CN118022716A - Oxygen-doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants - Google Patents
Oxygen-doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants Download PDFInfo
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- 239000010802 sludge Substances 0.000 title claims abstract description 116
- 230000003197 catalytic effect Effects 0.000 title claims abstract description 26
- 239000002957 persistent organic pollutant Substances 0.000 title claims abstract description 14
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- 238000006731 degradation reaction Methods 0.000 title claims abstract description 8
- 239000000843 powder Substances 0.000 claims abstract description 33
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 30
- 239000010439 graphite Substances 0.000 claims abstract description 30
- 239000003054 catalyst Substances 0.000 claims abstract description 19
- 239000000463 material Substances 0.000 claims abstract description 19
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- 239000005077 polysulfide Substances 0.000 claims abstract description 18
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- 238000007254 oxidation reaction Methods 0.000 claims abstract description 17
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 16
- 238000003763 carbonization Methods 0.000 claims abstract description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 239000001301 oxygen Substances 0.000 claims abstract description 12
- 239000012065 filter cake Substances 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 9
- 230000005684 electric field Effects 0.000 claims abstract description 8
- 238000000227 grinding Methods 0.000 claims abstract description 8
- 239000003792 electrolyte Substances 0.000 claims abstract description 7
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- 239000002994 raw material Substances 0.000 claims abstract description 7
- 238000012546 transfer Methods 0.000 claims abstract description 7
- 239000000243 solution Substances 0.000 claims description 39
- 238000004519 manufacturing process Methods 0.000 claims description 10
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 229920002584 Polyethylene Glycol 6000 Polymers 0.000 claims description 7
- 229940093429 polyethylene glycol 6000 Drugs 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 6
- 239000010865 sewage Substances 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 4
- 238000007598 dipping method Methods 0.000 claims description 4
- 239000010842 industrial wastewater Substances 0.000 claims description 4
- 239000011593 sulfur Substances 0.000 claims description 4
- ODHAQPXNQDBHSH-UHFFFAOYSA-N Dicyclohexyl disulfide Chemical compound C1CCCCC1SSC1CCCCC1 ODHAQPXNQDBHSH-UHFFFAOYSA-N 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 239000000835 fiber Substances 0.000 claims description 3
- 238000003786 synthesis reaction Methods 0.000 claims description 3
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- 230000035484 reaction time Effects 0.000 claims description 2
- 238000001914 filtration Methods 0.000 abstract description 7
- 238000005406 washing Methods 0.000 abstract description 7
- 238000011068 loading method Methods 0.000 abstract description 3
- 238000002791 soaking Methods 0.000 abstract description 2
- RBTBFTRPCNLSDE-UHFFFAOYSA-N 3,7-bis(dimethylamino)phenothiazin-5-ium Chemical compound C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 RBTBFTRPCNLSDE-UHFFFAOYSA-N 0.000 description 9
- 229960000907 methylthioninium chloride Drugs 0.000 description 9
- 125000000524 functional group Chemical group 0.000 description 7
- 239000002028 Biomass Substances 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 239000003610 charcoal Substances 0.000 description 6
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- 229910021645 metal ion Inorganic materials 0.000 description 4
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- 238000000643 oven drying Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 238000000197 pyrolysis Methods 0.000 description 3
- BTJIUGUIPKRLHP-UHFFFAOYSA-N 4-nitrophenol Chemical compound OC1=CC=C([N+]([O-])=O)C=C1 BTJIUGUIPKRLHP-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- PGSADBUBUOPOJS-UHFFFAOYSA-N neutral red Chemical compound Cl.C1=C(C)C(N)=CC2=NC3=CC(N(C)C)=CC=C3N=C21 PGSADBUBUOPOJS-UHFFFAOYSA-N 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229960005404 sulfamethoxazole Drugs 0.000 description 2
- JLKIGFTWXXRPMT-UHFFFAOYSA-N sulphamethoxazole Chemical compound O1C(C)=CC(NS(=O)(=O)C=2C=CC(N)=CC=2)=N1 JLKIGFTWXXRPMT-UHFFFAOYSA-N 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 1
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- 230000004913 activation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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- 239000004566 building material Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
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- 230000029087 digestion Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000004185 ester group Chemical group 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000010335 hydrothermal treatment Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000010525 oxidative degradation reaction Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000011085 pressure filtration Methods 0.000 description 1
- 238000011027 product recovery Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 231100001234 toxic pollutant Toxicity 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/18—Carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
