CN110064368B - Preparation method of silicon-manganese modified biochar composite material - Google Patents
Preparation method of silicon-manganese modified biochar composite material Download PDFInfo
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- CN110064368B CN110064368B CN201910428238.7A CN201910428238A CN110064368B CN 110064368 B CN110064368 B CN 110064368B CN 201910428238 A CN201910428238 A CN 201910428238A CN 110064368 B CN110064368 B CN 110064368B
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Abstract
The invention provides a preparation method of a silicon-manganese modified biochar composite material, which comprises the following steps: 1) crushing and grinding cleaned and air-dried corn straws (BM) into powder, sieving with a 100-mesh sieve (0.154mm), storing in a wide-mouth bottle, and sealing for later use; 2) suspending and dispersing the BM powder prepared in the step 1) in a sodium silicate solution, and stirring for 12 hours at normal temperature; performing suction filtration, washing the solid to be neutral, drying and grinding to obtain Si-BM treated by silicon; 3) suspending and dispersing the Si-BM prepared in the step 2) in a manganese salt solution, and stirring for 1h at normal temperature; slowly dropwise adding a sodium hydroxide solution to separate out a manganese hydroxide suspension colloid, stopping dropwise adding when the pH is 8-9, and stirring at normal temperature; performing suction filtration, washing the solid to be neutral, and drying to obtain Si/Mn-BM; 4) putting the Si/Mn-BM prepared in the step 4) into a vacuum tube type high-temperature sintering furnace in N2And (3) pyrolyzing for 2h under the atmosphere, cooling to room temperature, grinding and sieving to obtain the modified biochar Si/Mn-BC. The modified biochar provided by the invention is simple in preparation process and strong in adsorption capacity.
Description
Technical Field
The invention relates to the technical field of environmental functional materials and water treatment, in particular to a preparation method of a silicon-manganese modified biochar composite material.
Background
Biochar is a solid-state porous carbonaceous material prepared by high-temperature pyrolysis of waste biomass (agricultural or marine waste) under oxygen-limited conditions. The surface of the biochar has a large number of active functional groups such as carboxyl, hydroxyl and the like, and has stronger surface complexing and ion exchange capacities on heavy metal ions. However, due to limitations in inherent characteristics of lignocellulose and the influence of factors such as pyrolysis temperature, the surface area and porosity of raw biochar directly prepared from biomass are low, thereby limiting the number of effective adsorption sites and the ability for electron transfer. Researches show that the adsorption effect of the composite material prepared by combining the biochar with other substances is far greater than that of single biochar, so that modification researches on the biochar materials are carried out. Currently, modification studies on biochar materials are roughly divided into the following categories:
1) iron-manganese oxide modified biochar composite material
Placing corn stalks in a muffle furnace at 600 ℃ in N2Cracking for 2h in the atmosphere to generate original biochar. Soaking 5g of charcoal in 40mL of 0.24M KMnO4And 40mL of 0.18M Fe (NO)3)3Ultrasonically dispersing the solution for 2h, drying the solution for 22h in a water bath at 95 ℃, finally cracking the solution for 0.5h in a muffle furnace at 600 ℃ under a nitrogen atmosphere, and then cleaning and drying the solution to obtain the biological carbon composite material modified by the ferro-manganese binary oxide with the mass ratio of Fe to Mn to BC being 1:3: 32. The preparation technology of the ferro-manganese modified biochar has various steps and complex process, and the time required for the adsorption to reach the balance is long, so that the application of the ferro-manganese modified biochar in practical engineering is limited
2) Nano zero-valent iron modified silicon-rich biochar
After grinding and sieving the straws, they were placed in muffle furnaces at 300, 500 and 700 ℃ respectively, pyrolyzed for 2h under nitrogen atmosphere, after cooling to room temperature, these biochar were treated in 1.0mol/L HCl solution (S: V ═ 1:25) for 4h and centrifuged to remove the supernatant. And finally, washing the biochar with distilled water until the pH value is stable, and drying in an oven at 80 ℃, wherein the biochar is marked as RS300, RS500 and RS 700. Meanwhile, in order to remove insoluble silica, 1.0g of RS700 biochar after acid treatment was taken and put into 25mL of 1.0mol/L HF solution and stirred for 24 hours, and the supernatant was removed by centrifugation. The sample was then washed with distilled water to remove soluble salts, residual acid and silicon until the pH stabilized. Finally, the sample was screened through a 0.154mm sieve and designated RS700 (-Si).
