CN116173905A - Preparation and application of pyrolytic biochar/geopolymer composite material - Google Patents
Preparation and application of pyrolytic biochar/geopolymer composite material Download PDFInfo
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- CN116173905A CN116173905A CN202310280974.9A CN202310280974A CN116173905A CN 116173905 A CN116173905 A CN 116173905A CN 202310280974 A CN202310280974 A CN 202310280974A CN 116173905 A CN116173905 A CN 116173905A
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- 239000002131 composite material Substances 0.000 title claims abstract description 54
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims abstract description 68
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- 239000002689 soil Substances 0.000 claims abstract description 42
- 239000010881 fly ash Substances 0.000 claims abstract description 38
- 238000000197 pyrolysis Methods 0.000 claims abstract description 35
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- 150000002500 ions Chemical class 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 15
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- 239000002243 precursor Substances 0.000 claims abstract description 14
- 238000011065 in-situ storage Methods 0.000 claims abstract description 13
- 239000012153 distilled water Substances 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 11
- 238000003756 stirring Methods 0.000 claims abstract description 10
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract description 5
- 238000005406 washing Methods 0.000 claims abstract description 5
- 238000001179 sorption measurement Methods 0.000 claims description 28
- 238000002161 passivation Methods 0.000 claims description 18
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- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 4
- RVPVRDXYQKGNMQ-UHFFFAOYSA-N lead(2+) Chemical compound [Pb+2] RVPVRDXYQKGNMQ-UHFFFAOYSA-N 0.000 description 4
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- 238000011010 flushing procedure Methods 0.000 description 3
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- 230000004048 modification Effects 0.000 description 3
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- 239000011591 potassium Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
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- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 description 1
- 241000723418 Carya Species 0.000 description 1
- 229920001661 Chitosan Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 241000588724 Escherichia coli Species 0.000 description 1
- 206010027439 Metal poisoning Diseases 0.000 description 1
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- 229910004283 SiO 4 Inorganic materials 0.000 description 1
- 206010070863 Toxicity to various agents Diseases 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
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- 102000004169 proteins and genes Human genes 0.000 description 1
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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
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
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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
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/26—Synthetic macromolecular compounds
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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
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
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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
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/285—Treatment of water, waste water, or sewage by sorption using synthetic organic sorbents
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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
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a preparation method of a pyrolytic biochar/geopolymer composite material, which comprises the steps of crushing wheat straw, uniformly mixing the crushed wheat straw with fly ash, adding potassium hydroxide solution, placing the mixture into a stirring device for stirring, curing the mixture to obtain a biochar/geopolymer composite material precursor, placing the precursor into a nitrogen atmosphere for pyrolysis, and then washing, drying and granulating the pyrolyzed biochar/geopolymer composite material. Wherein the dosages of the straw powder, the potassium hydroxide and the distilled water are respectively 5% -35%, 65% -85% and 30% -90% of the mass of the fly ash, the pyrolysis temperature is 300 ℃ -700 ℃ and the pyrolysis time is 2 hours; the prepared pyrolytic biochar/geopolymer composite material has good effects when being used for adsorbing and removing lead ions in water and passivating lead in soil in situ. The method has the advantages of simple process, low cost, resource utilization of solid waste and environmental protection, and the obtained composite material has wide application prospect in the treatment of water and soil polluted by heavy metal.
Description
Technical Field
The invention belongs to the field of solid waste resource utilization and heavy metal pollution water and soil treatment, and particularly relates to preparation of a pyrolytic biochar/geopolymer composite material and application of the prepared pyrolytic biochar/geopolymer composite material in adsorbing lead ions in water and passivating lead in soil in situ.
