Application of Lewis acid-base eutectic solvent in sludge modification, modified sludge, preparation method and application of modified sludge, sludge coke slurry and application of sludge coke slurry

Abstract

The invention provides application of a Lewis acid-base eutectic solvent in sludge modification, modified sludge, a preparation method and application of the modified sludge, sludge coke slurry and application of the sludge coke slurry, and relates to the technical field of sludge resource utilization. According to the invention, the Lewis acid-base eutectic solvent is adopted to modify the sludge, so that the catalytic degradation of hydrophilic oxygen-containing functional groups (HOFG) in the sludge can be effectively promoted, the interaction between the hydrophilic oxygen-containing functional groups and water molecules is weakened, the conversion from bound water to free water is promoted, and the water content of the sludge is remarkably reduced. Moreover, the Lewis acid-base eutectic solvent promotes bound water to be converted into free water, so that not only is the viscosity of the sludge reduced, but also the flowability of the sludge is improved, and the treatment and processing characteristics of the sludge are optimized. The modified sludge obtained through modification of the Lewis acid-base eutectic solvent is used for preparing slurry fuel, the addition amount of the modified sludge is large, and resource utilization of the sludge is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sludge resource utilization, and in particular to application of Lewis acid-base eutectic solvent in sludge modification, modified sludge and a preparation method and application thereof, and sludge coke slurry and application thereof. Background Art

[0002] Municipal sludge refers to the solid waste generated in the process of urban sewage treatment. It mainly comes from the sedimentation tanks, concentration tanks and dewatering equipment of sewage treatment plants, and is an inevitable by-product of urban sewage treatment. The composition of municipal sludge is complex, usually containing a large amount of organic matter, pathogenic microorganisms, heavy metals and other pollutants. It is generally viscous and flocculent, often with long-term toxicity and non-degradability. If it is discharged in an unordered manner, it will become a dangerous secondary pollution source, enter the food chain through the atmosphere, groundwater, surface water and soil and other media, seriously damage the ecological environment and affect human health.

[0003] Municipal sludge is rich in hydrophilic oxygen-containing functional groups (HOFG) such as hydroxyl (-OH), carboxyl (-COOH) and carbonyl (C=O). These functional groups easily combine with water molecules, making municipal sludge extremely hydrophilic and the moisture content usually maintained at a very high level. The moisture content of municipal sludge that has not been mechanically dehydrated is generally above 90%, the moisture content of sludge that has been dehydrated by conventional machinery (centrifugal dehydrator) is generally above 80%, and the moisture content of sludge that has been dehydrated by deep machinery (centrifugal dehydrator and plate and frame filter press) is usually between 60% and 80%. Municipal sludge is difficult to dehydrate. High moisture content not only increases the difficulty of sludge treatment, but also greatly increases the treatment cost. Therefore, improving the dewaterability of sludge and promoting its resource utilization have become the subject of extensive research.

[0004] In order to solve the problem of high moisture content in municipal sludge, the current dehydration technologies mainly include thermal drying and sludge modification. Compared with thermal drying, sludge modification has high energy consumption and low cost. At present, the main methods for modifying sludge include alkali treatment, heat treatment, thermal-chemical combined treatment, ultrasonic treatment, anaerobic digestion treatment, modified phosphogypsum pretreatment, alkaline ferrate treatment, low eutectic solvent treatment, etc. However, the moisture content of the sludge after modification by the existing sludge modification methods is still not low enough, resulting in that when the modified sludge is used to prepare slurry fuel, the sludge slurryability is improved, but the sludge blending ratio is still at a low level. Summary of the invention

[0005] In view of this, the object of the present invention is to provide the application of Lewis acid-base eutectic solvent in sludge modification, modified sludge and its preparation method and application, sludge coke slurry and its application. The sludge modified by Lewis acid-base eutectic solvent in the present invention has a low water content, and when used to prepare slurry fuel, the amount of modified sludge added is large.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides application of Lewis acid-base eutectic solvent in sludge modification; the Lewis acid-base eutectic solvent comprises Lewis acid and Lewis base.

[0008] Preferably, the Lewis acid comprises one or more of a metal chloride and a metal sulfate;

[0009] The Lewis base includes choline chloride;

[0010] The molar ratio of the Lewis base to the Lewis acid is 1:1-8.

[0011] The present invention provides a method for preparing modified sludge, comprising the following steps:

[0012] The sludge is mixed with a Lewis acid-base eutectic solvent and subjected to modification treatment to obtain modified sludge;

[0013] The Lewis acid-base eutectic solvent comprises Lewis acid and Lewis base, and the Lewis acid comprises one or more of metal chloride and metal sulfate.

[0014] Preferably, the Lewis base comprises choline chloride;

[0015] The molar ratio of the Lewis base to the Lewis acid is 1:1 to 8;

[0016] The mass ratio of the sludge to the Lewis acid-base eutectic solvent is 1:0.01-0.15.

[0017] The temperature of the modification treatment is 25 to 85° C., and the time is 1 to 24 hours.

[0018] The present invention also provides modified sludge obtained by the sludge modification treatment method described in the above technical solution.

[0019] The invention provides a sludge coke slurry, and the raw materials for preparing the sludge slurry include the modified sludge described in the above technical solution, petroleum coke, a dispersant and water; the mass of the modified sludge accounts for 20-50% of the dry mass of the petroleum coke.

[0020] Preferably, the dispersant includes one or more of lignin sulfonate, naphthalene water reducer and polycarboxylate;

[0021] The mass of the dispersant accounts for 0.6-1.5% of the mass of the petroleum coke dry basis;

[0022] The solid content of the sludge char slurry is 40-65%.

[0023] Preferably, the method comprises the following steps:

[0024] The raw materials for preparing the sludge char slurry are mixed to obtain the sludge char slurry.

[0025] The present invention also provides the use of the sludge char slurry described in the above technical solution or the sludge char slurry prepared by the preparation method described in the above technical solution as fuel or gasification raw material.