- B01J37/084—Decomposition of carbon-containing compounds into carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/10—Heat treatment in the presence of water, e.g. steam
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/74—Treatment of water, waste water, or sewage by oxidation with air
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
- C02F2001/46133—Electrodes characterised by the material
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- Chemical & Material Sciences (AREA)
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- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
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Abstract
The invention discloses oxygen-doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants, which are prepared by taking municipal sludge dry powder as a raw material, soaking the municipal sludge dry powder in H 2SO4, filtering and washing the municipal sludge dry powder to be neutral, dispersing a filter cake in polysulfide-containing solution for hydrothermal carbonization, filtering, washing and drying the filter cake, grinding the filter cake into powder, loading the powder on the surface of a graphite felt, and carrying out heat treatment at 800 ℃ in a nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material. In a three-electrode system at normal temperature and normal pressure, an oxygen doped modified sludge-based biochar material is used as an anode catalyst, na 2SO4 is used as an electrolyte, air is blown into the bottom of the reactor to increase reaction mass transfer and provide O 2, and the air oxidation reaction is catalyzed under the driving of a weak electric field, so that an organic pollutant solution with a certain concentration can be completely removed within 2 hours, and the circulating stability is good.
Description
Technical Field
The invention belongs to the field of sewage treatment, and particularly relates to oxygen-doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants.
Background
With the development of cities, the scale of sewage plants and the sewage treatment capacity are continuously increased, and the total amount of sludge generated is increased year by year. Municipal sludge contains not only organic matter but also heavy metals, microorganisms, toxic pollutants and the like, and if not properly treated, the environment is seriously affected. At present, municipal sludge treatment and disposal technologies mainly comprise landfill, incineration, agricultural increment, anaerobic digestion to produce biogas, building material substitution and the like. The disposal techniques have the defects of secondary pollution, low product recovery rate, harmful gas generation and the like. Therefore, it is of great importance to develop a cost-effective and environmentally friendly sludge treatment disposal process. The high-temperature pyrolysis is converted into the sludge biochar with high added value, which is a way for solving the problem of sludge treatment and disposal and has development prospect.
The sludge biochar is a carbon-based material obtained by high-temperature treatment of a sludge precursor under anaerobic conditions, and the main preparation methods of the sludge biochar include a hydrothermal carbonization method, a pyrolysis method, a microwave pyrolysis method and the like. The sludge biochar surface contains C, O, H, N and other elements, has the advantages of large specific surface area, rich pore structure and functional groups and self-doping of elements, and is widely studied in the aspect of catalytic oxidation of organic pollutants in water. In order to improve the catalytic performance of the sludge biochar, the sludge biochar is usually required to be further subjected to preparation process regulation, activation or doping modification. By modifying or loading the functional nano particles, the functional groups on the surface of the sludge biochar can be increased, and active sites participating in the reaction are increased.
Disclosure of Invention
The invention aims to provide oxygen doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants. The invention utilizes organic matters in sludge and polysulfide in industrial sulfur-containing wastewater to react under hydrothermal condition to obtain hydrothermal carbonized sludge, and then obtains oxygen-doped sludge-based biochar through anaerobic high-temperature heat treatment, and the oxygen-doped sludge-based biochar is used as a catalyst for electrically-assisted catalytic wet-type air oxidation reaction and is applied to purification of organic wastewater. The invention prepares the sludge-based biochar catalyst material from municipal sludge, fully exerts the advantages of rich nonmetallic functional groups on the surface of the sludge biochar, large specific surface area, easy doping modification and the like, and remarkably enhances the catalytic activity of the sludge-based biochar catalyst material in the electro-assisted catalytic wet air oxidation reaction.
The invention relates to a preparation method of oxygen-doped modified sludge-based biochar, which takes municipal sludge dry powder as a raw material, is immersed by H 2SO4, is filtered and washed to be neutral, a filter cake is dispersed in polysulfide-containing solution for hydrothermal carbonization, is filtered, washed and dried, is ground into powder, is loaded on the fiber surface of a graphite felt, and is subjected to heat treatment at 800 ℃ in nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material.
