Method for preparing pore-channel-adjustable carbon molecular sieve through binary activation of heavy oil and application of pore-channel-adjustable carbon molecular sieve

Abstract

The invention discloses a method for preparing a pore-adjustable carbon molecular sieve through binary activation of heavy oil and application, and belongs to the technical field of biomass resource utilization and water treatment. The method comprises the following steps: (1) mixing heavy oil and a binary activator, and standing to form a carbon-containing precursor mixture; wherein the binary activating agent is calcium citrate and potassium oxalate; (2) performing pyrolysis activation on the carbon-containing precursor mixture in an inert atmosphere, and cooling after the pyrolysis is completed to obtain biological activated carbon; and (3) washing and drying the biological activated carbon to obtain the carbon molecular sieve. The method has the advantages of greenness, environmental protection, convenient process and efficient production. The prepared carbon molecular sieve is developed in pore structure, concentrated in pore size distribution and good in adsorption characteristic, has a wide application prospect in water treatment, and realizes comprehensive treatment of resource utilization of two pollutants, namely waste heavy oil and dye wastewater.

Description

Technical Field

[0001] The present invention relates to the technical fields of biomass resource utilization and water treatment, and a method for preparing a carbon molecular sieve with adjustable pore channels by dual activation of heavy oil and its application. Background Art

[0002] With the accelerating progress of the global industrialization process, the problem of industrial wastewater treatment has become a major challenge threatening the sustainable development of the ecological environment. Statistical data shows that the annual discharge of industrial wastewater that has not been treated up to standard globally has exceeded hundreds of billions of cubic meters, and among them, dye wastewater accounting for up to 80% is directly discharged into natural water bodies, with an annual total discharge reaching hundreds of millions of tons and still showing a continuous upward trend. This kind of industrial wastewater containing complex organic macromolecular dyes, especially typical pollutants such as methyl orange, congo red, and methylene blue (MB), has posed a serious threat to the water environment system. MB has received key attention due to its special physical and chemical properties. This substance not only has significant environmental persistence and bioaccumulation, but can also cause multiple toxic effects on organisms through the food chain. Research has confirmed that MB exposure can trigger oxidative stress responses in aquatic organisms, leading to DNA damage and abnormal reproductive functions. More alarmingly, MB pollution has spread from the water environment to the soil system, forming a complex pollution pattern, posing potential risks to farmland ecological safety and groundwater quality. Based on this, the effective purification treatment of dye wastewater has attracted wide attention.

[0003] In the existing water treatment technology field, porous activated carbon materials are widely used in the fields of wastewater treatment and purification due to their low cost, high specific surface area, large pore volume, renewable nature, and excellent adsorption characteristics. The most commonly used activators in the traditional process for producing activated carbon materials are KOH and K 2 CO 3 .

[0004] For example, the literature (Wang K, Xu S. Preparation of High Specific Surface Area Activated Carbon from Petroleum Coke by KOH Activation in a Rotary Kiln[J]. Processes, 2024, 12(2). DOI: 10.3390 / pr12020241.) developed a new method for preparing activated carbon (AC) from petroleum coke (PC) by KOH activation using a rotary kiln equipped with steel balls. It uses molten KOH to cause the reaction mixture to expand at a lower activation temperature, while molten K 2O causes particle agglomeration at higher temperatures. Steel balls alleviate swelling and agglomeration by promoting heat and mass transfer in the reactor, and promote the pore structure development of AC. CO is introduced during the activation process 2 , by converting K 2 O into thermosetting K 2 CO 3 to further reduce particle agglomeration and form more mesopores in AC. In addition, the literature (Wu C, Liu J, Wang Y, et al. A clean method for controlling pore structure development in potassium activation systems to improve CO 2 adsorption properties of biochar[J]. Science of the Total Environment, 2024, 954. DOI:10.1016 / j.scitotenv.2024.176429.) adopted a KCl-assisted activation process and used three activators (KOH, KHCO 3 , K 2 CO 3 ) to prepare CO 2 adsorbents with high specific surface area and excellent adsorption properties. However, these methods are corrosive, which not only causes serious corrosion to equipment, but also poses a risk of heavy metal pollution. From the microscopic structure analysis of carbon materials, the activated carbon produced by these methods has a well-developed pore structure and a large pore volume, but its pore size structure is relatively dispersed, and most pores cannot effectively play their roles, thus limiting the overall performance of activated carbon. Based on this, developing a binary activation technology based on the concept of green chemistry, constructing a hierarchical pore system through a synergistic physical-chemical activation mechanism, and realizing precise control of pore size distribution have become the key research directions to break through the performance bottleneck of carbon molecular sieve materials, which has important engineering application value for promoting the development of environmental functional material science.