[0026] Lewis acid can coordinate with oxygen atoms in oxygen-containing functional groups, activate oxygen-containing functional groups, and make them easier to decompose. At the same time, the hydrogen bonding effect in Lewis base can stabilize the reaction intermediates and promote the decomposition process of oxygen-containing functional groups. Therefore, the use of Lewis acid-base eutectic solvent to modify sludge can effectively promote the catalytic degradation of hydrophilic oxygen-containing functional groups (HOFG) in sludge and weaken its interaction with water molecules. It promotes the conversion of bound water to free water, significantly reduces the bound water content in sludge, makes it easier to deeply remove water in sludge, enhances the dehydration performance of sludge, and significantly reduces the water content of sludge. Moreover, Lewis acid-base eutectic solvent promotes the conversion of bound water into free water, which not only reduces the viscosity of sludge, but also improves the fluidity of sludge and optimizes its handling and processing characteristics. The sludge obtained by Lewis acid-base eutectic solvent modification is used to prepare slurry fuel. The amount of modified sludge added is large, realizing the resource utilization of sludge.

[0027] The preparation method of the modified sludge provided by the invention has simple process, simple operation, is green and environmentally friendly, has low production cost, and is suitable for industrial production.

[0028] As shown in the test results of the embodiment, the test results show that the Lewis acid-base eutectic solvent effectively promotes the catalytic degradation of hydrophilic oxygen-containing functional groups (HOFG) in the sludge, thereby promoting the conversion of bound water to free water. As the modification treatment temperature increases from 25°C to 70°C, the modification effect of the sludge is improved, and the modification effect tends to be optimal at 55°C; the bound water content in the sludge modified at 55°C (S-55) is about 40% lower than that of the original sludge; the calorific value of the modified sludge is greater than 13200kJ / kg, and the calorific value is high.

[0029] The present invention provides a sludge coke slurry, and the raw materials for preparing the sludge coke slurry include the modified sludge, petroleum coke, dispersant and water described in the above technical scheme; the mass of the modified sludge accounts for 20-50% of the dry mass of the petroleum coke. The bound water in the modified sludge obtained by Lewis acid-base eutectic solvent modification is converted into free water, the modified sludge has a low moisture content, a large amount of sludge coke slurry addition, and a higher sludge coke slurry concentration and a lower viscosity can be obtained under the same sludge dosage. The sludge coke slurry has a high calorific value, good fluidity and strong stability. Moreover, the modified sludge contains a large amount of organic matter, which is easy to combine with other components in the sludge coke slurry to form a three-dimensional network structure or flocculation, thereby enhancing the structural strength of the sludge coke slurry. When the modified sludge modified by Lewis acid-base eutectic solvent is added, the pseudoplastic rheological characteristics of the sludge coke slurry decrease.

[0030] As shown in the test results of the embodiment, compared with the unmodified original sludge, the sludge coke slurry (PCSS) prepared by using S-55 with a sludge blending amount of 20% showed significant improvements in multiple key properties: the solid concentration of PCSS increased from less than 50% to nearly 60%. The calorific value of the sludge coke slurry increased from less than 15,000 kJ / kg to more than 18,000 kJ / kg. After the sludge coke slurry was left to stand for 7 days, the pourability rate increased from less than 40% of the original sludge to about 90%, and the fluidity was improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The capillary water absorption time test results of the modified sludge obtained by modifying the advanced anaerobic digestion sludge in Examples 1 to 4 and Comparative Examples 1 to 3;

[0032] Figure 2 The XPS analysis results of the hydrophilic oxygen-containing functional groups (HOFG) on the surface of the original sludge and the modified sludge in Examples 5 to 8 are shown;

[0033] Figure 3 The graphs are the results of the changes in oxygen-to-carbon ratio (O / C), hydrogen content and calorific value of the original sludge and the modified sludge in Examples 5 to 8;

[0034] Figure 4 Thermogravimetric curves of the original sludge and modified sludge in Examples 5 to 8;

[0035] Figure 5 The figure is a graph showing the moisture content analysis results of the original sludge and the modified sludge in Examples 5 to 8;

[0036] Figure 6 The solid concentration and calorific value test results of the sludge slurry in Examples 9 to 24 and Comparative Example 4 are shown in FIG.

[0037] Figure 7 The curves showing the change of apparent viscosity of the sludge slurry with shear rate in Examples 9 to 24 and Comparative Example 4;

[0038] Figure 8 The thixotropy test results of the sludge slurry (sludge blending amount 20%) in Examples 9 to 12 and Comparative Example 4 are shown in FIG.

[0039] Fig. 9 The thixotropic ring area test results of the sludge slurry (sludge blending amount 20%) in Examples 9 to 12 and Comparative Example 4 are shown;

[0040] Fig.10 The figures are result graphs of the pouring rate of sludge char slurry in Examples 9 to 12 and Comparative Example 4, wherein (a) is a graph showing the changing trend of the pouring rate with the modified sludge, and (b) is a graph showing the changing trend of the pouring rate with the sludge blending amount. DETAILED DESCRIPTION

[0041] The invention provides application of Lewis acid-base eutectic solvent (DES) in sludge modification; the Lewis acid-base eutectic solvent comprises Lewis acid and Lewis base.

[0042] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0043] In the present invention, the Lewis acid preferably includes one or more of metal chloride and metal sulfate; the metal chloride preferably includes one or more of AlCl3, FeCl3 and ZnCl2; the metal sulfate preferably includes Al2(SO4)3. In the present invention, the Lewis base preferably includes choline chloride (ChCl). In the present invention, the molar ratio of the Lewis base to the Lewis acid is preferably 1:1 to 8, and in specific embodiments can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8.

[0044] Lewis acids have empty orbitals or electron-deficient centers that can form coordination bonds with electron pairs provided by other substances. Lewis bases have lone pairs of electrons that can form coordination bonds with Lewis acids to form a stable solvent system, which is named Lewis acid-base eutectic solvent.

[0045] The present invention adopts Lewis acid-base eutectic solvent to modify the sludge, which can effectively promote the catalytic degradation of hydrophilic oxygen-containing functional groups (HOFG) in the sludge, reduce the hydrophilicity of the sludge, promote the conversion of bound water into free water, and thus significantly reduce the water content of the sludge, improve the sludge slurry properties, and can be used to prepare high-quality slurry fuel.

[0046] The invention provides a method for preparing modified sludge, comprising the following steps: mixing sludge and a Lewis acid-base eutectic solvent, performing modification treatment, and obtaining modified sludge; the Lewis acid-base eutectic solvent comprises Lewis acid and Lewis base, and the Lewis acid comprises one or more of metal chloride and metal sulfate.