Nano zero-valent iron modified charcoal: first, 1.0g of ferrous sulfate (FeSO4 & 7H)2O) and 0.05g of biochar (RS300, RS500, RS700 and RS700(-Si)) were added to 50mL of distilled water (the solution pH was adjusted to 4.0), and shaken at 150rpm and 25 ℃ for 24 hours on a shaker. The solution was then transferred to a three-necked flask containing 50mL of ethanol, and the N was added with vigorous stirring2Blowing into the solution for 1hTo exclude dissolved O2. Then, 100mL of 0.5mol/L KBH was added under vigorous stirring4The solution (about 5mL/min) was added dropwise to the above solution, and the reaction was allowed to proceed for 0.5 h. Then separating the biochar sample loaded with the nano zero-valent iron from the liquid phase by using a magnet. Finally, the separated solid was washed three times with 200mL ethanol and finally dried in vacuo. Silicon particles in the biochar are mainly used as carriers of nano zero-valent iron, and the removal of Cr (VI) in an aqueous solution is enhanced.
3) Pyrolytic method for preparing biochar loaded nano zero-valent iron composite material in one step
Firstly, washing and drying the corn straws by deionized water, then grinding the corn straws by a grinder and sieving the corn straws by a 100-mesh sieve. 0.405g of FeCl3·6H2O was dissolved in 40mL of deionized water, 1g of straw powder was added and stirred at room temperature for 24 h. Putting the mixture into an oven at 80 ℃ for 3d to obtain Fe (III) impregnated straw powder. And then placing the obtained Fe (III) -impregnated straw powder in a tubular furnace, heating to 800 ℃ at the speed of 5 ℃/min under the atmosphere of introducing nitrogen (80mL/min), keeping for 2h, and naturally cooling to room temperature in the tubular furnace to obtain the biochar-loaded nano zero-valent iron material. When the adding amount of the prepared biochar composite material is 1.0g/L, the removal rate of Se (IV) can reach more than 90 percent.
The magnetic biochar prepared in types 2 and 3 is magnetic biochar, magnets are required to be arranged around a reactor in a static adsorption process, but in industrial application, a strong magnetic field can interfere normal operation of peripheral instruments, and Fe is mostly used in an adsorbent magnetization process3O4、γ-Fe2O3And the like, which occupy active adsorption sites and decrease adsorption capacity.
4) Sodium hydroxide activated modified charcoal
6.0g of biochar is accurately weighed, dipped in 100mL of NaOH aqueous solution (2mol/L) for 5.0h under full stirring, and the filtered filter cake is dried for 24h at 105 ℃, and then pyrolyzed in a tubular sintering furnace under the nitrogen atmosphere of 0.01 MPa. The temperature rising speed is 5 ℃/min, and the temperature is kept for 2.0h after the set temperature is reached. And fully washing the pyrolyzed biochar material to be neutral by using deionized water and dilute hydrochloric acid to remove soluble inorganic salts, and then filtering and drying. According to the method, NaOH is used for activation treatment, the subsequent treatment operation is complex, the corrosivity is high, the temperature requirement is high, and certain safety risk exists in the operation process.
5)MnO2-SiO2Composite resin adsorbent
MnO preparation by sol-gel method2-SiO2And (3) compounding the resin. By mixing 19.7g KMnO4Solution 1 was prepared by mixing with 1.2L HCl (37%) and 1.25L water glass. By mixing 1L MnCl2·4H2Solution 2 was prepared by mixing O (3%) with 200mL of HCl (37%) and 1.25L of water. Solutions 1 and 2 were mixed, stirred for 2h and left overnight. The mixture was filtered and the precipitate was washed with deionized water until no chloride was detected in the wash water. The filter cake was then dried at 60 ℃ for 24h and sieved. MnO prepared by the method2-SiO2The composite resin adsorbent is oxidized by oxidizing substances in the adsorption process, and has poor thermal stability and reduced use effect.
