CT / Ni2O3@SBC, a preparation method and application thereof

Abstract

The present application relates to a kind of CT / Ni2O3@SBC and its preparation method and application, the preparation method of CT / Ni2O3@SBC provided by the present application, different material is loaded to dry sludge to improve the persistence of free radicals (PFRs) of SBC, obtain CT / Ni2O3@SBC.The residual activated sludge discharged from sewage treatment plant is concentrated first, and then the prepared biochar CT / Ni2O3@SBC and persulfate are added in sequence, nitrogen is passed for 10 minutes, to achieve anaerobic environment, do not adjust the acid-base nature of sludge to be treated, sealed and placed in the temperature 35 DEG C, the shaking speed is 180rpm of shaking table and carries out anaerobic fermentation, fermentation time is 7 days.Compared with prior art, the present application is simple in operation, reaction condition is mild, is used for the resourceization and harmlessness of concentrated residual sludge in sewage treatment plant, and has good economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sludge treatment and resource utilization, and particularly relates to CT / Ni2O3@SBC, a preparation method and application thereof. BACKGROUND

[0002] A large amount of waste activated sludge (WAS) is produced in municipal wastewater treatment plants, which contains a large amount of organic matter (such as protein and carbohydrate). If WAS is treated by land use or incineration, not only resources will be wasted, but also secondary pollution to the environment will be caused. In recent years, WAS anaerobic fermentation to produce volatile fatty acids (VFAs) has attracted extensive attention, and VFAs dominated by acetic acid can be used as a high-quality carbon source for biological denitrification and phosphorus removal.

[0003] However, dissolution and hydrolysis are the main rate-limiting steps of WAS anaerobic fermentation. In addition, most studies only focus on the total VFAs production in sludge anaerobic fermentation liquid, and do not focus on the VFAs composition, especially the acetic acid content. Studies have shown that acetic acid plays an important role in the process of biological denitrification and phosphorus removal, and therefore, when sludge fermentation liquid is used as a carbon source, increasing the proportion of acetic acid in the sludge fermentation liquid is beneficial to improving the effect of biological denitrification and phosphorus removal. At the same time, most studies ignore the harmful and refractory organic matter in the sludge fermentation liquid. Studies have shown that in the process of wastewater treatment, sludge will adsorb a large amount of harmful and refractory organic matter, such as surfactants, personal care products, drugs and estrogens, and traditional anaerobic fermentation will cause the sludge to dissolve and release, so that the fermentation liquid contains a large amount of harmful and refractory organic matter. SUMMARY

[0004] The purpose of the present application is to provide a CT / Ni2O3@SBC, a preparation method and application thereof. The CT / Ni2O3@SBC and persulfate (PMS) are added to sludge for anaerobic fermentation, which can destroy lignocellulose, extracellular polymeric substances and cell wall structure, promote the dissolution of protein and polysaccharide, strengthen the electron transfer in the process of anaerobic fermentation by using the CT / Ni2O3@SBC, effectively improve the production of short-chain fatty acids, and inhibit the methanogenesis process, thereby being beneficial to the accumulation of acetic acid.

[0005] The purpose of the present application can be achieved by the following technical solutions.

[0006] The first purpose of the present application is to provide a preparation method of CT / Ni2O3@SBC, and the specific steps are as follows.

[0007] Dry sludge, catechol (CT) and nickel sesquioxide (Ni2O3) are mixed, heated under a carbon dioxide gas atmosphere, and pyrolyzed to obtain CT / Ni2O3@SBC.

[0008] Further, the mass fraction of the catechol (CT) in the dry sludge is 3-8%.

[0009] The mass fraction of the nickel trioxide (Ni2O3) in the dry sludge is 3-8%.

[0010] As a preferred technical solution, the mass fraction of the catechol (CT) in the dry sludge is 5%.

[0011] The mass fraction of the nickel trioxide (Ni2O3) in the dry sludge is 5%.

