Method for removing organic pollutants by nitrogen-doped cotton stalk charcoal loaded LaCoO3 catalyst
By combining nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst with a PMS system, the problem of traditional water treatment technologies being unable to remove organic pollutants has been solved, achieving efficient and stable degradation of organic pollutants, and is applicable to the field of wastewater treatment.
Patent Information
- Application Number
- CN202511622262.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-02-10
AI Technical Summary
Traditional water treatment technologies are ineffective at removing structurally stable organic pollutants, such as pesticides and recalcitrant substances in industrial silicon-containing wastewater. Existing single-metal catalysts have insufficient catalytic activity and stability, which limits oxidation capacity and reaction rate.
A nitrogen-doped cotton stalk biochar supported on a LaCoO3 catalyst was used to prepare nitrogen-doped cotton stalk biochar and support it with LaCoO3. Combined with a persulfate (PMS) system, a heterogeneous reaction was formed to remove organic pollutants.
It increases the number of active sites and synergistic effect of the catalyst, achieving efficient degradation of a variety of organic pollutants. It has good stability and wide applicability, and the raw materials are environmentally friendly with no secondary pollution.
Smart Images
Figure CN121490802A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment, and more particularly to a method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst. Background Technology
[0002] In the process of industrial and agricultural development, the emission of organic pollutants has become an increasingly prominent problem. For example, pesticides (such as imidacloprid), antibiotics (such as sulfamethoxazole), and recalcitrant organic pollutants in industrial silicon-containing wastewater (such as m-cresol) have stable structures, making them difficult to remove effectively with traditional water treatment technologies, thus exacerbating water pollution problems. The complexity and diversity of these organic pollutants pose a huge challenge to water body management, and there is an urgent need to develop efficient and environmentally friendly treatment technologies.
[0003] In recent years, advanced oxidation processes (AOPs) based on persulfate (PMS) have shown outstanding performance in degrading recalcitrant organic pollutants due to their ability to generate reactive oxygen species (such as sulfate radicals and hydroxyl radicals). Among these, transition metal ions (such as Co) are particularly effective at degrading recalcitrant organic pollutants. 2+ Fe 2+ (etc.) can promote the generation of free radicals by activating the asymmetric structure of PMS, thereby improving the pollutant removal efficiency.
[0004] However, in single-metal transition metal oxide (e.g., Co3O4) catalysts, the catalytic activity usually depends on the single metal active site, which limits the catalyst's oxidation capacity and reaction rate.
[0005] Perovskite oxides such as LaCoO3 can not only increase the number of active sites in catalysts, but also improve catalytic efficiency through intermetallic synergistic effects. They also have significant advantages over single-metal transition metal oxides in terms of structural stability, anti-interference ability, and reusability.
[0006] Nitrogen-doped biochar-supported perovskite-type LaCoO3 catalysts, due to their unique electronic structure, excellent redox performance and good stability, are expected to achieve efficient degradation of a variety of organic pollutants (such as imidacloprid, m-cresol, sulfamethoxazole, etc.), providing a new technical route for the deep treatment of complex organic pollutant wastewater.
[0007] Therefore, developing a highly efficient and stable catalytic material containing LaCoO3 active sites is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0008] In view of this, the present invention provides a method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst.
[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0010] A method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst includes the following steps:
[0011] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0012] The cotton stalks are cut into small pieces, crushed, and sieved to obtain cotton stalk powder.
[0013] Wash and dry the cotton stalk powder and dicyandiamide in a tube furnace crucible at a mass ratio, heat under an argon atmosphere, and wash the product after it has cooled to room temperature until it is neutral.
[0014] Dry to obtain nitrogen-doped cotton stalk biochar, for later use;
[0015] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0016] Weigh the nitrogen-doped cotton stalk biochar prepared in step 1 and add it to a mixed solution of Co(NO3)2·6H2O and La(NO3)2·6H2O in anhydrous ethanol;
[0017] Disperse under stirring, filter, dry the solid sample, and then place the dried sample in a tube furnace;
[0018] The nitrogen-doped cotton stalk biochar supported on LaCoO3 catalyst was obtained by heating and calcination under an argon atmosphere and then set aside.
[0019] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0020] Different pollutant aqueous solutions were added to a light-protected catalytic reactor, and a heterogeneous reaction was initiated by adding nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and PMS.
