Method for resource utilization of organic waste
By combining catalytic wet oxidation and selective adsorption, and using biochar-prepared superstructured carbon-based catalysts and modified resin-based carbon spheres, the problem of difficult oxidation and selective adsorption of small molecule carboxylic acids has been solved, realizing the efficient resource utilization of organic waste and improving economic and environmental benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANXI JINHUAN KEYUAN ENVIRONMENTAL RESOURCES TECH CO LTD
- Filing Date
- 2023-07-10
- Publication Date
- 2026-07-31
AI Technical Summary
In existing technologies, small molecule carboxylic acids are difficult to completely oxidize, and traditional adsorbents have weak selectivity for small molecule carboxylic acids, resulting in unsatisfactory resource utilization of organic waste.
A superstructured carbon-based catalyst prepared from biochar was used for catalytic wet oxidation, and then combined with modified resin-based carbon spheres for selective adsorption and alkali washing to achieve the separation and enrichment of small molecule carboxylic acids.
It improves the selectivity and recovery rate of small molecule carboxylic acids, realizes the efficient resource utilization of organic waste, and has good economic and environmental benefits.
Abstract
Description
Technical Field
[0001] This application relates to a method for the resource utilization of organic waste, belonging to the field of organic waste resource utilization. Background Technology
[0002] The resource utilization of organic waste can avoid secondary environmental pollution caused by traditional treatment methods such as landfill and incineration, and can also generate resources and promote material recycling. The resource utilization of organic waste includes material recycling, material conversion, and energy conversion.
[0003] Traditional landfill and incineration remain the main methods for treating organic solid waste. Fermentation and composting methods are gaining more attention, but problems such as long treatment cycles, large land areas, and unsatisfactory results urgently need to be addressed.
[0004] Small molecule carboxylic acids are common intermediates in catalytic wet oxidation processes, characterized by their difficulty in achieving complete oxidation and their poor biochemical properties. Some small molecule carboxylic acids, such as acetic acid, are widely considered the "end" of wet oxidation processes. However, small molecule carboxylic acids possess resource potential, significant material recovery value, and can be applied in industrial production. They can be used as additives in pharmaceuticals and food, and as external carbon sources for wastewater treatment.
[0005] Therefore, the recovery of small-molecule carboxylic acid products is an important issue in the application of wet oxidation technology to the resource utilization of organic waste. Adsorbents are widely used in the field of organic waste recovery, achieving material recovery through adsorption and desorption steps. However, commonly used adsorbents, such as coconut shell charcoal and wood charcoal, have weak selectivity and poor adsorption effect for small-molecule carboxylic acids.
[0006] Based on the above research and published inventions, this invention attempts to combine catalytic wet oxidation and selective adsorption to form a resource utilization treatment method for organic wastewater and organic solid waste. Summary of the Invention
[0007] This application uses biochar as a raw material to grow carbon nanotubes through catalytic pyrolysis to obtain a superstructured carbon-based catalyst, which is then applied to catalytic wet oxidation to replace existing catalytic wet oxidation catalysts. This effectively degrades organic waste, improves the selectivity of the catalytic wet oxidation process for small molecule carboxylic acids, and realizes the material transformation of organic waste.
[0008] Meanwhile, this application uses waste resin as raw material to obtain modified resin carbon through loading and modification, thereby achieving selective adsorption of small molecule carboxylic acids. By combining selective adsorption with catalytic wet oxidation, the separation and enrichment of small molecule carboxylic acids are achieved, and finally, the recovery of small molecule carboxylic acid salts is achieved through alkaline washing.
[0009] According to one aspect of this application, a method for the resource utilization of organic waste is provided, comprising the following steps:
[0010] (1) Catalytic wet oxidation degradation of macromolecular organic matter into small molecule carboxylic acids;
[0011] (2) Selective adsorption separation and enrichment of small molecule carboxylic acids;
[0012] (3) Inorganic alkaline solution is used to wash and recover small molecule carboxylate salts to regenerate the adsorbent.