Background
Since the innovation is open, the industrialization process of China is accelerated, and a large amount of heavy metal lead polluted wastewater and land are generated. Lead ions can cause damage to the liver and kidneys or cause neurological disorders [ 1 ] through thiol interactions with proteins in the organism, and excessive lead can cause multiple toxic symptoms in plants [2] For example, slow development, sallow and black roots, etc., lead can inhibit photosynthesis of plants, destroy mineral nutrition and water balance, change hormone state, and influence cell membrane structure and permeability. Therefore, the water and soil treatment of lead pollution is highly emphasized in China, and the action plan for water pollution control and the action plan for soil pollution control are issued in sequence. Therefore, the development of lead-polluted water and soil treatment is imperative. Among the numerous lead-polluted water treatment methods, the adsorption method has the advantages of simple operation, low cost and the like, and is widely applied, and the material with the lead ion adsorption characteristic can generally passivate lead pollutants in soil, so that the adsorption material becomes a hot spot subject in the field of lead-polluted water and soil treatment. At present, researchers at home and abroad have developed various lead adsorption materials including clay minerals, organic polymers, biochar and the like, and have obtained great research results [ 2-5 ]. Wherein the biochar is a porous carbon material generated by pyrolysis of biomass raw materials under anaerobic or anoxic conditions, and has the advantages of wide raw material sources, capability of effectively reducing emission of greenhouse gases, capability of improving soil fertility, crop yield and the like [ 6 ]And 8, the method has a great deal of attention in adsorption removal of Pb (II) in water and in-situ passivation of soil lead. However, the biochar prepared by direct pyrolysis has fewer pores and surface active groups, and the adsorption and passivation properties are not ideal, so that certain modification is required. Ding et al [ 9 ] further modify the hickory biochar with NaOH, after modification, the specific surface area, cation exchange capacity and thermal stability of the biochar are significantly improved, and the modified biochar exhibits a better (2.6-5.8 times) heavy metal adsorption capacity than the original biochar; deng et al [ 10 ] studied chitosan and pyromellitic dianhydride modified biochar, the novel modified biochar having more surface functional groups.
The geopolymer is amorphous to semi-crystalline inorganic polymerized aluminosilicate which is produced by dissolving and polycondensing aluminosilicate raw materials such as calcined clay mineral or fly ash under the action of strong alkaline excitant, and has the following characteristics of [ SiO 4 ] 4- Tetrahedra and [ AlO ] 4 ] 5- The zeolite-like porous anionic framework structure formed by tetrahedra linked by covalent bonds formed by sharing the top oxygen atoms represents a zeolite-like ion exchange and adsorption property. Pang [ 11 ] reports the circulating fluidized bed fly ash base polymer pair Pb 2+ As a result, it was found that the removal rate of the geopolymer to lead ions tended to be gradually increased after the increase of the amount of addition, and the removal rate of the geopolymer to lead ions was 92.01% at an amount of addition of 0.5g/L and Pb at a pH of 5 2+ The maximum adsorption amount of (C) was 93.72mg/g. The research results also indicate that the geopolymer has potential application prospects in soil heavy metal passivation restoration.
The applicant refers to a large number of domestic and foreign patents and literature data through a system, and does not find out related reports about biochar/geopolymer composite materials and adsorption removal of lead in water and in-situ passivation of soil lead.
The following are references given by the inventors:
【1】Needleman H.Lead poisoning[J].Annu.Rev.Med.，2004，55：209-222。
【2】 He Jiakang, wang Baoming, wu Bingyu, etc. the development of attapulgite adsorption of Pb (ii) [ J ]. Industrial water treatment, 2020, 40 (08): 11-16.
【3】 Wang Luxing, zhou Xintao, luo Zhongqiu, etc. the agricultural and forestry waste adsorbs heavy metal Pb in the waste water 2+ Performance and mechanism development of (J)]Material guide 2020, 34 (17): 17115-17123.
【4】 Polyacrylamide composite material for adsorbing Pb in wastewater 2+ Research progress [ J]Industrial water treatment, 2018, 38 (06): 6-11.
【5】 Zhang Xiaoying, chen Su, liu Ying. Charcoal aging and its effect on heavy metal adsorption fixation research progress [ J/OL ]. Agricultural resources and environmental school report: 1-15[2023-03-08].