In view of this, the invention is particularly proposed.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a preparation method of a silicon-manganese modified biochar composite material, wherein the biochar is modified by a one-step sintering method, and the preparation method has the advantages of simple process, high production efficiency and low production cost, and is suitable for large-scale production and use.
Specifically, the invention adopts the following technical scheme that the preparation method of the silicon-manganese modified biochar composite material comprises the following steps:
1) crushing and grinding cleaned and air-dried corn straws (BM) into powder, sieving with a 100-mesh sieve (0.154mm), storing in a wide-mouth bottle, and sealing for later use;
2) suspending and dispersing the BM powder prepared in the step 1) in a sodium silicate solution, and stirring at normal temperature for 12 hours to fully load the sodium silicate on the corn straws; performing suction filtration, washing the solid to be neutral, drying in a vacuum drying oven at 80 ℃, and grinding to obtain silicon-treated corn straw (Si-BM);
3) suspending and dispersing the Si-BM prepared in the step 2) in a manganese salt solution, and stirring for 1h at normal temperature; slowly dropwise adding 0.2mol/L sodium hydroxide solution to separate out manganese hydroxide suspension colloid, stopping dropwise adding when the pH value is 8-9, and stirring at normal temperature until no layering occurs after standing; performing suction filtration, washing the solid to be neutral, and drying in a vacuum drying oven at 80 ℃ to obtain silicomanganese-treated corn straws (Si/Mn-BM);
4) putting the Si/Mn-BM prepared in the step 4) into a vacuum tube type high-temperature sintering furnace in N2Heating to 400-600 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, grinding and sieving to obtain the silicomanganese modified biochar composite (Si/Mn-BC).
Preferably, the mass ratio of the BM powder to the sodium silicate in the step 2) is (4-6): 1, and the concentration of the sodium silicate solution is 0.1-0.15 mol/L.
Preferably, the mass ratio of the Si-BM to the manganese hydroxide suspension colloid in the step 3) is (4-6) to 1, and the concentration of the manganese salt solution is 0.018-0.02 mol/L.
Preferably, the mesh number of the silicon-manganese modified biochar composite material prepared in the step 4) is 50-100 meshes.
The raw materials and instruments used in the preparation process of the silicon-manganese modified biochar composite material are not specially specified, and the silicon-manganese modified biochar composite material can be purchased from the market.
The invention also aims to provide the silicon-manganese modified biochar composite material prepared by the preparation method of the silicon-manganese modified biochar composite material.
The invention also aims to provide an application of the silicon-manganese modified biochar composite material in adsorption of heavy metal ions in a water body.
Compared with the prior art, the preparation process of the silicon-manganese modified biochar composite material is simple, the production efficiency is improved, and the production cost is reduced; other used original and auxiliary reagents are nontoxic and harmless and belong to environment-friendly products; the silicon and manganese modified biochar provides stronger cation replacement capability, strengthens the physical and chemical properties of the biochar, improves the specific surface area and the number of active adsorption sites of a product, can quickly reach adsorption balance, simultaneously ensures excellent heavy metal removal effect, and greatly improves the application value of the biochar in the aspect of adsorbing heavy metal ions in a water body.
Drawings
Fig. 1 is a Scanning Electron Micrograph (SEM) of the silicomanganese modified biochar composite prepared in example 1.
Figure 2 is a Scanning Electron Micrograph (SEM) of Pure Biochar (PBC).
FIG. 3 shows the IR spectra of the Si-Mn modified biochar composite prepared in example 1 and Pure Biochar (PBC).
FIG. 4 is a process flow chart of the preparation method of the silicon-manganese modified biochar composite material.
FIG. 5 shows the effect of the dosage of the adsorbent on the adsorption amount and removal rate when the Si-Mn modified biochar composite prepared in example 1 is used as the adsorbent.
Fig. 6 shows the influence of pH on the adsorption amount and removal rate when the silicomanganese-modified biochar composite prepared in example 1 is used as an adsorbent.
