CN116393096B - Composite material, method for synchronously producing methane and removing ammonia nitrogen and application - Google Patents
Composite material, method for synchronously producing methane and removing ammonia nitrogen and application Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 68
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 title claims abstract description 55
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 25
- 239000007800 oxidant agent Substances 0.000 claims abstract description 70
- 230000001590 oxidative effect Effects 0.000 claims abstract description 66
- 230000029087 digestion Effects 0.000 claims abstract description 60
- DCYOBGZUOMKFPA-UHFFFAOYSA-N iron(2+);iron(3+);octadecacyanide Chemical class [Fe+2].[Fe+2].[Fe+2].[Fe+3].[Fe+3].[Fe+3].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] DCYOBGZUOMKFPA-UHFFFAOYSA-N 0.000 claims abstract description 60
- 239000000126 substance Substances 0.000 claims abstract description 17
- 238000011065 in-situ storage Methods 0.000 claims abstract description 13
- 239000000243 solution Substances 0.000 claims description 90
- 238000000855 fermentation Methods 0.000 claims description 75
- 230000004151 fermentation Effects 0.000 claims description 67
- 239000002054 inoculum Substances 0.000 claims description 48
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 44
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 42
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 42
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 41
- 239000000758 substrate Substances 0.000 claims description 39
- 210000003608 fece Anatomy 0.000 claims description 33
- 239000007787 solid Substances 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 27
- 239000002243 precursor Substances 0.000 claims description 23
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 22
- 238000002360 preparation method Methods 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 18
- 239000007853 buffer solution Substances 0.000 claims description 16
- 229920000642 polymer Polymers 0.000 claims description 15
- 239000011734 sodium Substances 0.000 claims description 13
- 239000000872 buffer Substances 0.000 claims description 12
- 239000000264 sodium ferrocyanide Substances 0.000 claims description 12
- GTSHREYGKSITGK-UHFFFAOYSA-N sodium ferrocyanide Chemical compound [Na+].[Na+].[Na+].[Na+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] GTSHREYGKSITGK-UHFFFAOYSA-N 0.000 claims description 12
- 235000012247 sodium ferrocyanide Nutrition 0.000 claims description 12
- 239000011592 zinc chloride Substances 0.000 claims description 11
- 235000005074 zinc chloride Nutrition 0.000 claims description 11
- XPFJYKARVSSRHE-UHFFFAOYSA-K trisodium;2-hydroxypropane-1,2,3-tricarboxylate;2-hydroxypropane-1,2,3-tricarboxylic acid Chemical compound [Na+].[Na+].[Na+].OC(=O)CC(O)(C(O)=O)CC(O)=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O XPFJYKARVSSRHE-UHFFFAOYSA-K 0.000 claims description 10
- 230000001079 digestive effect Effects 0.000 claims description 9
- 235000011389 fruit/vegetable juice Nutrition 0.000 claims description 9
- 239000010802 sludge Substances 0.000 claims description 9
- 230000007547 defect Effects 0.000 claims description 6
- 239000008187 granular material Substances 0.000 claims description 6
- 239000011701 zinc Substances 0.000 claims description 6
- 230000002378 acidificating effect Effects 0.000 claims description 4
- 230000002708 enhancing effect Effects 0.000 claims description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 23
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 17
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 abstract description 15
- 230000000694 effects Effects 0.000 abstract description 15
- 239000007788 liquid Substances 0.000 abstract description 8
- 238000004064 recycling Methods 0.000 abstract description 2
- 239000002910 solid waste Substances 0.000 abstract description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 33
- 239000010871 livestock manure Substances 0.000 description 25
- 238000012360 testing method Methods 0.000 description 23
- 238000003756 stirring Methods 0.000 description 20
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 18
- 238000001179 sorption measurement Methods 0.000 description 16
- 125000000524 functional group Chemical group 0.000 description 12
- 239000000203 mixture Substances 0.000 description 11
- 238000005728 strengthening Methods 0.000 description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 10
- 239000001301 oxygen Substances 0.000 description 10
- 229910052760 oxygen Inorganic materials 0.000 description 10
- 238000000197 pyrolysis Methods 0.000 description 10
- 239000008367 deionised water Substances 0.000 description 9
- 229910021641 deionized water Inorganic materials 0.000 description 9
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 8
- 230000005764 inhibitory process Effects 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 238000004140 cleaning Methods 0.000 description 7
- 238000001914 filtration Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000012986 modification Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- AZQWKYJCGOJGHM-UHFFFAOYSA-N 1,4-benzoquinone Chemical compound O=C1C=CC(=O)C=C1 AZQWKYJCGOJGHM-UHFFFAOYSA-N 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 6
- 239000003153 chemical reaction reagent Substances 0.000 description 6
- 230000006870 function Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 230000004048 modification Effects 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000010902 straw Substances 0.000 description 6
- 239000000725 suspension Substances 0.000 description 6
- 229910021529 ammonia Inorganic materials 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000001509 sodium citrate Substances 0.000 description 5
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 5
- 240000008042 Zea mays Species 0.000 description 4
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 4
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 4
- CKUAXEQHGKSLHN-UHFFFAOYSA-N [C].[N] Chemical compound [C].[N] CKUAXEQHGKSLHN-UHFFFAOYSA-N 0.000 description 4
- 238000009825 accumulation Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 4
- 235000005822 corn Nutrition 0.000 description 4
- 244000005700 microbiome Species 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 239000013522 chelant Substances 0.000 description 3
- 239000000084 colloidal system Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000001186 cumulative effect Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
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- 238000005470 impregnation Methods 0.000 description 3
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- 238000011068 loading method Methods 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- 230000000813 microbial effect Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 125000004151 quinonyl group Chemical group 0.000 description 3
- 244000025254 Cannabis sativa Species 0.000 description 2
- 238000005411 Van der Waals force Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 238000001994 activation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- -1 citrate ions Chemical class 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 235000013399 edible fruits Nutrition 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 239000010813 municipal solid waste Substances 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000020477 pH reduction Effects 0.000 description 2
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 2