The municipal sludge dry powder is prepared by taking municipal sludge with the water content of 80% of a sewage treatment plant as a raw material, conditioning the raw material with sulfuric acid with the concentration of 10%, performing thin-layer filter pressing to obtain sludge cakes with the water content of 40%, drying, and grinding the dried sludge cakes into sludge dry powder with the particle size smaller than 80 meshes.
The concentration of the H 2SO4 solution used in the dipping is 0.1-3 mol.L -1, and the dipping time is 12-24 hours.
The polysulfide-containing solution is from reddish brown industrial wastewater of a dicyclohexyl disulfide synthesis section in the production of a rubber scorch retarder CTP, wherein the sulfur content is 2-2.2%, the pH value of the solution is 14, and the solution can be diluted 1-10 times before use.
The reaction temperature of the hydrothermal carbonization is 120-180 ℃ and the reaction time is 6-18 h.
The particle size of the grinded hydrothermal carbonized sludge is below 200 meshes.
The method for loading the sludge after the hydrothermal carbonization into the graphite felt comprises the steps of dispersing the sludge powder after the hydrothermal carbonization into 2% polyethylene glycol-6000 aqueous solution, sucking the solution after the uniform stirring into the graphite felt, and suspending the solution in a 60 ℃ oven for drying.
The mass ratio of the polyethylene glycol to the hydrothermal carbonized sludge to the graphite felt is 1-2:1-5:5.
The application of the oxygen-doped modified sludge-based biochar is to take the oxygen-doped modified biomass charcoal as an anode catalyst, and catalyze air oxidation to degrade organic pollutants under the promotion of a weak electric field.
Specifically, in a three-electrode system, oxygen doped modified sludge-based biochar is used as an anode catalyst, na 2SO4 is used as an electrolyte, air is blown into the bottom of a reactor to increase reaction mass transfer and provide O 2, and the air oxidation reaction is catalyzed under the driving of a weak electric field, so that organic pollutants can be completely removed within 2 hours, and the circulating stability is good.
The current intensity of the weak electric field is constant at 10mA.
The concentration of the organic pollutants is 30-100 mg.L -1, and the air flow rate is 2 L.min -1.
The organic pollutants comprise methylene blue, neutral red, sulfamethoxazole and p-nitrophenol.
Compared with the prior art, the invention has the beneficial effects that:
1. The invention prepares the sludge-based biochar catalyst material from municipal sludge, fully exerts the advantages of rich organic functional groups, large specific surface area, easy doping modification and the like on the surface of the sludge biochar, and remarkably enhances the catalytic activity in the electro-assisted catalytic wet air oxidation reaction.
2. According to the invention, municipal sludge solid waste is taken as a biochar precursor, polysulfide-containing industrial wastewater is taken as a modifier, so that the preparation cost of a catalyst material is reduced, and a thought is provided for recycling treatment of two wastes.
3. According to the invention, the non-metal element doped modified sludge-based biochar material is adopted, the prepared catalyst does not have metal ion leaching in the weak electric field action process, and the material has good use stability.
Drawings
FIG. 1 is an XPS total spectrum of the sludge hydrothermal doping and undoped product and the biomass charcoal material after the high temperature heat treatment thereof used in example 1. It can be seen that the undoped hydrothermal sludge contains C, S, O and N nonmetallic elements, the O and N contents are obviously reduced after the heat treatment under the anaerobic condition at 800 ℃, and the S and C contents are increased. The S and O contents of the sludge after the hydrothermal treatment in the sulfide solution are obviously increased, the C and N contents are reduced, and after the anaerobic carbonization treatment at 800 ℃, the O content is obviously increased compared with that of undoped sludge biochar, and other three elements are lower than that of undoped materials, so that the sludge after the hydrothermal reaction with polysulfide and the high-temperature carbonization treatment mainly undergoes oxygen doping reaction.
