A method for dewatering and pretreatment of oily sludge

Abstract

This invention relates to the field of oily sludge resource utilization technology, specifically to a method for pre-treatment of oily sludge dewatering. The invention provides a method for pre-treatment of oily sludge dewatering, comprising: mixing biomass carbon aerogel with oily sludge, and then dewatering the oily sludge under light irradiation. This invention utilizes the hierarchical porous structure of biomass carbon aerogel to achieve rapid dewatering of oily sludge, providing a novel approach to oily sludge dewatering.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oily sludge resource utilization, and particularly relates to a method for dehydrating and pretreating oily sludge. BACKGROUND

[0002] Oily sludge is a kind of hazardous waste (HW08) generated in the petroleum and petrochemical industry, which contains petroleum, water and mineral residues. It has the dual attributes of resource and environmental pollution. Therefore, its treatment and disposal process and method should meet the dual management objectives of recycling resources and environmental harmlessness.

[0003] Oily sludge pyrolysis technology can separate oily sludge into valuable petroleum resources and treatment residues, and produce less secondary pollutants. However, oily sludge usually contains different amounts of water, which will result in the need to consume a large amount of energy to overcome the latent heat of water vaporization during pyrolysis. Therefore, it is necessary to dehydrate and pretreat the oily sludge. The water in the oil sludge is mainly interstitial water distributed between mineral particles. However, the oil-in-water and water-in-oil phenomenon caused by oil-water emulsification makes it difficult to separate oil and water. The complex mineral composition, exogenous additives and oil-water environment (pH, acidity and alkalinity, biological community, etc.) in the oil sludge affect the emulsion degree and stability, and the high viscosity (the viscosity of crude oil at room temperature is 10 3 ~ 10 5 mPa) results in the difficulty of breaking emulsion separation at room temperature. Therefore, physical separation means cannot achieve efficient dehydration of oil sludge, and thermal drying becomes a common means of dehydration pretreatment. However, the latent heat of water vaporization is very large (2260 kJ / kg), and the energy consumption during the water evaporation stage is high. In addition, the process flow related to dehydration and purification is complex, and the indirect carbon emission is very large. Solar evaporation, as one of the oldest solar heat utilization technologies, can save energy consumption in the process of oil sludge dehydration and drying.

[0004] However, for the oil-water emulsion phenomenon, the traditional evaporation technology is difficult to break through the rigid film of the oil-water interface, and thus to realize efficient water evaporation. In addition, the high viscosity characteristics of oil sludge further hinder the water evaporation efficiency. Therefore, how to realize the dehydration pretreatment of oily sludge still needs to be expanded. SUMMARY

[0005] The present application provides a method for dehydrating and pretreating oily sludge. The biomass carbon aerogel in the present application has the characteristics of photothermal heating, demulsification and directional oil absorption, can realize rapid heating under solar irradiation, thereby reducing the viscosity of petroleum, realizing oil-water demulsification combined with surface properties, and petroleum components entering the confined space of pores, and finally realizing efficient and rapid dehydration.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] The application provides a method for dewatering pretreatment of oily sludge, comprising: mixing biomass carbon aerogel with oily sludge, and completing dewatering of the oily sludge under light.

[0008] The applicant finds that the biomass carbon aerogel has a multi-level pore structure, can help adsorb oil, and realize oil-water separation. The biomass carbon aerogel as a whole is black, has good light absorption performance, and contains part of the graphitization structure which can convert light energy into heat energy, so that the biomass carbon aerogel generates heat under light. The oil-water separation of the oily sludge exactly needs a material with a multi-level pore structure to assist in realizing the oil-water separation.

[0009] Therefore, the applicant considers mixing the biomass carbon aerogel with the oily sludge, and accelerating the overall warming rate under light, so that the oil-water emulsion in the oily sludge is adsorbed into the interior of the biomass carbon aerogel. After the biomass carbon aerogel completely adsorbs the oil-water emulsion in the oily sludge, the heat conduction efficiency of the biomass carbon aerogel is improved due to the fact that the internal gap is occupied by the oil-water emulsion in the oily sludge, which is beneficial to the continuous warming of the whole under light, accelerates the evaporation of water in the oily sludge, and thus realizes the low-carbon dewatering treatment of the oily sludge.

