Detailed Description
The invention provides a preparation method of a biochar loaded nano zero-valent iron sulfide material, which comprises the following steps:
under vacuum or inert atmosphere, biomass and FeSO4Mixing the solution, evaporating to dryness, grinding and drying to obtain the FeSO load4The biomass of (a);
the FeSO is loaded4The biomass is pyrolyzed at 800-1000 ℃ under inert atmosphere to obtain the biochar loaded nano zero-valent iron sulfide material.
Compared with the prior art, the biochar loaded nano zero-valent iron sulfide material prepared by the one-pot pyrolysis method is adopted, and no additional chemical reduction reagent or vulcanizing reagent is needed to be added, so that the aims of simultaneously carrying the biochar of the zero-valent iron and vulcanizing modification are fulfilled, and the method is simple; and the prepared material can quickly and effectively treat the sewage containing halogenated organic matters.
In the present invention, the particle size of the biomass is preferably 100 to 200 mesh. The biomass is preferably one or more of sawdust, wheat straw and rice husk; the sawdust is made of fir. The FeSO4The solution is preferably FeSO4·7H2O is dissolved in water.
In the present invention, the FeSO4The solvent in the solution is deoxygenated water fully aerated by nitrogen. The mass ratio of the amount of ferrous sulfate substances in the ferrous sulfate solution to the biomass is (0.1-10) mmol:1g of a compound; in a specific embodiment, the mass ratio of the amount of the ferrous sulfate in the ferrous sulfate solution to the biomass is specifically 2 mmol:1g, or 0.1 mmol:1g of the total weight of the composition. The FeSO4The concentration of the solution is preferably 0.01-0.1 mol/L. FeSO4The amount of the catalyst is an important factor if FeSO4Too much or too little loading of (A) can not form the optimal proportion and form of FeS and nZVI in S-nZVI, thereby affecting the catalytic activity of the material.
The biomass and FeSO4The solution mixing means is preferably selected from ultrasonic mixing and/or oscillatory mixing; preferably, the ultrasonic dispersion is carried out for a certain time, and then the vibration mixing is carried out for a certain time. The oscillation rate during oscillation and mixing is 170-190 rpm; detailed description of the preferred embodimentsThe oscillation rate was 180 rpm. The mixing temperature is preferably 20-30 ℃; the mixing time is preferably 6-18 h.
Obtain the FeSO load4After the biomass is treated, the FeSO is treated by the invention4And pyrolyzing the loaded biomass at 800-1000 ℃ in an inert atmosphere to obtain the biochar loaded nano zero-valent iron sulfide material.
In the invention, the supported FeSO4Preferably rapidly from room temperature to pyrolysis temperature under an inert atmosphere; more preferably, the supported FeSO4The biomass is pyrolyzed from room temperature to 800-1000 ℃ within 0.3-0.5 s under inert atmosphere. Fast pyrolysis to produce reducing gas and H2S gas; the reducing gas comprises H2、CH4CO and other small hydrocarbon gases. The reducing gas and H2S gas is fully utilized to react FeSO4Reducing the product into S-nZVI.
In the invention, the pyrolysis temperature is 800-1000 ℃; in specific embodiments, the pyrolysis temperature is 800 ℃, 900 ℃ or 1000 ℃. The pyrolysis time is preferably 0.5-1.5 h; in a specific example, the pyrolysis time is 1 h. The inert atmosphere is preferably a nitrogen atmosphere.
The invention provides a method for removing halogenated organic matters in sewage, which comprises the following steps:
adding the biochar loaded nano zero-valent iron sulfide material prepared by the preparation method in the technical scheme into sewage, and reacting to obtain treated sewage;
the sewage contains halogenated organic matters.
In the present invention, the halogenated organic substance is diclofenac. When the concentration of the halogenated organic matters is 9-11 mg/L, the adding amount of the biochar loaded nano zero-valent iron sulfide material is 0.4-0.6 g/L. In a specific embodiment, the concentration of the halogenated organic compound is 10 mg/L.