FIG. 2 is a graph of the C1s high-definition XPS spectrum of the sludge hydrothermal doped and undoped products and the biomass charcoal material after the high temperature heat treatment thereof used in example 1. It can be seen that the surface of undoped hydrothermal sludge and carbonized sludge contains C-C/c= C, C-O-C and C-COOH groups, and both c=o and O-c=o functional groups are added to the doped hydrothermal sludge and carbonized sludge. Indicating that the active sites of the catalyst are mainly c=o and o—c=o functional groups.
FIG. 3 is an evaluation of catalytic oxidative degradation performance of different catalysts on methylene blue under the conditions of example 1. It can be seen that the oxygen-doped sludge-based biochar is used as an anode catalyst for electrically promoting the wet air oxidation reaction, and the removal efficiency of methylene blue reaches 100% within 2 hours. The removal rate of methylene blue of the undoped sludge biochar is only slightly higher than that of the graphite felt carrier due to the lack of the catalytic active site, and the electric adsorption of the sludge-based biochar is enhanced probably due to the high specific surface area of the sludge-based biochar. Although the hydrothermal doped sludge has catalytic active sites, the material is not carbonized at high temperature, the conductivity is poor, and the electric field cannot effectively activate the catalytic active sites, so that the removal efficiency of methylene blue is the lowest.
Fig. 4 is an evaluation of the cycling stability of oxygen-doped sludge biomass charcoal to electro-assist catalytic wet air oxidation degradation of methylene blue under the conditions of example 1. It can be seen that the active site of the oxygen-doped sludge-based biochar catalyst is carbonyl or ester functional group, so that the problem of metal ion leaching does not exist, and the cycle stability is very excellent.
FIG. 5 shows the effect of municipal sludge dry powder immersed in H 2SO4 solutions of different concentrations for 12H on the catalytic oxidation of methylene blue by the prepared oxygen-doped sludge biomass charcoal under the conditions of example 1. It can be seen that the catalytic performance of the prepared sludge biochar gradually decreases after the concentration of sulfuric acid is lower than 1 mol.L -1. Mainly municipal sludge contains metal ions such as iron and aluminum, and the metal ions are easy to form hydroxide or sulfide sediment in alkaline polysulfide solution, prevent doping modification of organic functional groups, and form non-catalytic active metals and compounds thereof after high-temperature heat treatment, so that the catalytic active sites of the catalyst are reduced.
Fig. 6 shows the effect of polysulfide solution dilution on the catalytic oxidation of methylene blue by prepared oxygen-doped sludge biomass charcoal under the same hydrothermal pH conditions (pH adjusted with NaOH) under the conditions of example 1. It can be seen that the lower the mass ratio of polysulfide to sludge, the less favorable the oxygen doping reaction, especially when polysulfide concentrations are diluted more than 2 times, the catalytic performance of the sludge biochar begins to decrease.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to some embodiments.
Municipal sludge used in the following examples is municipal sludge with water content of 80% of a sewage treatment plant, and is subjected to thin-layer pressure filtration after being conditioned by sulfuric acid with concentration of 10% to obtain sludge cake with water content of 40%, and is dried and ground into sludge dry powder with particle size smaller than 80 meshes.
The polysulfide solution used in the following examples is from the reddish brown industrial wastewater of dicyclohexyl disulfide synthesis section in the production of rubber scorch retarder CTP, wherein the sulfur content is 2-2.2%, the pH value of the solution is 14, and the polysulfide solution can be diluted 1-10 times before use.
Example 1:
5.0g of municipal sludge dry powder is taken in 1 mol.L -1H2SO4 solution, stirred uniformly and immersed for 12 hours, filtered and washed to be neutral, the filter cake is placed in polysulfide solution diluted by 1 time, and the mixture is subjected to hydrothermal carbonization for 12 hours at 180 ℃ after uniform dispersion. Cooling, filtering, washing, oven drying at 60deg.C for 24 hr, grinding, and collecting powder below 200 mesh. Dispersing the powder of the hydrothermal carbonized sludge into 2% polyethylene glycol-6000 aqueous solution according to the weight ratio of the polyethylene glycol to the hydrothermal carbonized sludge to the graphite felt of 2:5:5, fully and uniformly stirring, placing the graphite felt into the solution until the solution is completely absorbed into the graphite felt, and suspending the graphite felt in a 60 ℃ oven for drying for 12 hours. And finally, placing the graphite felt loaded with the hydrothermal sludge into a tube furnace, and performing heat treatment at 800 ℃ for 2 hours in a nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material.