Fig. 7 shows the effect of adsorption time on adsorption amount and removal rate of the silicon-manganese modified biochar composite prepared in example 1 as an adsorbent.
Fig. 8 shows the adsorption amount and removal rate of cu (ii) by the silicomanganese-modified biochar composite material prepared in example 1, pure biochar, and magnetic biochar under the same adsorption conditions.
Detailed Description
The invention will be further described with reference to specific examples:
example 1
1) Crushing and grinding cleaned and air-dried corn straws (BM) into powder, sieving with a 100-mesh (0.154mm) sieve, storing in a wide-mouth bottle, and sealing for later use;
2) suspending and dispersing the BM prepared in the step 1) in 100mL of 0.1mol/L sodium silicate solution, wherein the mass ratio of the added BM powder to the sodium silicate is 5:1, stirring at normal temperature for 12h to fully load the sodium silicate on the corn straws, and at the moment, enabling the mixed suspension to be viscous; performing suction filtration, washing the solid to be neutral, drying the solid in a vacuum drying oven at 80 ℃, and grinding the solid for later use to obtain the corn straw (Si-BM) treated by silicon;
3) suspending and dispersing the Si-BM prepared in the step 2) in 0.02mol/L manganese sulfate solution, and stirring for 1h at normal temperature; slowly dripping 0.2mol/L sodium hydroxide solution to separate out a manganese hydroxide suspension colloid, stopping dripping when the pH is 8-9, wherein the mass ratio of Si-BM to the manganese hydroxide suspension colloid is 5:1, stirring at normal temperature for 12 hours to fully mix and contact the Si-BM with the manganese hydroxide suspension colloid until no obvious layering occurs between Si-BM powder and the manganese hydroxide suspension colloid after standing, and completely wrapping the manganese hydroxide suspension colloid on the corn straws; performing suction filtration, washing the solid to be neutral, and drying in a vacuum drying oven at 80 ℃ to obtain silicomanganese-treated corn straws (Si/Mn-BM);
4) putting the Si/Mn-BM prepared in the step 3) in a vacuum tube type high-temperature sintering furnace in N2Heating to 450 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, grinding, and sieving with a 100-mesh sieve to obtain the silicon-manganese modified biochar composite material (Si/Mn-BC).
1. Characterization of silicomanganese modified biochar composites
1.1 SEM scanning Electron microscopy analysis
The specific operation steps are as follows: a small amount of the Si/Mn-BC powder prepared in example 1 and Pure Biochar (PBC) were placed on a silicon wafer, and after preparing a sample by the SEM test method, the apparent morphology of each sample was observed under a scanning electron microscope (FESEM, JSM 46700F) at a test voltage of 10kV and a magnification of 10000 times.
As is apparent from FIGS. 1 and 2, the surface morphology of the biochar before and after modification is greatly changed. The PBC surface is smooth and compact, the Si/Mn-BC honeycomb and layered structure is very obvious, and a plurality of granular agglomerates are loaded on the surface and become uneven. The reason for this result is probably that the silicon and manganese loaded on the surface of the biomass react with various active functional groups on the surface under the condition of high temperature and limited oxygen, which greatly promotes the formation of the honeycomb-shaped pore structure of the biochar, so that metal ions are easier to enter the pores, and the adsorption capacity is greatly increased. Meanwhile, agglomerated small particles are generated and coated on the surface of the biochar or enter pores, so that the surface area is greatly increased, the adsorption sites are obviously increased, and the adsorption quantity of the biochar to metal ions can be greatly increased. This is a good indication of the success of modifying biochar with silicon and manganese.
1.2 FTIR Spectroscopy
The IR spectrum of the biochar was measured by Fourier transform Infrared Spectroscopy (FTIR, IRaffinity-1). The specific operation steps are as follows: before sample measurement, KBr and charcoal powder samples were dried overnight at 105 ℃ respectively. A sample of 0.2mg of biochar and a sample of 80mg of KBr were mixed and ground thoroughly under irradiation with an infrared lamp. The discs containing the sample and KBr were pressed for 2min at 10 MPa and placed in an infrared spectrometer for FTIR analysis. The scanning range of the sample is 500-4000cm-1Resolution of 4cm-1And scanned 64 times. Pure KBr was subtracted as a blank sample.