[0012] Further, the dry sludge, catechol (CT) and nickel trioxide (Ni2O3) are placed in a quartz boat and sealed in a tube furnace, heated under a carbon dioxide gas atmosphere, cooled to room temperature after pyrolysis for a period of time, washed, adjusted to neutral pH, and dried and crushed to obtain CT / Ni2O3@SBC.

[0013] Further, the heating temperature of the tube furnace is 80-120°C, and the heating time is 40-60 min.

[0014] As a preferred technical solution, the heating temperature of the tube furnace is 100°C, and the heating time is 50 min.

[0015] Further, the pyrolysis temperature is 400-500°C, and the pyrolysis time is 80-100 min.

[0016] As a preferred technical solution, the pyrolysis temperature is 450°C, and the pyrolysis time is 90 min.

[0017] Further, the washing step is to wash with deionized water multiple times to remove residual salt.

[0018] Further, the pH range is 7.53-7.47.

[0019] Further, the drying temperature is 95-115°C, and the drying time is 20-30 hours.

[0020] As a preferred technical solution, the drying temperature is 105°C, and the drying time is 24 hours.

[0021] The sludge pyrolysis biochar (SBC) contains organic chemical groups such as quinone groups and phenolic groups (persistent free radicals (PFRs)), has a certain redox capacity, and can transfer electrons. Based on the PFRs formation mechanism, the catechol (CT) and nickel trioxide (Ni2O3) are loaded on the biochar to increase the PFRs content, and added to the sludge anaerobic fermentation to improve the fermentation yield and achieve waste treatment with waste.

[0022] The second object of the present application is to provide a CT / Ni2O3@SBC prepared by the above preparation method, comprising biochar and catechol and nickel sesquioxide loaded on the biochar.

[0023] Further, the particle size of the CT / Ni2O3@SBC is <0.075 mm.

[0024] The third object of the present application is to provide an application of the CT / Ni2O3@SBC prepared by the above preparation method, wherein the CT / Ni2O3@SBC is used for producing volatile fatty acids (VFAs) by anaerobic fermentation of sludge.

[0025] Further, the specific steps of the method for producing volatile fatty acids (VFAs) by anaerobic fermentation of sludge using the CT / Ni2O3@SBC are as follows:

[0026] The CT / Ni2O3@SBC and persulfate (PMS) are added to the sludge to be treated, and volatile fatty acids (VFAs) are obtained after a period of time of anaerobic fermentation under oscillation.

[0027] Further, the sludge to be treated is waste activated sludge (WAS), and the concentration (VSS) of the sludge to be treated is 10-11 g / L.

[0028] As a preferred technical solution, the concentration (VSS) of the sludge to be treated is 10.54 g / L.

[0029] Further, the persulfate (PMS) is commercially available analytical pure potassium hydrogen persulfate complex salt.

[0030] Further, the mass ratio of CT / Ni2O3@SBC: sludge to be treated: persulfate is 0.1-0.3:1:0-0.24.

[0031] As a preferred technical solution, the mass ratio of CT / Ni2O3@SBC: sludge to be treated: persulfate is 0.2:1:0.2.

[0032] Further, the anaerobic environment is formed by passing nitrogen for 8-12 minutes.

[0033] Further, the oscillation speed is 160-200 rpm.

[0034] As a preferred technical solution, the oscillation speed is 180 rpm.

[0035] Further, the anaerobic fermentation temperature is 30-40 DEG C, and the anaerobic fermentation time is 5-10 days.

[0036] As a preferred technical solution, the anaerobic fermentation temperature is 35 DEG C, and the anaerobic fermentation time is 7 days.

[0037] The present application first concentrates the residual activated sludge discharged from the sewage treatment plant, and then adds the prepared biochar CT / Ni2O3@SBC and persulfate in turn, passes nitrogen for 10 minutes to achieve an anaerobic environment, does not adjust the acid-base of the sludge to be treated, and is sealed and placed in a shaker with a temperature of 35 DEG C and a shaking speed of 180 rpm for anaerobic fermentation, and the fermentation time is 7 days.