[0047] In the present invention, the preparation method of the Lewis acid-base eutectic solvent preferably includes the following steps: heat-mixing Lewis acid and Lewis base to obtain Lewis acid-base eutectic solvent. In the present invention, the temperature of the heat-mixing is preferably 70-130°C, and in specific embodiments, it can be 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or 130°C; the present invention has no special limitation on the time of the heat-mixing, and the heat-mixing is performed until a colorless Lewis acid-base eutectic solvent is obtained; the heat-mixing is preferably hot stirring mixing. In the present invention, the Lewis acid-base eutectic solvent is preferably stored in a bottle with a screw cap and placed in a drying tray for later use.

[0048] In the present invention, the Lewis acid includes one or more of metal chloride and metal sulfate; the metal chloride preferably includes one or more of AlCl3, FeCl3 and ZnCl2; the metal sulfate preferably includes Al2(SO4)3. In the present invention, the Lewis base preferably includes choline chloride. In the present invention, the molar ratio of the Lewis base to the Lewis acid is preferably 1:1 to 8, and in specific embodiments it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8.

[0049] In the present invention, the sludge preferably includes municipal sludge; the moisture content of the sludge is preferably ≤98%, more preferably 88-98%, and in specific embodiments it can be 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97% or 98%.

[0050] In the present invention, the mass ratio of the sludge to the Lewis acid-base eutectic solvent is preferably 1:0.01-0.15, and in specific embodiments it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, 1:0.11, 1:0.12, 1:0.13, 1:0.14 or 1:0.15.

[0051] In the present invention, water is preferably added during the mixing process of the sludge and the Lewis acid-base eutectic solvent. Specifically, the sludge, the Lewis acid-base eutectic solvent and water are mixed. In the present invention, the mass ratio of water to sludge is preferably ≤3.5, and the mass ratio of water to sludge is preferably 0 to 3.5:1. In specific embodiments, it can be 0:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1 or 3.5:1.

[0052] In the present invention, the temperature of the modification treatment is preferably 25-85°C, and in specific embodiments it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or 85°C; the time of the modification treatment is preferably 1-24h, and in specific embodiments it can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h.

[0053] The present invention also provides modified sludge obtained by the sludge modification treatment method described in the above technical solution. In the present invention, the calorific value of the modified sludge is preferably greater than 13200 kJ / kg. The modified sludge provided by the present invention has low water content and high calorific value and can be used to prepare slurry fuel.

[0054] The present invention also provides a sewage sludge coke slurry (PCSS), the preparation raw materials of which include the modified sewage sludge described in the above technical solution, petroleum coke, a dispersant and water.

[0055] In the present invention, the particle size of the petroleum coke is preferably ≥100 mesh.

[0056] In the present invention, the mass of the modified sludge accounts for 20-50% of the dry mass of petroleum coke, and in specific embodiments it can be 20%, 25%, 30%, 35%, 40%, 45% or 50%.

[0057] In the present invention, the dispersant preferably includes one or more of lignin sulfonate, naphthalene water reducer and polycarboxylate; the lignin sulfonate preferably includes one or more of lignin sulfonate sodium salt, lignin sulfonate calcium salt and lignin sulfonate ammonium salt. In the present invention, the mass of the dispersant preferably accounts for 0.6-1.5% of the dry mass of petroleum coke, and in specific embodiments, it can be 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%.

[0058] In the present invention, the solid content of the sludge slurry is preferably 40-65%, and in a specific embodiment it can be 40%, 45%, 50%, 55%, 60% or 65%; the sludge slurry is subjected to a shear rate of 100s -1 The average apparent viscosity (referred to as representative apparent viscosity) is preferably 800 to 1200 mPa·s, and in specific embodiments may be 800 mPa·s, 900 mPa·s, 1000 mPa·s, 1100 mPa·s or 1200 mPa·s.

[0059] The present invention utilizes Lewis acid-base eutectic solvent to modify sludge, so that bound water in the sludge can be converted into free water, and the free water in the sludge can be removed in the mechanical dehydration step, thereby reducing the energy consumption in the thermal drying step.

[0060] The hydrogen bond acceptor (choline chloride) and the hydrogen bond donor (oxalic acid, citric acid, malic acid or lactic acid) form a deep eutectic solvent (DES) through hydrogen bonding. The catalytic activity of the DES system mainly depends on the effect of the hydrogen bond network. Therefore, the catalytic activity of the above-mentioned deep eutectic solvent is relatively low. When used for sludge modification, the dehydration performance of the sludge is not good enough. In the present invention, a hydrogen bond network is formed between the hydroxyl group (-OH) of choline chloride and the Lewis acid (such as the chloride ion Cl- of the metal chloride) to form a stable Lewis acid-base eutectic solvent, but the catalytic activity of the Lewis acid-base eutectic solvent is not mainly dependent on the effect of the hydrogen bond network, but mainly depends on the following factors: Lewis acid (metal chloride and / or metal sulfate) and Lewis base cooperate to form a eutectic solvent, metal ions are the main active center, Lewis acidity is strong, and the catalytic activity of the Lewis acid-base eutectic solvent is strong. Therefore, the Lewis acid-base eutectic solvent has a better modification effect on sludge than DES.

[0061] The dehydration effect of the existing modification method is not significant. The modified sludge obtained is used to prepare sludge coke slurry. The sludge slurryability is improved, but the sludge blending ratio is still at a low level. The modified sludge obtained by the existing modification method is used to prepare sludge coke slurry with a solid concentration of 60%, and the blending amount of the modified sludge is less than 15% of the mass of petroleum coke. The present invention uses Lewis acid-base eutectic solvent to modify the sludge, which can greatly reduce the bound water in the sludge. The bound water of the sludge treated under the best working conditions can be reduced by 40% compared with the original sludge, and the slurrying characteristics are greatly improved. The blending amount of the modified sludge in the sludge coke slurry can be increased to 50%, which is far beyond other modification methods (alkali treatment, heat treatment, ultrasonic treatment, other chemical treatments, etc.).

[0062] The bound water in the modified sludge obtained by Lewis acid-base eutectic solvent modification is converted into free water. The modified sludge has low moisture content and high calorific value. The amount of sludge coke added is large, and a higher sludge coke concentration and lower viscosity can be obtained at the same sludge dosage. The sludge coke has high calorific value, good fluidity and strong stability. Moreover, the modified sludge contains a large amount of organic matter, which is easy to combine with other components in the sludge coke to form a three-dimensional network structure or flocculation, thereby enhancing the structural strength of the sludge coke. When the modified sludge modified by Lewis acid-base eutectic solvent is added, the pseudoplastic rheological characteristics of the sludge coke decrease.