[0013] The specific method includes the following steps:
[0014] (1) Catalytic wet oxidation: Under oxygen-containing conditions, organic waste is contacted with catalyst A to undergo an oxidation reaction, yielding a mixture of small molecule carboxylic acids;
[0015] (2) Selective adsorption: The small molecule carboxylic acid mixture obtained in step (1) is cooled to room temperature and contacted with adsorbent B for adsorption to obtain an adsorbent saturated with adsorption.
[0016] (3) Alkaline washing: The saturated adsorbent obtained in step (2) is washed with alkali to obtain a saturated carboxylate solution, and adsorbent B is regenerated;
[0017] Catalyst A is a carbon-based superstructure catalyst, and adsorbent B is a modified resin-based carbon ball.
[0018] In step (1) catalytic wet oxidation, the material containing organic waste is charged with high-purity oxygen at a reaction temperature of 150-300℃ and a reaction pressure of 2.0-10.0MPa, which is 1.2-4 times the theoretical oxygen demand of the material. Powdered catalyst of 1-10g / L is added, and the mixture is subjected to intermittent reaction in a high-pressure reactor for 2 hours to obtain a mixture containing small molecule carboxylic acid.
[0019] In this application, the degradation rate of macromolecular organic matter is improved by controlling the reaction conditions and the amount of oxygen supplied.
[0020] Optionally, the material containing organic waste is selected from one of organic wastewater, organic solid waste pulping, or organic wastewater-solid waste mixture pulping.
[0021] Optionally, the COD range of the material containing organic waste is 5000 to 100000 mg / L.
[0022] Optionally, the oxidation reaction temperature is selected from any value or a range between any two of 150℃, 200℃, 225℃, 245℃, 265℃, 270℃, 280℃, and 300℃.
[0023] Optionally, the oxidation reaction pressure is selected from any value or a range between any two of 2.0 MPa, 4.0 MPa, 5.0 MPa, 6.0 MPa, 8.0 MPa, and 10.0 MPa.
[0024] Optionally, the oxygen supply amount is selected from any value among 1.2 times, 2 times, 3 times, and 4 times the theoretical oxygen demand of the material.
[0025] Optionally, the catalyst dosage is selected from any value of 1 g / L, 5 g / L, 10 g / L, or a range between any two values.
[0026] In this application, the selectivity for small molecule carboxylic acids is improved during catalytic wet oxidation by selecting a superstructured carbon-based catalyst.
[0027] The superstructured carbon-based catalyst comprises a biochar carbon-based substrate, carbon nanotubes, and metal element I and metal element II;
[0028] The carbon nanotubes are multi-walled nitrogen-doped carbon nanotubes.
[0029] The metal element I is distributed on the outside of the carbon nanotube and / or embedded in the carbon nanotube wall;
[0030] The metallic element II is distributed inside the carbon nanotubes;
[0031] The metal element I is selected from Fe and Ce, and the metal element II is Ni.
[0032] Optionally, the metal element I accounts for 0.2 to 4.3 wt% of the carbon-based superstructure catalyst;
[0033] Metal element II accounts for 2 to 33 wt% of the carbon-based superstructure catalyst.
[0034] Specifically, the catalyst has a CNT / PC superstructure with a large number of coral-like carbon nanotubes grown on the surface of a PC carbon substrate.
[0035] Specifically, the metal element I is distributed in a single-element state on the outside of the carbon nanotube, and some of the metal element I is embedded in the carbon nanotube wall in a particulate form.
[0036] Specifically, the metal element II is distributed in a reduced state inside the carbon nanotube.
[0037] Optionally, the preparation method of catalyst A includes the following steps:
[0038] S001. Add biochar to a salt solution containing metal element I and metal element II, impregnate with equal volume, and vacuum dry to obtain the impregnated sample.
[0039] S002. The impregnated sample is mixed with a nitrogen source and calcined under a nitrogen atmosphere to obtain a calcined sample;
[0040] S003. The calcined sample is subjected to acid treatment to obtain catalyst A.
[0041] Optionally, in step S001, the biochar is selected from at least one of potato residue biochar, corn stalk biochar, and sewage sludge biochar.