【6】Colantoni A，Evic N,Lord R，et al.Characterization of biochars produced from pyrolysis of pelletized agricultural residues[J].Renew.Sust.Energ.Rev.，2016，64：187-194。
【7】Mohanty S K,Cantrell K B,Nelson K L,et al.Efficacy of biochar to remove Escherichia coli from stormwater under steady and intermittent flow[J].Water res.，2014，61：288-296。
【8】Fang J，Zhan L，Ok Y S，et al.Minireview of potential applications of hydrochar derived from hydrothermal carbonization of biomass[J].J.Ind.Eng.Chem.，2018，57：15-21。
【9】Ding Z，Xin H，Wan Y，et al.Removal of lead,copper,cadmium,zinc,and nickel from aqueous solutions by alkali-modified biochar:Batch and column tests[J].J.Ind.Eng.Chem.，2016，33:239-245。
【10】Deng J，Liu Y，Liu S，et al.Competitive adsorption of Pb(II),Cd(II)and Cu(II)onto chitosan-pyromellitic dianhydride modified biochar[J].J.Colloid Interface Sci.，2017，506：355-364。
【11】 Pang preparation of circulating fluidized bed fly ash base polymer and Pb adsorption method thereof 2+ Investigation of Properties [ D]University of Shanxi, 2021.
【12】 Huang Yi, wu Di, yao Xia, li, deng Zixuan, tan Rui (Na, K) baseIn-situ synthesis of zeolite by mass polymer and passivation of soil Cu by zeolite 2+ 、Zn 2+ Pollution Performance study [ J]The Hunan urban university school journal (natural science edition), 2022,31 (03): 74-78.
Disclosure of Invention
The invention aims to provide a preparation method of a pyrolytic biochar/geopolymer composite material, and application of the prepared composite material in adsorption removal of lead ions in water or in-situ passivation of soil lead.
In order to achieve the above task, the present invention adopts the following technical solutions:
a preparation method of a pyrolytic biochar/geopolymer composite material is characterized in that fly ash, straw powder and aqueous solution of potassium hydroxide are put into a stirring device to be stirred to form evenly mixed slurry, a biochar/geopolymer precursor is obtained through curing, and then the pyrolytic biochar/geopolymer composite material is obtained through pyrolysis in nitrogen atmosphere, washing and drying; wherein: the dosages of the straw powder, the potassium hydroxide and the water respectively account for 5% -35%, 65% -85% and 30% -90% of the mass of the fly ash, the pyrolysis temperature is 300 ℃ -700 ℃, and the pyrolysis time is 2 hours.
The method specifically comprises the following steps:
(1) Weighing fly ash according to the formula amount, and placing the fly ash in an automatic stirrer with a set program;
(2) Weighing straws according to the formula amount, crushing the straws by using a crusher, sieving the crushed straws by using a 100-mesh sieve, and adding the crushed straws into the automatic stirrer in the step (1) for fully and uniformly dry mixing;
(3) Weighing solid potassium hydroxide according to the formula amount;
(4) Weighing water according to the formula, and dissolving solid potassium hydroxide in water;
(5) Cooling the potassium hydroxide solution to room temperature, adding the potassium hydroxide solution into the stirrer in the step (2), and stirring for 10min to obtain uniform slurry;
(6) Placing the slurry into a plastic film sealing bag, placing the plastic film sealing bag into an incubator, curing for 8 hours at 80 ℃, taking out the incubator, and curing for 48 hours at room temperature to obtain a biochar/geopolymer composite material precursor;
(7) Putting the precursor in the step (6) into a tube furnace, carrying out pyrolysis under nitrogen atmosphere, setting the heating rate to be 10 ℃/min, the pyrolysis temperature to be 300-700 ℃ and the pyrolysis time to be 2h, and obtaining a product;
(8) Washing the product obtained in the step (7) with distilled water and absolute ethyl alcohol alternately, filtering until the filtrate is neutral, drying for 12 hours at 105 ℃ in a constant-temperature drying oven, and granulating to obtain granules with the grain diameter of 0.250-0.600 mm, thus obtaining the pyrolytic biochar/geopolymer composite material.
Experiments of the applicant show that the prepared pyrolytic biochar/geopolymer composite material can be used for adsorbing lead ions in water and passivating lead in soil in situ.