[0063] The present invention also provides a method for preparing the sludge char slurry described in the above technical solution, comprising the following steps: mixing the raw materials for preparing the sludge char slurry to obtain the sludge char slurry. In the present invention, the mixing temperature is preferably 15 to 40°C, and in a specific embodiment it can be 15°C, 20°C, 25°C, 30°C, 35°C or 40°C; the mixing time is preferably 10 to 30 minutes, and in a specific embodiment it can be 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes; the mixing preferably includes stirring and mixing; the stirring and mixing speed is preferably 800 to 1200 r / min, and in a specific embodiment it can be 800 r / min, 850 r / min, 900 r / min, 950 r / min, 1000 r / min, 1050 r / min, 1100 r / min, 1150 r / min or 1200 r / min;.

[0064] The present invention also provides the use of the sludge coke slurry described in the above technical solution or the sludge coke slurry prepared by the preparation method described in the above technical solution as a fuel or a gasification raw material. In the present invention, the gasification raw material preferably includes a gasification raw material for preparing H2 and CO. In the present invention, the fuel preferably includes fuel for power station boilers, industrial boilers and industrial kilns.

[0065] The sludge coke slurry provided by the present invention can be used as a gasification raw material to prepare H2 and CO, thereby providing a raw material basis for the gasification industry.

[0066] The sludge coke slurry provided by the invention is a co-slurry of sludge and petroleum coke, and the alkali metals (potassium, sodium, etc.) in the sludge can significantly improve the gasification activity of the petroleum coke.

[0067] The sludge coke provided by the present invention can also be used as fuel and burned in power station boilers, industrial boilers and industrial kilns. The combustion efficiency can reach 96-99%. It is an energy-saving fuel, and the combustion temperature is lower than the temperature of oil and coal, which is beneficial to reducing the generation of NOx and increasing the sulfur fixation rate. It is also a clean fuel.

[0068] In order to further illustrate the present invention, the application of the Lewis acid-base eutectic solvent in sludge modification, the modified sludge and its preparation method and application, the sludge char slurry and its application provided by the present invention are described in detail below in combination with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0069] The sludge used in Examples 1 to 4 and Comparative Examples 1 to 3 is fresh sludge that has not been mechanically dehydrated and is taken from the anaerobic digestion area of ​​a sewage treatment plant in Ningbo. It is high-grade anaerobic digestion sludge that is extremely difficult to dehydrate, has a capillary suction time (CST) of 821s, and a moisture content of about 95%.

[0070] The raw sludge in Examples 5 to 24 and Comparative Examples 4 to 7 was sourced from Ningbo Water Environment Group, and the water content of the sludge was about 90%.

[0071] Preparation of Lewis acid-base eutectic solvent (DES) in Examples 5 to 24: ChCl and ZnCl2 were stirred at 100° C. until they became colorless. The molar ratio of ChCl to ZnCl2 was 1:2.

[0072] Petroleum coke was sourced from Sinopec Ningbo Zhenhai Refining and Chemical Co., Ltd., ground into powder and sieved to remove particles larger than 100 mesh.

[0073] The test method is as follows:

[0074] (1) XPS analysis method

[0075] The morphology of HOFG on the sludge surface was analyzed by X-ray photoelectron spectroscopy (XPS). The instrument used was AxisSupra+ (Shimadzu, Japan), and the excitation source was AlK (α) rays (hγ = 1486.6 eV). The channel energy of the full spectrum was fixed at 100 eV, and the narrow spectrum channel energy of all elements was fixed at 50 eV. The C1s peak of 284.80 eV was used as a reference for charge correction. Subpeak fitting was performed using the Marquardt method.

[0076] (2)TG analysis method

[0077] A thermogravimetric analyzer (TG, NETZSCH, Germany) was used to distinguish the different forms of water present in the sludge. In the experiment, a sample weighing 10.0±0.1 mg was placed in a TG crucible. The analysis was carried out under a nitrogen atmosphere with a flow rate of 30 mL / min. The temperature was increased from 40°C to 90°C with a heating rate of 3°C / min. During this heating process, the weight loss of the sludge sample was defined as the free water content of the sample. The weight loss of a 10.0±0.1 mg sample placed in a drying oven at 105±1°C for about 2 hours was defined as the total water content. The bound water content of the sample was calculated using formula (1).

[0078] W bound =W total -W free Formula (1),

[0079] Among them, W bound W is bound water content; total is the total water content; W free is the free water content.

[0080] (3) Determination method of apparent viscosity and rheological data of sludge slurry

[0081] The apparent viscosity and shear stress of the sludge slurry were measured using a rotational viscometer (NXS-4C, Thermo, China). The test sample was placed in the viscometer and the shear rate was gradually increased from 0 to 100 s -1 Keep the shear rate at 100s -1 The shear rate was then reduced from 100 to 0 s. -1 During this process, the viscosity and shear stress of the test sample are recorded. The representative apparent viscosity of the sludge slurry is defined as the shear stress at a shear rate of 100 s -1 The average apparent viscosity at 37°C was calculated. During the whole process, the water bath temperature in the viscometer was maintained at 20±1°C.

[0082] (4) Method for determining the stability of sludge slurry

[0083] The sludge slurry was placed in a container and allowed to stand at room temperature (18-28°C) for 7 days to evaluate its stability. After this period of time, the container was tilted 45° for 30 seconds to allow the sludge slurry to flow out freely, and then the container was inverted vertically for 8 minutes. The stability of the sludge slurry was evaluated by measuring the ratio of the outflow mass fraction to the total sludge slurry mass (pouring rate). A larger pouring rate indicates that the sludge slurry has better fluidity after standing for 7 days, and therefore better stability.

[0084] Example 1

[0085] AlCl3 and choline chloride were fully mixed in a molar ratio of 1:3, and stirred at 100°C until transparent to obtain a Lewis acid-base eutectic solvent.

[0086] The Lewis acid-base eutectic solvent is mixed with the sludge, and subjected to modification treatment at 50°C for 4 hours to obtain modified sludge, wherein the mass of the Lewis acid-base eutectic solvent is 7% of the dry mass of the sludge. The sludge is advanced anaerobic digestion sludge.

