CN114367278B - Method for preparing biochar composite catalytic material and application - Google Patents
Method for preparing biochar composite catalytic material and application Download PDFInfo
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- CN114367278B CN114367278B CN202210282525.3A CN202210282525A CN114367278B CN 114367278 B CN114367278 B CN 114367278B CN 202210282525 A CN202210282525 A CN 202210282525A CN 114367278 B CN114367278 B CN 114367278B
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
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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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
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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
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
- C02F2101/345—Phenols
Abstract
The invention relates to a method for preparing a biochar composite catalytic material and application thereof. The invention takes solid waste corn straws and cheap carnallite as raw materials, and prepares a novel biochar composite catalytic material by a simple and convenient process. Compared with the traditional purifying material in the technical field of soil/water organic pollution purification, the material has remarkable advantages, can achieve the removal efficiency of more than 90 percent of various organic matters at low cost on the premise of using as little catalyst as possible under the same condition, and has remarkable effect.
Description
Technical Field
The invention belongs to the technical field of soil/water organic pollution purification, and particularly relates to a method for preparing a biochar composite catalytic material by using corn stalks and carnallite as raw materials and application of the biochar composite catalytic material.
Background
With the increase of industrial activities, the problems of ecological environment safety and human health caused by the fact that organic chemicals enter soil/water environment due to leakage of pipelines and storage tanks or other accidents are receiving increasing attention.
In the technology of purifying organic soil/water pollution, Advanced Oxidation Processes (AOPs) are considered as an effective method for degrading organic pollutants. Persulfate-based AOPs utilize sulfate free radicals (SO) generated by activating persulfate4 -· OH), hydroxyl radicals (·) or non-radical reactive oxygen species (such as singlet oxygen,1O2) And the organic pollutants in the soil/water can be efficiently removed by oxidation.
Examples of the method for activating the persulfate include thermal activation, ion activation, activation of a carbon-based material, and the like. The thermal activation method has the problem of high energy consumption; the ion activation method has the problem that activated ions are easy to lose and even cause secondary pollution. The carbon-based material has the advantages of large specific surface area, adjustable pore structure and surface functional group, good conductivity, good adsorption performance on organic pollutants and the like, and has good application prospect in the technical fields of catalytic activity persulfate and organic pollutant purification in soil/water media.
In order to further improve the performance of the persulfate with the catalytic activity of the carbon-based material, people develop an ion-doped modified carbon-based composite catalytic material, which can not only improve the performance of the persulfate with the catalytic activity, but also effectively inhibit ion loss, and is an activated persulfate functional material with great development potential.
So far, researches on catalytic activation of persulfate to oxidize and degrade organic pollutants in soil/water by doping and modifying a carbon-based material with carnallite have not been reported.
Disclosure of Invention
The invention provides a method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials and application of the biochar composite catalytic material in removing organic pollutants in soil/water by activating persulfate.
In order to achieve the purpose, the invention adopts the technical scheme that:
the method comprises the steps of dissolving carnallite in water, adding a certain amount of corn straws, soaking, evaporating, drying, roasting and cooling to prepare the biochar composite catalytic material capable of catalytically activating persulfate, wherein activated oxygen species after the persulfate is catalytically activated can be oxidized to remove organic pollutants in soil/water. The active oxygen species include sulfate radicals (SO)4 -· OH), hydroxyl radical (· OH), singlet oxygen.
Wherein the preferred raw materials comprise the following components in percentage by mass: 80-95% of corn straw and 5-20% of carnallite.
The method for preparing the biochar composite catalytic material by taking the corn straws and the carnallite as raw materials comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.3-1.2 g of carnallite in 200 mL of water;
2) dipping: crushing corn straws, sieving the crushed corn straws by a sieve of 80-200 meshes, adding the sieved corn straws into the prepared solution, and stirring and mixing the corn straws at the speed of 200-400 r/min for 4-10 hours;
3) and (3) evaporation: removing water from the stirred mixture at 80-120 ℃ to constant weight;
4) roasting: roasting the material with the water removed firstly in nitrogen atmosphereHeating to 400-850 deg.C, maintaining the temperature and switching to CO2Atmosphere of CO2Continuously roasting for 40-80 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 6-12 h to obtain the biochar composite catalytic material.
Preferably, the nitrogen heating rate is 5-15 ℃/min, and the temperature of the nitrogen atmosphere is 400-850 ℃.