- 239000012286 potassium permanganate Substances 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000013138 pruning Methods 0.000 description 2
- 229960003351 prussian blue Drugs 0.000 description 2
- 239000013225 prussian blue Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
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- 230000002194 synthesizing effect Effects 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- WGIWBXUNRXCYRA-UHFFFAOYSA-H trizinc;2-hydroxypropane-1,2,3-tricarboxylate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O.[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O WGIWBXUNRXCYRA-UHFFFAOYSA-H 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- HMUNWXXNJPVALC-UHFFFAOYSA-N 1-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)C(CN1CC2=C(CC1)NN=N2)=O HMUNWXXNJPVALC-UHFFFAOYSA-N 0.000 description 1
- 241000195493 Cryptophyta Species 0.000 description 1
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- 208000002720 Malnutrition Diseases 0.000 description 1
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- 239000003463 adsorbent Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
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- 150000001413 amino acids Chemical class 0.000 description 1
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- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
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- 238000000354 decomposition reaction Methods 0.000 description 1
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- 238000012851 eutrophication Methods 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
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- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
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Classifications
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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
-
- 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
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/3085—Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/60—Biochemical treatment, e.g. by using enzymes
- B09B3/65—Anaerobic treatment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/02—Biological treatment
- C02F11/04—Anaerobic treatment; Production of methane by such processes
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- Inorganic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Health & Medical Sciences (AREA)
- Molecular Biology (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Fertilizers (AREA)
Abstract
The invention belongs to the technical field of solid waste recycling, and particularly relates to a composite material, a method for synchronously producing methane and removing ammonia nitrogen and application thereof. The invention provides a strong oxidant modified biochar-loaded Prussian blue analog composite material, which forms a polymeric carrier through the bonding effect and the chemical bond bonding effect of strong oxidant modified biochar and CMC, and then the Prussian blue analog grows in situ on the polymeric carrier to form a CMC bonded or coated composite material. The composite material provided by the invention can strengthen anaerobic digestion and digestion liquid ammonia nitrogen removal simultaneously, obviously reduce ammonia nitrogen concentration in digestion liquid and improve methane yield.
Description
Technical Field
The invention belongs to the technical field of environmental protection in the fields of solid waste recycling and energy conservation, and particularly relates to a composite material, a method for synchronously producing methane and removing ammonia nitrogen and application thereof.
Background
Anaerobic digestion is a widely applied biotechnology, and under the synergistic effect of various microorganisms, organic matters in waste are converted into biogas through four continuous steps of hydrolysis, acidification, acetylation and methanogenesis, so that the anaerobic digestion is widely applied to the treatment of wastes such as agriculture, industry and the like. However, when livestock manure, sewage sludge, rural organic household garbage and the like are used as raw materials for anaerobic digestion, the gas production efficiency is improvedThe anaerobic digestion system has poor efficiency and stability particularly when the raw materials with high nitrogen content such as livestock manure are used as the sole substrates, and the inherent low carbon/nitrogen ratio causes malnutrition of the anaerobic digestion system and the microbial activity is influenced. Excess inorganic Nitrogen (NH) during anaerobic digestion of nitrogen-rich feedstock 3 /NH 4+ ) Accumulation becomes a remarkable inhibitor, ammonia nitrogen concentration is too high and acidification is easy to cause, while certain ammonia nitrogen is beneficial to bacterial growth, the concentration of the ammonia nitrogen is gradually increased along with the decomposition of a large amount of available proteins and amino acids in a substrate, and when the ammonia nitrogen concentration exceeds a certain value, microbial activities are permanently inhibited for digestion, or a microbial community is required to adapt to digestion environment, so that the digestion stage is remarkably prolonged (Yellezuome D, zhu X, wang Z, et al Mitigation of ammonia inhibition in anaerobic digestion of nitrogen-rich substrates for biogas production by ammonia stripping:A review [ J ]]. Renewable &Sustainable Energy reviews 2022, 157.). Meanwhile, high-concentration ammonia nitrogen flows out along with the digestive juice, so that a large amount of ammonia nitrogen remains in the digestive juice, the digestive juice is commonly used for preparing liquid fertilizer or is discharged after being treated to reach the standard, but the digestive juice containing high-concentration ammonia nitrogen can cause eutrophication of water bodies, excessive propagation of microorganisms and algae, the growth of crops is not facilitated, and the follow-up treatment process is complicated due to the too high concentration of ammonia nitrogen. Therefore, the low anaerobic digestion efficiency and the ammonia nitrogen removal of the digestive juice are one of the problems to be solved in the urgent need.
The adsorption method is a common method for treating ammonia nitrogen pollutants, and among a plurality of adsorption materials, the biochar has the characteristics of higher specific surface area, rich oxygen-containing functional groups, good regeneration performance, low price and the like. Biochar plays an important role in the field of sewage adsorption, is also used as a functional material for enhancing anaerobic digestion, and has a more pore structure and a plurality of oxygen-containing functional groups, plays a role in improving the electron transfer efficiency in an anaerobic digestion system, and is an important anaerobic digestion enhancing material. However, it is reported that although biochar has many applications in enhancing anaerobic digestion systems, it does not have good ability to reduce ammonia nitrogen concentration by alleviating ammonia inhibition, and secondly, biochar has no specificity for adsorption of ammonia nitrogen, and adsorbs other substances at the same time, resulting in unsatisfactory adsorption capacity of biochar for ammonia nitrogen. Aiming at the problems of anaerobic digestion strengthening technology and digestion liquid ammonia nitrogen adsorption, the research of strengthening the modified biochar composite material is necessary.