[0087] Example 2

[0088] The only difference from Example 1 is that the Lewis acid is FeCl3.

[0089] Example 3

[0090] The only difference from Example 1 is that the Lewis acid is Al2(SO4)3.

[0091] Example 4

[0092] The only difference from Example 1 is that the Lewis acid is ZnCl2.

[0093] Comparative Example 1

[0094] The only difference from Example 1 is that the Lewis acid is ZnI2.

[0095] Comparative Example 2

[0096] Sludge dehydration conditioning method based on "deep eutectic solvent + inorganic agent"

[0097] Choline chloride and oxalic acid were fully mixed in a molar ratio of 1:1, and stirred at 80° C. until transparent to obtain a deep eutectic solvent.

[0098] The low eutectic solvent is mixed with the sludge, and the mixture is modified at 50°C for 2 minutes, and then polyaluminium chloride is added and mixed, and the mixture is modified at 50°C for 20 minutes to obtain modified sludge. The mass of the low eutectic solvent is 6% of the dry mass of the sludge, and the mass of the polyaluminium chloride is 1% of the dry mass of the sludge. The sludge is advanced anaerobic digestion sludge.

[0099] Comparative Example 3

[0100] Sludge dehydration conditioning method based on "deep eutectic solvent + inorganic agent"

[0101] Choline chloride and lactic acid were fully mixed in a molar ratio of 1:1, and stirred at 70° C. until transparent to obtain a deep eutectic solvent.

[0102] The low eutectic solvent and the biochar were stirred and mixed in a mass ratio of 60:1, and reacted at 90° C. for 4 hours to obtain a solid-liquid mixture.

[0103] The solid-liquid mixture is mixed with sludge, and modified at 50°C for 2 minutes, and then polyaluminium chloride is added and mixed, and modified at 50°C for 30 minutes to obtain modified sludge. The mass of the solid-liquid mixture is 6% of the mass of the dry basis of the sludge, and the mass of the polyaluminium chloride is 1.5% of the mass of the dry basis of the sludge. The sludge is advanced anaerobic digestion sludge.

[0104] Test Example 1

[0105] Capillary Suppression Time (CST) Test

[0106] Table 1 and Figure 1The capillary water absorption time test results of the modified sludge obtained by modifying the advanced anaerobic digestion sludge in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Tables 1 and Figure 1 It can be seen that the modification method of the present invention can reduce the CST of the extremely difficult to dehydrate advanced anaerobic digestion sludge from more than 800s to less than 600s. In addition, the Lewis acid-base eutectic solvent used in the present invention is small in dosage, low in cost, and the modification method is simple to operate and has environmentally friendly characteristics.

[0107] Table 1 Capillary absorption time (CST) of modified sludge of Examples 1 to 4 and Comparative Examples 1 to 3

[0108] Modified working conditions Capillary absorption time of sludge (s) Raw sludge 821 Example 1 549 Example 2 557 Example 3 574 Example 4 592 Comparative Example 1 658 Comparative Example 2 635 Comparative Example 3 639

[0109] The Lewis acidity of ZnCl2 is moderate, so the catalytic activity of ChCl-ZnCl2 is moderate. The Lewis acidity of AlCl3 and FeCl3 is strong, so the catalytic activity of ChCl-AlCl3 and ChCl-FeCl3 is stronger. 3+ with Fe 3+ The charge is the same, Al 3+ The radius is smaller, so the Lewis acidity of AlCl3 is stronger; in addition, the central aluminum atom of AlCl3 has an empty orbit, which is more likely to accept electron pairs. Therefore, the catalytic activity of ChCl-AlCl3 is stronger than that of ChCl-FeCl3, and the modification effect on sludge is better.

[0110] In addition to chlorides, other halogen metal salts (such as bromides and iodides) are also Lewis acids, but the Lewis acidity usually weakens as the halogen changes from chlorine to iodine.

[0111] Example 5

[0112] 100 g of original sludge and 6 g of Lewis acid-base eutectic solvent were mixed evenly, and then placed in a constant temperature water bath at 25° C. for modification treatment for 4 h to obtain modified sludge (named S-25).

[0113] Example 6

[0114] The only difference from Example 5 is that the modification treatment temperature is 40°C, and the obtained modified sludge is named S-40.

[0115] Example 7

[0116] The only difference from Example 5 is that the modification treatment temperature is 55°C, and the obtained modified sludge is named S-55.

[0117] Example 8

[0118] The only difference from Example 5 is that the modification treatment temperature is 70°C, and the obtained modified sludge is named S-70.

[0119] Test Example 2

[0120] Performance tests of the original sludge used in Examples 5 to 8 and the modified sludge prepared

[0121] 1. Test of hydrophilic oxygen-containing functional groups of modified sludge

[0122] X-ray photoelectron spectroscopy (XPS) was used to analyze the effect of Lewis acid-base eutectic solvent on high oxygen functional groups (HOFG) in sludge. The C1s peak was decomposed into four different peaks: CC / CH peak at 284.8eV, C-OH / COC peak at 286.2eV, C=O peak at 287.5eV, and O=C-OH peak at 289.0eV. The relative content of HOFG in sludge was determined by calculating the area percentage of each peak in the overall C1s peak.

[0123] Figure 2 The XPS analysis results of hydrophilic oxygen-containing functional groups (HOFG) on the surface of the original sludge and the modified sludge show that the content of HOFG in the sludge treated with Lewis acid-base eutectic solvent is reduced compared with that of the untreated original sludge. This indicates that DES promotes the decomposition of HOFG in the sludge, and its mechanism is that Lewis acid (Al 3+ , Fe 3+ 、Zn 2+ ) can coordinate with the oxygen atoms in the oxygen-containing functional groups to activate the oxygen-containing functional groups and make them easier to decompose. At the same time, the hydrogen bonding effect in the Lewis base (choline chloride) can stabilize the reaction intermediates and promote the decomposition process of the oxygen-containing functional groups. Figure 2 The results of the C1s peak segment fitting analysis are also shown. It can be seen that with the increase of the modification temperature, the relative content of HOFG gradually decreases. When the temperature exceeds 55°C, this downward trend tends to converge. Therefore, considering the effectiveness and economic factors of HOFG decomposition, the optimal modification temperature is 55°C.

[0124] 2. Elemental analysis of sludge (O / C ratio, H content, calorific value)

[0125] The calorific value (received low calorific value, Q b,ad ) and elemental analysis results are shown in Table 2 and Figure 3 .

