Composite material for sludge dewatering and method for preparing the same, sludge dewatering conditioner

Abstract

The application provides a composite material for sludge dewatering, a preparation method thereof and a sludge dewatering conditioner. The composite material for sludge dewatering comprises magnetic porous carbon and molybdenum disulfide loaded on the magnetic porous carbon, wherein the magnetic porous carbon comprises porous carbon and ferroferric oxide loaded on the porous carbon. The preparation method comprises the following steps: mixing the magnetic porous carbon with a molybdenum source and a sulfur source, and performing a hydrothermal reaction to make the molybdenum source and the sulfur source react to generate molybdenum disulfide; after the reaction is completed, performing solid-liquid separation, collecting the solid product, and calcining the solid product under an inert atmosphere at 350-450 DEG C to obtain the molybdenum disulfide magnetic porous carbon composite material; wherein the magnetic porous carbon comprises porous carbon and ferroferric oxide loaded on the porous carbon; and the composite material for sludge dewatering can construct a molybdenum disulfide magnetic carbon-based composite material with a large specific surface area, high catalytic activity and high universality, and the composite material can improve the sludge dewatering performance.

Description

Technical Field

[0001] This invention belongs to the field of sludge treatment and disposal, specifically relating to a composite material for sludge dewatering and its preparation method, a sludge dewatering conditioner, and especially to a molybdenum disulfide magnetic biochar composite material based on advanced oxidation technology and its preparation method, a sludge dewatering conditioner containing the composite material, and a sludge dewatering method. Background Technology

[0002] Municipal sludge is a high-moisture, complex-composition byproduct generated during municipal wastewater treatment. To mitigate or avoid the environmental impact of municipal sludge, it must be treated and disposed of in a way that reduces its volume, renders it harmless, and facilitates its resource recovery. Dewatering is a necessary and crucial step in the safe disposal of municipal sludge. By dewatering municipal sludge, its volume can be effectively reduced, its solids content increased, its transportation costs lowered, and its subsequent treatment and disposal facilitated.

[0003] Studies have shown that most of the water in sludge exists in extracellular polymeric substances (EPS), which are also a major obstacle to sludge dewatering. Furthermore, the structure and particle size distribution of sludge flocs also affect dewatering efficiency. Traditional sludge dewatering methods involve mechanically compressing and conditioning the sludge using coagulants or flocculants. However, mechanical compression is difficult to break down EPS, resulting in low dewatering efficiency and high costs. Subsequently, various sludge conditioning methods have been proposed, such as microwave-ultrasonic conditioning, hydrothermal treatment, electro-oxidation, ultraviolet photocatalytic oxidation, ozone oxidation, and biological methods. However, all of these methods have limitations to varying degrees, and their dewatering efficiency needs further improvement.

[0004] Advanced oxidation processes (AOPs) utilize highly oxidizing free radicals and other active groups to oxidize and decompose organic pollutants in wastewater into smaller molecules, or into carbon dioxide, water, and inorganic substances. Initially widely applied in wastewater treatment, AOPs have seen recent reports on their use in sludge dewatering, but the dewatering results have been less than ideal. Therefore, there is a need to develop a composite material based on AOPs for deep sludge dewatering, as well as a sludge dewatering conditioner based on AOPs. Summary of the Invention

[0005] Based on the above-mentioned situation, this invention provides a composite material for sludge dewatering and its preparation method. This composite material can be combined with persulfate as a sludge dewatering conditioner to achieve deep sludge dewatering. This invention also provides a sludge dewatering conditioner and a sludge dewatering method.

[0006] To achieve the above objectives, a first aspect of the present invention provides a composite material for sludge dewatering, comprising magnetic porous carbon and molybdenum disulfide supported on the magnetic porous carbon, wherein the magnetic porous carbon comprises porous carbon and iron(III) oxide supported on the porous carbon. In the aforementioned magnetic porous carbon, the mass ratio of porous carbon to iron(III) oxide can be controlled at 10:(1-5).