[0010] In summary, the application provides a method for dewatering pretreatment of oily sludge, which is realized by matching the material characteristics of the biomass carbon aerogel with the characteristics of the oily sludge. Specifically, the hierarchical porous structure of the biomass carbon aerogel can ensure that both the micron-level large pores promote the rapid penetration of the oil-water emulsion in the oily sludge and the nanometer-level small pores improve the adsorption capacity of the oil. This structure can effectively increase the contact area and accelerate the process of oil-water separation in the oily sludge, so as to realize the rapid dewatering of the oily sludge.

[0011] Preferably, the condition of the light is that the light power density is 100 Mw / cm 2 and the treatment is performed for 2-4 h.

[0012] Further preferably, the condition of the light is that the light power density is 100 Mw / cm 2 and the treatment is performed for 3-4 h.

[0013] Further preferably, the condition of the light is that the light power density is 100 Mw / cm 2 and the treatment is performed for 3 h.

[0014] Preferably, the mass ratio of the oily sludge to the biomass carbon aerogel is 10:(1-2.5).

[0015] Further preferably, the mass ratio of the oily sludge to the biomass carbon aerogel is 10:(1-2).

[0016] More preferably, the mass ratio of the oily sludge to the biomass carbon aerogel is 10:(1.5-2).

[0017] More preferably, the mass ratio of the oily sludge to the biomass carbon aerogel is 10:(1.8-2).

[0018] More preferably, the mass ratio of the oily sludge to the biomass carbon aerogel is 10:2.

[0019] Preferably, the preparation method of the biomass carbon aerogel includes: dispersing biomass in water, freezing and drying to obtain biomass aerogel, and then pyrolyzing in anoxic conditions to obtain biomass carbon aerogel.

[0020] Preferably, the biomass is carboxymethyl cellulose or degreased cotton.

[0021] Preferably, the biomass is carboxymethyl cellulose and degreased cotton.

[0022] More preferably, the mass ratio of the carboxymethyl fiber, the mass of the degreased cotton, and the volume of water is 7.5g:1g:100mL.

[0023] Preferably, the freezing temperature is -75 to -85°C, and the freezing time is 5 to 7 hours.

[0024] More preferably, the freezing temperature is -80°C and the freezing time is 6 hours.

[0025] Preferably, the drying method is vacuum drying, the drying temperature is 20-25°C, and the drying time is 48-72 hours.

[0026] More preferably, the drying method is vacuum drying, the drying temperature is 25°C, and the drying time is 48 hours.

[0027] It should be noted that the solution provided in this application can complete the drying at room temperature, that is, a temperature of 20-25°C close to room temperature can meet the requirements without the need for additional heating and energy consumption.

[0028] Preferably, the conditions for the anoxic pyrolysis are: pyrolysis at 300–600°C for 50–70 min under a nitrogen atmosphere.

[0029] More preferably, the conditions for the anaerobic pyrolysis are: pyrolysis at 400–600°C for 60 min under a nitrogen atmosphere.

[0030] More preferably, the conditions for the anoxic pyrolysis are: pyrolysis at 500–600°C for 60 min under a nitrogen atmosphere.

[0031] More preferably, the conditions for the anoxic pyrolysis are: pyrolysis at 600°C for 60 min under a nitrogen atmosphere.

[0032] Therefore, the present invention has the following beneficial effects:

[0033] (1) This invention utilizes the hierarchical porous structure and excellent photothermal properties of biomass carbon aerogel to achieve rapid dewatering of oily sludge, providing a new method for dewatering oily sludge and opening up new application avenues for biomass carbon aerogel.

[0034] (2) In this invention, biomass carbon aerogel is mixed with oily sludge and then irradiated under light so that the oil-water emulsion in the oily sludge is adsorbed into the target biomass carbon aerogel. When the target biomass carbon aerogel is fully adsorbed with the oil-water emulsion in the oily sludge, the thermal conductivity of the biomass carbon aerogel is improved because the pores inside are occupied by the oil-water emulsion in the oily sludge. This causes the mixture of oily sludge and biomass carbon aerogel to heat up rapidly, thereby accelerating the evaporation of water from the oily sludge. Attached Figure Description

[0035] Figure 1 A schematic diagram illustrating the process of an oily sludge treatment method according to an embodiment of the present disclosure is shown.

[0036] Figure 2 The graph shows the adsorption performance of biomass carbon aerogel.

[0037] Figure 3 Performance diagram of BCA600 for emulsion oil-water separation;

[0038] Figure 4 This is a test diagram of the photothermal conversion performance of biomass carbon aerogel.