The biochar composite catalytic material is used for treating organic contaminated soil, the catalyst biochar composite catalytic material and the oxidant persulfate are respectively prepared into solutions, the solutions are injected into the organic contaminated soil, and the agents and the soil are uniformly mixed through mechanical stirring. And after reacting for 30-60 days, taking a soil sample, purifying, and analyzing the content of the residual organic pollutants in the soil by using a gas or liquid chromatograph. The concentration of organic pollutants in the soil is 20-1000 mg/kg, the dosage of the catalyst biochar composite catalytic material is 1-5 g/L, the dosage of the oxidant persulfate is 1-8 g/L, the water content of the soil is 15% -40%, the removal efficiency can reach more than 90%, and the mass ratio of the dosages of the catalyst to the oxidant is preferably 1:1-1: 1.7.
The biochar composite catalytic material is used for treating organic pollutant wastewater, a catalyst biochar composite catalytic material and an oxidant persulfate are added into the organic wastewater, the materials are uniformly mixed and then react for 10-120 min, and a reacted water sample is taken and a gas or liquid chromatograph is adopted to analyze the content of residual organic matters in a water body. Wherein the concentration of organic pollutants in the wastewater is 20-100 mg/L, the dosage of the catalyst composite biochar material is 0.3-1.5 g/L, and the dosage of the oxidant persulfate is 0.2-2 g/L, so that the removal efficiency can reach more than 99%.
The organic contaminated soil is soil contaminated by polycyclic aromatic hydrocarbons (such as benzo (a) pyrene, phenanthrene and the like) or benzene series (such as toluene, xylene and the like). The organic pollutant wastewater is phenol (such as phenol, chlorophenol and the like) wastewater or halogenated hydrocarbon (such as dichloroethylene, trichloroethylene and the like) wastewater and the like.
Compared with the prior art, the invention has the beneficial effects that:
the invention takes solid waste corn straws and cheap carnallite as raw materials, and prepares a novel biochar composite catalytic material by a simple and convenient process. Compared with the traditional purification material in the technical field of soil/water organic pollution purification, the material has remarkable advantages, can achieve the removal efficiency of more than 90 percent of various organic matters at low cost on the premise of using as little catalyst as possible under the same condition, has remarkable effect, and has specific comparison data shown in tables 1 and 2
The initial concentration of benzo (a) pyrene in the contaminated soil was: 120 mg/kg, the initial concentration of toluene is 330 mg/kg; catalyst: 2 g/L; oxidizing agent: 2 g/L; reaction time 40 d
The initial concentrations of phenol in the wastewater were: 50 mg/L; catalyst: 0.5 g/L; oxidizing agent: 0.6 g/L; the reaction time was 60 min.
Detailed Description
In order to better understand the contents of the present invention, the following embodiments are further described, but the scope of the present invention is not limited by the examples.
The invention creatively uses carnallite (KCl MgCl)2·6H2O) is used as a raw material, the carbon-based material is doped and modified, the preparation cost can be obviously reduced on the premise of greatly improving the catalytic efficiency, and great economic benefit is brought.
Example 1
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.6g of carnallite in 200 mL of water;
2) dipping: crushing corn straws, sieving the crushed corn straws with a 80-mesh sieve, adding 5.4 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 9: 1), and stirring and mixing the corn straws and the carnallite for 6 hours at the speed of 300 r/min;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere, and then CO is switched at 800 DEG C2Atmosphere of CO2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) Experiment for purifying organic pollutants in soil:
the biochar composite catalytic material is used for removing benzo (a) pyrene in benzo (a) pyrene polluted soil. The experimental process comprises the following specific steps:
in the soil polluted by benzo (a) pyrene in the embodiment of the invention, the water content is 25%, and the content of benzo (a) pyrene is 120 mg/kg.
Treating the soil polluted by benzo (a) pyrene by using the biochar composite catalytic material, and respectively distributing 200 mg of catalyst biochar composite catalytic material and 200 mg of oxidant sodium persulfate into 100 mL of water to prepare mixed liquid; and (2) injecting 50 mL of mixed liquid prepared from the biochar composite catalytic material into 1 kg of benzo (a) pyrene polluted soil, then injecting 50 mL of mixed liquid prepared from sodium persulfate, and mechanically stirring to uniformly mix the medicament (the medicament comprises an oxidant and a catalyst) and the soil. After reacting for 40 days, taking a soil sample, purifying, and analyzing the content of the residual benzo (a) pyrene in the soil by using a high performance liquid chromatography-ultraviolet method.