[0007] Because of their ability to fully and effectively decompose organic pollutants, advanced oxidation technologies (AEs) were initially applied to wastewater treatment. For example, electro-Fenton (EF) technology introduces hydrogen peroxide and ferrous ions to generate highly reactive hydroxyl radicals, thereby rapidly degrading organic pollutants in wastewater. Persulfate-based AEs activate permonosulfate (PMS) or perdisulfate (PDS) with energy or transition metals to generate highly reactive sulfate radicals, effectively reducing organic pollutants in wastewater. In recent years, researchers have attempted to apply AEs such as electro-Fenton to sludge conditioning, but the dewatering effect has not met expectations. Furthermore, the application of persulfate-based AEs in sludge dewatering remains limited.

[0008] The inventors discovered that combining the composite material for sludge dewatering provided in this invention with persulfate, especially with permonosulfate, can act as a sludge dewatering conditioner, achieving deep sludge dewatering. Based on XRD, BET, and other test results, as well as sludge dewatering experiments, the inventors further speculate that the presence of numerous sulfur-based active sites on the surface of the molybdenum disulfide supported on the magnetic porous carbon in this composite material, along with its stable chemical properties and the large specific surface area and porous structure of molybdenum disulfide, allows for effective loading of the magnetic porous carbon, forming a large-pore framework. Therefore, this composite material can catalyze persulfate, especially permonosulfate, to generate highly oxidizing sulfate radicals, effectively breaking down extracellular polymers within the sludge, promoting the release of bound water from these polymers, enhancing dewatering performance, and improving the compressibility of the sludge.

[0009] In particular, by rationally controlling the molar ratio of molybdenum disulfide to iron in ferric oxide (Mo / Fe, or molybdenum-iron molar ratio) in the composite material, the sludge dewatering effect can be further improved. In specific implementation, the molybdenum-iron molar ratio is usually controlled at (1-5):1, further at (1.5-3):1, and even further at (1.5-2.5):1, especially around 2:1.

[0010] The aforementioned composite material for sludge dewatering can be obtained by a preparation method including the following steps: mixing magnetic porous carbon with a molybdenum source and a sulfur source and carrying out a hydrothermal reaction, so that the molybdenum source and the sulfur source react to generate molybdenum disulfide. After the reaction is completed, the solid and liquid are separated, the solid product is collected and calcined at 350-450℃ under an inert atmosphere to obtain a molybdenum disulfide magnetic porous carbon composite material, which is the composite material for sludge dewatering; wherein, the magnetic porous carbon includes porous carbon and iron(III) oxide supported on the porous carbon.

[0011] The second aspect of this invention provides a method for preparing a composite material for sludge dewatering, comprising the following steps: mixing magnetic porous carbon with a molybdenum source and a sulfur source and carrying out a hydrothermal reaction, so that the molybdenum source and the sulfur source react to generate molybdenum disulfide; after the reaction is completed, the solid and liquid are separated, the solid product is collected and calcined at 350-450°C under an inert atmosphere to obtain a molybdenum disulfide magnetic porous carbon composite material; wherein the magnetic porous carbon includes porous carbon and iron(III) oxide supported on the porous carbon.

[0012] The porous carbon used as a carrier can be biochar or activated carbon, or a mixture of biochar and activated carbon, such as coconut shell activated carbon, wood activated carbon, fruit shell activated carbon, etc., as long as the porous carbon can easily form stable and abundant pores and does not contain a large amount of impurities that can react with molybdenum disulfide to form molybdenum disulfide derivatives.

[0013] As mentioned above, the aforementioned magnetic porous carbon includes porous carbon and iron(III) oxide supported on the porous carbon. The loading process may include: mixing the porous carbon with Fe... 2+ / Fe 3+ The solution is mixed under alkaline conditions, and then the solid portion of the mixture is collected and calcined to obtain magnetic porous carbon. The mass ratio of porous carbon to iron oxide is usually controlled at 10:(1-5), that is, the mass of porous carbon is 2 to 10 times the mass of iron oxide.