FTIR of Si/Mn-BC powder prepared in example 1 and Pure Biochar (PBC) are shown in FIG. 3. As can be seen from FIG. 3, the peaks of certain groups of the silicon-manganese modified biochar are changed compared with those of pure biochar, which indicates that the chemical functional groups of the biochar are changed before and after modification. 3452cm-1And 3440cm-1The peak at (A) belongs to a stretching vibration peak of-OH, which indicates that alcohol or phenolic organic matters possibly exist; 1430cm-1And 850-990 cm-1The peaks appearing are assigned to the-OH in-plane and out-of-plane bending vibration peaks, respectively, indicating the presence of carboxylic acid; 2926cm-1The peak at (A) belongs to the stretching vibration peak of C-H; 1600cm-1The peaks appearing nearby represent the presence of an aromatic C ═ C or C ═ O group; after the modification of the biochar, the antisymmetrical stretching vibration peak of Si-O-Si is from 1100cm-1Displacement to 1123cm-1And the absorption peak is obviously enhanced, which indicates that the silicon is successfully loaded on the biochar; compared with pure biochar, the modified biochar is 533cm-1And 862cm-1A new peak appears, which is attributed to the nascent MnO2And Mn3O4The telescopic vibration absorption of the medium Mn-O fully shows that the manganese is successfully loaded on the biochar.
1.3 BET specific surface area analysis
The specific surface area is determined by a specific surface area determinator under the assumption of a BET model. The BET model assumes that the adsorption layer is an ideal uniform surface without change, and horizontal intermolecular forces between the layers are not generated, so that the adsorption layer is multi-layer adsorption, and the acting force is Van der Waals force. The specific surface area and pore size distribution are determined by N2The adsorption and desorption method is characterized in that a full-automatic specific surface area and pore size analyzer is used at 77K, a sample is subjected to degassing treatment before the test, and degassing is carried out for 4 hours under the vacuum condition of 200 ℃.
TABLE 1 specific surface area testing of Si/Mn-BC and PBC prepared in example 1
Table 1 shows BET test data for silicomanganese modified biochar (Si/Mn-BC) prepared in example 1 and Pure Biochar (PBC). It can be seen that there are large differences in specific surface area, pore volume and average pore diameter between the silicomanganese modified biochar and the pure biochar. The specific surface area and pore volume of Si/Mn-BC are much larger than that of PBC, but the average pore diameter is smaller than that of PBC. The reason for this result may be that silicon and manganese loaded on the biomass generate agglomerated small particles at high temperature, and part of the agglomerated small particles are attached to the surface of the biochar, so that the surface of the modified biochar is rough and uneven, the specific surface area is increased, more adsorption sites are provided, and adsorption of heavy metals is facilitated; part of the gas enters the pores of the biochar to change the internal pore structure, so that the number of macropores and mesopores is reduced, the number of micropores is increased, and the average pore diameter is reduced while the pore volume is increased. This can also be seen from the SEM characterization results.
2. The method for testing the adsorption performance of the silicon-manganese modified biochar composite material as the adsorbent comprises the following steps:
adding a certain amount of silicon-manganese modified biochar composite material (Si/Mn-BC) into a centrifuge tube containing a Cu (II) solution, placing the centrifuge tube into a water bath constant-temperature shaking table, and shaking at the speed of 175r/min at 25 ℃; after the adsorption is balanced, filtering the obtained mixed solution through a filter membrane of 0.45 mu m, diluting the filtrate by 10 times, measuring the absorbance of the solution and the concentration of Cu (II) by using an atomic absorption spectrophotometer, and calculating the corresponding removal rate and the adsorption quantity.
The removal rate (. eta.) is calculated by the following formula:
wherein: eta-removal rate of Cu (II)%;
C0-initial concentration of solution, mg/L;
Ct-concentration of the solution at time t, mg/L.
Amount of adsorption (q)t) Calculated according to the following formula:
wherein: q. q.st-the amount of adsorption at time t, mg/g;
C0-initial concentration of solution, mg/L;
Ct-concentration of the solution at time t, mg/L;
v-volume of solution, mL;
m is the amount of adsorbent, g.