[0038] The content of persistent free radicals in CT / Ni2O3@SBC is increased (11.17 x 10 16 spins / g); the activated oxygen substances generated by activated persulfate can destroy lignocellulose, extracellular polymer, and cell wall structure in sludge, promote the dissolution of protein and polysaccharide, increase the acidification degree of soluble organic matter, inhibit the methanogenesis process, and through the use of persistent free radicals in CT / Ni2O3@SBC to strengthen the electron transfer in the anaerobic fermentation process, thereby facilitating the accumulation of volatile fatty acids; the VFAs yield is the highest (3337.12 mg COD / L) on the 4th day of fermentation, and the acetic acid proportion is 58.84%; the lignocellulose is reduced from 24.56% to 12.79% on the 4th day of fermentation, wherein the lignin is reduced from 11.27% to 7.69%, the cellulose is reduced from 5.23% to 2.32%, and the hemicellulose is reduced from 8.06% to 2.78%; many harmful and refractory organic matters (tetracontane, phthalate ester, eicosanal, benzaldehyde, stearic acid amide, cyclopentasiloxane, norepinephrine, and p-acetylaminobenzene, etc.) in the fermentation broth are effectively removed on the 4th day of fermentation; meanwhile, CT / Ni2O3@SBC can adsorb part of phosphate to reduce the phosphorus content. The present application has the advantages of simple operation, mild reaction conditions, and is used for the resourceization and harmlessness of concentrated residual sludge in a sewage treatment plant, and has good economic and social benefits.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] 1、The preparation method of CT / Ni2O3@SBC provided by the present application uses different materials to load on dry sludge to improve the persistent free radicals (PFRs) of SBC, and obtain CT / Ni2O3@SBC; the PFRs in the CT / Ni2O3@SBC prepared by the present application are improved from 2.08 x 10 16 spins / g of SBC to 11.17 x 10 16spins / g, PFRs are oxygen-centered radicals (g>2.0040), mainly semiquinone radicals.

[0041] 2、The CT / Ni2O3@SBC and PMS are added in the sludge for anaerobic fermentation, the lignocellulose, extracellular polymer, and cell wall structure are destroyed, the protein and polysaccharide are promoted to be dissolved out, the electron transfer in the anaerobic fermentation process is strengthened by utilizing the CT / Ni2O3@SBC, the short-chain fatty acid yield is effectively improved, the methanogenesis process is inhibited, thereby the accumulation of acetic acid is beneficial, the proportion of acetic acid is 58.83%, compared with the control group without adding the CT / Ni2O3@SBC, the total volatile fatty acid yield is increased by 1.05 times, and the acetic acid yield is increased by 1.22 times.

[0042] 3、The CT / Ni2O3@SBC and PMS are added in the sludge for anaerobic fermentation, lignocellulose degradation in the sludge is promoted, the lignocellulose is reduced from 24.56% to 12.79% on the 4th day of fermentation, wherein the lignin is reduced by 7.69% from 11.27%, the cellulose is reduced to 2.32% from 5.23%, and the hemicellulose is reduced to 2.78% from 8.06%.

[0043] 4、The CT / Ni2O3@SBC and PMS are added in the sludge for anaerobic fermentation, harmful and refractory organic matters in the sludge fermentation liquor are effectively removed, compared with the control group with only PMS added, the harmful and refractory organic matters are reduced from 51 to 33 on the 4th day of fermentation, wherein tetracontane, phthalate, eicosanal, benzaldehyde, stearic acid amide, cyclopentasiloxane, norepinephrine and p-acetylaminobenzene are completely removed.