[0014] In the specific implementation stage, the process of obtaining magnetic porous carbon includes: mixing porous carbon with Fe 2+ / Fe 3+ The solution was mixed, and the Fe was adjusted by adding alkaline compounds such as sodium hydroxide. 2+ / Fe 3+ Adjust the pH of the solution to alkaline, for example, to pH 9-11, and keep it at 50-70°C for at least 30 minutes. After cooling, separate the solid and liquid components. If centrifugation is used to achieve solid-liquid separation, collect the solid portion and wash the impurities with deionized water until neutral. Then dry it to fully remove the water and calcine it at a high temperature of 500-600°C to obtain magnetic porous carbon.

[0015] Fe 2+ / Fe 3+A solution refers to an aqueous solution containing both Fe(II) and Fe(III), such as a mixed aqueous solution of ferrous chloride and ferric chloride. In Fe... 2+ / Fe 3+ In solution, Fe 2+ with Fe 3+ The molar ratio of Fe can be controlled at 1:2 or as close to 1:2 as possible to ensure sufficient reaction for the synthesis of Fe3O4. In the specific synthesis process, the molar ratio of porous carbon to Fe can be controlled. 2+ / Fe 3+ The ratio of porous carbon to Fe3O4 can be controlled by the impregnation ratio of the solution. For example, the mass ratio of porous carbon to Fe3O4 generated subsequently can be determined to be 10:(1-5). 2+ / Fe 3+ The impregnation ratio of the solution.

[0016] The molybdenum source used in the synthesis of molybdenum disulfide can be molybdic acid or molybdate, such as at least one selected from ammonium molybdate, sodium molybdate, phosphomolybdic acid, etc., and the sulfur source is selected from at least one selected from thiourea, thioacetamide, cysteine, sodium sulfide, etc. It should be noted, and is not difficult to understand, that the compounds that can be used as molybdenum sources also include their corresponding hydrates. For example, ammonium molybdate can also be ammonium molybdate tetrahydrate (NH4)2Mo7O. 24 • 4H2O. In the specific implementation process, sodium molybdate dihydrate Na2MoO4·2H2O was selected as the molybdenum source, and thioacetamide was selected as the sulfur source.

[0017] In the specific implementation stage, the process of obtaining molybdenum disulfide magnetic porous carbon composite material using magnetic porous carbon, molybdenum source, and sulfur source as raw materials includes: dispersing magnetic porous carbon, molybdenum source, and sulfur source in water to ensure thorough mixing, followed by hydrothermal reaction. The hydrothermal reaction temperature is controlled at 160–200°C, and the reaction time is not less than 18 hours, allowing the molybdenum source and sulfur source to react and generate molybdenum disulfide. Subsequently, the mixture is cooled to room temperature, and the reaction products are separated into solid and liquid components. If the reaction products are centrifuged, the solid portion is vacuum dried, and the dried solid product is calcined at 350–450°C under an inert atmosphere, such as by passing nitrogen gas at 400°C, to obtain the molybdenum disulfide magnetic porous carbon composite material.

[0018] The molar ratio (Mo / Fe) of molybdenum disulfide to iron in magnetic porous carbon is (1-5):1, more preferably (1.5-3):1, and most preferably (1.5-2.5):1. In practice, a molar ratio of molybdenum to iron of 2:1 yields better overall results. Of course, the amounts of molybdenum and sulfur sources used in the hydrothermal synthesis process should be sufficient to allow for complete reaction and formation of molybdenum disulfide.

[0019] A third aspect of the present invention provides a sludge dewatering conditioner, comprising persulfate and a composite material for sludge dewatering, wherein the composite material for sludge dewatering may be the composite material for sludge dewatering provided in the first aspect, or a composite material for sludge dewatering prepared by the preparation method of the second aspect, wherein the persulfate and the composite material are packaged separately.