[0005] Heavy oil is a non-water-soluble liquid, mainly generated by the deposition of macromolecules during processes such as biomass pyrolysis or gasification. Heavy oil has the characteristics of complex composition, high carbon content, low ash content, high viscosity, good thermoplasticity, and easy polymerizability. These characteristics make it difficult to directly purify and upgrade it to high-value-added chemicals and liquid fuels through purification methods such as distillation and extraction. If a new processing and utilization process is developed to convert waste heavy oil into a carbon-based molecular sieve adsorbent material with a highly concentrated pore structure through thermochemical means, and use it as a high-performance adsorbent material to remove pollutants through water treatment, it can not only achieve waste recycling, but also effectively solve the problem of the difficulty of directly using heavy oil, providing a new way for environmental pollution control. SUMMARY OF THE INVENTION

[0006] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a method for preparing a carbon molecular sieve with adjustable pore channels by binary activation of heavy oil with convenient and efficient process is provided, which includes the following steps: (1) Mix heavy oil and a binary activator, and let it stand to form a carbon precursor mixture; wherein, the binary activator is calcium citrate and potassium oxalate; (2) Pyrolytically activate the carbon precursor mixture under an inert atmosphere, and after pyrolysis is completed, cool it to obtain bioactive carbon; (3) Wash and dry the bioactive carbon to obtain a carbon molecular sieve.

[0007] Preferably, in the step (1), by mass ratio, the ratio of heavy oil, calcium citrate, and potassium oxalate is 2:1:0.25 - 2.

[0008] The component ratio of heavy oil and the binary activator should be controlled within the preferred range of the present invention. If the ratio of calcium citrate is too low, it will weaken the orderly arrangement process of carbon microcrystals, which is not conducive to the formation of carbon with a high degree of graphitization, and will weaken the reaction of subsequent K + or CO 2 molecules with the carbon skeleton. If the ratio of calcium citrate is too high, its pyrolysis will generate a CaO templating agent, and more site-occupying pore-forming reactions will occur, and the mesoporous structure of the produced activated carbon will increase significantly, which is not conducive to the production of an activated carbon adsorbent material with a highly concentrated pore size distribution. If the overall dosage of the binary activator continues to increase, it is not conducive to environmental / economic sustainability. Based on this, a binary activator with a suitable mass mixing ratio can benefit from the synergistic effect between the binary activators, thereby forming an activated carbon with a highly concentrated pore size distribution and molecular sieve characteristics.

[0009] Preferably, in the step (1), the mixing time is 5 - 30 min, and the standing time is 5 - 30 min.

[0010] Letting it stand after mixing helps to ensure uniform mixing of each component.

[0011] Preferably, in the step (2), the initial temperature of pyrolysis is room temperature, the heating rate is 5 - 10 °C / min, the pyrolysis temperature is 600 - 800 °C, and the holding time is 10 - 60 min.

[0012] Preferably, in the step (2), the gas type of the inert atmosphere includes at least one of nitrogen, argon, and helium; the gas flow rate is 50 - 100 mL / min.

[0013] Those skilled in the art can select a suitable pyrolysis device based on actual conditions, such as a pyrolysis furnace. General pyrolysis furnaces include fluidized bed reactors, fixed bed reactors, etc. Among them, the fixed bed reactor has certain advantages compared with the fluidized bed reactor, that is, the activator can fully contact with heavy oil and react.

[0014] Preferably, in the step (3), the biological activated carbon is washed with dilute acid and water, and then dried at 100-150 °C to obtain a carbon molecular sieve.

[0015] More preferably, the type of the dilute acid includes at least one of hydrochloric acid, nitric acid, and sulfuric acid; the concentration of the dilute acid is 0.1-1 mol / L.