Disclosure of Invention
The invention aims to provide a strong oxidant modified biochar-loaded Prussian blue analog composite material, and the composite material can be used for simultaneously strengthening anaerobic digestion and digestion liquid ammonia nitrogen removal by anaerobic digestion, so that the ammonia nitrogen concentration in digestion liquid is obviously reduced.
The invention provides a strong oxidant modified biochar Prussian blue analog-loaded composite material, which comprises a polymer carrier and Prussian blue analog loaded on the polymer carrier; the polymer carrier is formed by combining strong oxidant modified biochar and carboxymethyl cellulose.
Preferably, the means of bonding comprises physical bonding and/or chemical bonding.
Preferably, the Prussian blue analogues are supported in the lamellar layers and/or defect sites of the strong oxidant modified biochar.
The invention provides a preparation method of the composite material, which comprises the following steps:
firstly mixing strong oxidant modified biochar with carboxymethyl cellulose solution to obtain precursor solution;
second mixing the precursor solution and sodium ferrocyanide to obtain a first solution;
thirdly mixing the weak acid buffer solution with zinc chloride to obtain a second solution;
adding the first solution into the second solution to obtain a composite material;
the pH value of the weak acid buffer solution is 3.5-5.6.
Preferably, the molar ratio of the mass of the strong oxidant modified biochar to the molar ratio of sodium ferrocyanide is 5-10 g: 1-2 mM.
Preferably, the mass concentration of zinc chloride in the second solution is 10-25 g/L; the weak acidic buffer comprises a citric acid-sodium citrate buffer.
Preferably, the mass concentration of the carboxymethyl cellulose in the carboxymethyl cellulose solution is 0.25-0.5wt%.
The invention provides a method for synchronously strengthening anaerobic digestion to produce methane and remove ammonia nitrogen in situ, which comprises the steps of mixing a composite material prepared by the technical scheme or a composite material prepared by the preparation method of the technical scheme, an inoculum, a fermentation substrate and water to obtain a fermentation system, and carrying out anaerobic fermentation;
the inoculum comprises anaerobic sludge granules and cow dung mixed culture.
Preferably, when the total solid content of the fermentation substrate and the inoculum is 8.5% -10.5%, adding a composite material when the pH value of the fermentation system is more than 7.8 or less than 6.5, wherein the addition amount of the composite material accounts for 10% -15% of the total solid content of the fermentation substrate;
when the total solid content of the fermentation substrate and the inoculant is more than 10.5%, the addition amount of the composite material accounts for 5% of the total solid content of the fermentation substrate, and the composite material and the fermentation substrate are added simultaneously.
The invention provides the composite material prepared by the technical scheme or the preparation method of the technical scheme or the application of the method of the technical scheme in improving the yield of anaerobic digestion methane and/or reducing the ammonia nitrogen concentration of digestion liquid.
The invention has the following effective effects: the invention provides a strong oxidant modified biochar Prussian blue analog-loaded composite material, which comprises a polymer carrier and Prussian blue analog loaded on the polymer carrier; the polymer carrier is formed by combining strong oxidant modified biochar and carboxymethyl cellulose.
According to the composite material provided by the invention, the methane-producing strengthening effect of the strong oxidant modified biochar is organically coupled with the efficient coordination effect of the Prussian blue analogue on ammonia nitrogen, so that the anaerobic digestion efficiency is improved and the in-situ ammonia nitrogen in the digestive juice is removed. Specifically, the strong oxidant modified biochar can increase the content of oxygen-containing functional groups of the biochar to strengthen the methane yield; simultaneously improve living thingsCarbon and carboxymethylcellulose (CMC) form a polymeric support in a chemically bonded ratio; while sodium ferrocyanide (Na 4 Fe(CN) 6 ) Is a precursor for synthesizing Prussian blue analogues, citrate ions and zinc chloride in a buffer solution form chelate in the form of citrate-zinc ions, and the solution and Na 4 Fe(CN) 6 Co-precipitate is formed after mixing, namely Na 2 Zn 3 [Fe(CN) 6 ] 2 . Under the action of citric acid buffer solution, na 4 Fe(CN) 6 Reacts with zinc chloride to form Prussian blue analogues (Na 2 Zn 3 [Fe(CN) 6 ] 2 ) And then the Prussian blue analogues grow in situ on the polymeric carrier to form a composite material bonded or coated by CMC, and the Prussian blue analogues are further fixed between strong oxidant modified biochar sheets and in defect sites of the strong oxidant modified biochar by the bonding action of CMC, so that interaction among Prussian blue crystals is avoided, and the ammonia nitrogen loading efficiency of the Prussian blue analogues is greatly improved by combining chemical grafting and physical bonding in the whole process. The strong oxidant modified biochar Prussian blue analogue loaded composite material provided by the invention can simultaneously strengthen anaerobic digestion and digestion liquid ammonia nitrogen removal, obviously reduce ammonia nitrogen concentration in digestion liquid and improve methane yield.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments will be briefly described below.
FIG. 1 is a graph showing the cumulative methane yield change for test examples 1-3;
FIG. 2 is a graph showing the ammonia nitrogen concentration change of test examples 1 to 3;
FIG. 3 is a functional group fitting analysis result of the modified biochar prepared in example 1;
FIG. 4 shows the result of functional group fitting analysis of the biochar prepared in example 1.