[0044] 5、The CT / Ni2O3@SBC prepared in the application can also adsorb part of phosphate, reduce the content of phosphorus, the content of phosphorus in the obtained fermentation liquor is low, and the influence on the subsequent biological treatment section of the sewage plant as a high-quality carbon source is small, compared with the control group with only PMS added, the content of phosphorus is reduced by 7.80 times. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The SEM diagram of the CT / Ni2O3@SBC prepared in the embodiment 1 of the application;

[0046] Figure 2 The FTIR diagram of the CT / Ni2O3@SBC prepared in the embodiment 1 of the application;

[0047] Figure 3 The XRD diagram of the CT / Ni2O3@SBC prepared in the embodiment 1 of the application;

[0048] Figure 4EPR diagram of CT / Ni2O3@SBC prepared for the embodiment 1 of the present application;

[0049] Figure 5 CV diagram of CT / Ni2O3@SBC prepared for the embodiment 1 of the present application;

[0050] Figure 6 Figure of the effect of PMS addition amount on the change of acid production with time in sludge anaerobic fermentation in the embodiment 2 to the embodiment 8 of the present application;

[0051] Figure 7 Figure of the change of total VFAs with time in sludge anaerobic fermentation in the experimental group of adding PMS and biochar CT / Ni2O3@SBC under the optimal conditions in the embodiment 7 of the present application and the control group of adding PMS only in the comparative example 1;

[0052] Figure 8 Figure of VFAs of each group in sludge anaerobic fermentation on the 4th day in the experimental group of adding PMS and biochar CT / Ni2O3@SBC under the optimal conditions in the embodiment 7 of the present application and the control group of adding PMS only in the comparative example 1;

[0053] Figure 9 Schematic diagram of lignocellulose degradation in the experimental group of adding PMS and biochar CT / Ni2O3@SBC under the optimal conditions in the embodiment 7 of the present application and the control group of adding PMS only in the comparative example 1;

[0054] Figure 10 Schematic diagram of harmful and refractory organic matters in supernatant of raw sludge of the present application;

[0055] Figure 11 Schematic diagram of harmful and refractory organic matters in fermentation liquid on the 4th day in the control group of adding PMS only in the comparative example 1 of the present application;

[0056] Figure 12 Schematic diagram of harmful and refractory organic matters in fermentation liquid on the 4th day in the experimental group of sludge anaerobic fermentation under the optimal conditions of adding PMS and biochar CT / Ni2O3@SBC in the embodiment 7 of the present application;

[0057] Figure 13 Schematic diagram of the change of phosphate in fermentation liquid in the experimental group of adding PMS and biochar CT / Ni2O3@SBC under the optimal conditions in the embodiment 7 of the present application and the control group of adding PMS only in the comparative example 1. DETAILED DESCRIPTION

[0058] The present application will be described in detail below in conjunction with the drawings and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present application, and detailed implementation and specific operation process are given, but the protection scope of the present application is not limited to the following embodiments.

[0059] Some embodiments of the present application will be described in detail with reference to the drawings. The following examples and features in the examples can be combined with each other in the case of no conflict.

[0060] Example 1

[0061] The present embodiment provides a preparation method of CT / Ni2O3@SBC, and the specific steps are as follows:

[0062] (1) Put dry sludge + CT (5% mass fraction / dry sludge) + Ni2O3 (5% mass fraction / dry sludge) into a quartz boat, seal in a tube furnace (SK3-2-10-4), and the carrier gas is carbon dioxide throughout the process;

[0063] (2) Flush with carbon dioxide gas for 10 min to remove excess air in the tube furnace;

[0064] (3) Heat the tube furnace to 100℃ for 50 min;

[0065] (4) Control the temperature of the tube furnace at 450℃ for pyrolysis for 90 min;

[0066] (5) Cool to room temperature, wash the pyrolyzed product with deionized water for 3 times to remove residual salt, and neutralize the pH to 7.50±0.03;

[0067] (6) Dry the product after neutralizing the pH at 105℃ for 24 hours, crush to obtain CT / Ni2O3@SBC, the particle size of the CT / Ni2O3@SBC is <0.075mm, and the CT / Ni2O3@SBC is stored in a desiccator before use.

[0068] Figure 1 The SEM image of the biochar CT / Ni2O3@SBC prepared in Example 1 of the present application shows that the material has a larger spatial size and a rough surface structure, which is beneficial to the contact of microorganisms and provides more active sites for the adhesion of microorganisms. At the same time, the electron transfer is strengthened, and the acid production performance of anaerobic fermentation is improved.