[0016] In the second aspect of the present invention, there is provided a carbon molecular sieve with a well-developed pore structure and a concentrated pore size distribution, which is prepared by the method provided in the first aspect of the present invention.

[0017] In the third aspect of the present invention, there is provided an application of the carbon molecular sieve in the second aspect of the present invention as an adsorbent material in water treatment.

[0018] Preferably, the carbon molecular sieve is used as an adsorbent material to remove dye pollutants in wastewater.

[0019] Based on the above technical solutions, the design concept and principle of the present invention are as follows: The present invention proposes a method for preparing an activated carbon material by subjecting heavy components in heavy oil to a polymerization reaction by simple thermochemical conversion (pyrolysis activation). In the process, by virtue of the characteristics of complex composition, high carbon content, low ash content, good thermoplasticity, and easy polymerization of heavy oil, the disadvantages of high viscosity, poor fluidity, and difficult direct utilization are made up, so that waste heavy oil can be efficiently converted and used for purifying water treatment; at the same time, the synergistic coupling effect between the binary green activators is fully exerted to promote the efficient progress of the activation reaction. The biomass-derived heavy oil used has a wide source, high carbon content, high viscosity, and is in a semi-liquid state, which can perfectly dissolve the binary organic salt activator, so that the macromolecular components in the heavy oil can fully contact with the activator molecules, which is beneficial to the efficient action of the activator and promotes the efficient progress of the activation reaction.

[0020] In the traditional method for the selection of "activator" in the process of thermochemical conversion, inorganic salts such as KOH and K 2 CO 3 etc. have strong self-corrosion and are not green and environmentally friendly enough. The present invention selects relatively mild organic salts such as calcium citrate and potassium oxalate as activators, which are not only green and environmentally friendly, but also the prepared carbon material has the characteristics of a molecular sieve.

[0021] The pyrolysis activation process of heavy oil is relatively complex. The calcium citrate activator generates metal oxides (CaO) and releases CO during the pyrolysis process. 2 gas. Among them, CaO is designed as a template agent to guide the orderly arrangement of carbon microcrystals and form carbon materials with a high degree of graphitization. The overflow of CO 2 is used to form microporous carbon. In addition, during the activation process, the calcium citrate activator can dissociate calcium ions (Ca 2+ in the solution. Due to its high charge density, Ca 2+ can promote intermolecular cross-linking, connect the macromolecular components in heavy oil to form a macromolecular framework bridge, and facilitate the polymerization reaction of macromolecules.

[0022] The potassium oxalate activator can form potassium oxides and release CO during the pyrolysis process. 2 Among them, potassium oxides can undergo a gasification reaction with carbon-containing small molecules in heavy components at high temperatures (C + K 2 O → CO↑+ 2K), and the generated CO 2 can react with the carbon skeleton by etching (CO 2 + C → 2CO), which helps to form microporous carbon. In addition, during the activation process, the potassium oxalate activator can dissociate potassium ions (K + ) in the solution. K + can promote the generation of free radicals and accelerate the chain cleavage reaction. The presence of K + is beneficial to the occurrence of the chain cleavage reaction to form more aromatic radicals, and this process helps Ca 2+ to capture the free radicals generated by cleavage. The synergistic effect between the two promotes the polycondensation reaction to form polycyclic aromatic hydrocarbons. In addition, the synergistic effect between binary activators helps to dynamically adjust the pore structure.

[0023] Therefore, this method is conducive to the formation of carbon molecular sieves with uniform pore structures and concentrated pore size distributions, greatly improving the quality of carbon products. Applying the carbon molecular sieve to efficient water treatment can synergistically purify dye wastewater while effectively treating waste heavy oil, achieving the comprehensive disposal of the resource utilization of two pollutants, waste heavy oil and dye wastewater.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides a method for preparing carbon molecular sieves with adjustable pore channels by binary activation of heavy oil, which has the advantages of environmental friendliness, convenient process, and high production efficiency.

[0025] The present invention provides a carbon molecular sieve with a well-developed pore structure and a concentrated pore size distribution, having good adsorption characteristics.