[0042] Optionally, the metal element I is selected from Fe and / or Ce, and the metal element II is Ni;
[0043] The salt solution is selected from at least one of nitrates, sulfates, and hydrochlorides.
[0044] Optionally, in S001, the mass ratio of biochar, metal element I, and metal element II is 1-5:0.01-0.05:0.1-0.5.
[0045] Optionally, in S001, the conditions for the equal-volume impregnation are: ultrasonic impregnation for 15 to 30 minutes.
[0046] Optionally, in S001, the temperature of the vacuum drying is 60–80°C.
[0047] Optionally, in S002, the nitrogen source is selected from any one of dicyandiamide, melamine, and urea.
[0048] Optionally, in S002, the mass ratio of the impregnated sample to the nitrogen source is 1:0.5 to 2.
[0049] Optionally, in S002, the calcination includes a first-stage calcination and a second-stage calcination;
[0050] The temperature of the first-stage roasting is 400-500℃, and the roasting time is 2-3 hours.
[0051] The temperature of the second-stage roasting is 600-800℃, and the roasting time is 2-3 hours.
[0052] Optionally, the acid in the acid treatment described in S003 is an acid solution with a concentration of 2 to 5 mol / L; the acid is selected from any one of nitric acid, sulfuric acid, and hydrochloric acid.
[0053] Optionally, the acid treatment temperature in S003 is 30–80°C, and the treatment time is 2–6 hours.
[0054] In step (2) selective adsorption, the mixture containing small molecule carboxylic acids obtained in step (1) is cooled to an adsorption temperature of 15–35 °C, and a continuous adsorption reaction is carried out in a fixed adsorption bed with countercurrent circulation injection. The volume hourly space velocity (VHSV) of the adsorption reaction is 0.5–5 h⁻¹.-1 Thus, an adsorbent with saturated adsorption capacity is obtained.
[0055] In this application, the adsorption efficiency of small molecule carboxylic acids is improved by controlling the adsorption temperature and volume hourly space velocity.
[0056] Optionally, the adsorption temperature is selected from any value of 15℃, 20℃, 25℃, 30℃, 35℃ or a range between any two values.
[0057] Optionally, the volume hourly space velocity (VHSV) for the adsorption reaction is selected from 0.5 h⁻¹. -1 1.0h -1 2.0h -1 4.0h -1 5.0h -1 Any value in the range or any two values between them.
[0058] In this application, adsorbent B is selected as modified resin-based carbon spheres to improve the adsorption selectivity for small molecule carboxylic acids.
[0059] The modified resin-based carbon spheres are metal-supported nitrogen-doped modified carbon spheres.
[0060] The modified resin-based carbon spheres include micropores;
[0061] Optionally, the specific surface area of the resin-based modified carbon spheres is greater than 700 m². 2 / g; average pore volume greater than 0.4mL / g.
[0062] The load metal element is selected from at least one of Fe, Ce, and Ni.
[0063] Optionally, the mass of the loaded metal element is 0.1 to 10 wt.% of the mass of the carbon spheres.
[0064] Optionally, the preparation method of the adsorbent B includes the following steps:
[0065] a. Oxidize the waste resin balls in an oxygen-containing atmosphere to obtain oxidized resin;
[0066] b. Add the oxidized resin to a salt solution containing metal III, impregnate with an equal volume, and dry to obtain the precursor;
[0067] c. Mix the precursor and nitrogen source, and perform carbonization treatment in a nitrogen atmosphere to obtain modified resin-based carbon spheres.
[0068] Optionally, in step a, the pore volume of the waste resin balls is 0.2–1.0 mL / g; the specific surface area is 50–500 m² / g. 2 / g.
[0069] Optionally, in step a, the oxidation treatment is an oxidation reaction, and the conditions for the oxidation treatment are: reaction at 250-300°C for 5-10 hours in an oxygen-containing atmosphere.
[0070] Optionally, in step a, the oxygen-containing atmosphere is either an air atmosphere or a high-purity oxygen atmosphere.
[0071] Optionally, in step b, the salt solution is selected from an ethanol solution containing any one of nitrate, sulfate, or hydrochloride.