[0021] The initial solution pH was precisely controlled using H2SO4 and NaOH, and samples were extracted and filtered at selected time intervals.
[0022] Methanol is added to act as a reaction terminator to remove residual free radicals before HPLC detection.
[0023] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0024] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column and a UV absorbance detector.
[0025] Preferably, in step 1, the cotton stalks are cut into small pieces and crushed, then sieved through an 80-100 mesh sieve to obtain cotton stalk powder; then washed three times with deionized water and dried at 60°C for 6-12 hours.
[0026] Preferably, in step 1, cotton stalk powder and dicyandiamide are placed in a tube furnace crucible at a mass ratio of 1:1 and heated to 400-700°C under an argon atmosphere, and maintained at this temperature for 2 hours.
[0027] Preferably, in step 1, after heating, the product that has cooled naturally to room temperature is washed with deionized water until neutral, and then dried at 60°C for 4-6 hours.
[0028] Preferably, in step 2, 0.1-0.3 parts of the nitrogen-doped cotton stalk biochar prepared in step 1 are weighed and added to 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.01-0.3 mol / L La(NO3)2·6H2O anhydrous ethanol, and dispersed at a stirring speed of 400-800 rpm for 4-8 hours.
[0029] Preferably, in step 2, the solid sample is dried at 60°C for 4-6 hours, and after drying, the sample is placed in a tube furnace and calcined at 500-900°C for 2-4 hours under an argon atmosphere.
[0030] Preferably, in step 3, 100 portions of 20 mg / L aqueous solutions of different pollutants are added to a light-protected catalytic reactor, and a heterogeneous reaction is initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0031] Preferably, in step 3, the initial solution pH is precisely controlled using 0.1 mol / L H2SO4 and NaOH, 1 mL of sample is extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol is added.
[0032] The present invention achieves the following technical effects compared to the prior art:
[0033] (1) This invention uses biochar as the carbon source of the catalyst and dicyandiamide as the nitrogen source. This results in a catalyst rich in nitrogen-containing functional groups (including pyridine nitrogen, pyrrole nitrogen, graphitic nitrogen, and nitrogen oxides), among which pyridine nitrogen accelerates the reaction. Simultaneously, the introduction of these nitrogen-containing functional groups can improve the overall electronegativity of the material, thereby improving the electronic environment around the supported metal;
[0034] (2) The nitrogen-doped cotton stalk biochar supported LaCoO3 catalyst of the present invention has good catalytic activity, specific surface area and stability. Under optimal conditions, the nitrogen-doped cotton stalk biochar supported LaCoO3 catalyst can remove more than 90% of pollutants within 10 min.
[0035] (3) The raw materials used in this invention are all environmentally friendly and green materials, which are environmentally friendly and avoid secondary pollution;
[0036] Experimental results show that the catalyst not only has a wide range of applications, but also exhibits excellent removal efficiency for a variety of organic pollutants in other industrial wastewater.
[0037] (4) The present invention has simple steps, readily available raw materials, does not pollute the environment, and is applicable to the field of wastewater treatment. Attached Figure Description
[0038] Figure 1 This is a SEM image of the nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst in this invention;
[0039] Figure 2 The graph shows the performance of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS reaction system with different cobalt-lanthanum ratios in removing imidacloprid from water in this invention.
[0040] Figure 3 This is a diagram of the main active oxygen species generated during the activation of PMS by LaCoO3 supported on nitrogen-doped cotton stalk biochar, obtained by EPR spectrum testing in this invention.
[0041] Figure a shows SO4. •- EPR spectra of O2 and •OH; Figure b shows the EPR spectra of O2. •- EPR spectrum. Detailed Implementation
[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0043] like Figure 1-3 As shown, this invention discloses a method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst, comprising the following steps:
[0044] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0045] After cutting the cotton stalks into small pieces, crush them and sieve them through an 80-100 mesh sieve to obtain cotton stalk powder;
[0046] Then wash three times with deionized water and dry at 60 °C for 6-12 h;
[0047] Cotton stalk powder and dicyandiamide were placed in a tube furnace crucible at a mass ratio of 1:1 and heated to 400-700 °C under an argon atmosphere. The mixture was maintained at this temperature for 2 hours. After heating, the product was allowed to cool naturally to room temperature and washed with deionized water until neutral.