Detailed Description
The invention provides a strong oxidant modified biochar Prussian blue analog-loaded composite material, which comprises a polymer carrier and Prussian blue analog loaded on the polymer carrier; the polymer carrier is formed by combining strong oxidant modified biochar and carboxymethyl cellulose.
In the present invention, the means of bonding preferably includes adhesive fixation and/or chemical bond bonding, more preferably adhesive fixation and chemical bond bonding. The adhesive immobilization and chemical bond bonding according to the invention are preferably achieved by means of carboxymethyl cellulose.
In the present invention, the Prussian blue analogues are preferably supported in the lamellar layers and/or defect sites of the strong oxidant modified biochar.
The strong oxidant modified biochar Prussian blue analogue loaded composite material is used for anaerobic digestion, and can achieve the technical effects of reducing ammonia nitrogen concentration in digestive juice and improving methane yield.
The invention provides a preparation method of the composite material, which comprises the following steps:
firstly mixing strong oxidant modified biochar with carboxymethyl cellulose solution to obtain precursor solution;
second mixing the precursor solution and sodium ferrocyanide to obtain a first solution;
thirdly mixing the weak acid buffer solution with zinc chloride to obtain a second solution;
adding the first solution into the second solution to obtain a composite material;
the pH value of the weak acid buffer solution is 3.5-5.6.
Firstly, the strong oxidant modified biochar is first mixed with a carboxymethyl cellulose solution to obtain a precursor solution.
In the invention, the strong oxidant modified biochar is preferably prepared by the following method: the biochar is modified after being mixed with the strong oxidant aqueous solution, so as to obtain the strong oxidant modified biochar. The biochar is preferably prepared by pyrolysis of lignocellulose waste; the lignocellulose waste of the invention preferably comprises one or more than two of corncob, corn straw, grass wood, fruit tree pruning and straw, more preferably one of corncob, corn straw, grass wood, fruit tree pruning and straw, and even more preferably one of corncob or corn straw. The pyrolysis temperature is preferably 450-650 ℃, more preferably 550 ℃, and the pyrolysis time is preferably 2h after reaching the set pyrolysis temperature.
After the biochar is obtained, the biochar is preferably activated first. The activation of the invention is preferably carried out by immersing biochar in aqueous hydrochloric acid; the molar concentration of hydrochloric acid in the hydrochloric acid aqueous solution is preferably 0.1-0.5M, more preferably 0.2-0.4M, and even more preferably 0.3M; in the embodiment of the present invention, the molar concentration of hydrochloric acid in the aqueous hydrochloric acid solution is preferably 0.1M or 0.5M. The volume ratio of the mass of the impregnated biochar to the hydrochloric acid aqueous solution is preferably 5-10 g:100 to 250mL, more preferably 5g:200mL.
The time of the impregnation is preferably 12-24 hours, more preferably 16-24 hours, even more preferably 20-24 hours, and even more preferably 24 hours; the temperature of the impregnation is preferably 30 to 60 ℃, more preferably 30 to 50 ℃, still more preferably 30 to 40 ℃, and still more preferably 30 ℃.
The dipping is preferably carried out under stirring conditions, and the stirring speed is preferably 110-130 rpm, more preferably 120rpm; the stirring according to the invention is preferably effected by means of a magnetic stirrer.
After the impregnation is finished, the activated charcoal powder is preferably obtained by sequentially carrying out suction filtration, cleaning, drying and grinding on the impregnated product of the charcoal. The suction filtration and the cleaning are preferably completed by deionized water with the temperature of 90-100 ℃, and the biological carbon impregnated product is cleaned to be neutral. The neutral pH of the present invention is preferably at least 6.5. The invention is not particularly limited to the drying, and conventional parameters are adopted. The invention preferably grinds the dried biochar and then sieves the ground biochar to obtain undersize, namely activated biochar powder. The mesh number of the screen according to the present invention is preferably 100 mesh. The hydrochloric acid impregnating function of the invention is to activate the biochar and remove tar and ash on the surface of the biochar.
After activated biochar powder is obtained, the activated biochar powder is preferably mixed with a strong oxidant aqueous solution for modification, so that strong oxidant modified biochar is obtained. The molar concentration of the strong oxidizing agent in the strong oxidizing agent aqueous solution is preferably 0.2 to 1M, more preferably 0.3 to 0.7M, and even more preferably 0.5M. The strong oxidizing agent of the present invention preferably comprises potassium dichromate, potassium permanganate or hydrogen peroxide, more preferably potassium permanganate or hydrogen peroxide, and still more preferably hydrogen peroxide. The temperature of the modification is preferably 30-55 ℃, more preferably 35-55 ℃, still more preferably 40-55 ℃, and more preferably 55 ℃; the modification time is preferably 12-24 hours, more preferably 16-24 hours, still more preferably 18-24 hours, and still more preferably 24 hours; the modification is preferably completed under the vibration condition, and the rotation speed of vibration is preferably 120-150 rmp, more preferably 140-150 rmp, and even more preferably 150rmp; the invention preferably cleans and dries the modified biological carbon. The cleaning is preferably carried out by using deionized water for pumping, filtering and washing for 3-5 times, and more preferably 4 times.
In the prior art, the biochar has numerous applications in strengthening anaerobic digestion and methanogenesis, mainly due to numerous advantages of the biochar, such as rich oxygen-containing functional groups, multiple pores, large specific surface area and the like, but the original biochar (before being unmodified) has no outstanding effect in strengthening methanogenesis and the capability of absorbing ammonia nitrogen and relieving ammonia nitrogen inhibition in an anaerobic digestion system. The original biochar can strengthen anaerobic digestion and methane production, but can not absorb ammonia nitrogen in a large amount to relieve ammonia nitrogen inhibition, and the effect of strengthening the anaerobic digestion and methane production of high-nitrogen raw materials is poor, so that the strong oxidant modified biochar is prepared by a strong oxidant; the strong oxidizer modified biochar can also increase the ratio of chemical bond bonding of the original biochar to CMC.