[0072] Optionally, in step b, the conditions for equal volume are: stirring at room temperature for 6 to 12 hours, with a stirring speed of 400 to 600 rpm / min.
[0073] Optionally, in step b, the drying is carried out in an oven at a temperature of 60–80°C.
[0074] Optionally, in step c, the nitrogen source is selected from any one of dicyandiamide, melamine, and urea.
[0075] Optionally, in step c, the mass ratio of the nitrogen source itself to the precursor metal element is 0.5 to 1.5:1.
[0076] Optionally, in step c, the carbonization treatment is gradient carbonization, with the carbonization temperature increasing gradually within the range of 800 to 1200°C, and the temperature gradient being 50 to 100°C; the carbonization time within each temperature gradient is 0.5 to 5 hours.
[0077] In step (3) alkaline washing, the adsorbent-saturated fixed bed obtained in step (2) is subjected to continuous alkaline washing using inorganic alkaline solution. The alkaline solution is injected in a co-current circulation manner. The alkaline washing conditions are as follows: inorganic alkaline solution is circulated in a co-current circulation manner, the alkaline washing temperature is 35-85℃, and the volume hourly space velocity (VHSV) during the alkaline washing process is 1-10 h⁻¹. -1 .
[0078] Optionally, the inorganic alkaline solution is selected from at least one of potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, and sodium phosphate.
[0079] Optionally, the concentration of the inorganic alkaline solution is 1% to 20%.
[0080] After alkali washing, a saturated carboxylate solution is obtained, and after further alkali washing, a regenerated adsorbent is obtained.
[0081] The regenerated adsorbent can be reused in step (3) after being washed with water and dried.
[0082] This application successfully achieves the material transformation and recovery of organic waste through a combination of catalytic wet oxidation and selective adsorption technologies. It converts large organic molecules in organic wastewater and solid waste into small-molecule carboxylic acids and achieves efficient recovery of carboxylate salts. Compared to traditional biochemical treatment technologies, advanced oxidation technologies (AOPs) exhibit stronger degradation capabilities and faster treatment effects in treating organic pollutants. Wet oxidation (WAO) is a widely used advanced oxidation technology for treating high-concentration, toxic, harmful, and recalcitrant wastewater and sludge, and is an effective method for achieving material transformation. Based on this, the introduction of a wet oxidation catalyst forms a catalytic wet oxidation (CWAO) system, which can effectively improve the degradation efficiency of large-molecule organic matter. Simultaneously, by modifying the catalyst, the selectivity of the catalyst for the products can be improved.
[0083] The beneficial effects that this application can produce include:
[0084] 1) The resource recovery method combining catalytic wet oxidation and selective adsorption provided in this application can simultaneously realize the resource recovery treatment of organic wastewater and organic solid waste, and has good economic benefits.
[0085] 2) The method and process provided in this application have few steps and can realize material recycling within the process, which has good prospects for industrialization.
[0086] 3) The method provided in this application can transform organic waste into carboxylate with high added value, realize the material transformation and recycling of organic waste, and has high environmental and economic value.
[0087] 4) The catalytic wet oxidation catalyst and selective adsorbent provided in this application both use renewable resources as raw materials, effectively utilizing waste and having good environmental benefits. Detailed Implementation
[0088] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0089] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0090] The preparation method of biochar in the example is as follows: dried potato residue, corn stalk residue, and domestic sludge residue are crushed, mixed evenly with an equal mass of KOH powder, and calcined at 500°C for 120 min under a nitrogen atmosphere to obtain the biochar.
[0091] In the examples, the specific surface area and pore volume of the samples were analyzed by N2 adsorption-desorption test, and the analytical instrument was QuantaChrome's Autosorb iQ Station 2.
[0092] In this embodiment, the chemical oxygen demand (COD) was quantitatively determined using a Lianhua Technology COD measuring instrument.
[0093] In the examples, the selectivity of carboxylic acid in catalytic wet oxidation was quantitatively determined by high performance liquid chromatography, and the concentration of small molecule carboxylic acid C (carboxylic acid) was obtained by external standard method.
