Preparation method of carbon-based catalyst using organic pollutants recovered from organic wastewater as raw material and application thereof

Abstract

The present application belongs to the technical field of solid waste disposal and persulfate activation, and discloses a preparation method of a carbon-based catalyst using organic pollutants recovered from organic wastewater as raw materials and application thereof, wherein the preparation method is to use solid-state organic polymerization products recovered from organic wastewater as raw materials, mix the solid-state organic polymerization products with a modifier after water washing, pyrolyze in an inert atmosphere to obtain a carbon-based catalyst; the modifier is one or several of a pore-forming agent or a heteroatom doping agent; wherein the heteroatom doping agent is used to introduce metal atoms or non-metal atoms other than C, H and O. 2 The present application directly mixes the solid-state organic polymerization products recovered from wastewater with a modifier, pyrolyzes at 600-1000 DEG C to obtain a carbon-based catalyst with a high specific surface area (841-1321 m 2 / g), which exhibits excellent performance when applied to adsorb pollutants and activate persulfate to remove organic pollutants in water, and can be regenerated and recycled.

Description

Technical Field

[0001] This invention belongs to the field of solid waste disposal and persulfate activation technology, and more specifically, relates to a method for preparing a carbon-based catalyst using organic pollutants recovered from organic wastewater as raw materials and its application. Background Technology

[0002] Carbon-based catalysts for the activation of persulfate to remove pollutants from water have been extensively studied and applied. Common carbon-based catalysts often use graphene oxide (GO), carbon nanotubes (CNTs), and biochar (BC) as the carbon matrix. However, GO and CNTs are relatively expensive. For example, the catalyst O-CNTs-2 (Yang W, Jiang Z, Hu X, et al. Enhanced activation of persulfate by nitric acid / annealing modified multi-walled carbon nanotubes via non-radical process[J]. Chemosphere) uses CNTs costing 600 yuan / kg. BC is often prepared from biomass such as wood, nutshells, or organic sludge. Although the raw material cost is lower, it requires complex pretreatment (e.g., mechanical crushing, ultrasonic treatment, alkaline washing or acid washing) to obtain the carbon matrix. These pretreatment processes not only increase the cost of the catalyst but also pose a risk of secondary pollution to the environment. Obtaining inexpensive raw materials with simple pretreatment will help promote the practical application of carbon-based catalysts.

[0003] As described in Chinese patent applications CN202010873326.0, CN201810997000.1, CN201710262422.X, and CN202011157768.1, dissolved organic pollutants in organic wastewater can be converted into solid organic particles through polymerization reactions and then directly separated and recovered from the wastewater. However, these recovered solid organic polymer particles require proper treatment and disposal to avoid triggering new environmental risks. Promoting the resource utilization of solid organic polymer products can not only avoid secondary pollution but also transform pollutants into high-value products, forming a closed loop of "pollution reduction - resource regeneration - economic gain," which is an effective path for the green upgrading of water treatment technology. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a method for preparing a carbon-based catalyst using organic pollutants recovered from organic wastewater as raw materials, and its application. The resulting carbon-based catalyst possesses the ability to adsorb and remove pollutants from water and to activate persulfate oxidation to remove pollutants. It can solve the problem of resource utilization of solid organic polymer products generated during organic wastewater treatment, and provides a low-cost catalyst with a large specific surface area (841–1321 m²). 2 / g), a carbon-based catalyst with good environmental adaptability.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a carbon-based catalyst using organic pollutants recovered from organic wastewater as raw materials is provided. The method involves using solid organic polymer products recovered from organic wastewater as raw materials, washing them with water, mixing them with a modifier, and then pyrolyzing them in an inert atmosphere to obtain a carbon-based catalyst.

[0006] The pyrolysis temperature is 600–1000℃;

[0007] The modifier is one or more of a pore-forming agent or a heteroatom doping agent; wherein the heteroatom doping agent is used to introduce metal atoms or non-metal atoms other than C, H, and O.

[0008] As a further preferred embodiment of the present invention, the solid organic polymer product recovered from the organic wastewater is a solid organic polymer recovered by filtration from an organic wastewater system in which a polymerization chemical reaction has occurred.