The specific application comprises the following steps:
(1) Putting a certain amount of pyrolytic biochar/geopolymer composite material into a container with a certain volume and a concentration of C o Pb (NO) 3 ) 2 In the solution, the solution was subjected to centrifugation by shaking with a water bath constant temperature shaker for 24 hours, and Pb in the supernatant was detected by ICP 2+ The concentration, and the removal rate and the adsorption quantity of lead ions in water by the pyrolytic biochar/geopolymer composite material are calculated;
(2) Adding a certain amount of pyrolytic biochar/geopolymer composite material particles into simulated lead polluted soil, uniformly mixing, adding distilled water to keep 50% of field water holding capacity, taking out after 7d, air-drying, leaching effective-state lead in the soil by using diethyl triamine pentaacetic acid, detecting the concentration of lead ions in the extracting solution by using ICP, and calculating the passivation rate of the pyrolytic biochar/geopolymer composite material on the lead in the soil.
The invention is innovative in that the strong alkaline environment of the geopolymer is skillfully utilized to carry out alkali modification on the biochar, and simultaneously, the high-temperature environment required by preparing the biochar is utilized to promote the further polycondensation of the geopolymer to obtain more pore structures, so that the pyrolytic biochar/geopolymer composite material for adsorbing and removing lead ions in water or passivating soil lead in situ is obtained.
Drawings
FIG. 1 is a process flow for the preparation and application of a pyrolyzed biochar/geopolymer composite material;
FIG. 2 is a scanning electron micrograph of the pyrolyzed biochar/geopolymer composite material prepared in example 3;
FIG. 3 shows the adsorption removal rate and adsorption amount of lead ions in water by the pyrolysis biochar/geopolymer composite material of application examples 1-3.
FIG. 4 is the passivation rate of lead in soil by the pyrolysis biochar/geopolymer composite material of application examples 1-3.
The invention will now be described in further detail with reference to the drawings and examples.
Detailed Description
In the examples below, the applicant gives examples of the preparation of a pyrolytic biochar/geopolymer composite and its application in the adsorption removal of lead ions from water or in-situ passivation of soil lead.
The following examples are only for better explanation of the present invention, and the present invention is not limited to these examples.
The preparation of the pyrolytic biochar/geopolymer composite material adopts the main raw materials of industrial solid waste fly ash, agricultural solid waste wheat straw powder and potassium hydroxide, wherein the mixing amount of the straw powder, the potassium hydroxide and the water is based on the mass of the fly ash; the mixing amount of the straw powder is 5-35% of the mass of the fly ash, the mixing amount of the potassium hydroxide is 65-85% of the mass of the fly ash, the mixing amount of the water is 30-90% of the mass of the fly ash, and the pyrolysis atmosphere is N 2 The pyrolysis temperature is 300-700 ℃ and the pyrolysis time is 2h.
The preparation method comprises the following steps:
(1) Wheat straw is collected in a local farmland, dried, crushed and sieved by a 100-mesh sieve for standby.
(2) The fly ash is selected from class I fly ash of Henan Sanjia power plant, the fly ash is dried in an oven for 10 hours at 105 ℃, and the main oxide composition (mass percent) of the fly ash is shown in table 1.
Table 1: oxide composition of fly ash (wt%)
| Oxide compound | SiO 2 | Al 2 O 3 | Fe 2 O 3 | CaO | Na 2 O | MgO | K 2 O | SO 3 | TiO 2 | Loss | Impurity(s) |
| wt％ | 52.77 | 29.14 | 5.81 | 4.49 | 0.48 | 0.98 | 2.53 | 0.81 | 1.44 | 0.84 | Allowance of |
(3) Potassium hydroxide, available from national pharmaceutical chemicals, inc.
Preparation example 1:
200g of fly ash raw material is accurately weighed, and based on the weighing (100%), the mass of straw powder is 20% of the mass of the fly ash, the doping amount of potassium hydroxide is 75% of the mass of the fly ash, and the mass of water is 50% of the mass of the fly ash by adopting an externally doping method.
Before preparation, water and potassium hydroxide are prepared into potassium hydroxide solution for standby.
