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CN-118022716-B - Oxygen-doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants

CN118022716BCN 118022716 BCN118022716 BCN 118022716BCN-118022716-B

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 2 SO 4 , 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 2 SO 4 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.

Inventors

  • ZHAI LINFENG
  • LI ANRAN
  • SUN MIN
  • Dong Nianxia
  • XIA YUE

Assignees

  • 合肥工业大学

Dates

Publication Date
20260505
Application Date
20240206

Claims (8)

  1. 1. The preparation method of the oxygen doped modified sludge-based biochar is characterized by comprising the following steps of: Taking municipal sludge dry powder as a raw material, soaking the raw material in H 2 SO 4 solution, filtering and washing the raw material 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 obtained hydrothermal carbonized sludge powder on the surface of graphite felt fibers, and carrying out heat treatment in a nitrogen atmosphere to obtain the oxygen-doped modified sludge-based biochar material; The concentration of the H 2 SO 4 solution used in the impregnation is 0.1-3 mol.L -1 , and the impregnation 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 2.0-2.2%, the pH value of the solution is 14, and the solution is diluted by 1-10 times before use.
  2. 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. 3. 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.
  4. 4. 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.
  5. 5. The method of manufacturing according to claim 1, characterized in that: the method for loading the hydrothermal carbonized sludge powder on the surface of the graphite felt fiber is realized by dispersing the hydrothermal carbonized sludge powder in 2% polyethylene glycol-6000 aqueous solution, sucking the uniformly stirred solution into the graphite felt, and suspending and drying at 60 ℃.
  6. 6. The method of manufacturing according to claim 5, 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.
  7. 7. Use of oxygen-doped biochar obtained by the preparation method according to any one of claims 1 to 6 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.
  8. 8. The use according to claim 7, characterized in that: 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 2 SO 4 is used as an electrolyte, air is blown into the bottom of a reactor to increase reaction mass transfer and provide O 2 , air oxidation reaction is catalyzed under the driving of a weak electric field, and organic pollutants are degraded, wherein the current intensity of the weak electric field is constant at 10mA.

Description

Oxygen-doped modified sludge-based biochar and application thereof in catalytic degradation of organic pollutants 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 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 impregnation is 0.1-3 mol.L -1, and the impregnation 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 polysulfide-containing 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 is to disperse the powder of the sludge after the hyd