[0009] Preferably, the organic wastewater system in which the polymerization chemical reaction has occurred is specifically an activated persulfate-treated organic wastewater system or an activated hydrogen peroxide-treated organic wastewater system.

[0010] As a further preferred embodiment of the present invention, the mixing is performed by mixing the raw materials after washing and drying with the modifier at a mass ratio of 1:(0.5 to 1.5).

[0011] As a further preferred embodiment of the present invention, the mixing is to mix and grind the raw materials after washing and drying with the modifier to obtain a mixture, or to mix the raw materials after washing with water with the modifier in deionized water and then sequentially perform ultrasonication, water bath stirring, drying, and grinding to obtain a mixture.

[0012] As a further preferred embodiment of the present invention, the heteroatom doping reagent can simultaneously introduce metal atoms and non-metal atoms. In this case, the modifier is a mixture of reagents containing metal atoms and reagents containing non-metal atoms.

[0013] As a further preferred embodiment of the present invention, the pore-forming agent is at least one selected from nitrates, carbonates, bicarbonates, sulfates, chlorides, moderately strong acids, strong acids, strong bases, and strong oxidizing agents; wherein the moderately strong acid is at least one selected from phosphoric acid, boric acid, carbonic acid, oxalic acid, citric acid, sulfurous acid, hydrofluoric acid, and hydrosulfuric acid; the strong acid is at least one selected from hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid; the strong base is at least one selected from potassium hydroxide and sodium hydroxide; and the strong oxidizing agent is at least one selected from potassium permanganate, potassium dichromate, and sodium hypochlorite.

[0014] The heteroatom doping reagent introduces transition metal atoms and nitrogen, boron, and sulfur atoms.

[0015] As a further preferred embodiment of the present invention, the heteroatom doping reagent used to introduce transition metal atoms is at least one of transition metal salts and transition metal complexes, and the heteroatom doping reagent used to introduce non-metal atoms is any one of nitrogen-containing reagents, boron-containing reagents, and sulfur-containing reagents.

[0016] According to another aspect of the present invention, the present invention provides the application of a carbon-based catalyst prepared by the above method to adsorb and remove organic pollutants in water and / or activate persulfate oxidation to remove organic pollutants in water and / or activate peroxide oxidation to remove organic pollutants in water, wherein the persulfate includes one or more of permonosulfate (PMS) and perdisulfate (PDS); the peroxide is preferably H2O2.

[0017] As a further preferred embodiment of the present invention, after the removal of organic pollutants from the water is completed, the carbon-based catalyst in the system can be reused for adsorption removal of organic pollutants from the water and / or activated persulfate oxidation removal of organic pollutants from the water and / or activated peroxide oxidation removal of organic pollutants from the water after filtration and water washing recovery.

[0018] As a further preferred embodiment of the present invention, after the removal of organic pollutants from the water is completed, the carbon-based catalyst in the system can be reused for adsorption removal of organic pollutants from the water and / or activated persulfate oxidation removal of organic pollutants from the water and / or activated peroxide oxidation removal of organic pollutants from the water after filtration, water washing, drying, and pyrolysis regeneration.

[0019] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following results.

[0020] Beneficial effects:

[0021] (1) The raw material for the carbon-based catalyst prepared in this invention comes from solid organic polymer products generated during the treatment of organic wastewater. This helps to solve the problem of treatment and disposal of recovered solid organic polymer products and realize the resource-based reuse of organic wastewater. During the treatment of organic wastewater systems using polymerization chemical reactions, dissolved organic pollutants in the wastewater will undergo polymerization chemical reactions to produce solid organic products with large molecular weights that precipitate in the form of solid particles and can be directly filtered and separated from the water. Therefore, solid organic polymer products can be recovered from organic wastewater. This invention uses solid organic polymer products recovered from organic wastewater as raw materials to prepare a low-cost, high-specific-surface-area, and environmentally adaptable carbon-based catalyst.