Placing the fly ash and straw powder into an automatic stirrer, pouring the prepared potassium hydroxide solution, uniformly mixing and stirring, and reacting to form uniform slurry; and filling the slurry into a plastic film sealing bag for sealing, placing the plastic film sealing bag into an incubator for curing for 8 hours at 80 ℃, taking out the plastic film sealing bag, and curing for 48 hours at room temperature to obtain the biochar/geopolymer composite material precursor. Then 30g of the precursor is weighed and put into a tube furnace, and the pyrolysis atmosphere is set as N 2 The pyrolysis temperature is 300 ℃ and the pyrolysis time is 2h. Taking out after pyrolysis is finished, alternately flushing and suction filtering with distilled water and absolute ethyl alcohol until filtrate is neutral, drying at 105 ℃ for 12 hours, crushing and granulating to obtain particles with the particle size of 0.25-0.60 mm, and recording as 30PBCGC-300.
Preparation example 2:
200g of fly ash raw material is accurately weighed, and based on the weighing (100%), the mass of straw powder is 20% of the mass of the fly ash, the solid potassium hydroxide doping amount is 75% of the mass of the fly ash, and the mass of water is 50% of the mass of the fly ash by adopting an externally doping method.
Before preparation, water and potassium hydroxide are prepared into potassium hydroxide solution for standby.
Placing the fly ash and straw powder into an automatic stirrer, pouring the prepared potassium hydroxide solution, uniformly mixing and stirring, and reacting to form uniform slurry; filling the slurry into a plastic film sealing bag for sealing, and placingCuring for 8 hours at 80 ℃ in a constant temperature box, then taking out, and curing for 48 hours at room temperature to obtain the biochar/geopolymer composite material precursor. Then 30g of the precursor is weighed and put into a tube furnace, and the pyrolysis atmosphere is set as N 2 The pyrolysis temperature is 500 ℃ and the pyrolysis time is 2h. Taking out after pyrolysis is finished, alternately flushing and suction filtering with distilled water and absolute ethyl alcohol until filtrate is neutral, drying at 105 ℃ for 12 hours, crushing and granulating to obtain particles with the particle size of 0.25-0.60 mm, and recording as 30PBCGC-500.
Preparation example 3:
200g of fly ash raw material is accurately weighed, and based on the weighing (100%), the mass of straw powder is 20% of the mass of the fly ash, the solid potassium hydroxide doping amount is 75% of the mass of the fly ash, and the mass of water is 50% of the mass of the fly ash by adopting an externally doping method.
Before preparation, water and potassium hydroxide are prepared into potassium hydroxide solution for standby.
Placing the fly ash and straw powder into an automatic stirrer, pouring the prepared potassium hydroxide solution, uniformly mixing and stirring, and reacting to form uniform slurry; and filling the slurry into a plastic film sealing bag for sealing, placing the plastic film sealing bag into an incubator for curing for 8 hours at 80 ℃, taking out the plastic film sealing bag, and curing for 48 hours at room temperature to obtain the biochar/geopolymer composite material precursor. Then 30g of the precursor is weighed and put into a tube furnace, and the pyrolysis atmosphere is set as N 2 The pyrolysis temperature is 700 ℃, and the pyrolysis time is 2 hours. Taking out after pyrolysis is finished, alternately flushing and filtering with distilled water and absolute ethyl alcohol until filtrate is neutral, drying at 105 ℃ for 12 hours, crushing and granulating to obtain particles with the particle size of 0.25-0.60 mm, and recording as 30PBCGC-700, wherein a scanning electron microscope photograph is shown in figure 2. It can be seen that the long columnar biochar particles are embedded in the geopolymer matrix, so that rich pore channels are formed, and the pore channels provide a substance transmission channel for lead ion adsorption/passivation.