The Si/Mn-BC prepared in example 1 is taken as an adsorbent to carry out various tests, and the specific tests are as follows:
3. test of influence of adsorbent amount on adsorption Performance
Adding a certain amount of silicon-manganese modified biochar composite material into 25mL of a centrifugal tube containing 50mg/L Cu (II) respectively to enable the concentrations of the adsorbents to be 1, 1.5, 2.5, 3 and 4g/L respectively, carrying out other steps according to the experimental method of the product performance test method 1, and testing results of adsorption performance are shown in FIG. 5.
The dosage of the adsorbent is an important influence factor of an adsorbent-adsorbate balance system, and fig. 5 shows the influence of the dosage of the silicomanganese modified biochar on the Cu (II) adsorption quantity and the removal efficiency. As is evident from the figure, when the dosage of the adsorbent is increased from 1g/L to 4g/L, the removal efficiency of Cu (II) is increased from 97.66 percent to 98.83 percent; although the adsorption capacity is reduced from 48.83mg/g to 12.35mg/g, the silicon-manganese modified biochar still shows strong adsorption and removal capacity to Cu (II).
4. pH Effect on adsorption Performance test
With 0.01M HNO3And 0.01M NaOH is used for adjusting the pH value of 50mg/L Cu (II) solution to 2.0-6.0, 25mL of Cu (II) solutions with different pH values are respectively put into a centrifuge tube, 0.05g of silicon-manganese modified biochar composite material is added into the centrifuge tube, other steps are carried out according to the experimental method of the product performance test method 1, and the adsorption performance test data are shown in figure 6.
The initial pH of the solution affects not only the surface charge of the biochar but also the morphology of heavy metal ions, and fig. 6 shows the effect of the silicomanganese modified biochar on the cu (ii) adsorption amount and removal rate in the range of 2-6 at the initial pH of the solution. As can be seen from the graph, when the pH is increased from 2 to 3, the adsorption quantity and the removal rate of Cu (II) by the silicon-manganese modified biochar are rapidly increased, the adsorption quantity is increased from 23.85mg/g to 24.64mg/g, and the removal rate is also increased from 95.39% to 98.56; the pH value is between 3 and 5, and the change range of the adsorption quantity and the removal rate is not large; when the pH is 5-6, the adsorption amount and the removal rate of Cu (II) are slightly increased. The above results may be due to H at low pH+There is competitive adsorption with metal ions, with increasing pH, H+The reduction and the deprotonation effect on the surface of the adsorbent are more and more remarkable, so that the competitive adsorption is weakened, the exposure degree of negative charges on the surface is increased, the electrostatic interaction between the biochar and Cu (II) is enhanced, and the adsorption capacity and the removal rate are increased.
5. Test of the influence of adsorption time on adsorption Performance
0.2g of silicon-manganese modified biochar composite material is added into 200mL of 50mg/L Cu (II) solution, then supernate is taken at 1min, 2.5min, 5min, 10min, 30min, 60min, 100min, 150min, 200min, 300min, 400min, 500min and 600min respectively, and then the test is carried out according to the experimental method of the product performance test method 1, wherein the test data is shown in figure 7.
The effect of adsorption time on cu (ii) removal rate and adsorption amount is shown in fig. 7. As is apparent from FIG. 7, when the adsorbent was added to a 50mg/L Cu (II) solution, the adsorption rate at the initial stage of adsorption (first 5min) was very fast, and the removal rate and the adsorption amount at 5min reached maximum of 97.38% and 24.345mg/g, respectively. After this time, the adsorption rate begins to slow down and then reaches adsorption equilibrium. The phenomenon is probably caused by that a large number of active sites exist on the surface of the silicon-manganese modified charcoal adsorbent in the initial stage of adsorption, a large concentration gradient exists in a solid-liquid two-phase, and Cu (II) can be quickly adsorbed and fixed. With the increase of the oscillation time, the adsorption amount and the removal rate reach dynamic equilibrium, which is because the active sites on the surface of the adsorbent are reduced and the adsorption gradually reaches a saturated state.