[0020] Research results show that, compared with persulfate PDS, permonosulfate PMS, due to its asymmetrical structure, is more easily activated to generate sulfate free radicals, thus exhibiting advantages such as high efficiency, rapid reaction, and convenient addition in the degradation of organic pollutants. Therefore, the sludge dewatering conditioner provided by this invention uses permonosulfate as the main component, which, in combination with the composite materials mentioned in the first and second aspects, can effectively remove water from municipal sludge.

[0021] It should be noted that the persulfate and the composite material for sludge dewatering are packaged separately. During use, the persulfate can be added to the sludge to be treated first, mixed thoroughly, and then the composite material for sludge dewatering can be added.

[0022] The fourth aspect of the present invention provides a sludge dewatering method, comprising the following steps: mixing the sludge to be treated with persulfate and a composite material successively to obtain conditioned sludge; and dewatering the conditioned sludge, wherein the composite material can be the composite material for sludge dewatering provided in the first aspect, or a composite material prepared by the preparation method of the second aspect.

[0023] In the specific implementation process, an appropriate amount of water and persulfate can be added to the sludge to be treated first. The water and persulfate can be added simultaneously or sequentially, as long as it facilitates thorough and effective mixing between the persulfate and the sludge. The specific amount of persulfate added can be determined reasonably based on the actual condition of the sludge. In practice, based on the total dry weight of the sludge, the amount of persulfate used can be 350–650 mg / g, for example, 500 mg / g. Subsequently, a composite material for sludge dewatering is added to the sludge and mixed evenly to obtain conditioned sludge. The amount of the composite material used can be 20–40% of the dry weight of the sludge to be treated, for example, 30%.

[0024] Finally, the conditioning sludge is dewatered to remove moisture. This can be achieved using conventional solid-liquid separation methods, such as vacuum filtration.

[0025] The composite material for sludge dewatering and its preparation method provided by this invention use magnetic porous carbon loaded with iron oxide as a substrate. It can effectively exert or even enhance the catalytic performance of the loaded molybdenum disulfide (MoS2), activate persulfate to generate a large number of sulfate free radicals with strong oxidizing properties, thereby breaking down the rigid structure of the extracellular polymeric substance (EPS) of sludge, releasing the proteins and polysaccharides within the EPS, and combining it with magnetic biochar material to construct a large-pore framework, promoting the full release of internal water that is difficult to treat within the sludge, achieving deep dewatering of sludge, improving the compressibility of sludge, reducing treatment costs, and reducing environmental pollution.

[0026] The sludge dewatering conditioner provided by this invention includes persulfate and the above-mentioned composite material for sludge dewatering. Therefore, it can be applied to the deep dewatering of sludge, especially municipal sludge, significantly improving the efficiency and quality of sludge dewatering, and has important economic and social value.

[0027] The sludge dewatering method provided by this invention, by employing the aforementioned composite material for sludge dewatering, can effectively release the internal water that is difficult to treat within the sludge, thereby achieving deep dewatering of municipal sludge and facilitating subsequent sludge reduction, harmlessness, and resource utilization treatment and disposal. Attached Figure Description

[0028] Figure 1 The XRD patterns of the composite materials prepared in Examples 1-4 and Comparative Examples 1-2 of this invention are shown.

[0029] Figure 2 The BET adsorption diagrams are of the composite materials prepared in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0030] Figure 3 This is a comparison chart of the capillary water absorption time and sludge specific resistance test results of the conditioned sludge obtained in Example 5 of the present invention.

[0031] Figure 4 This is a graph showing the moisture content test results of the conditioning sludge obtained in Example 5 of the present invention;

[0032] Figure 5 The figure shows the effect of different composite materials on the composition of extracellular polymers in the conditioned sludge treated in Example 5 of this invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. 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.