[0048] Then dry at 60°C for 4-6 h to obtain nitrogen-doped cotton stalk biochar for later use;
[0049] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0050] Weigh 0.1-0.3 parts of the nitrogen-doped cotton stalk biochar prepared in step 1, add 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.01-0.3 mol / L La(NO3)2·6H2O in anhydrous ethanol, disperse at a stirring speed of 400-800 rpm for 4-8 h, filter, and dry the solid sample at 60 °C for 4-6 h;
[0051] After drying, the sample was placed in a tube furnace and calcined at 500-900 °C for 2-4 h under an argon atmosphere to obtain nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst for later use.
[0052] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0053] 100 portions of 20 mg / L aqueous solutions of different pollutants (imidacloprid, sulfamethoxazole and m-cresol) were added to a light-protected catalytic reactor. The heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0054] The initial solution pH was precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample was extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol was added.
[0055] Methanol was used as a reaction terminator to remove residual free radicals before HPLC detection;
[0056] To improve the reliability of the experimental results, each experiment was conducted three times simultaneously, and the standard deviation was controlled.
[0057] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0058] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column (5 μm, 4.6 mm × 250 mm) and a UV absorbance detector.
[0059] Example 1:
[0060] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0061] After cutting the cotton stalks into small pieces, crush them and sieve them through an 80-mesh sieve to obtain cotton stalk powder;
[0062] Then wash three times with deionized water and dry at 60 °C for 6 h;
[0063] Cotton stalk powder and dicyandiamide were placed in a tube furnace crucible at a mass ratio of 1:1 and heated to 400 °C under an argon atmosphere, and maintained at this temperature for 2 h.
[0064] After heating, the product, which was allowed to cool naturally to room temperature, was washed with deionized water until neutral, and then dried at 60 °C for 4 h to obtain nitrogen-doped cotton stalk biochar for later use.
[0065] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0066] Weigh 0.1 part of the nitrogen-doped cotton stalk biochar prepared in step 1, add 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.01 mol / L La(NO3)2·6H2O in anhydrous ethanol, disperse at 400 rpm for 4 h, filter, and dry the solid sample at 60 °C for 4 h.
[0067] After drying, the sample was placed in a tube furnace and calcined at 500 °C for 2 h under an argon atmosphere to obtain a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst for later use.
[0068] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0069] 100 portions of 20 mg / L aqueous solutions of different pollutants (imidacloprid, sulfamethoxazole and m-cresol) were added to a light-protected catalytic reactor. The heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0070] The initial solution pH was precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample was extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol was added.
[0071] Before HPLC detection, methanol was used as a reaction terminator to remove residual free radicals.
[0072] To improve the reliability of the experimental results, each experiment was conducted three times simultaneously, and the standard deviation was controlled.
[0073] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0074] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column (5 μm, 4.6 mm × 250 mm) and a UV absorbance detector.
[0075] Example 2:
[0076] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0077] After cutting the cotton stalks into small pieces, crush them and sieve them through an 80-mesh sieve to obtain cotton stalk powder;
[0078] Then wash three times with deionized water and dry at 60 °C for 7 h;
[0079] Cotton stalk powder and dicyandiamide were placed in a tube furnace crucible at a mass ratio of 1:1 and heated to 500 °C under an argon atmosphere, and maintained at this temperature for 2 h.
[0080] After heating, the product, which had cooled naturally to room temperature, was washed with deionized water until neutral, and then dried at 60 °C for 4.5 h to obtain nitrogen-doped cotton stalk biochar for later use.
[0081] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0082] Weigh 0.15 parts of the nitrogen-doped cotton stalk biochar prepared in step 1, add 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.03 mol / L La(NO3)2·6H2O in anhydrous ethanol, disperse at 500 rpm for 5 h, filter, and dry the solid sample at 60°C for 4.5 h.
[0083] After drying, the sample was placed in a tube furnace and calcined at 600 °C for 2.5 h under an argon atmosphere to obtain a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst for later use.
[0084] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0085] 100 portions of 20 mg / L aqueous solutions of different pollutants (imidacloprid, sulfamethoxazole and m-cresol) were added to a light-protected catalytic reactor. The heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0086] The initial solution pH was precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample was extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol was added.
[0087] Before HPLC detection, methanol was used as a reaction terminator to remove residual free radicals.
[0088] To improve the reliability of the experimental results, each experiment was conducted three times simultaneously, and the standard deviation was controlled.