[0026] The present invention provides an application of carbon molecular sieve as an adsorbent material in water treatment, which has broad application prospects. Description of the Drawings

[0027] Figure 1 It is a flow chart of the method for preparing a carbon molecular sieve with adjustable pore channels by dual activation of heavy oil and its application; Figure 2 It is a comparative micrograph of the carbon molecular sieve adsorbent prepared in the examples; among them, (a)-(f) correspond to the observation results of HBAC-0 to HBAC-5 in sequence; Figure 3 It is an X-ray diffraction comparison chart of the carbon molecular sieve adsorbent prepared in the examples; Figure 4 It is the physical parameter characterization result of the carbon molecular sieve adsorbent prepared in the examples; among them, (a) is the nitrogen adsorption and desorption curve of each carbon molecular sieve adsorbent, (b) is the total pore specific surface area of each carbon molecular sieve adsorbent, (c) is the micropore specific surface area of each carbon molecular sieve adsorbent, and (d)-(i) correspond to the pore size distribution curve comparison charts of HBAC-0 to HBAC-5 in sequence; Figure 5 It is a comparison chart of the adsorption rate and removal rate of the adsorbent samples for adsorbing MB under different experimental conditions in the application of the present invention; Figure 6 It is a comparison chart of the influence of the adsorbent samples on the adsorption of MB under different experimental conditions in the application of the present invention; among them, (a) is the relationship diagram between the initial concentration of MB and the adsorption capacity, and (b) is the relationship diagram between the adsorption time and the adsorption capacity. Detailed Embodiments

[0028] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. For the experimental methods without specific conditions in the following examples, they are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0029] In the following examples: The commercial source of the commercial activated carbon is Huajing Activated Carbon Co., Ltd., and the product type is coconut shell water purification carbon; The biomass heavy oil is obtained by pyrolyzing pine wood powder in an inert atmosphere (nitrogen atmosphere, purity 99.999%) at a temperature of 500 °C for 1 h and then collecting the viscous liquid phase at the lower layer of the bio-oil by condensation.

[0030] Example 1 The method for preparing a carbon molecular sieve with adjustable pore channels by dual activation of heavy oil is as follows: (1) A heavy component obtained by pyrolysis of pine wood was selected as a heavy oil sample, and the heavy oil, calcium citrate and potassium oxalate activator were weighed in a mass ratio of 2:1:0.125, and the mixture was fully mixed and allowed to stand to form a carbon-containing precursor mixture; (2) The mixed carbon precursor was transferred to a fixed bed reactor for pyrolysis, nitrogen was introduced as the reaction atmosphere, the nitrogen flow rate was 100 mL / min, the heating rate was 10 °C / min, the temperature was raised to 800 °C, and the temperature was kept for 60 min; after the pyrolysis was completed, the mixture was cooled to obtain biological activated carbon; (3) After collecting the biological activated carbon, it was washed several times with dilute acid and deionized water until it was neutral, and then dried in a forced air drying oven to obtain a carbon molecular sieve adsorbent, which was recorded as HBAC-1. Example 2 Method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil, such as Figure 1 As shown, the steps are as follows: (1) A heavy component obtained by pyrolysis of pine wood was selected as a heavy oil sample, and the heavy oil, calcium citrate and potassium oxalate activator were weighed in a mass ratio of 2:1:0.25, and the mixture was fully mixed and allowed to stand to form a carbon-containing precursor mixture; (2) The mixed carbon precursor was transferred to a fixed bed reactor for pyrolysis, nitrogen was introduced as the reaction atmosphere, the nitrogen flow rate was 100 mL / min, the heating rate was 10 °C / min, the temperature was raised to 800 °C, and the temperature was kept for 60 min; after the pyrolysis was completed, the mixture was cooled to obtain biological activated carbon; (3) After collecting the biological activated carbon, it was washed several times with dilute acid and deionized water until it became neutral, and then dried in a forced air drying oven to obtain a carbon molecular sieve adsorbent, which was recorded as HBAC-2.