[0034] Example 1

[0035] This embodiment provides a method for preparing a composite material for sludge dewatering, and the resulting composite material for sludge dewatering. The preparation method includes the following steps:

[0036] Step 1a: Immerse porous biochar (wood charcoal, coconut shell charcoal, etc.) in a mixed aqueous solution of ferric chloride and ferrous chloride (hereinafter referred to as Fe). 2+ / Fe 3+ In the solution, the mixture was stirred at a constant temperature of 60°C for approximately 30 minutes using a magnetic stirrer, in which Fe... 3+ with Fe 2+ The molar ratio of the substances is approximately 2:1, in which porous biochar and Fe... 2+ / Fe 3+ The impregnation ratio between solutions was determined based on a mass ratio of 10:2 for the theoretical production of porous biochar and iron oxide; subsequently, Fe... 2+ / Fe 3+ Sodium hydroxide solution is slowly added dropwise to the solution until Fe... 2+ / Fe 3+ The pH of the solution reached about 10; it was kept at 60℃ for about 1 hour, cooled and centrifuged, the solid part was taken and washed with deionized water to remove impurities until the washing solution was neutral; the washed solid was dried at 60℃ for about 12 hours to remove the water completely, and then the dried solid was placed in a tube furnace. Under a nitrogen atmosphere, the furnace temperature was increased at a rate of 10℃ / min to about 550℃ and calcined for about 60 minutes to obtain magnetic biochar.

[0037] Step 2a: Magnetic biochar, sodium molybdate dihydrate (Na2MoO4·2H2O), and thioacetamide are placed in deionized water and ultrasonically dispersed for 30 minutes, wherein the molar ratio of molybdenum to iron is 1:1 (Mo / Fe = 1:1). The mixed material is then hydrothermally reacted in a hydrothermal reactor at approximately 180°C for about 18 hours. After cooling to room temperature, it is centrifuged at 8000 r / min for 30 minutes to remove the supernatant. The solid product is collected and vacuum-dried in a vacuum drying oven at approximately 80°C for about 5 hours to fully remove moisture. The vacuum-dried solid product is then placed in a tube furnace and calcined at approximately 400°C under a nitrogen atmosphere for about 2 hours to obtain molybdenum disulfide magnetic biochar composite material, which is a composite material used for sludge dewatering.

[0038] Examples 2-4

[0039] Examples 2-4 each provide a method for preparing a composite material for sludge dewatering, and the resulting composite material for sludge dewatering. The specific preparation methods are basically the same as those in Example 1, except that the molar ratio (Mo / Fe) of molybdenum disulfide to iron in step 2a is different. Specifically, the Mo / Fe ratio in Example 2 is 2:1, the Mo / Fe ratio in Example 3 is 3:1, and the Mo / Fe ratio in Example 4 is 5:1.

[0040] Comparative Example 1

[0041] This comparative example provides a composite material whose preparation steps are consistent with step 1a in Example 1. That is, the composite material provided in this comparative example is actually magnetic biochar, including porous biochar and iron oxide supported on porous biochar.

[0042] Comparative Example 2

[0043] This comparative example provides a composite material whose preparation steps are similar to step 2a in Example 1, except that the magnetic biochar in step 2a is replaced with the porous biochar in step 1a. That is, the composite material provided in this comparative example includes porous biochar (not magnetic porous carbon) and molybdenum disulfide supported on the porous biochar.

[0044] The XRD patterns of the composite materials for sludge dewatering prepared in Examples 1-4, namely molybdenum disulfide magnetic biochar composite materials, and the composite materials in Comparative Examples 1-2 are as follows: Figure 1 As shown. In Figure 1 In the examples, Fe3O4-BC represents magnetic biochar, i.e., the composite material prepared in Comparative Example 1; MoS2-BC represents biochar loaded only with molybdenum disulfide, i.e., the composite material prepared in Comparative Example 2; Mo / Fe = 1:1 represents the molybdenum disulfide magnetic biochar composite material prepared in Example 1, in which the molar ratio of molybdenum disulfide to iron (Mo / Fe) in step 2a is 1:1; and so on, Mo / Fe = 2:1, Mo / Fe = 3:1 and Mo / Fe = 5:1 represent the molybdenum disulfide magnetic biochar composite materials prepared in Examples 2-4, respectively.