[0089] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0090] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column (5 μm, 4.6 mm × 250 mm) and a UV absorbance detector.
[0091] Example 3:
[0092] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0093] After cutting the cotton stalks into small pieces, crush them and sieve them through a 90-mesh sieve to obtain cotton stalk powder;
[0094] Then wash three times with deionized water and dry at 60 °C for 9 h;
[0095] Cotton stalk powder and dicyandiamide were placed in a tube furnace crucible at a mass ratio of 1:1 and heated to 600 °C under an argon atmosphere, and maintained at this temperature for 2 h.
[0096] After heating, the product, which was allowed to cool naturally to room temperature, was washed with deionized water until neutral, and then dried at 60°C for 5 h to obtain nitrogen-doped cotton stalk biochar for later use.
[0097] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0098] Weigh 0.2 parts of the nitrogen-doped cotton stalk biochar prepared in step 1, add 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.07 mol / L La(NO3)2·6H2O in anhydrous ethanol, disperse at 600 rpm for 6 h, filter, and dry the solid sample at 60 °C for 5 h.
[0099] After drying, the sample was placed in a tube furnace and calcined at 700 °C for 3 h under an argon atmosphere to obtain a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst for later use.
[0100] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0101] 100 portions of 20 mg / L aqueous solutions of different pollutants (imidacloprid, sulfamethoxazole and m-cresol) were added to a light-protected catalytic reactor. The heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0102] The initial solution pH was precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample was extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol was added.
[0103] Methanol was used as a reaction terminator to remove residual free radicals before HPLC detection;
[0104] To improve the reliability of the experimental results, each experiment was conducted three times simultaneously, and the standard deviation was controlled.
[0105] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0106] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column (5 μm, 4.6 mm × 250 mm) and a UV absorbance detector.
[0107] Example 4:
[0108] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0109] After cutting the cotton stalks into small pieces, crush them and sieve them through a 100-mesh sieve to obtain cotton stalk powder;
[0110] Then wash three times with deionized water and dry at 60 °C for 11 h;
[0111] Cotton stalk powder and dicyandiamide were placed in a tube furnace crucible at a mass ratio of 1:1.
[0112] Under an argon atmosphere, the product was heated to 650 °C and maintained at this temperature for 2 h. After heating, the product was allowed to cool naturally to room temperature and washed with deionized water until neutral. Then, it was dried at 60 °C for 5.5 h to obtain nitrogen-doped cotton stalk biochar for later use.
[0113] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0114] Weigh 0.25 parts of the nitrogen-doped cotton stalk biochar prepared in step 1, add 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.1 mol / L La(NO3)2·6H2O in anhydrous ethanol, disperse at 700 rpm for 7 h, filter, and dry the solid sample at 60 °C for 5.5 h.
[0115] After drying, the sample was placed in a tube furnace and calcined at 800 °C for 3.5 h under an argon atmosphere to obtain a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst for later use.
[0116] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0117] 100 portions of 20 mg / L aqueous solutions of different pollutants (imidacloprid, sulfamethoxazole and m-cresol) were added to a light-protected catalytic reactor. The heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0118] The initial solution pH was precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample was extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol was added.
[0119] Methanol was used as a reaction terminator to remove residual free radicals before HPLC detection;
[0120] To improve the reliability of the experimental results, each experiment was conducted three times simultaneously, and the standard deviation was controlled.
[0121] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0122] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column (5 μm, 4.6 mm × 250 mm) and a UV absorbance detector.
[0123] Example 5:
[0124] Step 1: Preparation of nitrogen-doped cotton stalk biochar
[0125] After cutting the cotton stalks into small pieces, crush them and sieve them through a 100-mesh sieve to obtain cotton stalk powder;
[0126] Then wash three times with deionized water and dry at 60°C for 12 hours;
[0127] Cotton stalk powder and dicyandiamide were placed in a tube furnace crucible at a mass ratio of 1:1.
[0128] Under an argon atmosphere, the mixture was heated to 700 °C and maintained at this temperature for 2 hours.
[0129] After heating, the product, which was allowed to cool naturally to room temperature, was washed with deionized water until neutral, and then dried at 60 °C for 6 h to obtain nitrogen-doped cotton stalk biochar for later use.