In order to further illustrate the present invention, the following will describe in detail the preparation method and application of a biochar-supported nano zero-valent iron sulfide material provided by the present invention with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 5mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred to a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried at 80 ℃ in a vacuum drying oven, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
1.3, under the nitrogen atmosphere, carrying out fast pyrolysis on 2g of the sawdust loaded with the ferrous sulfate at 800 ℃ by using a fast pyrolysis furnace for 1h to obtain the biochar-loaded nano zero-valent iron sulfide (SBC-800).
FIG. 1 is a TEM image of biochar-supported nano zero-valent iron sulfide (SBC-800) prepared in example 1 of the present invention; FIG. 2 is an XRD diagram of the biochar-supported nano zero-valent iron sulfide (SBC-800) prepared in example 1 of the present invention. As can be seen from fig. 1, most of the nanoparticles are uniformly dispersed on the surface of the biochar substrate. As can be seen from FIG. 2, FeS is present in the material, indicating that the surface of the zero-valent iron is successfully sulfurized, and the nano-sulfurized zero-valent iron is mainly composed of Fe1-xS (pyrrhotite), FeS (pyrite), and Fe0And (4) forming. From the figures 1-2, it can be concluded that the preparation method of the invention can successfully prepare the sulfuration zero-valent iron nanoparticles, and the nanoparticles can be dispersed on the surface of the biochar substrate.
The biochar-loaded nano zero-valent iron sulfide is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the adding amount of the material is 0.5 g/L. Fig. 3 shows the removal and dechlorination effects of the biochar-loaded nano zero-valent iron sulfide prepared in example 1 of the present invention. As can be seen from fig. 3: the removal efficiency of diclofenac after 4 hours of the biochar-loaded nano zero-valent iron sulfide is 80.1%, wherein the dechlorination efficiency is 38.7%.
Example 2
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 5mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred to a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried at 80 ℃ in a vacuum drying oven, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
1.3, under the nitrogen atmosphere, carrying out fast pyrolysis on 2g of the sawdust loaded with the ferrous sulfate at 900 ℃ by using a fast pyrolysis furnace for 1h to obtain the biochar loaded nano zero-valent iron sulfide (SBC-900).
The biochar-loaded nano zero-valent iron sulfide (SBC-900) is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the addition amount of the material is 0.5 g/L. FIG. 4 shows the removal and dechlorination effects of the biochar-loaded nano zero-valent iron sulfide prepared in examples 1 to 6 of the present invention and in comparative examples 1 to 2. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar loaded nano zero-valent iron sulfide prepared in the example is 97.0% after 4h, wherein the dechlorination efficiency is 18.8%.
Example 3
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 5mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred to a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried at 80 ℃ in a vacuum drying oven, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
1.3, under the nitrogen atmosphere, carrying out fast pyrolysis on 2g of the sawdust loaded with the ferrous sulfate at 1000 ℃ by using a fast pyrolysis furnace for 1h to obtain the biochar loaded nano zero-valent iron sulfide (SBC-1000).
The biochar-loaded nano zero-valent iron sulfide (SBC-1000) is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the addition amount of the material is 0.5 g/L. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar loaded nano zero-valent iron sulfide prepared in the example is 94.8% after 4h, wherein the dechlorination efficiency is 26.8%.
Example 4
1.1 pretreatment of raw materials: crushing saw powder, sieving, reserving the saw powder separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use;
1.2 adding 0.5mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred into a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is utilized to evaporate the water in the flask to dryness, the solid compound is dried in a vacuum drying oven at 80 ℃, and after uniform grinding, the biomass loaded with ferrous sulfate is obtained;
1.3, under the nitrogen atmosphere, rapidly pyrolyzing 2g of the sawdust loaded with the ferrous sulfate at 800 ℃ for 1h by using a rapid pyrolysis furnace to obtain biochar-loaded nano zero-valent iron sulfide;
the biochar-loaded nano zero-valent iron sulfide is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the adding amount of the material is 0.5 g/L. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar loaded nano zero-valent iron sulfide prepared in the example is 36.9% after 4 hours, wherein the dechlorination efficiency is 3.8%.
Example 5
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 10mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred into a flask, nitrogen is deoxygenated for 30min, the mixture is shaken for 12h at 180r/m in a water bath shaking table at 25 ℃, then the water in the flask is evaporated by a rotary evaporator, and the solid compound is put into a vacuum containerAnd drying the biomass in an air drying oven at the temperature of 80 ℃, and uniformly grinding to obtain the biomass loaded with ferrous sulfate.