[0045] XRD patterns can characterize the composite properties of materials, and are derived from... Figure 1 It can be seen that, compared with the standard card, the composite materials prepared in Examples 1-4 simultaneously have carbon peaks, molybdenum disulfide peaks, and iron oxide peaks. In particular, the characteristic peaks of Example 2 (Mo / Fe = 2:1) are relatively more obvious, indicating that molybdenum disulfide and magnetic biochar were composited in Examples 1-4, and the composite of molybdenum disulfide and magnetic biochar in Example 2 was the best.

[0046] The inventors discovered that the molybdenum disulfide magnetic biochar composite material provided in this invention can activate persulfate to generate a large number of highly oxidizing sulfate free radicals. Therefore, the molybdenum disulfide magnetic biochar composite material can be used as a sludge dewatering conditioner and effectively acts as a catalyst. As is well known, the specific surface area of ​​a catalyst characterizes its pore size and distribution, thus limiting the internal diffusion resistance of reactants and products, as well as the relative concentration of surface reactants. Therefore, specific surface area is an important parameter for the surface and morphology of reaction catalysts, and BET can be used to characterize the specific surface area of ​​catalysts.

[0047] Figure 2 Table 1 shows the BET adsorption diagrams of the composite materials provided in Examples 1-4 and Comparative Examples 1-2, and the specific surface area and total pore volume of the composite materials prepared in Examples 1-4 and Comparative Examples 1-2. Figure 1 It can be seen that, at a relative pressure (P / P0) of 1, the molybdenum disulfide magnetic biochar composites in Examples 2-4 have a larger specific surface area compared to the composites in Comparative Examples 1-2. This result is also consistent with the results in Table 1: compared to the magnetic biochar provided in Comparative Example 1 and the biochar supported only by molybdenum disulfide provided in Comparative Example 2, the molybdenum disulfide magnetic biochar composites in Examples 2-4 have a larger specific surface area and total pore volume.

[0048] Table 1

[0049]

[0050] Example 5

[0051] This embodiment provides a method for dewatering municipal sludge, including the following steps:

[0052] Step 1b: Add deionized water and potassium persulfate to the municipal sludge to be treated, wherein the amount of potassium persulfate added is 500 mg / g TS (TS: dry weight of sludge, i.e., total solids in sludge), and stir evenly.

[0053] Step 2b: Continue to add the molybdenum disulfide magnetic biochar composite material prepared in Examples 1-4 and the composite material prepared in Comparative Examples 1-2 to the mixture of municipal sludge and potassium persulfate. Shake at 120 rpm and 35°C for 60 min to obtain conditioned sludge. The amount of molybdenum disulfide magnetic biochar composite material and magnetic biochar added is 30% of the dry weight of municipal sludge.

[0054] Step 3b: Use a vacuum pump to dewater the conditioned sludge by filtration. The filter membrane is 0.45μm and the filtration time is about 10 minutes.

[0055] The conditioning sludge obtained in step 3b and dewatered by filtration was tested, and compared with the municipal sludge sample to be treated used in step 1b and the conditioning sludge obtained in step 1b. The test results of capillary suction time (CST) and sludge specific resistance (SRF) are shown in [the table below]. Figure 3 The water content test results are shown below. Figure 4 .