[0039] Figure 5 The organic solvent adsorption capacity of BCA600;

[0040] Figure 6 The weight loss curve of oily sludge mixed with biomass carbon aerogel under light irradiation;

[0041] Figure 7 This image shows the dewatering effect of mixing oily sludge with different carbon-based materials.

[0042] Figure 8 The image shows the dehydration effect after mixing the water-in-oil emulsion with BCA600.

[0043] Figure 9 This image shows the dehydration effect after the soil-water mixture is mixed with BCA600.

[0044] Figure 10 This image shows the dehydration effect after mixing oily sludge or water-in-oil emulsion with BCA600. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0046] The oily sludge in this section was prepared by mixing crude oil, water, and soil in a mass ratio of 6:4:5. The crude oil came from Daqing Oilfield, and the soil came from Tianjin Binhai. The activated carbon was produced by Tianjin Fuchen Chemical Reagent Co., Ltd. The water-in-oil emulsion in "2. Oil-water separation capacity test of biomass carbon aerogel" consisted of n-hexane or diesel, water, and Span-80, with n-hexane or diesel and water mixed in a volume ratio of 9:1, and the amount of Span-80 used was 0.02 g / mL. The water-in-oil emulsion in "7. Application of biomass carbon aerogel in dehydration of water-in-oil emulsion" was prepared by mixing crude oil and water in a mass ratio of 4:6 using a homogenizer. The water-soil mixture in "8. Application of biomass carbon aerogel in dehydration of water-soil mixture" was prepared by mixing soil and water in a mass ratio of 5:4.

[0047]

Example

[0048] Example 1

[0049] 3.0 g of carboxymethyl cellulose and 0.4 g of defatted cotton were uniformly dispersed in 100 mL of deionized water, and then vacuum dried at -80 °C for 48 h to obtain biomass aerogel. The biomass aerogel was then sent to a fixed bed for pyrolysis under nitrogen atmosphere at 600 °C for 60 min. After natural cooling to room temperature, biomass carbon aerogel, denoted as BCA600, was obtained.

[0050] Example 2

[0051] This embodiment is basically the same as Embodiment 1, except that the pyrolysis atmosphere is nitrogen and the temperature is 500℃, denoted as BCA500.

[0052] Example 3

[0053] This embodiment is basically the same as Embodiment 1, except that the pyrolysis atmosphere is nitrogen and the temperature is 400℃, denoted as BCA400.

[0054] Example 4

[0055] This embodiment is basically the same as Embodiment 1, except that the pyrolysis atmosphere is nitrogen and the temperature is 300℃, denoted as BCA300.

[0056] Example 5

[0057] The oily sludge was mechanically mixed with the BCA600 obtained in Example 1 at a mass ratio of 10:2.0, and the mixture was spread evenly on the surface of a petri dish. A xenon lamp equipped with an AM 1.5g filter was used to simulate sunlight at a light power density of 100 Mw / cm². 2 Place for 3 hours.

[0058] Example 6

[0059] This embodiment is basically the same as Example 1, except that the mass ratio of oily sludge to BCA600 obtained in Example 1 is 10:1.5.

[0060] Example 7

[0061] This embodiment is basically the same as that of embodiment 1, except that the mass ratio of oily sludge to BCA600 obtained in embodiment 1 is 10:1.0.

[0062] Comparative Example 1

[0063] Oily sludge was spread evenly on the surface of a petri dish, and sunlight was simulated using a xenon lamp equipped with an AM 1.5g filter at a light power density of 100 Mw / cm². 2 Place for 3 hours.

[0064] Comparative Example 2

[0065] Oily sludge and activated carbon were mixed evenly at a mass ratio of 10:2 and spread evenly on the surface of a petri dish. A xenon lamp equipped with an AM 1.5g filter was used to simulate sunlight at a light power density of 100 Mw / cm². 2 Place for 3 hours.

[0066] Comparative Example 3

[0067] The water-in-oil emulsion and the BCA600 obtained in Example 1 were mechanically mixed evenly at a mass ratio of 10:1.02, and the mixture was spread evenly on the surface of a petri dish. A xenon lamp equipped with an AM 1.5g filter was used to simulate sunlight at a light power density of 100 Mw / cm². 2 Place for 3 hours.

[0068] Comparative Example 4

[0069] This comparative example is basically the same as Comparative Example 3, except that the mass ratio of the water-in-oil emulsion to the BCA600 obtained in Example 1 is 10:2.04.