And 1.3, under the nitrogen atmosphere, rapidly pyrolyzing 2g of the sawdust loaded with the ferrous sulfate at 800 ℃ for 1h by using a rapid pyrolysis furnace to obtain the biochar loaded nano zero-valent iron sulfide.
The biochar-loaded nano zero-valent iron sulfide is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the adding amount of the material is 0.5 g/L. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar loaded nano zero-valent iron sulfide prepared in the example is 50.3% after 4 hours, wherein the dechlorination efficiency is 3.4%.
Example 6
1.1 pretreatment of raw materials: crushing wheat straws, sieving, reserving the wheat straws which are sieved out by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 10mmol of FeSO4·7H2O, 5g of wheat straw treated in 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred into a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaker at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried in a vacuum drying oven at 80 ℃, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
And 1.3, under the nitrogen atmosphere, carrying out fast pyrolysis on 2g of the wheat straw loaded with the ferrous sulfate at 800 ℃ by using a fast pyrolysis furnace for 1h to obtain the biochar loaded nano zero-valent iron sulfide.
The biochar-loaded nano zero-valent iron sulfide is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the adding amount of the material is 0.5 g/L. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar-supported nano zero-valent iron sulfide prepared in the example is 69.2% after 4 hours, wherein the dechlorination efficiency is 25.9%.
Example 7
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 mixing 5mmol FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred to a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried at 80 ℃ in a vacuum drying oven, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
And 1.3, under the nitrogen atmosphere, rapidly pyrolyzing 2g of the sawdust loaded with the ferrous sulfate at 800 ℃ for 1h by using a rapid pyrolysis furnace to obtain the biochar loaded nano zero-valent iron sulfide.
The biochar-loaded nano zero-valent iron sulfide is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the adding amount of the material is 0.5 g/L. After the first reaction was completed, the solid material was collected by centrifugation and used again for the removal of diclofenac at an initial concentration of 10 mg/L. And (3) repeatedly utilizing the materials for three times, collecting the materials, and calcining the materials at 800 ℃ for 1h by utilizing a pyrolysis furnace in a nitrogen atmosphere to obtain the regenerated biochar loaded nano zero-valent iron sulfide. The regenerated material is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the dosage of the material is 0.5 g/L. Fig. 5 shows the recycling effect and the recycling treatment effect of diclofenac treated by the biochar loaded nano zero-valent iron sulfide prepared in example 7 of the present invention. The removal efficiency of the biochar loaded nano zero-valent iron to diclofenac for the first time is 80.1% after 4 hours, wherein the dechlorination efficiency is 38.7%. The removal efficiency for the second time of diclofenac was 54.1% after 4h, with a dechlorination efficiency of 25.3%. The removal efficiency for diclofenac for the third time was 25.0% after 4h, with a dechlorination efficiency of 6.2%. The removal efficiency of diclofenac after 4 hours of the regenerated biochar loaded nano zero-valent iron sulfide is 80.0%, wherein the dechlorination efficiency is 39.33%.
Example 8
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 5mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred to a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried at 80 ℃ in a vacuum drying oven, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
And 1.3, under the nitrogen atmosphere, carrying out fast pyrolysis on 2g of the biomass loaded with the ferrous sulfate at 800 ℃ by using a fast pyrolysis furnace for 1h to obtain the biochar loaded nano zero-valent iron sulfide.
The charcoal-loaded nano zero-valent iron sulfide is used in a column experiment of diclofenac, the concentration of diclofenac in inlet water is 10mg/L, the diameter of the column is 8mm, and the height of the column is 30 mm. The long-term diclofenac removing effect of the biochar loaded nano zero-valent iron sulfide is obtained by continuously feeding water and testing the concentration of diclofenac in the water. FIG. 6 shows the long-term removal effect of diclofenac treated by charcoal-loaded nano zero-valent iron sulfide prepared in example 8 of the present invention. The column experiment effect of the charcoal-loaded nano zero-valent iron sulfide on diclofenac reaches the column experiment penetration point when the effluent reaches 2500ml, the removal effect of the material on diclofenac before failure is stable, the concentration of diclofenac in the effluent is lower than 1mg/L, and the concentration of diclofenac in the effluent is rapidly increased to more than 8mg/L after the column fails.