[0056] Figure 3-4 In this context, Blank represents the municipal sludge to be treated; PMS represents the conditioning sludge obtained in step 1b; Fe3O4-BC represents the magnetic biochar used in step 2b, i.e., the composite material prepared in Comparative Example 1; Mo / Fe = 1:1 represents the molybdenum disulfide magnetic biochar composite material prepared in Example 1 used in step 2b, and so on, Mo / Fe = 2:1, Mo / Fe = 3:1 and Mo / Fe = 5:1 respectively represent the molybdenum disulfide magnetic biochar composite materials prepared in Examples 2-4 used in step 2b.

[0057] like Figure 3 As shown, the capillary water absorption time (CST) of the municipal sludge (Blank) to be treated was 123.3 s, and the sludge specific resistance (SRF) was 6.15106E12 m / kg. Compared with the municipal sludge to be treated, the capillary water absorption time (CST) and sludge specific resistance (SRF) of the conditioned sludge after filtration and dewatering were significantly reduced after simply adding PMS, and after adding PMS followed by magnetic biochar from Comparative Example 1 and the composite materials from Examples 1-4, respectively. Among them, using the magnetic biochar Fe3O4-BC in Comparative Example 1, the sludge specific resistance (SRF) decreased the most, but the capillary water absorption time (CST) decreased the least. Using the molybdenum disulfide magnetic biochar composite material prepared in Examples 1 and 3-4, the capillary water absorption time (CST) of the conditioned sludge after filtration and dewatering was concentrated in the range of 80-88s, and the sludge specific resistance (SRF) was concentrated in the range of 2.5E12-3.7E12m / kg. Using the molybdenum disulfide magnetic biochar composite material prepared in Example 2 (Mo / Fe = 2:1), the conditioned sludge after filtration and dewatering showed the best overall performance, with a capillary water absorption time (CST) of only 46.2s, which was similar to the result of using PMS alone and significantly lower than that of Examples 1 and 3-4, and a sludge specific resistance (SRF) of only 1.34271E12 m / kg, which was significantly lower than that of Examples 1 and 3-4.

[0058] like Figure 4As shown, the moisture content of the municipal sludge (Blank) to be treated was 81%. Compared with the municipal sludge to be treated, the moisture content of the conditioned sludge obtained after filtration and dewatering was reduced to varying degrees by using PMS alone, adding PMS first and then adding the molybdenum disulfide magnetic biochar composite material in Examples 1-4, and the magnetic biochar in Comparative Example 1. Among them, the moisture content of the conditioned sludge after filtration and dewatering was not significantly reduced by using PMS alone, adding PMS first and then using the magnetic biochar Fe3O4-BC in Comparative Example 1, while the moisture content of the conditioned sludge decreased significantly by adding PMS first and then using the molybdenum disulfide magnetic biochar composite material in Examples 1-4, all of which decreased to below 76%. In particular, the moisture content of the conditioned sludge decreased most significantly by using the molybdenum disulfide magnetic biochar composite material prepared in Example 2 (Mo / Fe = 2:1), decreasing by about 10% to 71.18%.

[0059] The effects of these effects on the concentrations of protein, polysaccharide, and dissolved chemical oxygen demand (SCOD) in the extracellular polymeric substances (EPS) of the conditioned sludge after vacuum filtration and dewatering are shown in the following figures. Figure 5 In the figure, TB-EPS represents tightly bound extracellular polymeric materials.