In a three-electrode system at normal temperature and normal pressure, an oxygen doped modified sludge-based biochar electrode is used as an anode catalyst, na 2SO4 is used as an electrolyte, air is blown into the bottom of the reactor at the flow rate of 2 L.min -1 to increase the mass transfer of the reaction, and O 2 is provided, and the air oxidation reaction is catalyzed under the current intensity of 10mA, so that the removal rate of the methylene blue solution with the concentration of 50 mg.L -1 can reach 100 percent within 2 hours.
Example 2:
Taking 1.0g of municipal sludge dry powder in 0.1 mol.L -1H2SO4 solution, uniformly stirring, soaking for 24 hours, filtering and washing to be neutral, placing a filter cake into 10 times diluted polysulfide solution, and carrying out hydrothermal carbonization at 120 ℃ for 18 hours after uniform dispersion. Cooling, filtering, washing, oven drying at 60deg.C for 24 hr, grinding, and collecting powder below 200 mesh. Dispersing the powder of the hydrothermal carbonized sludge into 2% polyethylene glycol-6000 aqueous solution according to the weight ratio of the polyethylene glycol to the hydrothermal carbonized sludge to the graphite felt of 1:1:5, fully and uniformly stirring, placing the graphite felt into the solution until the solution is completely absorbed into the graphite felt, and suspending the graphite felt in a 60 ℃ oven for drying for 12 hours. And finally, placing the graphite felt loaded with the hydrothermal sludge into a tube furnace, and performing heat treatment at 800 ℃ for 2 hours in a nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material.
In a three-electrode system at normal temperature and normal pressure, an oxygen doped modified sludge-based biochar electrode is used as an anode catalyst, na 2SO4 is used as an electrolyte, air is blown into the bottom of the reactor at the flow rate of 2 L.min -1 to increase the mass transfer of the reaction, and O 2 is provided, and the air oxidation reaction is catalyzed under the current intensity of 10mA, so that the removal rate of neutral red with the concentration of 80 mg.L -1 can reach 100 percent within 2 hours.
Example 3:
3.0g of municipal sludge dry powder is taken and stirred uniformly in 1 mol.L -1H2SO4 solution, immersed for 18h, filtered and washed to be neutral, the filter cake is placed in polysulfide solution diluted by 2 times, and the filter cake is subjected to hydrothermal carbonization for 10h at 150 ℃ after uniform dispersion. Cooling, filtering, washing, oven drying at 60deg.C for 24 hr, grinding, and collecting powder below 200 mesh. Dispersing the powder of the hydrothermal carbonized sludge into 2% polyethylene glycol-6000 aqueous solution according to the weight ratio of the polyethylene glycol to the hydrothermal carbonized sludge to the graphite felt of 2:3:5, fully and uniformly stirring, placing the graphite felt into the solution until the solution is completely absorbed into the graphite felt, and suspending the graphite felt in a 60 ℃ oven for drying for 12 hours. And finally, placing the graphite felt loaded with the hydrothermal sludge into a tube furnace, and performing heat treatment at 800 ℃ for 2 hours in a nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material.
In a three-electrode system at normal temperature and normal pressure, an oxygen doped modified sludge-based biochar electrode is used as an anode, na 2SO4 is used as an electrolyte, air is blown into the bottom of the reactor at the flow rate of 2 L.min -1 to increase the mass transfer of the reaction, and the catalytic air oxidation reaction is carried out under the current intensity of O 2 and 10mA, so that the removal rate of the sulfamethoxazole solution with the concentration of 30 mg.L -1 in 2h can reach 100%.