[0126] Table 2 Elemental analysis and calorific value of five sludge samples

[0127]

[0128]

[0129] a ad means air dry basis.

[0130] From Table 2 and Figure 3 It can be seen that the O / C ratio of the modified sludge is lower than that of the original sludge, and it shows a downward trend with the increase of the modification treatment temperature. When the modification treatment temperature exceeds 55°C, the O / C ratio remains relatively stable at about 1.2. This trend of the O / C ratio is mainly attributed to the Lewis acid-base eutectic solvent promoting the decomposition of hydrophilic oxygen-containing functional groups (HOFG), which is consistent with the XPS analysis results mentioned above. In addition, the decomposition of HOFG such as hydroxyl and carboxyl groups also leads to a decrease in hydrogen content. However, the reduction in hydrogen content leads to a slight decrease in the calorific value of the sludge. Despite this, the calorific value of the modified sludge remains at 13207-13448 kJ / kg, and the calorific value is greater than 13200 kJ / kg. This shows that the effect of the Lewis acid-base eutectic solvent on the calorific value of the sludge is minimal.

[0131] 3. Sludge moisture content test

[0132] Thermogravimetric analysis (TG) was used to obtain quantitative data on the mass change of sludge samples during the drying process.

[0133] Figure 4 The TG curves of the original sludge and the modified sludge in Examples 5 to 8 show that the weight loss of the sludge samples continues to increase with the extension of the drying time. When the drying temperature is lower than 60°C, the mass of the sludge samples decreases approximately linearly with time, indicating that the rate of water loss remains consistent under these conditions. When the drying temperature exceeds 70°C, the mass loss of all sludge samples becomes negligible. During the entire drying process, the mass loss rates of the original sludge, S-25, S-40, S-55 and S-70 were 1.99%, 27.43%, 33.20%, 44.03% and 45.12%, respectively. These loss rates represent the free water content of the sludge. Before the thermogravimetric analysis process, the five sludge samples were pretreated so that their total moisture content was controlled to 65%. The bound water content in the sludge was calculated using formula (1), and the results are shown in Tables 3 and Figure 5 As shown, the bound water content of the sludge treated with Lewis acid-base eutectic solvent is significantly lower than that of the original sludge. As the temperature of the modification treatment increases, the bound water content gradually decreases. However, after exceeding 55°C, the bound water content stabilizes at about 20%, which is about 40% lower than that of the original sludge.

[0134] Table 3 Moisture content of five sludge samples

[0135] sample Total moisture content Free water content Bound water content Raw sludge 65％ 1.99％ 63.01％ S-25 65％ 27.43％ 37.57％ S-40 65％ 33.20％ 31.80％ S-55 65％ 44.03％ 20.97％ S-70 65％ 45.12％ 19.88％

[0136] In summary, the present invention uses Lewis acid-base eutectic solvents to significantly reduce the bound water content in sludge, thereby enhancing its dehydration performance. This improvement is attributed to the Lewis acid-base eutectic solvents promoting the catalytic decomposition ability of HOFG and weakening its interaction with water molecules. Therefore, the Lewis acid-base eutectic solvent helps to convert bound water into free water for easy removal. This conversion not only reduces viscosity, but also improves the fluidity of sludge and optimizes its handling and processing characteristics.

[0137] Example 9

[0138] Petroleum coke, sodium lignin sulfonate, modified sludge S-25 prepared in Example 5 and deionized water were stirred at a speed of 1000 r / min for 15 min to obtain sludge coke slurry (PCSS). The mass of sodium lignin sulfonate accounted for 8% of the mass of the petroleum coke dry basis, and the mass of the modified sludge accounted for 20% of the mass of the petroleum coke dry basis (recorded as sludge blending amount of 20%); the amount of deionized water added was based on obtaining a sludge coke slurry with a representative apparent viscosity of 1000 mPa·s.

[0139] Examples 10 to 24

[0140] The sludge slurry was prepared according to the method of Example 9. The type of modified sludge and the sludge blending amount are shown in Table 4.

[0141] Table 4 Sludge types and sludge blending amounts used in Examples 9 to 24

[0142] PCSS Sludge Type Sludge mixing amount PCSS Sludge Type Sludge mixing amount Example 9 S-25 20％ Embodiment 17 S-25 40％ Example 10 S-40 20％ Embodiment 18 S-40 40％ Embodiment 11 S-55 20％ Embodiment 19 S-55 40％ Example 12 S-70 20％ Embodiment 20 S-70 40％ Example 13 S-25 30％ Embodiment 21 S-25 50％ Embodiment 14 S-40 30％ Embodiment 22 S-40 50％ Embodiment 15 S-55 30％ Embodiment 23 S-55 50％ Example 16 S-70 30％ Embodiment 24 S-70 50％

[0143] Comparative Example 4

[0144] The sludge char slurry was prepared according to the method of Example 9, using original sludge and the sludge blending amount was 20%.

[0145] Test Example 3

[0146] Performance test of sludge coke slurry prepared in Examples 9 to 24 and Comparative Example 4

[0147] 1. Test on the changes of sludge coke slurry's slurry characteristics (solid concentration and calorific value)

[0148] Table 5 and Figure 6(a) shows the solid concentration of sludge coke slurry with different sludge types (original sludge, S-25, S-40, S-55, S-70). It can be seen that there is a continuous upward trend from original sludge to S-70. The solid concentration of S-70 is very close to that of S-55. This shows that the fluidity of the sludge is improved with the increase of the sludge modification treatment temperature. However, further increasing the modification treatment temperature to above 55°C has little effect on the fluidity. Moreover, with the increase of sludge dosage, the solid concentration of all sludge types decreases. For the original sludge, when its dosage reaches 20% of the mass of petroleum coke, the solid concentration drops below 50%. This is because its viscosity is too high, making it impractical to increase the dosage of original sludge to prepare PCSS. In contrast, for S-55 and S-70, at a dosage of 20%, the solid concentration can be close to 60%, and even at a dosage of 50%, it remains above 50%. Therefore, the use of Lewis acid-base eutectic solvent enables a higher sludge coke concentration to be obtained at the same sludge dosage. This is mainly because Lewis acid-base eutectic solvent helps to convert bound water in the sludge into free water, so that the sludge coke has a lower viscosity at the same solid concentration, and a higher solid concentration can be obtained at the same sludge coke viscosity.