[0022] (2) The advantages of the carbon-based catalyst prepared by this invention are that, compared with GO and CNT, the solid organic polymer used in this invention is a recycled waste material, which is cost-free. Compared with BC, it does not require a complicated raw material pretreatment process (such as mechanical crushing, ultrasonic treatment, alkaline washing or acid washing, etc.), which reduces costs and the risk of secondary pollution to the environment.

[0023] (3) The carbon-based catalyst prepared in this invention has good adsorption performance and the ability to activate persulfate to remove pollutants, and its specific surface area can reach up to 1321 m². 2 / g, even better than existing literature reports [for example: the nitrogen-doped porous carbon-based catalyst prepared by chemical deposition using pyridine as a raw material and sodium nitrate as a pore-forming agent, with an optimized specific surface area of ​​1224 m² / g, reported in the literature, has an optimized specific surface area of ​​1224 m² / g]. 2 / g(J.Wang,Z.Yang,Y.Li,X.Fan,F.Zhang,G.Zhang,etal.Synthesis of porous nitrogen doped carbon cage from carbide for catalytic oxidation.Carbon,2020,163:43-55). Furthermore, the carbon-based catalyst prepared in this invention exhibits strong adaptability. Experiments in the embodiments of this invention have demonstrated its excellent adsorption performance and ability to remove pollutants from activated persulfate under complex water background matrices (such as secondary effluent from MBR processes). Attached Figure Description

[0024] Figure 1 The nitrogen adsorption-desorption curves of the carbon-based catalysts modified with sodium nitrate at different mass ratios obtained in Examples 1-3 of this invention are shown.

[0025] Figure 2 The effects of carbon-based catalysts modified with sodium nitrate at different mass ratios obtained in Examples 1-3 of this invention on the activation of PMS for phenol treatment.

[0026] Figure 3 The effects of carbon-based catalysts prepared at different pyrolysis temperatures using sodium nitrate as a modifier on the activation of PMS for phenol treatment in Examples 2, 4, 5 and 6 of this invention are shown.

[0027] Figure 4 In Example 2 of this invention, the sodium nitrate-modified carbon-based catalyst P-RPL800-1 was used to activate PDS (denoted as "PDS / P-RPL800-1") and PMS (denoted as "PMS / P-RPL800-1") to treat phenol. The control group ① is the effect of PDS alone treating phenol (denoted as "PDS"), and the control group ② is the effect of PMS alone treating phenol (denoted as "PMS").

[0028] Figure 5 This invention describes the effect of using sodium nitrate-modified carbon-based catalyst P-RPL800-1 to activate PMS for phenol treatment in Example 2 of this invention under the background of MBR secondary effluent (denoted as "MBR") and pure water (denoted as "control group").

[0029] Figure 6 This invention's Example 7 illustrates the effects of using the iron-nitrogen co-modified carbon-based catalyst P-RPL-Fe1N1 to activate PMS (corresponding to solid illustrations) and using PMS alone (corresponding to hollow illustrations) to treat different pollutants.

[0030] Figures 2-6 In the diagram, with Time = 0 min as the boundary, the part to the left is based on adsorption, and the part to the right is based on activated persulfate oxidation. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] In general, the present invention provides a method for preparing a carbon-based catalyst using solid organic polymer products recovered from organic wastewater as raw materials, which may include the following steps:

[0033] Step 1: Separate and recover solid organic polymers from organic wastewater containing organic pollutants treated with activated persulfate, and then wash and dry them.

[0034] Step 2: Mix the solid organic polymer products recovered from the organic wastewater with the modifier in a certain proportion. The mixing method can be either direct grinding and mixing, or adding appropriate deionized water, ultrasonically dispersing, heating and stirring in a water bath, drying, and then further grinding and mixing.

[0035] The modifier is one or more of a pore-forming agent or a heteroatom doping agent; wherein the heteroatom doping agent is used to introduce metal atoms or non-metal atoms other than C, H, and O.

[0036] The pore-forming agent is at least one selected from nitrates, carbonates, bicarbonates, sulfates, chlorides, moderately strong acids, strong acids, strong bases, and strong oxidants; wherein the moderately strong acid is selected from phosphoric acid, boric acid, carbonic acid, oxalic acid, citric acid, sulfurous acid, hydrofluoric acid, and hydrosulfuric acid; the strong acid is selected from hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid; the strong base is selected from potassium hydroxide and sodium hydroxide; and the strong oxidant is selected from potassium permanganate, potassium dichromate, and sodium hypochlorite.