[0031] Example 3 A method for preparing a pore-adjustable carbon molecular sieve by binary activation of heavy oil, the steps are as follows: (1) A heavy component obtained by pyrolysis of pine wood was selected as a heavy oil sample, and the heavy oil, calcium citrate and potassium oxalate activator were weighed in a mass ratio of 2:1:0.5, and the mixture was fully mixed and allowed to stand to form a carbon-containing precursor mixture; (2) The mixed carbon precursor was transferred to a fixed bed reactor for pyrolysis, nitrogen was introduced as the reaction atmosphere, the nitrogen flow rate was 100 mL / min, the heating rate was 10 °C / min, the temperature was raised to 800 °C, and the temperature was kept for 60 min; after the pyrolysis was completed, the mixture was cooled to obtain biological activated carbon; (3) After collecting the biological activated carbon, it was washed several times with dilute acid and deionized water until it was neutral, and then dried in a forced air drying oven to obtain a carbon molecular sieve adsorbent, which was recorded as HBAC-3.

[0032] Example 4 A method for preparing a pore-adjustable carbon molecular sieve by binary activation of heavy oil, the steps are as follows: (1) A heavy component obtained by pyrolysis of pine wood is selected as a heavy oil sample, and the heavy oil, calcium citrate and potassium oxalate activator are weighed respectively in a mass ratio of 2:1:1, and are fully mixed, and then allowed to stand to form a carbon-containing precursor mixture; (2) The mixed carbon precursor was transferred to a fixed bed reactor for pyrolysis, nitrogen was introduced as the reaction atmosphere, the nitrogen flow rate was 100 mL / min, the heating rate was 10 °C / min, the temperature was raised to 800 °C, and the temperature was kept for 60 min; after the pyrolysis was completed, the mixture was cooled to obtain biological activated carbon; (3) After the biological activated carbon is collected, it is washed multiple times with dilute acid and deionized water until it becomes neutral, and then dried in a forced air drying oven to obtain a carbon molecular sieve adsorbent, which is recorded as HBAC-4.

[0033] Example 5 A method for preparing a pore-adjustable carbon molecular sieve by binary activation of heavy oil, the steps are as follows: (1) A heavy component obtained by pyrolysis of pine wood is selected as a heavy oil sample, and the heavy oil, calcium citrate and potassium oxalate activator are weighed respectively in a mass ratio of 2:1:2, and the mixture is fully mixed, and then allowed to stand to form a carbon-containing precursor mixture; (2) The mixed carbon precursor was transferred to a fixed bed reactor for pyrolysis, nitrogen was introduced as the reaction atmosphere, the nitrogen flow rate was 100 mL / min, the heating rate was 10 °C / min, the temperature was raised to 800 °C, and the temperature was kept for 60 min; after the pyrolysis was completed, the mixture was cooled to obtain biological activated carbon; (3) After the biological activated carbon is collected, it is washed multiple times with dilute acid and deionized water until it becomes neutral, and then dried in a forced air drying oven to obtain a carbon molecular sieve adsorbent, which is recorded as HBAC-5.

[0034] Comparative Example 1 In this comparative example, commercial activated carbon (CAC) was selected as the blank control adsorbent.

[0035] Comparative Example 2 The preparation steps of the mono-activated heavy oil-based activated carbon of this comparative example are as follows: (1) A heavy component obtained by pyrolysis of pine wood is selected as a heavy oil sample, and the heavy oil and potassium oxalate activator are weighed in a mass ratio of 1:1 and fully mixed, and then allowed to stand to form a carbon-containing precursor mixture; (2) Transfer the mixed carbon precursor to a fixed-bed reactor for pyrolysis. Introduce nitrogen as the reaction atmosphere with a flow rate of 100 mL / min. The heating rate is 10 °C / min. Heat up to 800 °C and hold for 60 min. After pyrolysis is completed, cool it to obtain bioactive carbon. (3) After collecting the bioactive carbon, wash it multiple times with dilute acid and deionized water until neutral, and then dry it in a forced-air drying oven to obtain a single-activated heavy-oil-based activated carbon, denoted as HBAC-0.

[0036] Test Example 1 Use a cold-field emission scanning electron microscope to observe the microscopic morphology of the carbon molecular sieve adsorbent. The results are as Figure 2 shown. The microscopic morphology of HBAC-0 is shown in Figure 2 (a). HBAC-0 is in the shape of irregular particles, and there are certain pore structures on its surface. The microscopic morphologies of HBAC-1 to HBAC-5 are shown in Figure 2 (b)-(f), all of which are irregular particle structures. In addition, with the increase in the dosage of potassium oxalate activator, the pore structures on their surfaces become more developed.