Comparative example 1
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 adding 5mmol of FeSO4·7H2O, 5g of the sawdust treated in the 1.1 and 200ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred to a flask, nitrogen is deoxygenated for 30min, the mixture is oscillated for 12h at 180r/m in a water bath shaking table at 25 ℃, then a rotary evaporator is used for evaporating the water in the flask to dryness, the solid compound is dried at 80 ℃ in a vacuum drying oven, and the biomass loaded with ferrous sulfate is obtained after uniform grinding.
1.3, under the nitrogen atmosphere, carrying out fast pyrolysis on 2g of the biomass loaded with the ferrous sulfate at 700 ℃ by using a fast pyrolysis furnace for 1h to obtain the biochar loaded nano zero-valent iron sulfide (SBC-700).
The biochar-loaded nano zero-valent iron sulfide (SBC-700) is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the addition amount of the material is 0.5 g/L. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar-supported nano zero-valent iron sulfide prepared in the comparative example 1 after 4 hours is 32.8%, wherein the dechlorination efficiency is 19.5%.
Comparative example 2
1.1 pretreatment of raw materials: crushing the sawdust, sieving, reserving the sawdust which is separated by a sieve with 100-200 meshes, and drying at 80 ℃ for later use.
1.2 in nitrogen atmosphere, 5g of biomass treated in 1.1 is subjected to fast pyrolysis at 800 ℃ by using a fast pyrolysis furnace, the pyrolysis time is 1h, and the biochar is obtained after grinding.
1.3 adding 0.5mmol of FeSO40.5g of the biochar obtained in 1.2 and 50ml of deoxygenated water are mixed and dispersed under the assistance of ultrasound, then the mixed solution is transferred into a three-neck flask, and nitrogen is deoxygenated for 30 min. 2.5mmol of NaBH4、0.05mmol Na2S·9H2And mixing and dispersing O (which is 10 percent of the S/Fe ratio in the example 1) and 100ml of deoxygenated water under the assistance of ultrasound, then uniformly dripping the mixed solution into a three-neck flask under the protection of nitrogen, continuously stirring for 30min after the reaction is finished, filtering and drying to obtain the biochar-loaded nano zero-valent iron sulfide.
The biochar-loaded nano zero-valent iron sulfide is used for removing diclofenac, the initial concentration of the diclofenac is 10mg/L, and the adding amount of the material is 0.5 g/L. As can be seen from fig. 4: the removal efficiency of diclofenac by the biochar-supported nano zero-valent iron sulfide prepared in the comparative example 2 after 4 hours is 27.0%, wherein the dechlorination efficiency is 12.4%.
From the above embodiments, the invention provides a preparation method of a biochar-loaded nano zero-valent iron sulfide material, which comprises the following steps: under vacuum or inert atmosphere, biomass and FeSO4Mixing the solution, evaporating to dryness, grinding and drying to obtain the FeS loadO4The biomass of (a); the FeSO is loaded4The biomass is pyrolyzed at 800-1000 ℃ under inert atmosphere to obtain the biochar loaded nano zero-valent iron sulfide material. The method adopts the one-pot type pyrolysis method to prepare the biochar-loaded nano zero-valent iron sulfide material, does not need to add additional chemical reduction reagents and vulcanizing reagents, achieves the aim of simultaneously carrying the biochar-loaded effect and the vulcanizing modification effect on the zero-valent iron, is simple, and can improve the dispersity and the stability of the nano zero-valent iron sulfide material, thereby improving the reaction activity of the nano zero-valent iron sulfide on halogenated organic matters and further quickly and effectively treating the sewage containing the halogenated organic matters. The vulcanization modification not only enhances the reactivity of the material, but also improves the anti-aging capability of the material in water, and simultaneously inhibits the passivation of the material, thereby improving the service life and the degradation capability of the zero-valent iron. The experimental results show that: the initial concentration of diclofenac is 10mg/L, and the material dosage is 0.5g/L, the removal efficiency of the material on diclofenac reaches 94.8 percent after 4 hours, wherein the dechlorination efficiency is 26.8 percent.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.