[0037] The metal atom introduced by the heteroatom doping reagent is a transition metal atom, and the introduced non-metal atom is a nitrogen atom, a boron atom, or a sulfur atom; preferably, the reagent for introducing the metal atom is at least one of a transition metal salt or a transition metal complex, and the reagent for introducing the non-metal atom is any one of a nitrogen-containing reagent, a boron-containing reagent, or a sulfur-containing reagent; more preferably, the modifier is a mixture of a reagent containing metal atoms and a reagent containing non-metal atoms.

[0038] The specified ratio is the mass ratio of the raw materials to the modifier being 1:(0.5~1.5).

[0039] Step 3: Pyrolyze the mixed material in an inert atmosphere (e.g., nitrogen, argon, etc.) at a heating rate of 5℃ / min, and pyrolyze and carbonize it at 600-1000℃ for 2 hours. Then cool and wash with water to obtain a carbon-based catalyst.

[0040] The prepared carbon-based catalyst can be used in experiments involving the adsorption and activation of persulfate to remove organic matter. The specific experimental procedure is as follows:

[0041] 0–50 mg of carbon catalyst (0 mg was taken as the control group) was added to 100 mL of solution containing 0.01–10 mM organic pollutants, and adsorption-desorption equilibrium was reached after a certain period of time. Subsequently, persulfate was added to study the performance of the catalyst in adsorbing and activating PMS to remove organic matter.

[0042] The moment when adsorption-desorption equilibrium is reached is defined as Time = 0 min (counting back from the catalyst addition time, the value is negative). From the addition of the catalyst until adsorption-desorption equilibrium is reached, the process is based on adsorption (not involving redox processes, but only physical processes). Persulfate is added at Time = 0 min, marking the start of the oxidation phase. This is based on the catalyst activating the persulfate, thereby oxidizing the pollutants (for the control group without a carbon catalyst, persulfate is added at Time = 0 min). The content of organic pollutants in the system is measured at different time points from the start of catalyst addition.

[0043] The following are specific examples:

[0044] Example 1 (Preparation of sodium nitrate modified catalyst):

[0045] S1: Recycling solid organic polymers

[0046] The specific steps are as follows: Prepare actual coking wastewater (its water quality parameters and types and concentrations of organic matter are shown in Table 1). Mix PDS with the actual coking wastewater to achieve a PDS concentration of 100 mM in the mixed solution. Place the resulting mixed solution in an Erlenmeyer flask and react it in an 80°C water bath for 35 minutes. After the reaction, cool the Erlenmeyer flask to room temperature in cold water. Filter the mixed suspension in the Erlenmeyer flask; the resulting solid substance is a solid organic polymer. Wash it with deionized water and dry it in an oven.

[0047] S2: Preparation of sodium nitrate modified catalyst

[0048] The recovered solid organic polymer was ground and mixed with NaNO3 at a mass ratio of 1:0.5, and then pyrolyzed in a nitrogen atmosphere at a heating rate of 5℃ / min to 800℃ for 2 hours. After washing with deionized water and drying, the catalyst P-RPL800-0.5 was obtained.

[0049] Under the same pyrolysis conditions, without the addition of NaNO3, the carbon material obtained by directly pyrolyzing and recovering the solid organic polymer is denoted as P-RPL800-0.

[0050] Table 1. Water quality parameters and organic matter types and concentrations in actual coking wastewater.

[0051]

[0052] Example 2 (Preparation of sodium nitrate modified catalyst):

[0053] S1: Recycling solid organic polymers

[0054] The specific process is the same as S1 in Example 1.

[0055] S2: Preparation of sodium nitrate modified catalyst

[0056] The recovered solid organic polymer was ground and mixed with NaNO3 at a mass ratio of 1:1, and then pyrolyzed in a nitrogen atmosphere at a heating rate of 5℃ / min to 800℃ for 2 hours. After washing with deionized water and drying, catalyst P-RPL800-1 was obtained.