The result shows that after the reaction is carried out for 40 days, the removal rate of the benzo (a) pyrene in the soil is 96.7 percent if the content of the benzo (a) pyrene in the soil is 4 mg/kg.
Example 2
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.3 g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 5.7 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 9.5: 0.5), and stirring and mixing for 6 hours at the speed of 300 r/min;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) Experiment for purifying organic pollutants in soil:
the biochar composite catalytic material is used for removing benzo (a) pyrene in benzo (a) pyrene polluted soil. The experimental process comprises the following specific steps:
in the soil polluted by benzo (a) pyrene in the embodiment of the invention, the water content is 25%, and the content of benzo (a) pyrene is 120 mg/kg.
The biochar composite catalytic material is used for treating benzo (a) pyrene contaminated soil, 250 mg of catalyst biochar composite catalytic material and 300 mg of oxidant sodium persulfate are respectively distributed into 100 mL of water to prepare mixed liquid, 50 mL of mixed liquid prepared from the biochar composite catalytic material is injected into 1 kg of benzo (a) pyrene contaminated soil, 50 mL of mixed liquid prepared from sodium persulfate is injected, and the mixture is mechanically stirred to uniformly mix the medicament and the soil. After reacting for 40 days, taking a soil sample, purifying, and analyzing the content of the residual benzo (a) pyrene in the soil by using a high performance liquid chromatography-ultraviolet method.
The result shows that after the reaction is carried out for 40 days, the removal rate of the benzo (a) pyrene in the soil is 97.1 percent when the content of the benzo (a) pyrene in the soil is 3.5 mg/kg.
Example 3
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 1.2 g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 4.8 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 8: 2), and stirring and mixing at the speed of 300 r/min for 6 hours;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) Experiment for purifying organic pollutants in soil:
the biochar composite catalytic material is used for removing benzo (a) pyrene in benzo (a) pyrene polluted soil. The experimental process comprises the following specific steps:
in the soil polluted by benzo (a) pyrene in the embodiment of the invention, the water content is 25%, and the content of benzo (a) pyrene is 120 mg/kg.
The biochar composite catalytic material is used for treating the soil polluted by benzo (a) pyrene, 300 mg of catalyst biochar composite catalytic material and 400 mg of oxidant sodium persulfate are respectively distributed into 100 mL of water to prepare solution, 50 mL of liquid prepared from the biochar composite catalytic material is injected into 1 kg of soil polluted by benzo (a) pyrene, 50 mL of liquid prepared from sodium persulfate is injected, and the liquid is mechanically stirred to uniformly mix the medicament and the soil. After reacting for 40 days, taking a soil sample, purifying, and analyzing the content of the residual benzo (a) pyrene in the soil by using a high performance liquid chromatography-ultraviolet method.
The result shows that after the reaction is carried out for 40 days, the removal rate of the benzo (a) pyrene in the soil is 98.1% when the content of the benzo (a) pyrene in the soil is 2.3 mg/kg.
Example 4
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.6g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 5.4 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 9: 1), and stirring and mixing for 6 hours at the speed of 300 r/min;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) Experiment for purifying organic pollutants in soil:
the biochar composite catalytic material is used for removing toluene in toluene-polluted soil. The experimental process comprises the following specific steps:
in the soil polluted by methylbenzene, the water content is 25%, and the methylbenzene content is 330 mg/kg.
The method comprises the steps of treating toluene-polluted soil by using the biochar composite catalytic material, respectively distributing 300 mg of catalyst biochar composite catalytic material and 500 mg of oxidant sodium persulfate into 100 mL of water to prepare a solution, taking 50 mL of liquid prepared from the biochar composite catalytic material, injecting the liquid into 1 kg of benzo (a) pyrene-polluted soil, then injecting the liquid prepared from 50 mL of sodium persulfate, and mechanically stirring to uniformly mix a medicament and the soil. After reacting for 40 days, taking a soil sample, purifying, and analyzing the content of the residual toluene in the soil by using a gas chromatography.
The results showed that after 40 days of reaction, when the toluene content in the soil was 9.2 mg/kg, the removal rate of toluene in the soil was 97.2%.
Example 5
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.3 g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 5.7 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 9.5: 0.5), and stirring and mixing for 6 hours at the speed of 300 r/min;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) Experiment for purifying organic pollutants in soil:
the biochar composite catalytic material is used for removing toluene in toluene-polluted soil. The experimental process comprises the following specific steps:
in the organic contaminated soil of the embodiment of the invention, the water content is 25%, and the toluene content is 330 mg/kg.