[0070] Comparative Example 5

[0071] This comparative example is basically the same as Comparative Example 3, except that the mass ratio of the water-in-oil emulsion to the BCA600 obtained in Example 1 is 10:3.06.

[0072] Comparative Example 6

[0073] This comparative example is basically the same as Comparative Example 3, except that the mass ratio of the water-in-oil emulsion to the BCA600 obtained in Example 1 is 10:4.08.

[0074] Comparative Example 7

[0075] The water-soil mixture was mechanically mixed with the BCA600 obtained in Example 1 at a mass ratio of 10:1.02, and the mixture was spread evenly on the surface of a petri dish. Sunlight was simulated using a xenon lamp equipped with an AM 1.5g filter at a light power density of 100 Mw / cm². 2 Place for 3 hours.

[0076] Comparative Example 8

[0077] This comparative example is basically the same as Comparative Example 7, except that the mass ratio of the water-soil mixture to the BCA600 obtained in Example 1 is 10:2.04.

[0078] Comparative Example 9

[0079] This comparative example is basically the same as comparative example 7, except that the mass ratio of the water-soil mixture to the BCA600 obtained in example 1 is 10:3.06.

[0080] Comparative Example 10

[0081] This comparative example is basically the same as comparative example 7, except that the mass ratio of the water-soil mixture to the BCA600 obtained in example 1 is 10:4.08.

[0082] [Performance Testing]

[0083] 1. Adsorption performance test of biomass carbon aerogel

[0084] The BCA300, BCA400, BCA500, and BCA600 obtained in Examples 1-4 were subjected to BET testing, and the results are as follows: Figure 2 As shown.

[0085] observe Figure 2It can be inferred that all biomass carbon aerogels exhibit type II isotherms (according to IUPAC classification). At low relative pressures (<0.1), the adsorption capacity increases rapidly, and the curve is convex, proving that these materials are macroporous. With increasing pyrolysis temperature, biomass carbon aerogels exhibit stronger adsorption-adsorbent interactions, which can be attributed to the activation of the material at high temperatures. The pore size distribution diagram of biomass carbon aerogels shows that the materials with the largest pore volumes mostly have pore sizes smaller than [missing information]. These micropores likely originate from the decomposition of biomass macromolecules. The pore volume is... The range decreases with increasing pyrolysis temperature, possibly due to framework collapse caused by higher pyrolysis temperatures. Overall, biomass carbon aerogels may exhibit a structure characterized by the coexistence of micropores and macropores. Macropores facilitate the adsorption of organic solvents, while micropores facilitate the separation of oil-water emulsions.

[0086] 2. Oil-water separation capability test of biomass carbon aerogel

[0087] The BCA600 obtained in Example 1 was used for oil-in-water emulsion separation tests with the assistance of a peristaltic pump, and the results are as follows: Figure 3 As shown.

[0088] observe Figure 3 It is known that biomass carbon aerogel, due to its porous and tortuous internal structure, can separate emulsions by causing micro-droplets to collide and aggregate within the pores, forming larger droplets that are then trapped by the pores. For hexane and diesel-in-water emulsions, the separation efficiency of biomass carbon aerogel can reach 97.28% and 88.81%, respectively, indicating that biomass carbon aerogel can effectively separate water-in-oil emulsions. Microscopic images of the separated emulsions clearly show a reduction in micron-sized water droplets, while the number of droplets after separation from the diesel-in-water emulsion is slightly higher than that from the hexane-in-water emulsion. This is consistent with the difference in separation efficiency between the two emulsions, which may be due to the viscosity difference between the two liquids. This means that crude oil emulsions with higher viscosity are more difficult to demulsify.

[0089] 3. Photothermal conversion capacity test of biomass carbon aerogel

[0090] The photothermal conversion capacity of BCA300, BCA400, BCA500, and BCA600 obtained in Examples 1-4, as well as pure oily sludge (OS), was tested, and the results are as follows: Figure 4 As shown.

[0091] observe Figure 4It can be seen that as the pyrolysis temperature increases, the equilibrium temperature of biomass carbon aerogel increases at the first light power density. Biomass carbon aerogel pyrolyzed at 600℃ has the highest equilibrium temperature, about 79.8℃, while the heating rate of oily sludge is relatively slow, only reaching 38.4℃ within 3 minutes. Therefore, it is believed that biomass carbon aerogel prepared at 600℃ pyrolysis temperature has the best photothermal conversion capability.