[0069] Figure 2 The FTIR image of the biochar CT / Ni2O3@SBC prepared in Example 1 of the present application shows that the biochar CT / Ni2O3@SBC loaded with CT and Ni2O3 has a characteristic peak of Ni-O stretching vibration at 557.34cm -1 , and characteristic absorption peaks of -OH, C=O and C-O-C at 3423.08cm -1 , 1627.65cm -1 and 1100.53cm -1 .

[0070] Figure 3 The XRD pattern of the biochar CT / Ni2O3@SBC prepared in Example 1 of the present application has peaks at 44.4, 51.62 and 75.66 degrees (2θ) corresponding to the 111, 200 and 220 crystal planes, respectively, which belong to the Ni2O3 nanoparticles (JCPDS No. 04-0850).

[0071] Figure 4 The EPR pattern of the biochar CT / Ni2O3@SBC prepared in Example 1 of the present application was obtained, and quantitative calculation showed that the PFRs of the biochar were 11.17 x 10 16 spins / g, while the PFRs were oxygen atom-centered free radicals (g > 2.0040), mainly semiquinone free radicals, which were conducive to microbial electron transfer.

[0072] Figure 5 The CV pattern of the biochar CT / Ni2O3@SBC prepared in Example 1 of the present application was obtained, and the prepared biochar had a strong reduction peak, indicating that it had strong electron-accepting ability; it can be seen that the biochar CT / Ni2O3@SBC had strong catalytic activity and electron transfer capacity.

[0073] Example 2

[0074] The present example provides a method for producing acetic acid by sludge anaerobic fermentation, which utilizes the preparation method described in Example 1 to prepare CT / Ni2O3@SBC to promote the production of acetic acid by sludge anaerobic fermentation.

[0075] First, the activated sludge discharged from the sewage treatment plant was concentrated to VSS = 10.54 g / L (pH = 7.52, SCOD = 113.76 mg / L), and 300 mL was taken in a 550 mL serum bottle. The prepared CT / Ni2O3@SBC and PMS were added in turn, nitrogen was introduced for 10 minutes to achieve an anaerobic environment, and the pH of the sludge to be treated was not adjusted. Then it was sealed and placed in a shaking bed at a temperature of 35°C and a shaking speed of 180 rpm for anaerobic fermentation, and the fermentation time was 7 days.

[0076] In this example, the biochar is the biochar CT / Ni2O3@SBC prepared by the present application, and the addition amount is 0.2 g of CT / Ni2O3@SBC per g of VSS.

[0077] In this example, PMS is commercially available analytical grade potassium hydrogen sulfate double salt, and the addition amount is 0 g / g VSS.

[0078] Example 3

[0079] This embodiment provides a method for producing acetic acid through anaerobic fermentation of sludge. Except for the addition amount of PMS being 0.08 g / g VSS, the other steps are the same as in Example 2.

[0080] Example 4

[0081] This embodiment provides a method for producing acetic acid through anaerobic fermentation of sludge. Except for the addition amount of PMS being 0.12 g / g VSS, the other steps are the same as in Example 2.

[0082] Example 5

[0083] This embodiment provides a method for producing acetic acid through anaerobic fermentation of sludge. Except for the addition amount of PMS being 0.16 g / gVSS, the other steps are the same as in Example 2.

[0084] Example 7

[0085] This embodiment provides a method for producing acetic acid through anaerobic fermentation of sludge. Except for the addition amount of PMS being 0.20 g / g VSS, the other steps are the same as in Embodiment 2.

[0086] Example 8

[0087] This embodiment provides a method for producing acetic acid through anaerobic fermentation of sludge. Except for the addition amount of PMS being 0.24 g / g VSS, the other steps are the same as in Example 2.

[0088] Comparative Example 1

[0089] This embodiment provides a method for producing acetic acid through anaerobic fermentation of sludge. Except for the absence of CT / Ni2O3@SBC and the addition of PMS at a rate of 0.20 g / g VSS, the remaining steps are the same as in Example 2.