[0094] In the examples, the selectivity of carboxylic acids was calculated using the following formula:
[0095] Carboxylic acid selectivity = (Theoretical COD of C(carboxylic acid)) / (Measured COD of the carboxylic acid-containing mixture) * 100%
[0096] In the examples, the carboxylic acid recovery rate was calculated using the following formula:
[0097] Carboxylic acid recovery rate = carboxylic acid concentration in alkaline washing recovery solution / C(carboxylic acid) * 100%.
[0098] Example 1
[0099] 1.1 Catalyst Preparation: 10.0 g of potato residue carbon was added to an equal volume of a mixed solution of ferric chloride and nickel chloride, with a mass ratio of potato residue, iron, and nickel of 1:0.05:0.5. After stirring evenly, the mixture was sonicated for 30 min, vacuum dried at 80 °C overnight. The dried sample was mixed with dicyandiamide at a mass ratio of 1:1, and calcined at 500 °C for 3 h under a nitrogen atmosphere, then further heated to 800 °C and calcined for another 3 h. The calcined sample was mixed with 5 mol / L hydrochloric acid, treated at 80 °C for 6 h, and dried to obtain the superstructured carbon-based catalyst-1.
[0100] 1.2 Adsorbent Preparation: Weigh 100g of waste resin balls and react them at 300℃ for 10h in air. Add the oxidized resin to an equal volume of ferric chloride solution at a mass ratio of 1:0.1, stir at 600rpm / min at room temperature for 12h, and dry in an oven at 80℃ overnight. Mix the precursor with dicyandiamide at a mass ratio of 1:1, and perform gradient carbonization under a nitrogen atmosphere. The carbonization temperature increases gradually within the range of 800-1200℃, with a temperature gradient of 100℃. The carbonization time within each temperature gradient is 5h. After washing with water multiple times and drying, modified resin-based carbon balls-1 are obtained.
[0101] 1.3 Methods for the resource utilization of organic waste:
[0102] 1) Catalytic wet oxidation: Take 200 mL of wastewater after semi-coke pretreatment into a high-pressure reactor, add 2 g of superstructured carbon-based catalyst-1, introduce oxygen, and introduce pure oxygen at twice the theoretical oxygen requirement. React at 300℃ and 10 MPa for 2 h, cool to room temperature, and filter to obtain a mixture containing small molecule carboxylic acids.
[0103] 2) Selective adsorption: 50 mL of modified resin-based carbon spheres-1 were packed into a fixed-bed reactor and compacted. The adsorption was carried out at an adsorption temperature of 25 °C and a space velocity of 0.5 h⁻¹ for continuous adsorption. -1 Adsorption was carried out under the following conditions: the above-mentioned mixture containing small molecule carboxylic acids was injected countercurrently, and water samples were removed every 6 hours until the COD and carboxylic acid quantitative values of the water sample did not change, thus obtaining the adsorbent saturated.
[0104] 3) Alkaline washing: Use 50 mL of 10% sodium hydroxide as the alkaline solution for alkaline washing, at an alkaline washing temperature of 85℃, and a volume hourly space velocity (VHSV) of 1 h⁻¹. -1 Under the specified conditions, alkaline washing was performed, with the alkaline solution circulating in the co-current flow for sample injection. The evaluation results are shown in Tables 1 and 2 below.
[0105] Example 2
[0106] Take 200 mL of sludge sample from a wastewater treatment plant in Dalian, and evaluate it using the same method as in Example 1 above, using the superstructured carbon-based catalyst-1 and modified resin-based carbon spheres-1 prepared in Example 1 above.
[0107] Example 3
[0108] Take 200 mL of a sample after mixing and pulping straw residue and domestic sewage, and evaluate it using the same method as in Example 1 above, using the superstructured carbon-based catalyst-1 and modified resin-based carbon sphere-1 prepared in Example 1 above.
[0109] Comparative Example 1
[0110] Take 200 mL of wastewater after semi-coke pretreatment, use a precious metal catalyst (KD-PrecMet-2023, Dalian Keduo Environment) as the catalytic wet oxidation catalyst, use coconut shell charcoal as the adsorbent, and evaluate it using the same method as in Example 1 above.