[0092] 4. Determination of the adsorption capacity of biomass carbon aerogel

[0093] The adsorption capacity of BCA600 obtained in Example 1 was determined, and the results are as follows: Figure 5 As shown.

[0094] observe Figure 5 It can be seen that the biomass carbon aerogel prepared by pyrolysis at 600℃ exhibits an adsorption capacity for a variety of organic solvents that is several times its own weight, among which the adsorption capacity for crude oil reaches 4.279 g / g, demonstrating the potential of biomass carbon aerogel for the treatment of large-scale oily sludge.

[0095] Based on the performance test results of biomass carbon aerogel in performance tests 1-4, the applicant determined that it can be used as a dehydration material in oil-containing systems. Therefore, the application characteristics of biomass carbon aerogel were explored as follows:

[0096] 5. Application of biomass carbon aerogel in dewatering oily sludge

[0097] The results of Examples 5-7 and Comparative Example 1 are recorded in Figure 6 In the middle. Observation Figure 6 It can be seen that after 3 hours of light exposure, the weight loss of oily sludge / biomass carbon aerogel is always higher than that of oily sludge exposed to light alone. Furthermore, as the proportion of biomass carbon aerogel increases, the total weight loss after drying also increases. When the mixing ratio of oily sludge / biomass carbon aerogel reaches 10:2.0, the weight loss reaches 2.46g, equivalent to an evaporation area of ​​488.85gm². -2 The weight loss reached 2.27 times that of the original oily sludge, which is close to the total water content of the oily sludge (about 2.67g). This is due to the synergistic effect of biomass carbon aerogel on the demulsification and heating of the crude oil water-in-oil emulsion and the evaporation promoted by the solid components of the oily sludge.

[0098] 6. Application of activated carbon in dewatering oily sludge

[0099] The results of Example 5 and Comparative Example 2 are recorded in Figure 7 In the middle. Observation Figure 7 It can be seen that, compared with biomass carbon aerogel, the weight loss of oily sludge mixed with activated carbon under light is only 293.39 gm.-2 It is lower than the 488.85 gm of biomass carbon aerogel. -2 This is mainly because although activated carbon also has a certain photothermal conversion capability, its pore structure is mainly composed of micropores and mesopores, lacking large pore channels that can effectively adsorb micron-sized oil droplets. As a result, it is difficult for the crude oil water-in-oil emulsion to break down when mixed with activated carbon, and the water is still covered by the crude oil, which is not conducive to heat transfer and evaporation.

[0100] 7. Application of biomass carbon aerogel in water-in-oil emulsion dehydration

[0101] The results of comparative examples 3–6 are recorded in Figure 8 In the middle. Observation Figure 8 It is known that the more biomass carbon aerogel there is, the more favorable it is for water evaporation. When the water-in-oil emulsion and biomass carbon aerogel are mixed at a mass ratio of 10:4.08, the maximum mass change can reach 594.9 gm. -2 However, when the biomass aerogel is insufficient to completely adsorb the emulsion, water evaporation is very slow. Light irradiation of the biomass aerogel causes a temperature increase, further reducing viscosity. Therefore, the crude oil flows and covers the surface of the biomass aerogel, inhibiting the photothermal conversion effect. However, excessive biomass aerogel can block the emulsion within its channels, preventing overflow. This demulsification and oil-water separation occur within the biomass aerogel, mitigating the inhibitory effect of the flowing emulsion covering it. Furthermore, the excess biomass aerogel can exert its inherent photothermal conversion effect, promoting the evaporation process.

[0102] 8. Application of biomass carbon aerogel in dehydration of water-soil mixtures

[0103] The results of comparative examples 7–10 are recorded in Figure 9 In the middle. Observation Figure 9 It can be seen that the soil-water system changes mass more rapidly, reaching near equilibrium within 90 minutes, while the oil-in-water emulsion system takes up to 180 minutes to complete the process. Furthermore, even with insufficient biomass carbon aerogel addition, the maximum weight loss of 80.37% was achieved, significantly higher than that of the oil-in-water emulsion system. This also indicates the negative role of the oil phase during evaporation, while the soil may have promoted heat transfer, allowing the heat generated by the biomass carbon aerogel to be transferred to the bottom more quickly, thus accelerating the overall evaporation rate.