[0090] Performance tests were conducted on Examples 2 to 8, and the results are as follows:

[0091] like Figure 6 As shown: the production of volatile fatty acids (VFAs) first increased and then decreased with the addition of PMS. VFAs reached their maximum on the fourth day, and the maximum VFAs were reached when the PMS addition was 0.20 g / g VSS, which was 3337.12 mg COD / L. This is 3.40 times (980.21 mg COD / L) of the experimental group in Example 2 that only added biochar CT / Ni2O3@SBC.

[0092] like Figure 7As shown: the VFAs yield of the experimental group with PMS and biochar CT / Ni2O3@SBC under the optimal conditions in Example 7 was 2.05 times that of the control group with only PMS (1624.07 mg COD / L) in Comparative Example 1, and the amount of PMS added in Comparative Example 1 was 0.20 g / g VSS.

[0093] As shown: Figure 8 As shown: the acetic acid content of the experimental group with PMS and biochar CT / Ni2O3@SBC under the optimal conditions in Example 7 was 1963.65 mg COD / L, accounting for 58.84%, which was 1.22 times the acetic acid yield (885.80 mg COD / L) of the control group with only PMS in Comparative Example 1.

[0094] As shown: Figure 9 As shown: the lignocellulose of the control group with only PMS in Comparative Example 1 decreased from 24.56% to 17.91% on the 4th day of fermentation, among which lignin decreased from 11.27% to 9.12%, cellulose decreased from 5.23% to 3.45%, and hemicellulose decreased from 8.06% to 5.34%; the lignocellulose of the experimental group with PMS and biochar CT / Ni2O3@SBC under the optimal conditions in Example 7 decreased from 24.56% to 12.79% on the 4th day of fermentation, among which lignin decreased from 11.27% to 7.69%, cellulose decreased from 5.23% to 2.32%, and hemicellulose decreased from 8.06% to 2.78%.

[0095] As shown: Figure 10 As shown, GC-MS was used to analyze the types and total detection frequency of harmful and refractory organic matter in the supernatant of the sludge sample. A total of 77 harmful and refractory organic compounds were detected in the three parallel samples of the original sludge sample. Most of these detected harmful and refractory organic compounds were from cosmetics (such as diisobutyl adipate, cyclopentasiloxane, benzyl alcohol, octadecene, methyl palmitate, isopropyl palmitate, chloromethyl decanoate, dodecanol, and decamethylcyclopentasiloxane), drugs (such as norepinephrine, p-acetylamino benzene, glycine, n-tetradecane, n-octadecane, n-nonadecane, triethyl citrate, pentadecanal, 2-indole ketone, and o-phthalic acid), pesticides (such as isophorone, 4-methyl benzoic acid, and di-tert-butyl-phenol), fragrances and spices (such as glycidyl ester and benzaldehyde), and textiles (such as octadecamethylcyclopentasiloxane, lauryl methacrylate, 1-ethoxy-2-propanol, and dodecamethyldihydrohexasiloxane), etc., which are difficult to degrade in traditional anaerobic fermentation processes.

[0096] As shown: Figure 11As shown, 51 harmful and refractory organic compounds were detected in the sludge fermentation broth of the control group with only PMS added in Comparative Example 1 on the 4th day, among which isophorone, n-octadecane, n-nonadecane, dodecamethyl dihydrogen hexa-siloxane, isopropyl palmitate, chloromethyl decanoate and isopropyl stearate were further degraded, indicating that PMS has a certain removal capacity for harmful and refractory organic compounds in sludge fermentation broth.

[0097] As shown in Figure 12 As shown in Comparative Example 1, the phosphate content in the control group with only PMS added gradually increased with the reaction time, and the phosphate concentration was 73.82 mg / L on the 4th day. In Example 7, the phosphate content in the experimental group with PMS and biochar CT / Ni2O3@SBC added under the optimal conditions gradually decreased with the reaction time, and the orthophosphate concentration was 8.39 mg / L on the 4th day, indicating that the biochar has good adsorption performance for phosphate. Compared with the control group with only PMS added, the phosphorus content was reduced by 7.80 times.