[0111] Table 1
[0112] Example 1 86.5 96.1 Example 2 73.4 95.8 Example 3 80.1 97.6 Comparative Example 1 42.3 76.5
[0113] Table 1 shows the effect of the reaction substrate on the effectiveness of the method described in this application. Substrate treatment has a certain impact on the selectivity of carboxylic acid in catalytic wet oxidation; the selectivity for carboxylic acid in organic wastewater treatment reaches as high as 86.5%. Non-wastewater samples have a certain negative impact on the selectivity of carboxylic acid in catalytic wet oxidation treatment, but the selectivity of both samples is still greater than 70% and 80%, respectively. Substrate treatment has no effect on the carboxylic acid recovery rate after adsorption-alkali washing; the carboxylic acid recovery rate of this method is greater than 95%. As shown in Comparative Example 1, the catalyst and adsorbent prepared using the method provided in this application can effectively improve the carboxylic acid selectivity and recovery rate of this method compared to the use of traditional precious metal catalysts and coconut shell carbon adsorbents. The selectivity can be increased by at least 30%, and the recovery rate can be increased by at least 20%. The results indicate that the method described in this application has good resource recovery effects on all types of organic waste mentioned in this application, namely organic wastewater, organic solid waste, and mixtures of organic wastewater and solid waste.
[0114] Example 4
[0115] Using the semi-coke wastewater sample and superstructured carbon-based catalyst-1 and modified resin-based carbon spheres-1 used in Example 1 above, catalytic wet oxidation was carried out at a reaction temperature of 280°C and a reaction pressure of 8.0 MPa, and the results were evaluated under the same conditions as other methods.
[0116] Example 5
[0117] Using the semi-coke wastewater sample and superstructured carbon-based catalyst-1 and modified resin-based carbon spheres-1 used in Example 1 above, catalytic wet oxidation was carried out at a reaction temperature of 265°C and a reaction pressure of 4.0 MPa, and the results were evaluated under the same conditions as other methods.
[0118] Example 6
[0119] Using the semi-coke wastewater sample and superstructured carbon-based catalyst-1 and modified resin-based carbon sphere-1 used in Example 1 above, catalytic wet oxidation was carried out at a reaction temperature of 225°C and a reaction pressure of 2.0 MPa, and the results were evaluated under the same conditions as other methods.
[0120] Table 2
[0121] Example 1 -300℃ -10MPa 86.5 96.1 Example 4 -280℃ -8.0MPa 86.2 96.0 Example 5 -265℃ -4.0MPa 89.4 97.2 Example 6 -225℃ -2.0MPa 82.3 95.4
[0122] Table 2 shows the effect of catalytic wet oxidation reaction conditions on the effectiveness of the method described in this application. The reaction temperature and pressure of catalytic wet oxidation affect the selectivity of carboxylic acids. With increasing reaction temperature and pressure, the selectivity initially increases and then decreases, possibly due to the increased proportion of organic pollutants completely oxidized to CO2 after 265℃. The water quality of the mixture containing small-molecule carboxylic acids after catalytic wet oxidation has little effect on subsequent selective adsorption and alkaline washing results. The results indicate that the method described in this application can effectively improve the selectivity and recovery rate of carboxylic acids by selecting the superstructured carbon-based catalyst and resin-based carbon spheres prepared by the method described in this application; this application can achieve improved carboxylic acid selectivity by controlling the catalytic wet oxidation reaction conditions.
[0123] Example 7
[0124] Using the semi-coke wastewater sample and superstructured carbon-based catalyst-1 and modified resin-based carbon spheres-1 used in Example 1 above, at an adsorption temperature of 25°C and a space velocity of 1.0 h⁻¹, the adsorption was carried out. -1 Selective adsorption was performed under the specified conditions, while other methods were evaluated using the conditions described in Example 5.