[0057] Example 3 (Preparation of sodium nitrate modified catalyst):

[0058] S1: Recycling solid organic polymers

[0059] The specific process is the same as S1 in Example 1.

[0060] S2: Preparation of sodium nitrate modified catalyst

[0061] The recovered solid organic polymer was ground and mixed with NaNO3 at a mass ratio of 1:1.5, and then pyrolyzed in a nitrogen atmosphere at a heating rate of 5℃ / min to 800℃ for 2 hours. After washing with deionized water and drying, the catalyst P-RPL800-1.5 was obtained.

[0062] Example 4 (Preparation of sodium nitrate modified catalyst):

[0063] S1: Recycling solid organic polymers

[0064] The specific process is the same as S1 in Example 1.

[0065] S2: Preparation of sodium nitrate modified catalyst

[0066] The recovered solid organic polymer was ground and mixed with NaNO3 at a mass ratio of 1:1, and then pyrolyzed in a nitrogen atmosphere at a heating rate of 5℃ / min to 400℃ for 2 hours. After washing with deionized water and drying, catalyst P-RPL400-1 was obtained.

[0067] Example 5 (Preparation of sodium nitrate modified catalyst):

[0068] S1: Recycling solid organic polymers

[0069] The specific process is the same as S1 in Example 1.

[0070] S2: Preparation of sodium nitrate modified catalyst

[0071] The recovered solid organic polymer was ground and mixed with NaNO3 at a mass ratio of 1:1, and then pyrolyzed in a nitrogen atmosphere at a heating rate of 5℃ / min to 600℃ for 2 hours. After washing with deionized water and drying, catalyst P-RPL600-1 was obtained.

[0072] Example 6 (Preparation of sodium nitrate modified catalyst):

[0073] S1: Recycling solid organic polymers

[0074] The specific process is the same as S1 in Example 1.

[0075] S2: Preparation of sodium nitrate modified catalyst

[0076] The recovered solid organic polymer was ground and mixed with NaNO3 at a mass ratio of 1:1, and then pyrolyzed in a nitrogen atmosphere at a heating rate of 5℃ / min to 1000℃ for 2 hours. After washing with deionized water and drying, the catalyst P-RPL1000-1 was obtained.

[0077] Example 7 (Preparation of iron-nitrogen co-modified catalyst):

[0078] S1: Recycling solid organic polymers

[0079] The specific process is the same as S1 in Example 1.

[0080] S2: Preparation of iron-nitrogen co-modified catalyst

[0081] The recovered solid organic polymer was washed and dried, then mixed with ferric nitrate and melamine in a 1:1:1 mass ratio, followed by mixing with deionized water. The mixture was ultrasonicated for 20 minutes, stirred in an 80°C water bath until dry, and then ground into powder. Under a nitrogen atmosphere, the powder was pyrolyzed at 800°C for 2 hours at a heating rate of 5°C / min. After washing with deionized water and drying, the catalyst P-RPL-Fe1N1 was obtained.

[0082] Example 1 of effect verification:

[0083] The catalysts (P-RPL800-0, P-RPL800-0.5, P-RPL800-1, and P-RPL800-1.5) prepared in Examples 1-3 were applied to the adsorption and activation of PMS for phenol removal at room temperature. 10 mg of catalyst was added to 100 mL of 0.1 mM phenol solution with continuous stirring, and adsorption-desorption equilibrium was reached after 60 min. Subsequently, PMS was added to bring the initial PMS concentration in the solution to 0.5 mM, and phenol removal experiments were conducted.

[0084] Figure 1 The nitrogen adsorption-desorption curves are shown for the catalysts modified with NaNO3 at different mass ratios obtained in Examples 1 to 3 of this invention.

[0085] Table 2 shows the specific surface area and pore size analysis results of NaNO3-modified catalysts with different ratios. When the ratio is 1:1, the specific surface area of ​​the carbon material reaches as high as 1320.73 m². 2 It contains / g and has a rich porous structure.