Experiments of the inventor prove that the pyrolytic biochar/geopolymer composite material prepared by the embodiment can efficiently adsorb and remove Pb in water 2+ And in-situ passivating Pb (II) in soil, which comprises the following steps:
(1) Putting a certain amount of pyrolytic biochar/geopolymer composite material into a container with a certain volume and a concentration of C o Pb (NO) 3 ) 2 In the solution, oscillating for 24h with a water bath constant temperature oscillator, centrifuging, collecting supernatant, and detecting Pb with ICP 2 + Concentration of C t And calculating the removal rate and adsorption quantity of the pyrolytic biochar/geopolymer composite material on lead ions in water;
(2) Adding a certain amount of pyrolytic biochar/geopolymer composite material particles into simulated lead polluted soil, uniformly mixing, adding distilled water to keep 50% of field water holding capacity, taking out after 7d, air-drying, leaching effective-state lead in the soil by using diethyl triamine pentaacetic acid, detecting the concentration of lead ions in the extracting solution by using ICP, and calculating the passivation rate of the pyrolytic biochar/geopolymer composite material on the lead in the soil.
Application experiment example 1:
(1) Adsorption: accurately weighing 0.05g of the pyrolytic biochar/geopolymer composite material sample (30 PBCGC-300) prepared in preparation example 1, adding the sample into 100mL of lead nitrate solution with the concentration of 100mg/L, oscillating for 24 hours by a water bath constant temperature oscillator, centrifuging, and detecting Pb in the supernatant by ICP 2+ The concentration is calculated, and the removal rate and adsorption capacity of lead ions are respectively 68.12 percent and 136.14mg/g;
(2) And (3) in-situ passivation: 3.6g of the pyrolytic biochar/geopolymer composite material sample (30 PBCGC-300) prepared in preparation example 1 was accurately weighed, 40g of simulated lead contaminated soil was added, distilled water was added after uniform mixing to maintain 50% of field water holding capacity, after 7d, the soil was taken out, air-dried, the effective state lead in the soil was leached with diethyl triamine pentaacetic acid, the lead ion concentration in the extract was detected with ICP, and the passivation rate of the soil lead was calculated to be 32.68%.
Application experiment example 2:
(1) Adsorption: accurately weighing 0.05g of the pyrolytic biochar/geopolymer composite material sample (30 PBCGC-300) prepared in preparation example 2, adding into 100mL of lead nitrate solution with the concentration of 100mg/L, oscillating for 24 hours by a water bath constant temperature oscillator, centrifuging, and detecting Pb in the supernatant by ICP 2+ Concentration and calculate its lead ion removalThe removal rate and the adsorption quantity are 77.46 percent and 154.92mg/g respectively;
(2) And (3) in-situ passivation: 3.6g of the pyrolytic biochar/geopolymer composite material sample (30 PBCGC-500) prepared in preparation example 2 is accurately weighed, 40g of simulated lead contaminated soil is added, distilled water is added after uniform mixing to maintain 50% of field water holding capacity, after 7d, the soil is taken out and air-dried, the effective lead in the soil is leached by diethyl triamine pentaacetic acid, the concentration of lead ions in the extract is detected by ICP, and the passivation rate of the soil lead is 52.15% is calculated.
Application experiment example 3:
(1) Adsorption: accurately weighing 0.05g of the pyrolytic biochar/geopolymer composite material sample (30 PBCGC-700) prepared in preparation example 3, adding the pyrolytic biochar/geopolymer composite material sample into 100mL of lead nitrate solution with concentration of 100mg/L, oscillating for 24 hours by a water bath constant temperature oscillator, centrifuging, and detecting Pb in the supernatant by ICP 2+ The concentration is calculated, and the removal rate and adsorption capacity of the lead ions are respectively 99.99 percent and 199.98mg/g;
(2) And (3) in-situ passivation: 3.6g of the pyrolytic biochar/geopolymer composite material sample (30 PBCGC-700) prepared in preparation example 3 is accurately weighed, 40g of simulated lead contaminated soil is added, distilled water is added after uniform mixing to maintain 50% of field water holding capacity, after 7d, the obtained product is taken out and air-dried, the effective lead in the soil is leached by diethyl triamine pentaacetic acid, the concentration of lead ions in the extract is detected by ICP, and the passivation rate of the lead in the soil is 76.33%. In addition, the addition of 30PBCGC-700 increases the quick-acting potassium content in the soil from 411.19mg/kg to 1007.96mg/kg, which shows that the potassium nutrient content in the soil can be effectively improved while the heavy metals are passivated.