The method comprises the steps of treating toluene-polluted soil by using the biochar composite catalytic material, respectively distributing 400 mg of catalyst biochar composite catalytic material and 600 mg of oxidant sodium persulfate into 100 mL of water to prepare a solution, taking 50 mL of liquid prepared from the biochar composite catalytic material, injecting the liquid into 1 kg of benzo (a) pyrene-polluted soil, then injecting the liquid prepared from 50 mL of sodium persulfate, and mechanically stirring to uniformly mix a medicament and the soil. After reacting for 40 days, taking a soil sample, purifying, and analyzing the content of the residual toluene in the soil by using a gas chromatography.
The results showed that after 40 days of reaction, when the toluene content in the soil was 7.4 mg/kg, the removal rate of toluene in the soil was 97.8%.
Example 6
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 1.2 g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 4.8 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 8: 2), and stirring and mixing at the speed of 300 r/min for 6 hours;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) Experiment for purifying organic pollutants in soil:
the biochar composite catalytic material is used for removing toluene in toluene-polluted soil. The experimental process comprises the following specific steps:
in the toluene-contaminated soil of the embodiment of the invention, the water content is 25%, and the toluene content is 330 mg/kg.
The method comprises the steps of treating toluene-polluted soil by using the biochar composite catalytic material, respectively distributing 500 mg of catalyst biochar composite catalytic material and 800 mg of oxidant sodium persulfate into 100 mL of water to prepare a solution, taking 50 mL of liquid prepared from the biochar composite catalytic material, injecting the liquid into 1 kg of benzo (a) pyrene-polluted soil, then injecting the liquid prepared from 50 mL of sodium persulfate, and mechanically stirring to uniformly mix a medicament and the soil. After reacting for 40 days, taking a soil sample, purifying, and analyzing the content of the residual toluene in the soil by using a gas chromatography.
The results showed that after 40 days of reaction, the toluene content in the soil was 3.2 mg/kg, and the removal rate of toluene in the soil was 99.0%.
Example 7
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.6g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 5.4 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 9: 1), and stirring and mixing at the speed of 300 r/min for 6 hours;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) The biochar composite catalytic material is used for removing phenol in organic pollutant wastewater. The experimental process comprises the following specific steps:
the phenol wastewater is treated in the embodiment of the invention, wherein the content of phenol is 50 mg/L.
Adding 50 mg of biochar composite catalytic material and 60 mg of persulfate into 100 mL of phenol wastewater with the concentration of 50 mg/L, and oscillating for reaction for 60 min. After the reaction is finished, a sample is purified, and then the concentration of phenol is detected by using high performance liquid chromatography-ultraviolet.
The result shows that the concentration of phenol in the wastewater after the reaction is 0.2 mg/L, and the removal efficiency of the biochar composite catalytic material on phenol in the wastewater is 99.6%.
Example 8
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 0.3 g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 5.7 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 9.5: 0.5), and stirring and mixing for 6 hours at the speed of 300 r/min;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) The biochar composite catalytic material is used for removing phenol in organic pollutant wastewater. The experimental process comprises the following specific steps:
the phenol wastewater is treated in the embodiment of the invention, wherein the content of phenol is 50 mg/L.
100 mg of the biochar composite catalytic material and 120 mg of persulfate are added into 100 ml of phenol wastewater with the concentration of 50 mg/L, and oscillation reaction is carried out for 60 min. After the reaction is finished, a sample is purified and then the phenol concentration is detected by using high performance liquid chromatography-ultraviolet.
The result shows that the concentration of phenol in the wastewater after the reaction is 0.14 mg/L, and the removal efficiency of the biochar composite catalytic material on phenol in the wastewater is 99.7%.
Example 9
(1) A method for preparing a biochar composite catalytic material by taking corn straws and carnallite as raw materials. The preparation method of the biochar composite catalytic material comprises the following specific steps:
1) dissolving carnallite in water: dissolving 1.2 g of carnallite in 200 mL of water;
2) dipping: crushing and sieving corn straws, adding 4.8 g of sieved corn straws into the solution (the mass ratio of the corn straws to the carnallite is 8: 2), and stirring and mixing for 6 hours at the speed of 300 r/min;
3) and (3) evaporation: removing water from the stirred mixture at 100 ℃ to constant weight;
4) roasting: the dried material is heated to 800 ℃ at the heating rate of 10 ℃/min in the nitrogen atmosphere and then CO is added2Continuously roasting for 60 min under the atmosphere;
5) and (3) cooling: stopping roasting, and cooling for 10 hours to obtain the biochar composite catalytic material.