[0098] As shown in Figure 13 As shown in Comparative Example 1, the phosphate content in the control group with only PMS added gradually increased with the reaction time, and the phosphate concentration was 73.82 mg / L on the 4th day. In Example 7, the phosphate content in the experimental group with PMS and biochar CT / Ni2O3@SBC added under the optimal conditions gradually decreased with the reaction time, and the orthophosphate concentration was 8.39 mg / L on the 4th day, indicating that the biochar has good adsorption performance for phosphate. Compared with the control group with only PMS added, the phosphorus content was reduced by 7.80 times.

[0099] In view of the problems of insufficient utilization of sludge organic matter, low VFAs yield, low acetic acid proportion, many harmful and refractory organic compounds in fermentation broth and high phosphorus content in the traditional anaerobic fermentation mode; in order to realize sludge anaerobic fermentation for acid production and use as high-quality carbon source, the present embodiment utilizes PFRs in biochar CT / Ni2O3@SBC to activate PMS to enhance sludge anaerobic fermentation, which can increase VFAs yield while reducing the phosphorus content in supernatant and reducing the impact on subsequent biological treatment section.

[0100] The above description of the embodiments is for the purpose of enabling a person of ordinary skill in the art to understand and use the present application. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A preparation method of CT / Ni2O3@SBC, characterized in that, The specific steps are as follows: The dry sludge, catechol and nickel trioxide are put into a quartz boat, sealed in a tube furnace, heated in a carbon dioxide gas atmosphere, pyrolyzed for a period of time, cooled to room temperature, washed, adjusted to neutral pH, dried and crushed to obtain CT / Ni2O3@SBC; The mass fraction of catechol in dry sludge is 3-8%; The mass fraction of nickel trioxide in dry sludge is 3-8%; The heating temperature of the tube furnace is 80-120℃, and the heating time is 40-60min; The pyrolysis temperature is 400-500℃, and the pyrolysis time is 80-100min; The CT / Ni2O3@SBC has a persistent free radical content of 11.17 x 10 16 spins / g.

2. The preparation method of the CT / Ni2O3@SBC according to claim 1, characterized in that, The washing step is: multiple washing with deionized water to remove residual salt; The pH range is 7.53-7.47; The drying temperature is 95-115℃, and the drying time is 20-30 hours.

3. A CT / Ni203@SBC, characterized in that, The CT / Ni2O3@SBC is prepared by the preparation method of any one of claims 1-2, comprising biochar and catechol and nickel trioxide loaded on the biochar.

4. The CT / Ni2O3@SBC of claim 3, wherein, The particle size of the CT / Ni2O3@SBC is <0.075mm.

5. Use of CT / Ni2O3@SBC, characterized in that, The CT / Ni2O3@SBC is prepared by the preparation method of any one of claims 1-2, and the CT / Ni2O3@SBC is used for sludge anaerobic fermentation to produce volatile fatty acids.

6. The use of a CT / Ni2O3@SBC according to claim 5, characterized by The specific steps of the method for producing volatile fatty acids by sludge anaerobic fermentation of the CT / Ni2O3@SBC are as follows: The CT / Ni2O3@SBC and persulfate are added to the sludge to be treated, and the sludge is subjected to anaerobic fermentation under an oxygen-free environment for a period of time to obtain volatile fatty acids.

7. The use of a CT / Ni2O3@SBC according to claim 6, characterized by The sludge to be treated is excess activated sludge, and the concentration of the sludge to be treated is 10-11g / L; The persulfate is potassium peroxymonosulfate composite salt; The mass ratio of CT / Ni2O3@SBC: sludge to be treated: persulfate is 0.1-0.3:1:0-0.

24.

8. The use of a CT / Ni2O3@SBC according to claim 6, characterized by The oxygen-free environment is formed by passing nitrogen for 8-12 minutes; The shaking speed is 160-200rpm; The anaerobic fermentation temperature is 30-40℃, and the anaerobic fermentation time is 5-10 days.

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