[0086] Table 2. Specific surface area and porosity analysis results of NaNO3 modified catalyst

[0087]

[0088] Figure 2 The effects of catalysts prepared with different NaNO3 ratios on the adsorption and activation of PMS for the removal of phenol were investigated. The results showed that NaNO3, as a modifier, can effectively enhance the adsorption capacity of carbon materials for pollutants and can successfully activate PMS to remove pollutants.

[0089] Figure 3 The effects of catalysts P-RPL400-1 (Example 4), P-RPL600-1 (Example 5), P-RPL800-1 (Example 2), and P-RPL1000-1 (Example 6) on the adsorption and activation of PMS for the oxidative removal of phenol were investigated. The results showed that the catalysts prepared in the pyrolysis temperature range of 600-1000℃ can effectively adsorb and remove phenol, and can also activate PMS for the oxidative removal of phenol.

[0090] Figure 4 The effect of catalyst P-RPL800-1 (prepared in Example 2) on activating PMS and PDS in the treatment of phenol was investigated (where PDS replaced PMS, and the catalyst P-RPL800-1 prepared in Example 2 was tested according to the operation steps of Effect Verification Example 1; PDS was added to make the concentration of PDS in the solution 0.5 mM). The results showed that P-RPL800-1 can effectively activate PMS and PDS to oxidize and remove phenol. In the figure, control group ① used PDS alone to remove phenol, with an initial PDS concentration of 0.5 mM, no catalyst added, and an initial phenol concentration of 0.1 mM, denoted as the "PMS" system; control group ② used PMS alone to remove phenol, with an initial PMS concentration of 0.5 mM, no catalyst added, and an initial phenol concentration of 0.1 mM, denoted as the "PMS" system.

[0091] Example 2 of effect verification:

[0092] Under the background of secondary effluent from a membrane bioreactor (MBR) process (water quality parameters are shown in Table 3), P-RPL800-1 (prepared in Example 2) was applied to the adsorption and activated PMS oxidation experiments for the removal of phenol. Under continuous stirring, 10 mg of the carbon catalyst P-RPL800-1 was added to 100 mL of a solution containing 0.1 mM phenol (prepared using MBR secondary effluent), and adsorption-desorption equilibrium was reached after 60 min. Subsequently, a certain amount of PMS was added to make the initial PMS concentration in the solution 0.5 mM, and the phenol removal experiment was conducted. This group is designated as the "MBR" group.

[0093] The experimental group that used P-RPL800-1 to adsorb phenol and activated PMS to remove phenol under pure water background was the control group, denoted as "control group".

[0094] Table 3. Secondary effluent parameters of MBR process

[0095]

[0096] *MBR secondary effluent comes from a municipal wastewater treatment plant in Wuhan.

[0097] The experimental results of the “MBR” group and the “control group” are as follows: Figure 5 As shown, P-RPL800-1 can effectively resist the interference of various ions in the actual water background and has little impact on the adsorption of phenol and the removal effect of activated PMS oxidation.

[0098] Example 3 of effect verification:

[0099] P-RPL800-1 (prepared in Example 2) was applied to a cyclic phenol removal experiment at room temperature. 10 mg of the carbon catalyst P-RPL800-1 was added to 100 mL of a solution containing 0.05 mM phenol and 0.5 mM PMS under continuous stirring. The reaction was carried out for 90 min, which was recorded as the "first use".

[0100] After the first use, the catalyst was filtered and recovered from the reaction. After washing with water and drying, it was used again in the experiment to remove phenol. The experimental conditions were the same as the first experiment, and this was recorded as the "second use".

[0101] After being reused 4 times, the catalyst recovered after the 4th use was washed with water, dried, and then re-pyrolyzed in a nitrogen atmosphere. The heating rate was 5℃ / min, the pyrolysis temperature was 800℃, and the pyrolysis time was 2h to obtain the pyrolyzed regenerated catalyst, which was then used again in the experiment to remove phenol under the same experimental conditions as the first experiment. This was recorded as "pyrolysis regeneration".

[0102] The data in Table 4 show that P-RPL800-1 has good recycling performance and can be regenerated through simple pyrolysis.