After the strong oxidant modified biochar is obtained, the strong oxidant modified biochar is first mixed with a carboxymethyl cellulose solution to obtain a precursor solution. The mass concentration of the carboxymethyl cellulose in the carboxymethyl cellulose solution (i.e., CMC solution) is preferably 0.25-0.5wt%, more preferably 0.3-0.4wt%, and even more preferably 0.35wt%. In the embodiment of the present invention, the mass concentration of the carboxymethyl cellulose in the CMC solution is preferably 0.25wt% or 0.5wt%. The first mixing according to the invention is preferably carried out under water bath and stirring conditions. The temperature of the water bath is preferably 50-90 ℃, more preferably 53-60 ℃, and even more preferably 55 ℃. The method is not particularly limited to the first mixing parameter, and the strong oxidant modified biochar is uniformly dispersed in the carboxymethyl cellulose solution by adopting conventional parameters.
In the invention, the biochar is sequentially activated and modified to obtain the strong oxidant modified biochar, and the strong oxidant modified biochar is first mixed with the carboxymethyl cellulose solution to obtain the precursor solution. The mass ratio of the biochar to the carboxymethyl cellulose solution is preferably (4-6) g:50mL, more preferably 5g:50mL.
CMC is a polymer compound with surface active colloid, and aqueous solution has the functions of thickening, film forming, adhesion, water retention, colloid protection, etc. in the mixing process, the strong oxidant modified biochar and CMC form a polymeric carrier through the bonding function and the bonding function of chemical bonds (oxygen-containing groups, hydroxyl groups and carboxyl groups).
After a precursor solution is obtained, the precursor solution and sodium ferrocyanide are mixed for the second time to obtain a first solution; more preferably sodium ferrocyanide, is added to the precursor solution and mixed to obtain a first solution. The molar ratio of the addition amount of the strong oxidant modified biochar to the sodium ferrocyanide is preferably 5-10 g: 1-2 mM, more preferably 5-8 g:1.5 to 2mM, more preferably 5g:2mM. The second mixing is preferably carried out under stirring conditions, the stirring parameters are not particularly limited, and the conventional parameters are adopted to ensure Na 4 Fe(CN) 6 And fully dissolving. In the present invention, sodium ferrocyanide (Na 4 Fe(CN) 6 ) Is a precursor substance for synthesizing Prussian blue analogues. The invention is characterized in thatThe precursor solution and sodium ferrocyanide are mixed to facilitate in-situ growth of the Prussian blue analogues, and no special reaction occurs in this step.
The invention obtains a second solution after the weak acid buffer solution is mixed with zinc chloride; more preferably zinc chloride is added to the weakly acidic buffer to give a second solution. The pH value of the weak acid buffer solution is 3.5-5.6, and more preferably 4.5-5.5. In the present invention, the weakly acidic buffer preferably includes a citric acid-sodium citrate buffer. The molar concentration of citric acid in the citric acid-sodium citrate buffer solution of the present invention is preferably 0.25 to 1.25mM, more preferably 0.5 to 1.1mM, and even more preferably 0.5mM or 1mM. The mass concentration of sodium citrate in the citric acid-sodium citrate buffer solution is preferably 20-50 g/L, more preferably 20-40 g/L, and even more preferably 20g/L or 25g/L. The zinc chloride of the present invention is preferably added in an amount of 10 to 25g/L, more preferably 15 to 25g/L, and even more preferably 20g/L or 25g/L. The third mixing parameter is not particularly limited and may be a conventional parameter.
The effect of adding the citric acid-sodium citrate buffer solution is two aspects, namely, the pH value is adjusted: the preparation of the Prussian blue analogues needs to be carried out within a certain pH range, and if the pH is too high or too low, the generation efficiency of the Prussian blue analogues can be reduced or other side reactions can be generated; the citric acid-sodium citrate buffer may stabilize the pH of the solution within a suitable range so that the preparation of the prussian blue analog can be performed under optimal conditions. Another aspect is the removal of metal ions: the citric acid-sodium citrate buffer may also act as a chelating agent to bind to metal ions in water to form chelates, thereby preventing these metal ions from reacting with the Prussian blue analog and interfering with the preparation of the Prussian blue analog.
After a first solution and a second solution are obtained, the first solution is added into the second solution to obtain a composite material; more preferably, the first solution is dropwise added into the second solution in the water bath heat preservation process of the second solution, and the composite material is obtained after mixing and stirring. In the present invention, sodium ferrocyanide (Na 4 Fe(CN) 6 ) Is a synthesized Prussian blue analogue precursor substance, and under the action of a citric acid-sodium citrate buffer solution, the citric acid-sodium citrate buffer solution and zinc chloride are mixed to form citric acid 3- ·Zn 2+ Chelate solution (i.e. citrate-zinc ion chelate solution), and Na 4 Fe(CN) 6 Action to form Prussian blue analog Na 2 Zn 3 [Fe(CN) 6 ] 2 . Prussian blue analogues have the characteristics of high ammonia nitrogen adsorption specificity and adsorption capacity, but the Prussian blue analogues are rarely applied to the research of strengthening anaerobic digestion. In the whole preparation process, strong oxidant modified biochar and CMC form a polymeric carrier through bonding and chemical bond bonding, then Prussian blue analogues grow in situ in the polymeric carrier, and are further fixed between biochar sheet layers and in defect sites of the biochar through the bonding of CMC, so that the CMC bonded or coated composite material is formed.