Compared with pure biochar or magnetic biochar, the silicon-manganese modified biochar composite material prepared by the invention has the advantages of larger adsorption capacity, higher adsorption rate and better adsorption effect.
Comparative example 1 comparative test of adsorption performances of silicon-manganese modified biochar composite material and pure biochar and magnetic biochar
Preparing pure biochar: BM is placed in a vacuum tube type high-temperature sintering furnace in N2Heating to 450 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, grinding, and sieving with a 100-mesh sieve to obtain the pure biochar.
Preparing magnetic biochar: weighing 1.605g BM, adding the BM into 1L of ferric chloride solution with the concentration of 0.015mol/L, and stirring for 1h at normal temperature; slowly dropwise adding 0.1mol/L sodium hydroxide solution into the solution until the pH value is 8-9, and stirring at normal temperature for 12 hours; performing suction filtration, washing the solid to be neutral, and drying in a vacuum drying oven at 80 ℃; placing the mixture in a vacuum tube type high-temperature sintering furnace in N2Heating to 450 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, grinding, and sieving with a 100-mesh sieve to obtain the magnetic biochar.
0.05g of silicon-manganese modified biochar composite material, pure biochar and magnetic biochar are respectively added into 3 centrifuge tubes containing 25mL of 50mg/L Cu (II) solution, other steps are carried out according to the experimental method of the product performance test method 1, and the adsorption performance test data are shown in FIG. 8.
Fig. 8 shows the adsorption amount and removal rate of cu (ii) by the silicon-manganese modified biochar composite material, pure biochar, and magnetic biochar under the same adsorption conditions. It is obvious from the figure that the silicon-manganese modified biochar composite material has improved adsorption amount and removal rate on Cu (II) compared with pure biochar and magnetic biochar. The removal rate of the silicon-manganese modified biochar composite material to Cu (II) can reach over 90 percent, and the removal rate of pure biochar and magnetic biochar to Cu (II) is only 51.01 percent and 73.54 percent. Therefore, the prepared silicon-manganese modified biochar composite material can greatly improve the adsorption quantity and removal rate of the biochar to Cu (II), and has better adsorption effect compared with pure biochar and magnetic biochar.
Example 2
1) Crushing and grinding cleaned and air-dried corn straws (BM) into powder, sieving with a 100-mesh (0.154mm) sieve, storing in a wide-mouth bottle, and sealing for later use;
2) suspending and dispersing BM prepared in the step 1) in 100mL of 0.15mol/L sodium silicate solution, wherein the mass ratio of the added BM powder to the sodium silicate is 4:1, stirring at normal temperature for 12h to fully load the sodium silicate on the corn straws, and at the moment, enabling the mixed suspension to be viscous; performing suction filtration, washing the solid to be neutral, drying in a vacuum drying oven at 80 ℃, and grinding for later use to obtain the corn straw (Si-BM) treated by silicon;
3) suspending and dispersing the Si-BM prepared in the step 2) in 0.0018mol/L manganese sulfate solution, and stirring for 1h at normal temperature; slowly dripping 0.2mol/L sodium hydroxide solution to separate out a manganese hydroxide suspension colloid, stopping dripping when the pH is 8-9, wherein the mass ratio of Si-BM to the manganese hydroxide suspension colloid is 4:1, stirring at normal temperature for 12 hours to fully mix and contact the Si-BM with the manganese hydroxide suspension colloid until no obvious layering occurs between Si-BM powder and the manganese hydroxide suspension colloid after standing, and completely wrapping the manganese hydroxide suspension colloid on the corn straws; performing suction filtration, washing the solid to be neutral, and drying in a vacuum drying oven at 80 ℃ to obtain the silicomanganese-treated corn straw (Si/Mn-BM);
4) will be provided withThe Si/Mn-BM prepared in the step 3) is put in a vacuum tube type high-temperature sintering furnace in N2Heating to 450 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, grinding, and sieving with a 50-mesh sieve to obtain the silicon-manganese modified biochar composite material (Si/Mn-BC).