[0125] Example 8
[0126] Using the semi-coke wastewater sample and superstructured carbon-based catalyst-1 and modified resin-based carbon spheres-1 used in Example 1 above, at an adsorption temperature of 15°C and a space velocity of 1.0 h⁻¹, the adsorption was carried out. -1 Selective adsorption was performed under the specified conditions, while other methods were evaluated using the conditions described in Example 5.
[0127] Example 9
[0128] Using the semi-coke wastewater sample and superstructured carbon-based catalyst-1 and modified resin-based carbon spheres-1 used in Example 1 above, at an adsorption temperature of 35°C and a space velocity of 1.0 h⁻¹, the adsorption was carried out. -1 Selective adsorption was performed under the specified conditions, while other methods were evaluated using the conditions described in Example 5.
[0129] Table 3
[0130] <![CDATA[Example 5 - 25°C - 0.5 h -1 > 89.4 97.2 <![CDATA[Example 7 - 25°C - 1.0 h -1 > 89.4 91.8 <![CDATA[Example 8 - 15°C - 1.0 h -1 > 89.4 95.6 <![CDATA[Example 9 - 35°C - 1.0 h -1 > 89.4 88.4
[0131] Table 3 shows the effect of selective adsorption conditions on the effectiveness of the method described in this application. Both adsorption temperature and space velocity have a significant impact on the carboxylic acid recovery rate. Lower space velocities, i.e., longer contact time with the adsorption bed, result in higher carboxylic acid recovery rates. Higher temperatures are less conducive to adsorption. The results indicate that the method described in this application can improve the carboxylic acid recovery rate by controlling selective adsorption conditions.
[0132] Example 10
[0133] Using the semi-coke wastewater sample and the superstructured carbon-based catalyst-1 described in Example 1, and the modified resin-based carbon spheres regenerated by alkaline washing in Example 5, other methods were evaluated using the conditions in Example 5. Using the regenerated modified resin-based carbon spheres, the final carboxylic acid recovery rate reached over 90% according to the method described in this application. The results demonstrate that the modified resin-based carbon spheres prepared according to the preparation method described in this application can be well regenerated by the alkaline washing step in the method described in this application and can be reused, achieving material recycling within the method.
[0134] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for the resource utilization of organic waste, characterized in that, Includes the following steps: (1) Catalytic wet oxidation: Under oxygen-containing conditions, organic waste is contacted with catalyst A to undergo an oxidation reaction, resulting in a mixture of small molecule carboxylic acids; (2) Selective adsorption: The mixture of small molecule carboxylic acids obtained in step (1) is cooled to room temperature and then contacted with adsorbent B to adsorb, thus obtaining an adsorbent saturated with adsorption. (3) Alkali washing: The saturated adsorbent obtained in step (2) is washed with alkali to obtain a saturated carboxylate solution, and adsorbent B is regenerated; The catalyst A is a carbon-based superstructure catalyst with a CNT / PC superstructure, which includes a biochar substrate, multi-walled nitrogen-doped carbon nanotubes grown on the substrate surface, metal element I distributed outside the carbon nanotubes and / or embedded in the tube walls, and metal element II distributed inside the carbon nanotubes. The adsorbent B is a modified resin-based carbon ball with a microporous structure, which is a metal-supported nitrogen-doped modified carbon ball. Furthermore, the regenerated adsorbent B obtained after alkaline washing in step (3) is reused in step (2). The carbon nanotubes are coral-shaped; The metal element I is selected from Fe and / or Ce, and the metal element II is Ni; The metal element I accounts for 0.2~4.3 wt% of the carbon-based superstructure catalyst; The metal element II accounts for 2-33 wt% of the carbon-based superstructure catalyst; The metal supported on the modified resin-based carbon spheres is selected from at least one of Fe, Ce, and Ni.