In the invention, the first solution is preferably dropwise added into the second solution in the water bath heat preservation process of the second solution, and the first solution is mixed and stirred while being added. The stirring time is 1-6 hours, more preferably 3-6 hours, still more preferably 4-6 hours, and still more preferably 6 hours; the stirring temperature is 35 to 65 ℃, more preferably 40 to 60 ℃, and still more preferably 55 ℃.
After the stirring is completed, the stirring resultant is preferably cleaned to obtain the strong oxidant modified biochar-loaded Prussian blue analog composite material. The cleaning according to the invention is preferably accomplished with deionized water.
Prussian Blue Analogues (PBA) are porous coordination polymers in the prior art, and have numerous applications in the medical field due to their good biocompatibility and various nano-enzyme activities. The most important feature is the void structure around the unit cell, and the multiple vacancies form a cavity network, namely a coordination site, so that the catalyst has stronger catalytic and coordination capacity. It is reported that the vacancy point in the Prussian blue analog has specificity for capturing ammonia, ammonia in air or water enters the vacancy point and performs coordination and other interactions, compared with the traditional adsorption material for adsorbing ammonia nitrogen through Van der Waals force, the Prussian blue analog has stronger coordination effect with ammonia nitrogen, and the adsorption capacity is several times higher than that of the traditional adsorbent. However, PBA has poor agglomeration and dispersion in water, is easy to crystallize and agglomerate, and has limited adsorption effect on ammonia nitrogen. And the PBA can adsorb ammonia nitrogen to relieve ammonia nitrogen inhibition but can not strengthen methane digestion under anaerobic conditions.
In the prior art, the biological carbon is used for adsorbing Prussian blue analogues or is combined by the traditional Van der Waals force, so that the combination capacity is poor, the combination efficiency is low, the cyclic application adsorption effect is poor, and the desorption is easy; the strong oxidant modified biochar and CMC form a polymeric carrier through bonding and chemical bond bonding, then Prussian blue analogues grow in situ in the polymeric carrier, and are further fixed between biochar sheet layers and in defect sites of the biochar through the bonding of the CMC to form a composite material bonded or coated by the CMC, and the whole process combines chemical grafting and physical bonding to greatly improve the ammonia nitrogen loading efficiency of the Prussian blue analogues; in addition, the strong oxidant modified biochar has better dispersibility in water, and compared with Prussian blue analogues easy to crystallize, the strong oxidant modified biochar has a plurality of oxygen-containing functional groups so as to have hydrophilic characteristics, so that interaction among Prussian blue crystals is avoided, the problem that PBA is easy to agglomerate and poor in dispersibility in water is solved, the specific adsorption effect of the Prussian blue analogues on ammonia nitrogen is ensured, and the ammonia nitrogen adsorption capacity is high. The chemical grafting is mainly characterized in that the strong oxidant modified biochar and CMC are connected, and the strong oxidant modified biochar rich in various functional groups and oxygen-containing functional groups in the CMC are subjected to chemical reaction and can be connected together in a chemical bond bonding mode to a certain extent. Meanwhile, CMC is used as a binder, has the functions of film forming, bonding, colloid protection, suspension and the like, and the combination of strong oxidant modified biochar and CMC can form a space system similar to a macromolecular polymer, so that Prussian blue analogues can grow in situ in space, and are fixed in the space.
The invention firstly modifies the biochar, the pore structure of the strong oxidant modified biochar and the number of oxygen-containing functional groups are increased, so as to realize the aim of strengthening anaerobic digestion, and the pretreatment is carried out for loading PBA, CMC is used as a binder to bridge the PBA and the strong oxidant modified biochar, and the PBA grows in situ in the strong oxidant modified biochar-CMC precursor material and is bonded and coated by CMC to form the porous composite material. The strong oxidant modified biochar can improve the content of oxygen-containing functional groups of the original biochar so as to strengthen the methane production capacity; the Prussian blue analogues grow in situ in the biochar-carboxymethyl cellulose polymer, so that the specific adsorption effect of the Prussian blue analogues on ammonia nitrogen is ensured, and the ammonia nitrogen adsorption capacity is high.
The strong oxidant modified biochar Prussian blue analogue loaded composite material can synchronously strengthen anaerobic digestion to produce methane and remove ammonia nitrogen in situ.
The invention provides a method for synchronously strengthening anaerobic digestion to produce methane and removing ammonia nitrogen in situ, which comprises the following steps of mixing a strong oxidant modified biochar loaded Prussian blue analog composite material, an inoculum, a fermentation substrate and water to obtain a fermentation system; anaerobic fermentation is carried out on the fermentation system;
the inoculum comprises anaerobic sludge granules and cow dung mixed culture.
In the present invention, the inoculum comprises a mixed culture of anaerobic sludge granules and cow dung, and the inoculum is preferably pre-cultured by a CSTR (continuous stirred reactor system) apparatus. The temperature of the preculture is preferably 36-38 ℃, more preferably 37 ℃. The inoculum pre-culture is stopped by taking continuous 4-5 days of gas production less than 10mL as a standard in the culture process. The function of the preculture culture is to increase the effective viable count of the microorganism in the anaerobic sludge granules in the fermentation of the specific substrate, enrich and culture the anaerobic microorganism which is beneficial to the specific system, so as to ensure that the inoculum can normally play a role in the formal fermentation.
In the invention, the mass ratio of the anaerobic sludge particles to the cow dung is preferably 1-2: 1, more preferably 1:1, a step of; the anaerobic sludge granules according to the invention are preferably purchased from sewage treatment plants.