Claims (5)
1. The preparation method of the pyrolytic biochar/geopolymer composite material is characterized by comprising the steps of placing pulverized fuel ash, straw powder and aqueous solution of potassium hydroxide into a stirring device for stirring to form uniform slurry, curing to obtain a biochar/geopolymer composite material precursor, and then carrying out pyrolysis, washing, drying and granulation in a nitrogen atmosphere to obtain the pyrolytic biochar/geopolymer composite material; wherein: the dosages of the straw powder, the potassium hydroxide and the water respectively account for 5% -35%, 65% -85% and 30% -90% of the mass of the fly ash, the pyrolysis temperature is 300 ℃ -700 ℃, and the pyrolysis time is 2 hours.
2. The method according to claim 1, characterized in that it comprises in particular the following steps:
(1) Weighing fly ash according to the formula amount, and placing the fly ash in an automatic stirrer with a set program;
(2) Weighing straws according to the formula amount, drying, crushing by using a crusher, sieving by using a 100-mesh sieve, and adding the crushed straws into the automatic stirrer in the step (1) for fully and uniformly dry mixing;
(3) Weighing solid potassium hydroxide according to the formula amount;
(4) Weighing water according to the formula, and dissolving solid potassium hydroxide in water;
(5) Cooling the potassium hydroxide solution to room temperature, adding the potassium hydroxide solution into the stirrer in the step (2), and stirring for 10min to obtain uniform slurry;
(6) Placing the slurry into a plastic film sealing bag, placing the plastic film sealing bag into an incubator, curing for 8 hours at 80 ℃, taking out the incubator, and curing for 48 hours at room temperature to obtain a biochar/geopolymer composite material precursor;
(7) Putting the precursor in the step (6) into a tube furnace, carrying out pyrolysis under nitrogen atmosphere, setting the heating rate to be 10 ℃/min, the pyrolysis temperature to be 300-700 ℃ and the pyrolysis time to be 2h, and obtaining a product;
(8) Washing the product obtained in the step (7) with distilled water and absolute ethyl alcohol alternately, filtering until the filtrate is neutral, drying for 12 hours at 105 ℃ in a constant-temperature drying oven, and granulating to obtain granules with the grain diameter of 0.250-0.600 mm, thus obtaining the pyrolytic biochar/geopolymer composite material.
3. The method of claim 1, wherein the fly ash comprises the following oxides in mass percent: siO (SiO) 2 ：52.77％，Al 2 O 3 ：29.14％，Fe 2 O 3 ：5.81％，CaO：4.49％，Na 2 O：0.48％，MgO：0.98％，K 2 O：2.53％，SO 3 ：0.81％，TiO 2 ：1.44％，Loss：0.84％，The balance being unavoidable impurities.
4. Use of the pyrolytic biochar/geopolymer composite material prepared by the method of claim 1 or 2 or 3 for adsorbing lead ions in water and passivating lead in soil in situ.
5. The use according to claim 4, characterized by the following implementation:
(1) Putting a certain amount of pyrolytic biochar/geopolymer composite material into a container with a certain volume and a concentration of C o Pb (NO) 3 ) 2 In the solution, the solution was subjected to centrifugation by shaking with a water bath constant temperature shaker for 24 hours, and Pb in the supernatant was detected by ICP 2+ The concentration, and the removal rate and the adsorption quantity of lead ions in water by the pyrolytic biochar/geopolymer composite material are calculated;
(2) Adding a certain amount of pyrolytic biochar/geopolymer composite material particles into simulated lead polluted soil, uniformly mixing, adding distilled water to keep 50% of field water holding capacity, taking out after 7d, air-drying, leaching effective-state lead in the soil by using diethyl triamine pentaacetic acid, detecting the concentration of lead ions in the extracting solution by using ICP, and calculating the passivation rate of the pyrolytic biochar/geopolymer composite material on the lead in the soil.
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