(2) The biochar composite catalytic material is used for removing phenol in organic pollutant wastewater. The experimental process comprises the following specific steps:
the phenol wastewater is treated in the embodiment of the invention, wherein the content of phenol is 50 mg/L.
150 mg of the biochar composite catalytic material and 180 mg of persulfate are added into 100 ml of phenol wastewater with the concentration of 50 mg/L, and oscillation reaction is carried out for 60 min. After the reaction is finished, a sample is purified and then the phenol concentration is detected by using high performance liquid chromatography-ultraviolet.
The result shows that the concentration of phenol in the wastewater after the reaction is 0.11 mg/L, and the removal efficiency of the biochar composite catalytic material on phenol in the wastewater is 99.8%.
To more conveniently see the data changes in the examples, as shown in table 3:
comparative example 1
The carnallite doped biochar composite catalytic material in the example 1 is replaced by a potassium chloride doped biochar composite catalytic material, and the conditions in the example 1 are adopted for removing the organic substance benzo (a) pyrene in the benzo (a) pyrene polluted soil, namely 0.6g of potassium chloride is added in the comparative example and dissolved in 200 mL of water, and the rest steps are the same as the example 1.
The result shows that after 40 days, the removal rate is 40.8 percent when the content of the organic substance benzo (a) pyrene in the soil is 71 mg/kg.
Comparative example 2
The carnallite-doped biochar composite catalytic material in the example 1 is replaced by a magnesium chloride-doped biochar composite catalytic material, and the conditions in the example 1 are adopted for removing the organic substance benzo (a) pyrene in the benzo (a) pyrene-polluted soil. That is, in this comparative example, 0.6g of magnesium chloride was added and dissolved in 200 mL of water, and the procedure was the same as in example 1.
The result shows that after 40 days, the removal rate is 45.8 percent when the content of the organic substance benzo (a) pyrene in the soil is 65 mg/kg.
Comparative example 3
The potassium chloride-doped biochar composite catalytic material of comparative example 1 was treated according to the experimental procedure for the removal of toluene from toluene-contaminated soil under the conditions of example 4.
The results showed that after 40 days, the removal rate was 53.6% when the content of organic toluene in the soil was 153 mg/kg
Comparative example 4
The magnesium chloride-doped biochar composite catalytic material of comparative example 2 was treated according to the experimental procedure for the removal of toluene from toluene-contaminated soil under the conditions of example 4.
The results show that after 40 days, the content of organic toluene in the soil is 126 mg/kg, and the removal rate is 61.8 percent
Comparative example 5
The potassium chloride-doped biochar composite catalytic material of comparative example 1 was used for the treatment of phenol wastewater according to the conditions of example 7.
The result shows that the concentration of phenol in the wastewater is 21 mg/L after the reaction is carried out for 60 min, and the removal efficiency of phenol in the wastewater is 58%.
Comparative example 6
The magnesium chloride-doped biochar composite catalytic material of comparative example 2 was used for the treatment of phenol wastewater according to the conditions of example 7.
The result shows that the concentration of phenol in the wastewater after the reaction for 60 min is 19.6 mg/L, and the removal efficiency of phenol in the wastewater is 60.8%.
Comparative example 7
This comparative example prepared a catalytic material by mixing chemically pure potassium chloride and magnesium chloride in a certain proportion according to the preparation method of example 1 and weighing 0.6g to dissolve in 200 mL of water. The prepared catalytic material is respectively used for removing organic matters in soil, namely benzo (a) pyrene and toluene and phenol in wastewater. The removal process of all organic matters is completed under the same experimental conditions, and the mixing mass ratio of potassium chloride to magnesium chloride is 1:1, 6:4 or 7: 3. After the reaction is finished, the removal rate of organic matters is below 62%.
From the above results, it is understood that the removal efficiency of the potassium chloride-doped biochar composite catalytic material and the magnesium chloride-doped biochar composite catalytic material to the organic substance benzo (a) pyrene in the soil under the experimental conditions of example 1 is still not high, and is only 40.8% and 45.8%, respectively, and the removal efficiency of the organic substance toluene in the soil under the experimental conditions of example 4 is not high, and is only 53.6% and 61.8%, respectively. The removal efficiency of the potassium chloride-doped biochar composite catalytic material and the magnesium chloride-doped biochar composite catalytic material to phenol in water under the experimental conditions of example 7 is still not high, and is only 58% and 60.8%, respectively.