[0130] Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst
[0131] Weigh 0.3 parts of the nitrogen-doped cotton stalk biochar prepared in step 1, add 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.3 mol / L La(NO3)2·6H2O anhydrous ethanol, disperse at 800 rpm for 8 h, filter, and dry the solid sample at 60 °C for 6 h.
[0132] After drying, the sample was placed in a tube furnace and calcined at 900 °C for 4 h under an argon atmosphere to obtain a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst for later use.
[0133] Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system.
[0134] 100 portions of 20 mg / L aqueous solutions of different pollutants (imidacloprid, sulfamethoxazole and m-cresol) were added to a light-protected catalytic reactor. The heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
[0135] The initial solution pH was precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample was extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol was added.
[0136] Before HPLC detection, methanol was used as a reaction terminator to remove residual free radicals.
[0137] To improve the reliability of the experimental results, each experiment was conducted three times simultaneously, and the standard deviation was controlled.
[0138] After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected.
[0139] The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column (5 μm, 4.6 mm × 250 mm) and a UV absorbance detector.
[0140] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst, characterized in that, Includes the following steps: Step 1: Preparation of nitrogen-doped cotton stalk biochar The cotton stalks are cut into small pieces, crushed, and sieved to obtain cotton stalk powder. Wash and dry the cotton stalk powder and dicyandiamide in a tube furnace crucible at a mass ratio, heat under an argon atmosphere, and wash the product after it has cooled to room temperature until it is neutral. Dry to obtain nitrogen-doped cotton stalk biochar, for later use; Step 2: Preparation of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst Weigh the nitrogen-doped cotton stalk biochar prepared in step 1 and add it to a mixed solution of Co(NO3)2·6H2O and La(NO3)2·6H2O in anhydrous ethanol; Disperse under stirring, filter, dry the solid sample, and then place the dried sample in a tube furnace; The nitrogen-doped cotton stalk biochar supported on LaCoO3 catalyst was obtained by heating and calcination under an argon atmosphere and then set aside. Step 3: Removal of organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst / PMS system. Different pollutant aqueous solutions were added to a light-protected catalytic reactor, and a heterogeneous reaction was initiated by adding nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and PMS. The initial solution pH was precisely controlled using H2SO4 and NaOH, and samples were extracted and filtered at selected time intervals. Methanol is added to act as a reaction terminator to remove residual free radicals before HPLC detection. After each experiment, the solid and liquid components were separated by vacuum filtration, and the used solid catalyst was collected. The residual concentration of pollutants was analyzed by ultra-high performance liquid chromatography (UHPLC) using a C18 column and a UV absorbance detector.
2. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 1, the cotton stalks are cut into small pieces and crushed, then sieved through an 80-100 mesh sieve to obtain cotton stalk powder; then washed three times with deionized water and dried at 60°C for 6-12 hours.
3. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 1, cotton stalk powder and dicyandiamide are placed in a tube furnace crucible at a mass ratio of 1:1 and heated to 400-700 °C under an argon atmosphere, and maintained at this temperature for 2 h.
4. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 1, after heating, the product, which has cooled naturally to room temperature, is washed with deionized water until neutral, and then dried at 60 °C for 4-6 h.
5. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 2, 0.1-0.3 parts of the nitrogen-doped cotton stalk biochar prepared in step 1 are weighed and added to 100 parts of a mixed solution of 0.1 mol / L Co(NO3)2·6H2O and 0.01-0.3 mol / L La(NO3)2·6H2O anhydrous ethanol. The mixture is dispersed at a stirring speed of 400-800 rpm for 4-8 hours.
6. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 2, the solid sample is dried at 60 °C for 4-6 h. After drying, the sample is placed in a tube furnace and calcined at 500-900 °C for 2-4 h under an argon atmosphere.
7. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 3, 100 portions of 20 mg / L aqueous solutions of different pollutants were added to a light-protected catalytic reactor, and a heterogeneous reaction was initiated by adding 0.3 g / L of nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst and 5 mmol PMS.
8. The method for removing organic pollutants using a nitrogen-doped cotton stalk biochar-supported LaCoO3 catalyst according to claim 1, characterized in that, In step 3, the initial solution pH is precisely controlled using 0.1 mol / L H2SO4 and NaOH. 1 mL of sample is extracted at selected time intervals, filtered through a 0.22 μm filter, and 0.1 mL of methanol is added.