[0149] Table 5 Solid concentration (wt%) of sludge slurry of different sludge types and blending amounts in Examples 9 to 24 and Comparative Example 4

[0150] Sludge type / mixing amount 20％ 30％ 40％ 50％ Raw 47.34 / / / S-25 52.71 48.23 43.86 40.15 S-40 54.17 52.08 47.64 43.02 S-55 58.84 56.29 52.67 50.72 S-70 59.27 56.38 53.14 51.23

[0151] Table 6 and Figure 6 (b) shows the calorific value of sludge char with different sludge types (original sludge, S-25, S-40, S-55, S-70). It can be seen that there is a positive correlation between the calorific value of sludge char and its solid concentration. As the solid concentration of PCSS increases, its calorific value also increases. As the sludge dosage increases, the solid concentration of PCSS decreases, resulting in a decrease in its calorific value. For the original sludge, when the sludge dosage reaches 20%, the calorific value of PCSS drops below 15000 kJ / kg. However, for the sludge S-55 and S-70 that have been optimized by Lewis acid-base eutectic solvent treatment, at a sludge dosage of 20%, the calorific value of PCSS can exceed 18000 kJ / kg, and even at a sludge dosage of 50%, its calorific value remains above 15000 kJ / kg.

[0152] Table 6 Calorific value of sludge slurry with different sludge types and blending amounts in Examples 9 to 24 and Comparative Example 4 (kJ / kg)

[0153] Sludge type / mixing amount 20％ 30％ 40％ 50％ Raw 14533.38 / / / S-25 16181.97 14806.61 13465.02 12326.05 S-40 16630.19 15988.56 14625.48 13207.14 S-55 18063.88 17281.03 16169.69 15571.04 S-70 18195.89 17308.66 16313.98 15727.61

[0154] 2. Rheological properties test of sludge coke slurry

[0155] Slurry fuels are generally expected to have a "shear thinning" pseudoplastic rheological property. This property is advantageous because higher viscosity enhances stability during storage, while lower viscosity improves flowability during transportation. Tables 7-10 and Figure 7 The rheological properties of PCSS with an apparent viscosity of 1000 mPa·s (representative apparent viscosity) are shown. It can be seen that the apparent viscosity of all PCSSs decreases significantly with the increase of shear rate, showing a strong pseudoplastic rheological property of "shear thinning" within the scope of this experiment. Moreover, the apparent viscosity of the sludge char slurry with the addition of original sludge, S-25, S-40, S-55 and S-70 shows a downward trend from large to small as the slope of the shear rate curve increases.

[0156] Table 7 Apparent viscosity (mPa·s) of sludge slurry (sludge blending amount is 20%) at different shear rates in Examples 9 to 12 and Comparative Example 4

[0157] <![CDATA[Shear rate (s -1 )]]> Raw S-25 S-40 S-55 S-70 10 2668 2428 2253 2034 1972 20 2117 1926 1789 1635 1569 30 1705 1571 1467 1350 1316 40 1393 1329 1268 1175 1145 60 1194 1165 1136 1090 1077 100 1096 1074 1057 1035 1028

[0158] Table 8 Apparent viscosity (mPa·s) of sludge slurry (sludge blending amount is 30%) at different shear rates in Examples 13 to 16

[0159] <![CDATA[Shear rate (s -1 )]]> S-25 S-40 S-55 S-70 10 2473 2346 2158 2065 20 1991 1887 1734 1656 30 1637 1544 1427 1375 40 1384 1323 1229 1184 60 1201 1171 1116 1093 100 1084 1067 1045 1034

[0160] Table 9 Apparent viscosity of sludge slurry (sludge blending amount is 40%) at different shear rates in Examples 17 to 20 (mPa·s)

[0161] <![CDATA[Shear rate (s -1 )]]> S-25 S-40 S-55 S-70 10 2612 2471 2275 2154 20 2114 1997 1843 1747 30 1721 1623 1501 1438 40 1446 1376 1280 1229 60 1228 1194 1138 1113 100 1104 1084 1059 1046

[0162] Table 10 Apparent viscosity (mPa·s) of sludge slurry (sludge blending amount is 50%) at different shear rates in Examples 21 to 24

[0163]

[0164]

[0165] This shows that the pseudoplastic characteristics of PCSS decreased after modification by Lewis acid-base eutectic solvent. In addition, the more significant the modification effect of sludge, the weaker the pseudoplastic characteristics of PCSS. This is because sludge usually contains a large amount of organic matter, which easily combines with other components in sludge char to form a three-dimensional network structure or flocculation. This enhances the structural strength of sludge char, causing PCSS to exhibit typical pseudoplastic characteristics. However, after the sludge was modified by Lewis acid-base eutectic solvent, organic components such as HOFG were decomposed. This decomposition weakened the three-dimensional network structure of PCSS, resulting in a decrease in its pseudoplastic rheological characteristics. In addition, pseudoplasticity often cooperates with thixotropy, and the structural strength of sludge char is characterized by the area of ​​the thixotropic circle. The larger the area of ​​the thixotropic circle, the greater the structural strength.

[0166] Figure 8 and Fig. 9 The thixotropy of PCSS made from five types of sludge in Examples 9 to 12 and Comparative Example 4 is demonstrated, and the sludge blending amount is 20% of the dry basis petroleum coke. The use of original sludge causes the thixotropic ring area of ​​PCSS to reach a maximum, exceeding 1000Pa / s. As the sludge modification treatment temperature increases, the thixotropic ring area of ​​PCSS gradually decreases. When the modification treatment temperature exceeds 55°C, the area is reduced to about 300Pa / s. This shows that the thixotropy of PCSS is consistent with its pseudoplastic characteristics. As the sludge modification treatment effect improves, the thixotropic ring area decreases, indicating that the structural strength is weakened, thus leading to a weakening of the pseudoplastic rheological characteristics. But in general, within the scope of this experiment, all sludge coke slurry samples have strong "shear thinning" pseudoplastic rheological properties, which meet the expectations of industrial applications.

[0167] 3. Stability test of sludge slurry

[0168] Stability mainly refers to the ability of solid particles in sludge slurry to resist stratification and sedimentation. The stability of sludge slurry directly affects its transportation, storage and utilization. In order to evaluate the effect of Lewis acid-base eutectic solvent on the stability of sludge slurry (PCSS), a stability test of PCSS was conducted. The results showed that the stability of PCSS varied significantly depending on the type and dosage of sludge. The PCSS stability trends of sludge of different types and dosages in Examples 9 to 12 and Comparative Example 4 are shown in Figure 2. Fig.10 As shown in Table 11.