[0104] 9. The role of soil solid components in the dewatering of oily sludge

[0105] The results of Example 5 and Comparative Example 4 are recorded in Figure 10 In the middle. Observation Figure 10It can be seen that when the mass ratio of oily sludge or water-in-oil emulsion to BCA600 is basically the same, the weight loss of oily sludge under light is higher than that of water-in-oil emulsion. This further confirms the promoting effect of soil solid components in the evaporation process of oily sludge.

[0106] Summarizing the results of "Performance Tests 5-6," we can see that biomass char aerogel exhibits a certain advantage in dehydrating water-in-oil emulsions. This is because the porous adsorption structure of biomass char aerogel can trap a large amount of oil, and under light irradiation, this trapped oil can conversely increase the heating rate, significantly accelerating the water evaporation rate. More importantly, even with oily sludge in more complex environments, biomass char aerogel still demonstrates rapid dehydration. However, when the carbon-based material is changed to activated carbon, the lack of the large pores that biomass char aerogel possesses for effectively adsorbing micron-sized oil droplets and oil-water emulsions makes it difficult for the oil-in-oil emulsion to break down when mixed with activated carbon. The water remains encapsulated by the crude oil, hindering heat transfer and evaporation.

[0107] Furthermore, the results in "Performance Tests 7-9" visually illustrate the mechanism of action of biomass carbon aerogel on oily sludge. Oily sludge is actually a mixture of water-in-oil emulsion and soil / mineral. The results in "7. Application of Biomass Carbon Aerogel in Dehydration of Water-in-Oil Emulsions" demonstrate that aerogel photothermal dehydration is not simply evaporation; for water-in-oil emulsions, oil-water separation is essential for efficient evaporation. Efficient separation and evaporation can only be achieved when the biomass carbon aerogel blending amount can saturate the emulsion. The results in "8. Application of Biomass Carbon Aerogel in Dehydration of Water-Soil Mixtures" illustrate the role of soil / mineral. Compared to oily sludge composed of water-in-oil emulsion and soil / mineral, wet soil composed solely of water and soil / mineral has a very high evaporation rate. This indicates that the evaporation of oily sludge is not simply a matter of photothermal water evaporation; the problem of water-in-oil emulsions must be addressed. Moreover, adding soil / mineral to the water-in-oil emulsion base resulted in an increased evaporation rate, further demonstrating that soil / mineral actually promotes evaporation. The results in "9. The role of soil solid components in dehydration of oily sludge" indicate that the addition of soil promotes evaporation.

Claims

1. A method for pre-treatment of oily sludge for dewatering, characterized in that, include: The light power density of the biomass carbon aerogel mixed with oily sludge is 100 Mw / cm². 2 The dewatering of oily sludge is completed in 2-4 hours. The mass ratio of the oily sludge to the biomass carbon aerogel is 10:2; The preparation method of the biomass carbon aerogel includes: dispersing biomass in water, freezing and drying to obtain biomass aerogel; Subsequently, under a nitrogen atmosphere, the biomass carbon aerogel was obtained by pyrolysis at 300~600℃ for 50~70 min; the biomass was carboxymethyl cellulose and defatted cotton, and the mass ratio of the carboxymethyl cellulose, the mass of the defatted cotton and the volume of water was 7.5 g:1 g:100 mL. Biomass carbon aerogel possesses a hierarchical porous structure, which facilitates oil adsorption and oil-water separation. Furthermore, the overall black color of the biomass carbon aerogel indicates excellent light absorption, and its graphitized structure converts light energy into heat energy, generating heat under illumination. This accelerates the overall heating rate under light, causing the oil-water emulsion in the oily sludge to be adsorbed into the biomass carbon aerogel. After the biomass carbon aerogel completely adsorbs the oil-water emulsion from the oily sludge, the internal pores are filled with the emulsion, improving the thermal conductivity of the biomass carbon aerogel. This allows for continued heating under light, accelerating the evaporation of water from the oily sludge, thereby achieving low-carbon dehydration treatment of the oily sludge. This method utilizes the material properties of biomass carbon aerogel in conjunction with the characteristics of oily sludge.

2. The method as described in claim 1, characterized in that, The freezing temperature is -75 to -85°C, and the freezing time is 5 to 7 hours.

3. The method as described in claim 1, characterized in that, The drying method is vacuum drying, the drying temperature is 20~25℃, and the drying time is 48~72 h.

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