Example 3
1) Crushing and grinding cleaned and air-dried corn straws (BM) into powder, sieving with a 100-mesh (0.154mm) sieve, storing in a wide-mouth bottle, and sealing for later use;
2) suspending and dispersing the BM prepared in the step 1) in 100mL of 0.12mol/L sodium silicate solution, wherein the mass ratio of the added BM powder to the sodium silicate is 6:1, stirring at normal temperature for 12h to fully load the sodium silicate on the corn straws, and at the moment, enabling the mixed suspension to be viscous; performing suction filtration, washing the solid to be neutral, drying the solid in a vacuum drying oven at 80 ℃, and grinding the solid for later use to obtain the corn straw (Si-BM) treated by silicon;
3) suspending and dispersing the Si-BM prepared in the step 2) in 0.02mol/L manganese sulfate solution, and stirring for 1h at normal temperature; slowly dripping 0.2mol/L sodium hydroxide solution to separate out a manganese hydroxide suspension colloid, stopping dripping when the pH is 8-9, wherein the mass ratio of Si-BM to the manganese hydroxide suspension colloid is 6:1, stirring at normal temperature for 12 hours to fully mix and contact the Si-BM with the manganese hydroxide suspension colloid until no obvious layering occurs between Si-BM powder and the manganese hydroxide suspension colloid after standing, and completely wrapping the manganese hydroxide suspension colloid on the corn straws; performing suction filtration, washing the solid to be neutral, and drying in a vacuum drying oven at 80 ℃ to obtain silicomanganese-treated corn straws (Si/Mn-BM);
4) putting the Si/Mn-BM prepared in the step 3) in a vacuum tube type high-temperature sintering furnace in N2Heating to 450 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, grinding, and sieving with a 80-mesh sieve to obtain the silicon-manganese modified biochar composite material (Si/Mn-BC).
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (4)
1. A silicon-manganese modified biochar composite material for adsorbing Cu (II) ions in a water body is prepared by the following steps:
1) crushing and grinding the cleaned and aired corn straws BM into powder, sieving the powder with a 100-mesh sieve, and storing the powder in a wide-mouth bottle for later use;
2) suspending and dispersing the BM powder prepared in the step 1) in a sodium silicate solution, and stirring at normal temperature for 12 hours to fully load the sodium silicate on the corn straws; performing suction filtration, washing the solid to be neutral, drying in a vacuum drying oven at 80 ℃, and grinding to obtain the corn straw Si-BM after silicon treatment;
3) suspending and dispersing the Si-BM prepared in the step 2) in a manganese salt solution, and stirring for 1h at normal temperature; slowly dropwise adding 0.2mol/L sodium hydroxide solution to separate out manganese hydroxide suspension colloid, stopping dropwise adding when the pH value is 8-9, and stirring at normal temperature until no layering occurs after standing; performing suction filtration, washing the solid to be neutral, and drying in a vacuum drying oven at 80 ℃ to obtain silicomanganese treated corn straw Si/Mn-BM;
4) putting the Si/Mn-BM prepared in the step 4) into a vacuum tube type high-temperature sintering furnace in N2Heating to 400-600 ℃ at the speed of 2-3 ℃/min under the atmosphere for cracking for 2h, cooling to room temperature, and grinding and sieving to obtain the silicon-manganese modified biochar composite material Si/Mn-BC.
2. The silicon-manganese modified biochar composite material for adsorbing Cu (II) ions in a water body according to claim 1, wherein the mass ratio of BM powder to sodium silicate in the step 2) is (4-6): 1, and the concentration of a sodium silicate solution is 0.1-0.15 mol/L.
3. The silicon-manganese modified biochar composite material for adsorbing Cu (II) ions in a water body according to claim 1, wherein the mass ratio of Si-BM to a manganese hydroxide suspension colloid in the step 3) is (4-6) to 1, and the concentration of a manganese salt solution is 0.018-0.02 mol/L.
4. The silicon-manganese modified biochar composite material for adsorbing Cu (II) ions in a water body as claimed in any one of claims 1-3, wherein the mesh number of the silicon-manganese modified biochar composite material prepared in the step 4) is 50-100 meshes.
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