Example 10
In this example, the temperature of the end of the temperature rise in the nitrogen atmosphere was changed to 400 ℃, 500 ℃, 600 ℃, 700 ℃ and 850 ℃ respectively, based on example 1. The catalytic materials prepared at different temperatures have slightly different performances, but the catalytic materials prepared by taking carnallite as a raw material have better catalytic effect than the catalytic materials prepared by taking pure potassium chloride and magnesium chloride as raw materials under the same condition.
The technology selects the corn straws and the carnallite as raw materials, prepares the cheap, environment-friendly and efficient biochar composite catalytic material for purifying organic pollutants in water/soil under the selected method, has good catalytic effect under the same condition, has small catalyst dosage and greatly reduces the use cost.
Nothing in this specification is said to apply to the prior art.
Claims (6)
1. A method for preparing a biochar composite catalytic material takes corn straws and carnallite as raw materials, the carnallite is dissolved in water, then the corn straws are added, and the biochar composite catalytic material capable of catalytically activating persulfate is prepared by impregnation, evaporation, drying, roasting and cooling, and the activated oxygen species after the persulfate is catalytically activated can oxidize and remove organic pollutants in soil/water;
the biochar composite catalytic material comprises the following raw materials in percentage by mass: 80-95% of corn straw and 5-20% of carnallite; the roasting temperature in the roasting process is 400-850 ℃, the roasting temperature is firstly increased to the roasting temperature under the nitrogen atmosphere, and then the roasting temperature is switched to the carbon dioxide atmosphere for continuous roasting for a period of time.
2. The method for preparing the biochar composite catalytic material according to claim 1, is characterized by comprising the following specific steps of:
step 1. dissolving carnallite in water: dissolving 0.3-1.2 g of carnallite in 200 mL of water,
step 2, dipping: crushing and sieving corn straws, adding the sieved corn straws into the solution prepared in the step 1, and stirring and mixing at the speed of 200-400 r/min for 4-10 hours;
and 3, evaporation: removing water from the stirred mixture at 80-120 ℃ to constant weight;
and step 4, roasting: roasting the dewatered material before N2Heating to 400-850 deg.C under atmosphere, maintaining the temperature, and switching to CO2Atmosphere of CO2Continuously roasting for 40-80 min under the atmosphere;
and 5, cooling: stopping roasting, and cooling for 6-12 h to obtain the biochar composite catalytic material.
3. The method for preparing the biochar composite catalytic material as recited in claim 2, wherein the nitrogen heating rate is 5-15 ℃/min, and the temperature rise final temperature of the nitrogen atmosphere is 400-850 ℃.
4. The application of the biochar composite catalytic material obtained by the method of any one of claims 1 to 3 is characterized in that the biochar composite catalytic material is used for treating organic contaminated soil, the catalyst biochar composite catalytic material and the oxidant persulfate are respectively prepared into mixed liquid, the mixed liquid is injected into the organic contaminated soil, and the catalyst, the oxidant and the soil are uniformly mixed through mechanical stirring; after reacting for 30-60 days, taking a soil sample, purifying, and analyzing the content of organic pollutants remained in the soil by adopting a gas or liquid chromatograph; the concentration of organic pollutants in the soil is 20-1000 mg/kg, the dosage of the catalyst biochar composite catalytic material is 1-5 g/L, the dosage of the oxidant persulfate is 1-8 g/L, the water content of the soil is 15-40%, and the removal efficiency can reach more than 90%.
5. The application of the biochar composite catalytic material as claimed in claim 4, wherein the mass ratio of the dosage of the catalyst to the dosage of the oxidant is 1 (1-1.7), and the organic contaminated soil is benzo (a) pyrene contaminated soil or toluene contaminated soil.
6. The application of the biochar composite catalytic material obtained by the method of any one of claims 1 to 3 is characterized in that the biochar composite catalytic material is used for treating organic pollutant wastewater, a catalyst biochar composite catalytic material and an oxidant persulfate are added into the organic wastewater, the materials are uniformly mixed and then react for 10 to 120 min, a water sample after reaction is taken, and a gas or liquid chromatograph is adopted to analyze the content of residual organic matters in a water body; wherein the concentration of organic pollutants in the wastewater is 20-100 mg/L, the dosage of the catalyst composite biochar material is 0.3-1.5 g/L, the dosage of the oxidant persulfate is 0.2-2 g/L, and the removal efficiency of the organic pollutants in the wastewater can reach more than 99%; the organic pollutant wastewater is phenol wastewater.
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