2. The method according to claim 1, characterized in that, The preparation method of catalyst A includes the following steps: S001. Add biochar to a salt solution containing metal element I and metal element II, impregnate with equal volume, and vacuum dry to obtain the impregnated sample. S002. The impregnated sample is mixed with a nitrogen source and calcined under a nitrogen atmosphere to obtain a calcined sample; S003. The calcined sample is subjected to acid treatment to obtain catalyst A; In step S001, the biochar is selected from at least one of potato residue biochar, corn stalk biochar, and domestic sewage sludge biochar. The salt solution is selected from at least one of nitrates, sulfates, and hydrochlorides; The mass ratio of biochar, metal element I, and metal element II is 1~5:0.01~0.05:0.1~0.5; The conditions for the equal-volume impregnation are: ultrasonic impregnation for 15-30 minutes; In step S002, the nitrogen source is selected from at least one of dicyandiamide, melamine, and urea; The mass ratio of the impregnated sample to the nitrogen source is 1:0.5~2; The roasting includes a first-stage roasting and a second-stage roasting; The temperature of the first stage of roasting is 400~500℃, and the roasting time of the first stage is 2~3h; The temperature of the second-stage roasting is 600~800℃, and the roasting time of the second stage is 2~3h; In step S003, the acid used for acid treatment is selected from at least one of nitric acid, sulfuric acid, and hydrochloric acid; The concentration of the acid is 2~5 mol / L; The acid treatment conditions are: temperature 30~80℃, time 2~6h.
3. The method according to claim 1, characterized in that, The modified resin-based carbon spheres are metal-supported nitrogen-doped modified carbon spheres; The modified resin-based carbon spheres have a specific surface area of 700~1000 m². 2 / g; the average pore volume of the modified resin-based carbon spheres is 0.4~0.6mL / g; The loaded metal element accounts for 0.1 to 10 wt% of the modified resin-based carbon spheres.
4. The method according to claim 1, characterized in that, The preparation method of the adsorbent B includes the following steps: a. Oxidize the resin balls to obtain oxidized resin; b. Add the oxidized resin to a salt solution containing metal III and impregnate it with an equal volume to obtain the precursor; c. Mix the precursor with a nitrogen source and perform carbonization treatment to obtain the adsorbent B; In step a, the resin balls are selected from waste resin; In step a, the oxidation treatment conditions are: reaction at 200~300℃ for 5~10h in an oxygen-containing atmosphere; In step b, the metal III in the salt solution containing metal III is selected from at least one of Fe, Ce, and Ni; The salt solution is selected from at least one of nitrates, sulfates, and hydrochlorides; The time for the equal-volume impregnation is 4~10 hours; In step c, the nitrogen source is selected from at least one of dicyandiamide, melamine, and urea; The mass ratio of the precursor to the nitrogen source is 1:0.5~2, and the precursor is based on the mass of metallic III element. The carbonization treatment conditions are: reaction at 400~1200℃ for 10~18h under a nitrogen atmosphere.
5. The method according to claim 1, characterized in that, The organic waste includes organic wastewater and / or organic solid waste; The organic wastewater is at least one of domestic sewage and industrial wastewater with a COD range of 5000~100000 mg / L; The organic solid waste is at least one of agricultural waste, industrial organic waste residue, and municipal organic waste.
6. The method according to claim 1, characterized in that, In step (1), the oxidation reaction is a batch reaction, and the oxidation reaction is carried out in a high-pressure reactor; The conditions for the oxidation reaction are: temperature 150~300℃; pressure 2.0~10.0MPa; The oxygen demand for the oxidation reaction is 1.2 to 4 times the theoretical oxygen demand; The mass ratio of catalyst A to oxygen source is 1~10 g / L.
7. The method according to claim 1, characterized in that, The adsorption described in step (2) is a continuous reaction. The adsorption conditions are: countercurrent circulation of the carboxylic acid mixture, adsorption temperature of 15~35℃, and volume hourly space velocity of 0.5~5h for the continuous adsorption reaction. -1 .
8. The method according to claim 1, characterized in that, In step (3), the alkaline washing is carried out in a fixed bed; The alkaline washing conditions are as follows: inorganic alkaline solution is circulated in a co-current manner for alkaline washing; the alkaline washing temperature is 35~85℃; and the volume hourly space velocity (VHSV) during the alkaline washing process is 1~10 h⁻¹. -1 ; The inorganic alkaline solution is selected from at least one of potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, and sodium phosphate.