[0060] like Figure 5 As shown, the EPS contents of the blank group Blank (municipal sludge to be treated) were 9.2 mg / g TS, 7.4 mg / g TS, and 1503 mg / L, respectively. When only PMS was added to the municipal sludge to be treated, the protein, polysaccharide, and dissolved chemical oxygen demand were all lower than those of the blank group Blank. After the sludge was treated with Fe3O4-BC and then dewatered by filtration, the protein, polysaccharide, and dissolved chemical oxygen demand contents were 3.6 mg / g TS, 4.2 mg / g TS, and 328 mg / L, respectively. It is noted that the polysaccharide content was higher than that of the blank group Blank. Compared with the control group and the results of sludge treatment with magnetic biochar Fe3O4-BC in Comparative Example 1, the concentrations of protein, polysaccharide, and SCOD in the EPS of the sludge treated with the composite materials in Examples 1-4 were significantly reduced after filtration and dewatering. In particular, the composite material in Example 2 (Mo / Fe = 2:1) resulted in protein, polysaccharide, and SCOD concentrations of 4.1 mg / g TS, 1.3 mg / g TS, and 258 mg / L, respectively, in the EPS. This indicates that the composite materials provided in Examples 1-4 can effectively break down protein, polysaccharide, and SCOD in EPS. In particular, the composite material in Example 2 showed the highest degree of damage to EPS, which is consistent with the previous dewatering results.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite material for sludge dewatering, characterized in that, The invention includes magnetic porous carbon and molybdenum disulfide supported on the magnetic porous carbon, wherein the magnetic porous carbon comprises porous carbon and iron(III) oxide supported on the porous carbon, and the molar ratio of iron in molybdenum disulfide to iron(III) oxide is 1.5-2.5:

1.

2. The composite material according to claim 1, characterized in that, In magnetic porous carbon, the mass ratio of porous carbon to iron oxide is 10:1-5.

3. The composite material according to claim 1 or 2, characterized in that, It is obtained by a preparation method including the following steps: Magnetic porous carbon is mixed with a molybdenum source and a sulfur source and subjected to a hydrothermal reaction, so that the molybdenum source and the sulfur source react to form molybdenum disulfide. After the reaction is completed, the solid and liquid are separated, the solid product is collected and calcined at 350-450℃ under an inert atmosphere to obtain a molybdenum disulfide magnetic porous carbon composite material; wherein the magnetic porous carbon includes porous carbon and iron(III) oxide supported on the porous carbon.

4. A method for preparing a composite material for sludge dewatering, characterized in that, Includes the following steps: Magnetic porous carbon is mixed with a molybdenum source and a sulfur source and subjected to a hydrothermal reaction, so that the molybdenum source and the sulfur source react to form molybdenum disulfide. After the reaction is completed, the solid and liquid are separated, the solid product is collected and calcined at 350-450℃ under an inert atmosphere to obtain a molybdenum disulfide magnetic porous carbon composite material. The magnetic porous carbon includes porous carbon and iron(III) oxide supported on the porous carbon, and the molar ratio of iron in molybdenum disulfide to iron(III) oxide is 1.5-2.5:

1.

5. The preparation method according to claim 4, characterized in that, In the magnetic porous carbon, the mass ratio of porous carbon to iron oxide is 10:1-5.

6. The preparation method according to claim 4 or 5, characterized in that, Also includes: Porous carbon and Fe 2+ / Fe 3+ Solution mixing, adjusting Fe 2+ / Fe 3+ The pH of the solution is adjusted to 9-11 and kept at 50-70℃ for at least 30 minutes. After cooling, the solid and liquid are separated, the solid fraction is collected, washed until neutral, and then calcined at 500-600℃ to obtain the magnetic porous carbon.

7. The preparation method according to claim 4 or 5, characterized in that, The porous carbon is selected from at least one of biochar and activated carbon; and / or The molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, and phosphomolybdic acid, and the sulfur source is selected from at least one of thiourea, thioacetamide, cysteine, and sodium sulfide.

8. The preparation method according to claim 4 or 5, characterized in that, The hydrothermal reaction is carried out at a temperature of 160–200°C for a duration of not less than 18 hours.

9. A sludge dewatering conditioner, characterized in that, It includes persulfate, and the composite material according to any one of claims 1-3 or the composite material prepared by the preparation method according to any one of claims 4-8, wherein the persulfate and the composite material are packaged separately.

10. A sludge dewatering method, characterized in that, Includes the following steps: The sludge to be treated was mixed with persulfate and composite material in sequence to obtain conditioned sludge; The sludge is dewatered. The composite material is the composite material according to any one of claims 1-3, or the composite material prepared by any one of claims 4-8.

Images