The strong oxidant modified biochar loaded Prussian blue analog composite material, the inoculant, the fermentation substrate and the water are mixed to obtain a fermentation system.
When the total solid content of the fermentation substrate and the inoculum of the fermentation system is preferably 8.5-10.5%, the composite material is not added together with the fermentation substrate at the beginning of fermentation starting, when the pH value of the fermentation system is more than 7.8 or less than 6.5, the strong oxidant modified biochar is added to load the Prussian blue analogue composite material, and the addition amount of the composite material accounts for preferably 10-15% of the total solid content of the fermentation substrate, and more preferably 12.5%. The pH value of the fermentation system is more than 7.8, which indicates that ammonia nitrogen accumulation occurs, and the pH value of the fermentation system is less than 6.5, which indicates that volatile fatty acid accumulation occurs, and ammonia nitrogen inhibition can lead to acid inhibition. When the total solid content of the fermentation substrate and the inoculum of the fermentation system is 8.5-10.5%, and the pH value of the fermentation system is more than 6.5 and less than 7.8, the fermentation substrate and the inoculum are in the optimal fermentation pH range of anaerobic fermentation (anaerobic digestion), and composite materials can not be added to promote anaerobic fermentation.
In the invention, preferably when the total solid content of the fermentation substrate and the inoculum of the fermentation system is more than 10.5%, the strong oxidant modified biochar-loaded Prussian blue analog composite material and the fermentation substrate are added simultaneously at the beginning of fermentation start, and the addition amount of the composite material accounts for preferably 5% of the mass percentage of the total solid of the fermentation substrate. When the total solid content of the fermentation substrate and the inoculum of the fermentation system is more than 10.5%, the pH value of the fermentation system is not considered, and because the total solid content of the fermentation substrate is higher, ammonia nitrogen accumulation easily occurs in the early fermentation period of the fermentation system, the pH value of the fermentation system changes very rapidly, at the moment, the composite material is directly added at the beginning of fermentation of the fermentation system, and the composite material plays a role from the beginning of fermentation of the fermentation system, so that the dosage of the composite material is lower.
In the invention, when the total solid content of the fermentation substrate of the fermentation system is less than 8.5%, the organic load of the anaerobic digestion system is very low, ammonia nitrogen and acid inhibition can not be generated basically, the fermentation substrate can be consumed quickly, and composite materials are not needed to be added in the whole fermentation process.
In the present invention, the fermentation substrate preferably comprises a nitrogen-rich feedstock; the nitrogen-rich raw material preferably comprises one or more than two of cow dung, chicken dung, pig dung, rural domestic organic garbage and kitchen waste; the carbon-nitrogen ratio of the nitrogen-rich raw material is less than 20:1.
In the invention, the anaerobic fermentation temperature is preferably 36-38 ℃, more preferably 37 ℃. The anaerobic fermentation is medium-temperature anaerobic fermentation.
The invention provides the composite material prepared by the technical scheme or the preparation method of the technical scheme or the application of the method of the technical scheme in improving the yield of anaerobic digestion methane and/or reducing the ammonia nitrogen concentration of digestion liquid.
The technical solutions provided by the present invention are described in detail below with reference to the drawings and examples for further illustrating the present invention, but they should not be construed as limiting the scope of the present invention.
Example 1
1. Preparation, activation and modification of carrier biochar
(1) And (3) preparing biochar. The corncob is used as a raw material to prepare the biochar by pyrolysis, the pyrolysis temperature is 550 ℃, and the terminal temperature is kept for 2 hours.
(2) And (5) activating biochar. 5g of the biochar prepared in the step (1) is added into 200mL of 0.1M hydrochloric acid solution for soaking, and the mixture is stirred for 24 hours by a magnetic stirrer with the temperature of 30 ℃ and the rotating speed of 120 rmp; filtering the stirred product by deionized water with the temperature of 100 ℃ until the pH value of the filtrate is above 6.5, drying and filtering the obtained biochar, grinding the biochar in a mortar and sieving the biochar with a 100-mesh sieve.
(3) And (5) modifying biochar. The biochar powder obtained in step (2) was added to 80ml of 0.5m hydrogen peroxide solution and placed on a shaker and shaken for 24h at a temperature of 55 ℃ and a rotational speed of 150 rmp. And after the vibration is finished, cleaning and drying the strong oxidant modified biochar for later use.
2. Prussian blue analogue composite material loaded with strong oxidant modified biochar
Uniformly dispersing 5g of the strong oxidant modified biochar obtained in the step (3) into 50mL of CMC solution with the mass concentration of 0.25wt%, and stirring the mixture under the water bath condition of 55 ℃ until the mixture is fully mixed to obtain a precursor solution a;
weigh 0.304g Na 4 Fe(CN) 6 Dissolving in the precursor solution a, and continuously stirring until the precursor solution is fully dissolved to obtain a solution a;
0.0096g of citric acid is weighed and dissolved in 50mL of deionized water to prepare 1mM of citric acid solution, 1g of sodium citrate is firstly weighed and dissolved in the citric acid solution, and then 1g of ZnCl is added 2 Buffer b was prepared by dissolving in citric acid solution containing sodium citrate.
Buffer b was placed in a 55 ℃ water bath and solution a was added dropwise at a constant temperature for 6h with continuous stirring. Prussian blue analog Na is generated during stirring 2 Zn 3 [Fe(CN) 6 ] 2 Prussian blue analogues are supported on strong oxidant modified biochar. And filtering the obtained liquid to obtain a solid after stirring, and cleaning the solid with deionized water to obtain the composite material.