[0169] Table 11 Discharge rate of sludge slurry with different sludge types and blending amounts in Examples 9 to 24 and Comparative Example 4 (%)

[0170] Sludge type / mixing amount 20％ 30％ 40％ 50％ Raw 37.86 / / / S-25 66.32 57.14 39.91 23.45 S-40 76.25 69.18 57.52 38.73 S-55 91.39 84.41 76.16 65.34 S-70 93.56 87.25 76.37 69.52

[0171] Fig.10(a) shows the pouring rate of different sludge types (raw sludge, S-25, S-40, S-55, S-70), indicating that the pouring rate shows a consistent upward trend as the sludge type changes from raw material to S-70. In addition, the pouring rate of S-70 is very close to that of S-55. This shows that as the sludge modification treatment temperature increases, the fluidity of PCSS and the ability to maintain fluidity after 7 days (stability) are improved. However, when the modification treatment temperature exceeds 55°C, further increasing the temperature has little effect on fluidity.

[0172] Fig.10 (b) shows that the pouring rate of all PCSSs shows a downward trend with the increase of sludge dosage. As the disposal temperature increases, the slope of this trend decreases, indicating that the Lewis acid-base eutectic solvent has a good modification treatment on the sludge and reduces its negative impact on the fluidity of the sludge coke slurry. When the dosage of the original sludge is 20% of the dry basis petroleum coke, the pouring rate drops below 40%. In contrast, for S-55 and S-70, the pouring rate can reach about 90% at a dosage of 20%, and it can still maintain about 70% at a dosage of 50%. Therefore, after 7 days of static storage, the use of Lewis acid-base eutectic solvents significantly improved the flowability of PCSS, and the pouring rate indicated its excellent stability. This improvement in fluidity is mainly due to the fact that the Lewis acid-base eutectic solvent promotes the conversion of bound water in the sludge to free water, thereby reducing the viscosity of the sludge.

[0173] in conclusion:

[0174] (1) The Lewis acid-base eutectic solvent promoted the catalytic decomposition of HOFG and the conversion of bound water to free water in the sludge, thereby improving the dewatering performance of the sludge. As the modification treatment temperature increased from 25°C to 70°C, the effectiveness of the Lewis acid-base eutectic solvent treatment gradually improved, reaching the optimal point at about 55°C (the bound water content was about 40% lower than that of the original sludge). After exceeding this temperature, the treatment effect tended to stabilize, indicating that further increasing the temperature would not significantly enhance the performance. This shows that 55°C is the optimal temperature for Lewis acid-base eutectic solvents to improve sludge properties.

[0175] (2) As the effect of using Lewis acid-base eutectic solvent to treat sludge increases, the solid concentration and calorific value of PCSS are significantly enhanced. For the original sludge, when the sludge dosage is 20%, the solid concentration of PCSS drops below 50% and the calorific value drops below 15000 kJ / kg. In contrast, for the sludge treated with Lewis acid-base eutectic solvent at 55°C (S-55), at the same sludge dosage, the solid concentration of PCSS is close to 60% and the calorific value exceeds 18000 kJ / kg. In addition, for S-55, even when the sludge dosage is 50%, the solid concentration of PCSS remains above 50% and the calorific value remains above 15000 kJ / kg.

[0176] (3) With the improvement of sludge treatment effect, the structural strength of PCSS decreased to a certain extent, resulting in a decrease in its pseudo-plastic rheological characteristics. However, all PCSS samples still showed strong "shear thinning" pseudo-plastic rheological characteristics within the scope of this experiment. Therefore, the effect of Lewis acid-base eutectic solvent on the rheological properties of PCSS is acceptable.

[0177] (4) The sludge treated with Lewis acid-base eutectic solvent contained more free water and exhibited lower viscosity, significantly enhancing the flowability of PCSS stored for 7 days. This resulted in excellent stability, as evidenced by the improved pouring rate. For S-55, the pouring rate was as high as 90% (50% higher than the original sludge) at a sludge dosage of 20%, and even at a sludge dosage of 50%, the pouring rate remained at about 70%.

[0178] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Application of Lewis acid-base eutectic solvent in sludge modification; the Lewis acid-base eutectic solvent comprises Lewis acid and Lewis base.

2. The use according to claim 1, characterized in that: The Lewis acid includes one or more of metal chlorides and metal sulfates; The Lewis base includes choline chloride; The molar ratio of the Lewis base to the Lewis acid is 1:1-8.

3. A method for preparing modified sludge, characterized in that: The following steps are involved: The sludge is mixed with a Lewis acid-base eutectic solvent and subjected to modification treatment to obtain modified sludge; The Lewis acid-base eutectic solvent comprises Lewis acid and Lewis base, and the Lewis acid comprises one or more of metal chloride and metal sulfate.

4. The sludge modification treatment method according to claim 3, characterized in that: The Lewis base includes choline chloride; The molar ratio of the Lewis base to the Lewis acid is 1:1 to 8; The mass ratio of the sludge to the Lewis acid-base eutectic solvent is 1:0.01-0.

15.

5. The sludge modification treatment method according to claim 3 or 4, characterized in that: The temperature of the modification treatment is 25 to 85° C., and the time is 1 to 24 hours.

6. Modified sludge obtained by the sludge modification treatment method according to any one of claims 3 to 5.

7. A sludge slurry, characterized in that: The preparation raw materials include the modified sludge according to claim 6, petroleum coke, a dispersant and water; The mass of the modified sludge accounts for 20-50% of the dry mass of petroleum coke.

8. The sludge coke slurry according to claim 7, characterized in that: The dispersant includes one or more of lignin sulfonate, naphthalene water reducer and polycarboxylate; The mass of the dispersant accounts for 0.6-1.5% of the mass of the petroleum coke dry basis; The solid content of the sludge char slurry is 40-65%.

9. The method for preparing sludge char slurry according to claim 7 or 8, characterized in that: The following steps are involved: The raw materials for preparing the sludge char slurry are mixed to obtain the sludge char slurry.

10. Use of the sludge char slurry according to claim 7 or 8 or the sludge char slurry prepared by the preparation method according to claim 9 as fuel or gasification raw material.

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