Example 4:
5.0g of municipal sludge dry powder is taken in 1 mol.L -1H2SO4 solution, stirred uniformly and immersed for 12h, filtered and washed to be neutral, the filter cake is placed in polysulfide solution diluted by 1 time, dispersed uniformly and carbonized for 6h under 180 ℃. Cooling, filtering, washing, oven drying at 60deg.C for 24 hr, grinding, and collecting powder below 200 mesh. Dispersing the powder of the hydrothermal carbonized sludge into 2% polyethylene glycol-6000 aqueous solution according to the weight ratio of the polyethylene glycol to the hydrothermal carbonized sludge to the graphite felt of 2:5:5, fully and uniformly stirring, placing the graphite felt into the solution until the solution is completely absorbed into the graphite felt, and suspending the graphite felt in a 60 ℃ oven for drying for 12 hours. And finally, placing the graphite felt loaded with the hydrothermal sludge into a tube furnace, and performing heat treatment at 800 ℃ for 2 hours in a nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material.
In a three-electrode system at normal temperature and normal pressure, an oxygen doped modified sludge-based biochar electrode is used as an anode catalyst, na 2SO4 is used as an electrolyte, air is blown into the bottom of the reactor at the flow rate of 2 L.min -1 to increase the mass transfer of the reaction, and O 2 is provided, and the catalytic air oxidation reaction is carried out under the current intensity of 10mA, so that the removal rate of p-nitrophenol with the concentration of 100 mg.L -1 can reach 100 percent within 2 hours.
Claims (10)
1. The preparation method of the oxygen doped modified sludge-based biochar is characterized by comprising the following steps of:
The municipal sludge dry powder is used as a raw material, is immersed in H 2SO4 solution, is filtered and washed to be neutral, a filter cake is dispersed in polysulfide-containing solution for hydrothermal carbonization, is filtered, washed and dried and is ground into powder, the obtained hydrothermal carbonized sludge powder is loaded on the surface of graphite felt fiber, and is subjected to heat treatment in nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material.
2. The method of manufacturing according to claim 1, characterized in that:
The municipal sludge dry powder is prepared by taking municipal sludge with the water content of 80% of a sewage treatment plant as a raw material, conditioning the raw material with sulfuric acid with the concentration of 10%, performing thin-layer filter pressing to obtain sludge cakes with the water content of 40%, drying, and grinding the dried sludge cakes into sludge dry powder with the particle size smaller than 80 meshes.
3. The method of manufacturing according to claim 1, characterized in that:
The concentration of the H 2SO4 solution used in the dipping is 0.1-3 mol.L -1, and the dipping time is 12-24 hours.
4. The method of manufacturing according to claim 1, characterized in that:
The polysulfide-containing solution is from reddish brown industrial wastewater of a dicyclohexyl disulfide synthesis section in the production of a rubber scorch retarder CTP, wherein the sulfur content is 2.0-2.2%, the pH value of the solution is 14, and the solution is diluted by 1-10 times before use.
5. The method of manufacturing according to claim 1, characterized in that:
the reaction temperature of the hydrothermal carbonization is 120-180 ℃ and the reaction time is 6-18 h.
6. The method of manufacturing according to claim 1, characterized in that:
The particle size of the hydrothermal carbonized sludge powder obtained after grinding is below 200 meshes.
7. The method of manufacturing according to claim 1, characterized in that:
The hydrothermal carbonized sludge powder is loaded on the surface of the graphite felt fiber by the following method: firstly, dispersing the hydrothermal carbonized sludge powder in 2% polyethylene glycol-6000 aqueous solution, sucking the uniformly stirred solution into a graphite felt, and suspending and drying at 60 ℃.
8. The method of manufacturing according to claim 7, wherein:
the mass ratio of the polyethylene glycol-6000 to the hydrothermal carbonized sludge powder to the graphite felt is 1-2:1-5:5.
9. Use of oxygen-doped biochar obtained by the preparation method according to any one of claims 1 to 8 for the catalytic degradation of organic pollutants, characterized in that:
And taking the oxygen doped biochar as an anode catalyst to catalyze the air oxidation and degradation of organic pollutants.
10. The use according to claim 9, characterized in that:
In a three-electrode system at normal temperature and normal pressure, oxygen doped modified sludge-based biochar material is used as an anode catalyst, na 2SO4 is used as an electrolyte, and air is blown into the bottom of a reactor to increase reaction mass transfer and provide O 2, and the air oxidation reaction is catalyzed under the driving of a weak electric field to degrade organic pollutants; the current intensity of the weak electric field is constant at 10mA.
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