[0037] Use an X-ray diffractometer to test the crystal structure of the carbon molecular sieve adsorbent. The results are as Figure 3 shown. It can be seen from the figure that the crystal structure of HBAC-0 shows the presence of two typical carbon crystal planes (002) and (100). The same two typical carbon crystal planes (002) and (100) can also be observed in HBAC-1 to HBAC-5.

[0038] Use a fully automatic specific surface area and pore structure analyzer to analyze the pore structure of the carbon molecular sieve adsorbent. The results are as Figure 4 shown. The nitrogen adsorption-desorption and pore size distribution curves of the HBAC-0 adsorbent are shown in Figure 4 (a) and Figure 4 (d). The specific surface area of its total pores and micropores are 1147 m 2 / g and 1050 m 2 / g, as shown in Figure 4 (b) and Figure 4 (c). The nitrogen adsorption-desorption and pore size distribution curves of the carbon molecular sieve adsorbent (HBAC-1 to HBAC-5) are shown in Figure 4 (a) and Figure 4 (e)-(i). It can be clearly found that their pore sizes are mainly concentrated around 0.8 nm, showing obvious molecular sieve structural characteristics. The specific surface area of the carbon molecular sieve is shown in Figure 4 (b) and Figure 4 (c). Among them, the specific surface area of the total pores and micropores of HBAC-5 reaches 1857 m 2 / g and 1559 m 2 / g.

[0039] Test Example 2 This test example tested the adsorption performance of the above various samples in practical applications. The steps are as follows: 1) Weigh 50 mg of the sample and add it to a conical flask containing 50 mL of MB with a specific concentration (25 - 1000 mg / L), and transfer it to a shaker to adsorb for a certain time (0 - 1440 min) at room temperature; 2) After the adsorption process ends, perform solid-liquid separation on the solution to obtain a liquid phase without solids; 3) Transfer the pure liquid phase to a cuvette and use an ultraviolet spectrophotometer to measure its absorbance. The UV wavelength is set to 664 nm.

[0040] Figure 5 It reflects the equilibrium adsorption capacity of each adsorbent sample (CAC, HBAC-0 to HBAC-5) and the removal rate of MB when the initial concentration of MB is 1000 mg / L. It can be seen from the figure that the equilibrium adsorption capacity of CAC can reach 428.9 mg / g, and the removal rate of MB is 42.9%. The equilibrium adsorption capacity of the HBAC-0 adsorbent obtained by activating heavy oil with a single activator is only 356.7 mg / g, and the removal rate of MB is 35.7%. The adsorption capacity of the carbon molecular sieve adsorbents (HBAC-1 to HBAC-5) obtained by activating heavy oil with a binary activator for MB has increased significantly. Among them, the adsorption capacity and removal rate of HBAC-5 reached the maximum, which were 819.3 mg / g and 81.9% respectively, 1.91 times that of commercial activated carbon and 2.30 times that of the single-activated HBAC-0 adsorbent.

[0041] At different initial concentrations of MB, the adsorption capacities of each adsorbent sample for MB are shown in Figure 6 (a). It can be seen that as the initial concentration of MB increases, the adsorption capacities of each adsorbent for MB also show a gradually increasing trend. When the initial concentration of MB reaches 800 mg / L, the adsorption capacity of HBAC-5 reaches 724.5 mg / g, and the adsorption capacity is 1.70 times that of CAC (425.8 mg / g) and 1.97 times that of HBAC-0 (368.3 mg / g) respectively. At different adsorption times, the adsorption capacities of each adsorbent sample for MB are shown in Figure 6(b), the results show that as the adsorption time increases, the adsorption capacity of each adsorbent for MB also shows a gradually increasing trend. Among them, the adsorption capacities of HBAC-3, HBAC-4, and HBAC-5 adsorbents after 24 h of adsorption are 674.6 mg / g, 676.3 mg / g, and 724.5 mg / g, respectively, and their adsorption capacities are much higher than those of CAC (425.9 mg / g) and HBAC-0 (356.7 mg / g).

