / 2, Co 2+ The four characteristic peaks of Co element 2p 3 / 2 indicate the presence of metallic iron and metallic cobalt in different valence states. By comparing the Fe 2p XPS graph and Co 2p XPS graph before and after the typical operation process of the above degradation experiment, it can be seen that after Co / PSB activates PMS to degrade AO7, Fe 2+ 、Co 2+ The content of Fe 3+ 、Co 3+ The corresponding content increased slightly, indicating that Fe 2+、Co 2+ The synergistic effect of Fe and Co on the degradation of AO7 by activating PMS improves the catalytic activity of Co / PSB and promotes 1 The generation of reactive oxygen species such as O2.

[0039] Figure 4 The magnetic properties of raw mud biochar and Co / PSB catalyst are shown. The magnetic saturation intensity of raw mud biochar is about 10emu·g -1 The magnetic saturation intensity of Co / PSB catalyst is about 40 emu·g -1 ; The magnetism of Co / PSB catalyst is stronger than that of raw mud biochar. The difference in saturation magnetization intensity may be caused by the difference in the form of iron element, which further indicates that Fe3O4 is generated in Co / PSB catalyst.

[0040] Figure 5 The effect of pH on the degradation of AO7 was demonstrated. Based on the typical operating procedures of the above degradation experiment, the pH of the reaction system was adjusted by acid and alkali. The results showed that within the range of pH = 4.24 ~ 10.19, the AO7 degradation rate could reach more than 95% at 60 min, and the degradation rate also exceeded 90% at pH = 11.86, indicating that the system has a wide pH application range.

[0041] In order to investigate the stability of Co / PSB catalyst, based on the typical operation flow of the above degradation experiment, the present invention carried out a coexisting ion interference experiment. - 、NO3 - 、H2PO4 - Three common water anions were used to investigate the anti-ion interference of Co / PSB. Figure 6 As shown in the figure, the concentration of anions has little effect on the degradation of AO7 by the system, while the type of anions has a relatively large effect on the degradation of AO7 by the system. - 、NO3 - 、H2PO4 - When the concentrations of are all 1.0 M, the removal rates of AO7 by the system can still reach 91.64%, 88.43% and 98.17% respectively. The above results show that Co / PSB has strong resistance to ion interference and excellent comprehensive stability.

[0042] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for degrading Acid Orange 7 using magnetic biochar-loaded catalyst from papermaking sludge, characterized in that: include: The paper sludge magnetic biochar-loaded catalyst is added to acid orange 7 sewage, and after adsorption equilibrium, peroxymonosulfate is added to start the reaction, and after the reaction is completed, the paper sludge magnetic biochar-loaded catalyst is recovered using a magnet; The preparation method of the papermaking sludge magnetic biochar-loaded catalyst comprises: drying the papermaking sludge after passing it through a 100-300 mesh screen, directly adding the dried powder into a Co(NO3)2 solution, stirring and mixing continuously for 1-25 hours, separating the solid from the liquid, drying the solid, and pyrolyzing it in an argon atmosphere, then washing it, and drying it again to obtain the papermaking sludge magnetic biochar-loaded catalyst; The papermaking sludge magnetic biochar-loaded catalyst has the following phases: Fe2O3, Co3O4, CaCO3 and Fe3O4.

2. The method for degrading Acid Orange 7 using magnetic biochar-loaded catalyst from papermaking sludge according to claim 1, characterized in that: In the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the ratio of the added mass of the papermaking sludge magnetic biochar-loaded catalyst to the mass of Acid Orange 7 in the Acid Orange 7 wastewater is 1-25:

10.

3. The method for degrading Acid Orange 7 using magnetic biochar-loaded catalyst from papermaking sludge according to claim 1, characterized in that: In the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the content of Acid Orange 7 in the Acid Orange 7 wastewater is 1-200 mg / L.

4. The method for degrading Acid Orange 7 using magnetic biochar-loaded catalyst from papermaking sludge according to claim 1, characterized in that: In the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the ratio of the added mass of permonosulfate to the added mass of the papermaking sludge magnetic biochar-loaded catalyst is 1-2:

1.

5. The method for degrading Acid Orange 7 using magnetic biochar-loaded catalyst from papermaking sludge according to claim 1, characterized in that: In the method for degrading Acid Orange 7 using papermaking sludge magnetic biochar-loaded catalyst, the reaction temperature is 10-30°C.

6. The method for degrading Acid Orange 7 using magnetic biochar-loaded catalyst from papermaking sludge according to claim 1, characterized in that: In the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the pH of the reaction system is 4-12.

7. The method for degrading Acid Orange 7 using magnetic biochar-supported catalyst from papermaking sludge according to claim 1, characterized in that: In the method for degrading Acid Orange 7 using a papermaking sludge magnetic biochar-loaded catalyst, the reaction is accompanied by stirring at a stirring speed of 200-300 rpm.

8. The method for degrading Acid Orange 7 using magnetic biochar-supported catalyst from papermaking sludge according to claim 1, characterized in that: In the method for preparing the papermaking sludge magnetic biochar-loaded catalyst, the ratio of the mass of the powder obtained by drying the papermaking sludge to the molar number of Co(NO3)2 in the Co(NO3)2 solution is 1 g:10-20 mmol.

9. The method for degrading Acid Orange 7 using magnetic biochar-supported catalyst from papermaking sludge according to claim 1, characterized in that: In the method for preparing the papermaking sludge magnetic biochar-loaded catalyst, the concentration of Co(NO3)2 in the Co(NO3)2 solution is 0.1-0.5 mol / L.

10. The method for degrading Acid Orange 7 using magnetic biochar-supported catalyst from papermaking sludge according to claim 1, characterized in that: In the method for preparing the papermaking sludge magnetic biochar-loaded catalyst, the pyrolysis temperature is 540-560° C. and the pyrolysis time is 2-3 h.

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