[0103] Table 4 shows the recycling efficiency of P-RPL800-1.

[0104]

[0105] Example 4 of effect verification:

[0106] P-RPL-Fe1N1 (prepared in Example 7) was applied to the adsorption and activation of PMS for the removal of different pollutants at room temperature. Under continuous stirring, 10 mg of the carbon catalyst P-RPL-Fe1N1 was added to different single-pollutant solutions, each solution having a volume of 100 mL and a pollutant concentration of 0.2 mM. Adsorption-desorption equilibrium was reached after 30 min. Subsequently, PMS was added to bring the initial PMS concentration in the solution to 0.5 mM, and pollutant removal experiments were conducted. The results are as follows: Figure 6 As shown, the iron-nitrogen co-modified catalyst can effectively activate PMS and effectively remove different pollutants (the hollow curve represents the effect of PMS alone in removing pollutants, where the pollutant concentration is 0.2 mM, the PMS concentration is 0.5 mM, and no catalyst is added).

[0107] In the application of activated persulfate for phenol removal, numerous studies have reported typical carbon-based catalysts such as carbon nanotubes, graphene, and biochar. The DOC removed under the conditions reported in the references or the experimental conditions of this invention (corresponding to Δ[DOC] in the table) r Based on the data for DOC (dissolved organic carbon), the required oxidant concentration (Equation 1) and catalyst concentration (Equation 2) for each catalyst system to remove 20 mg / L of DOC (Δ[DOC]) were calculated. These concentrations were determined using Equations 1 and 2, respectively. Where "[oxidant]" is the oxidant concentration. r "Δ[DOC] represents the removal of DOC under the conditions reported in the literature or the experimental conditions of this invention." r The required concentration of oxidant; "[catalyst]" r "Δ[DOC] represents the removal of DOC under the conditions reported in the literature or the experimental conditions of this invention." r The required catalyst concentration.

[0108] [Oxidizing agent] = (Δ[DOC] / Δ[DOC]) r )×[oxidizing agent] r (Equation 1)

[0109] [Catalyst] = (Δ[DOC] / Δ[DOC]) r )×[catalyst] r (Equation 2)

[0110] The calculation results are shown in Table 5. Compared with the literature reports, the two catalysts prepared by recycling solid organic polymers as carbon-based materials in this invention (i.e., the sodium nitrate-modified catalyst prepared in Example 2 and the iron-nitrogen co-modified catalyst prepared in Example 7) require the least amount of oxidant (persulfate) and the lowest required catalyst concentration when removing the same DOC (Δ[DOC] = 20 mg / L). This indicates that when removing the same DOC concentration, the two catalysts of this invention, which use recycled solid organic polymers as carbon-based materials, are more oxidant-efficient.

[0111] Table 5 shows the concentrations of oxidant and catalyst required for each catalyst system when Δ[DOC] = 20 mg / L.

[0112]

[0113]

[0114] Remark: a For details, see Song W, Xiao

[0115] b For details, see Liu Y, Lin Q, Guo Y, et al. The nitrogen-doped multi-walled carbonnanotubes modified membrane activated peroxymonosulfate for enhanced degradation of organics and membrane fouling mitigation in natural waterstreatment[J]. Water Research; based on graphene;

[0116] c See Xu L, Wu C, Liu P, et al. Peroxymonosulfate activation by nitrogen-doped biochar from sawdust for the efficient degradation of organic pollutants[J]. Chemical Engineering Journal; based on biochar;

[0117] The above embodiments are merely examples. For instance, in addition to nitrogen, other inert atmospheres such as argon can be used for pyrolysis. The polymerized solid organic polymer can be collected not only from the activated persulfate treatment system for organic wastewater but also from the activated hydrogen peroxide treatment system for organic wastewater, as detailed in Chinese invention patents ZL202010873326.0 and ZL201810997000.1.