[0042] Compared with the prior art, in a method for preparing a carbon molecular sieve with adjustable pore channels by binary green activation of heavy oil according to the present invention, by virtue of the characteristics of complex composition, high carbon content, low ash content, good thermoplasticity, and easy polymerization of heavy oil, the disadvantages of high viscosity, poor fluidity, and difficulty in direct utilization are compensated, so that waste heavy oil can be efficiently converted and used for purifying water treatment; at the same time, the synergistic coupling effect between the binary green activators is fully exerted to promote the efficient progress of the activation reaction. The biomass-derived heavy oil used in the present invention has a wide source, a high carbon content, a high viscosity, and is in a semi-liquid state, and can perfectly dissolve the binary organic salt activator, so that the macromolecular components in the heavy oil can be in full contact with the activator molecules, which is beneficial to the efficient exertion of the activator and promotes the efficient progress of the activation reaction, and is conducive to the formation of a carbon molecular sieve with a uniform pore structure and a concentrated pore size distribution, greatly improving the quality of the carbon product. Subsequently, the carbon molecular sieve is applied to efficient water treatment. While effectively treating waste heavy oil, it synergistically purifies and treats dye wastewater, realizing the resource utilization of two pollutants, namely waste heavy oil and dye wastewater.

[0043] In summary, the present invention innovatively uses a two-component green activator to be proportionally compounded with waste heavy oil, and through a programmed temperature-controlled pyrolysis activation coupling post-treatment process, a carbon-based molecular sieve material with a directional pore structure is successfully prepared. The obtained material has a significant three-dimensional hierarchical pore system, and the pore size distribution is highly concentrated compared with the carbon materials prepared by traditional methods. The material exhibits excellent adsorption performance for the typical organic pollutant methylene blue in water, with a maximum adsorption capacity of 819 mg / g, a 91% increase compared with commercially available activated carbon, and excellent adsorption kinetic characteristics. This technology has the advantages of simple preparation process, environmental friendliness, low cost, etc. It not only realizes the resource utilization of agricultural and forestry waste, but also provides an innovative solution for the development of high-efficiency water treatment adsorption materials, with significant environmental and economic benefits.

[0044] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A method for preparing pore-adjustable carbon molecular sieves by binary activation of heavy oil, characterized in that: The steps include: (1) mixing heavy oil and a binary activator, and allowing to stand to form a carbon-containing precursor mixture; wherein the binary activator is calcium citrate and potassium oxalate; (2) The carbon-containing precursor mixture is pyrolyzed and activated under an inert atmosphere, and after the pyrolysis is completed, it is cooled to obtain bioactivated carbon; (3) The biological activated carbon is washed and dried to obtain a carbon molecular sieve.

2. The method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil according to claim 1, characterized in that: In the step (1), the ratio of heavy oil, calcium citrate and potassium oxalate is 2:1:0.25-2 by mass.

3. The method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil according to claim 1, characterized in that: In the step (1), the mixing time is 5-30 min, and the standing time is 5-30 min.

4. The method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil according to claim 1, characterized in that: In the step (2), the initial temperature of the pyrolysis is room temperature, the heating rate is 5-10°C / min, the pyrolysis temperature is 600-800°C, and the holding time is 10-60 min.

5. The method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil according to claim 1, characterized in that: In the step (2), the gas type of the inert atmosphere includes at least one of nitrogen, argon, and helium; and the gas flow rate is 50-100 mL / min.

6. The method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil according to claim 1, characterized in that: In the step (3), the biological activated carbon is washed with dilute acid and water, and then dried at 100-150° C. to obtain a carbon molecular sieve.

7. The method for preparing pore-adjustable carbon molecular sieve by binary activation of heavy oil according to claim 6, characterized in that: The type of the dilute acid includes at least one of hydrochloric acid, nitric acid and sulfuric acid; the concentration of the dilute acid is 0.1-1 mol / L.

8. A carbon molecular sieve, characterized in that: The method is prepared by the method according to any one of claims 1 to 7.

9. Use of the carbon molecular sieve as claimed in claim 8 as an adsorption material in water treatment.

10. The use according to claim 9, characterized in that: The carbon molecular sieve is used as an adsorption material to remove dye pollutants in wastewater.

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