[0118] This invention relates to a method for treating wastewater containing organic pollutants using a polymerization mechanism, followed by the separation and collection of solid organic polymers. These solid organic polymers are produced by the polymerization of organic pollutants or their intermediate products during wastewater treatment. Organic monomers dissolved in water polymerize to a certain molecular weight and precipitate from the water, producing solid particles. These particles can be recovered through solid-liquid separation, and after simple washing and drying, a carbon-based catalyst precursor is obtained. The polymerization mechanism is detailed in Chinese invention applications CN202010873326.0, CN201810997000.1, CN201710262422.X, and CN202011157768.1, the entire contents of which are incorporated herein by reference.

[0119] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-based catalyst using organic pollutants recovered from organic wastewater as raw materials, characterized in that, A carbon-based catalyst was obtained by using solid organic polymer products recovered from organic wastewater as raw materials, washing them with water, mixing them with a modifier, and then pyrolyzing them in an inert atmosphere. The pyrolysis temperature is 600–1000℃; The modifier is one or more of a pore-forming agent or a heteroatom doping agent; wherein the heteroatom doping agent is used to introduce metal atoms or non-metal atoms other than C, H, and O.

2. The method as described in claim 1, characterized in that, The solid organic polymer product recovered from the organic wastewater is a solid organic polymer recovered by filtration from an organic wastewater system in which a polymerization chemical reaction has occurred. Preferably, the organic wastewater system in which the polymerization chemical reaction has occurred is specifically an activated persulfate-treated organic wastewater system or an activated hydrogen peroxide-treated organic wastewater system.

3. The method as described in claim 1, characterized in that, The mixing involves mixing the washed and dried raw materials with the modifier at a mass ratio of 1:(0.5 to 1.5).

4. The method as described in claim 1, characterized in that, The mixing process involves mixing and grinding the washed and dried raw materials with the modifier to obtain a mixture, or mixing the washed raw materials with the modifier in deionized water and then sequentially ultrasonicating, stirring in a water bath, drying, and grinding to obtain a mixture.

5. The method as described in claim 1, characterized in that, The heteroatom doping reagent can simultaneously introduce metal atoms and non-metal atoms. In this case, the modifier is a mixture of reagents containing metal atoms and reagents containing non-metal atoms.

6. The method as described in claim 1, characterized in that, The pore-forming agent is at least one of nitrates, carbonates, bicarbonates, sulfates, chlorides, moderately strong acids, strong acids, strong bases, and strong oxidizing agents; wherein the moderately strong acid is at least one of phosphoric acid, boric acid, carbonic acid, oxalic acid, citric acid, sulfurous acid, hydrofluoric acid, and hydrosulfuric acid; the strong acid is at least one of hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid; the strong base is at least one of potassium hydroxide and sodium hydroxide; and the strong oxidizing agent is at least one of potassium permanganate, potassium dichromate, and sodium hypochlorite. The heteroatom doping reagent introduces transition metal atoms and nitrogen, boron, and sulfur atoms.

7. The method as described in claim 6, characterized in that, The heteroatom doping reagent used to introduce transition metal atoms is at least one of transition metal salts and transition metal complexes, and the heteroatom doping reagent used to introduce non-metal atoms is any one of nitrogen-containing reagents, boron-containing reagents, and sulfur-containing reagents.

8. Applying the carbon-based catalyst prepared by any one of claims 1-7 to the adsorption and removal of organic pollutants in water and / or the activation of persulfate oxidation and / or the activation of peroxide oxidation to remove organic pollutants in water, characterized in that, The persulfate includes one or more of permonosulfate (PMS) and perdisulfate (PDS); the peroxide is preferably H2O2.

9. The application as described in claim 8, characterized in that, After the removal of organic pollutants from the water is completed, the carbon-based catalyst in the system can be reused for adsorption to remove organic pollutants from the water and / or activated persulfate oxidation to remove organic pollutants from the water and / or activated peroxide oxidation to remove organic pollutants from the water after filtration and water washing recovery.

10. The application as described in claim 8, characterized in that, After the removal of organic pollutants from the water is completed, the carbon-based catalyst in the system can be reused for adsorption to remove organic pollutants from the water and / or activated persulfate oxidation to remove organic pollutants from the water and / or activated peroxide oxidation to remove organic pollutants from the water after filtration, washing, drying, and pyrolysis regeneration.

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