Example 2
1. Preparation of carrier biochar
(1) Biochar (BC) preparation. The corn straw is used as a raw material for pyrolysis to prepare the biochar, the pyrolysis temperature is 550 ℃, and the terminal temperature is kept for 2 hours, so that the biochar is obtained.
(2) And (5) activating biochar. 5g of the biochar prepared in the step (1) is added into 200mL of 0.5M hydrochloric acid solution for soaking, and the mixture is stirred for 24 hours by a magnetic stirrer with the temperature of 30 ℃ and the rotating speed of 120 rmp; filtering the stirred product with deionized water at 100deg.C until the pH value of the filtrate is above 6.5, oven drying, filtering to obtain biochar, grinding in a mortar, and sieving with 100 mesh sieve.
(3) And (5) modifying biochar. The biochar powder obtained in step (2) was added to 80ml of 0.5m hydrogen peroxide solution and placed on a shaker and shaken for 24h at a temperature of 55 ℃ and a rotational speed of 150 rmp. And after the vibration is finished, cleaning and drying the strong oxidant modified biochar to obtain the modified biochar for later use.
2 strong oxidant modified biochar loaded Prussian blue analogue composite material
Uniformly dispersing 5g of the strong oxidant modified biochar obtained in the step (3) into 50mL of CMC solution with the mass concentration of 0.50wt%, and stirring the mixture until the mixture is fully mixed under the water bath condition of 55 ℃ to obtain a precursor solution a;
weigh 0.608g Na 4 Fe(CN) 6 Dissolving in the precursor solution a, and continuously stirring until the precursor solution is fully dissolved to obtain a solution a;
0.0048g of citric acid was dissolved in 50mL of deionized water to prepare a 0.5mM citric acid solution; 1.25g of sodium citrate is firstly weighed and dissolved in the citric acid solution, and then 1.25g of ZnCl is added 2 Buffer b was prepared by dissolving in citric acid solution containing sodium citrate.
And (3) placing the buffer solution b in a water bath at 55 ℃, continuously stirring the solution a for 6 hours when the temperature is constant, filtering the obtained liquid, and washing the solid with deionized water to obtain the composite material.
Comparative example 1
And (3) preparing biochar. The corncob is used as a raw material to prepare the biochar by pyrolysis, the pyrolysis temperature is 550 ℃, and the terminal temperature is kept for 2 hours.
Test example 1
The preparation method of the inoculum comprises the following steps: cow dung and anaerobic sludge particles are mixed according to the mass ratio of 1:1 is added into CSTR equipment for preculture, the preculture temperature is 37 ℃, and the culture is carried out until the gas yield is less than 10mL in 4-5 days continuously. The inoculum is a suspension of mixed culture of anaerobic sludge particles and cow dung.
The test device selects a 500mL reagent bottle (with an effective volume of 400 mL) as an anaerobic digestion reactor.
The total solids content of the fermentation substrate for pig manure was 37.4% and the total solids content of the inoculum suspension was 6%. 115.51g of pig manure, 2.16g of the composite material obtained in example 1 and 80mL of inoculum were initially introduced into an anaerobic digestion reactor. Wherein 115.51g of pig manure is the fresh weight of pig manure, the dry basis of pig manure is 43.2g, the carbon-nitrogen ratio of wet pig manure is less than 20:1, and pig manure is a fermentation substrate. The inoculum suspension volume was 20% of the reactor effective volume, the inoculum was added 80mL, the inoculum density was calculated as 1, the total solids TS of the inoculum was 6%, and the inoculum dry basis was 4.8g.
Pig manure and inoculum are used as total fermentation substrates, and the total solid mass of the total fermentation substrates is 48g.
The pig manure, the composite material prepared in example 1 and the inoculum are added simultaneously, and the mixture obtained after the addition is diluted to the following state by tap water400mL, total solids TS in the reagent bottles was 12%. After that, the mixture was stirred uniformly, and a mixed gas (volume ratio: 70% N) was blown into the reactor 2 And volume ratio of 30% CO 2 ) So as to discharge the air in the top of the reactor, ensure the anaerobic environment and perform anaerobic digestion. The anaerobic digestion reactor is covered and sealed, then the reactor is placed in a biochemical incubator, and anaerobic digestion test is carried out under the constant temperature condition of (37+/-1). Test example 13 parallel experiments were set up.
Test example 2
The preparation method of the inoculum comprises the following steps: the same as in test example 1.
The test device selects a 500mL reagent bottle (with an effective volume of 400 mL) as an anaerobic digestion reactor. 115.51g of pig manure, 2.16g of the biochar prepared in comparative example 1 (i.e., the original corncob biochar) and the inoculum were added to the reactor. Wherein 115.51g of pig manure is the fresh weight of pig manure, the dry basis of pig manure is 43.2g, and the carbon-nitrogen ratio of wet pig manure is less than 20:1. The inoculum suspension volume was 20% of the reactor effective volume, the inoculum was added 80mL, the inoculum density was calculated as 1, the total solids TS of the inoculum was 6%, and the inoculum dry basis was 4.8g.
Pig manure and inoculum are used as total fermentation substrates, and the total solid mass of the total fermentation substrates is 48g.
The pig manure, the composite material prepared in the comparative example 1 and the inoculum are added simultaneously, the mixture obtained after the addition is diluted to 400mL by tap water, and the total solid TS in the reagent bottle is 12%. After that, the mixture was stirred uniformly, and a mixed gas (volume ratio: 70% N) was blown into the reactor 2 And volume ratio of 30% CO 2 ) So as to discharge the air in the top of the reactor, ensure the anaerobic environment and perform anaerobic digestion. After sealing with a cover, the reactor was placed in a biochemical incubator, and anaerobic digestion was performed at a constant temperature of (37.+ -. 1) °c. Test example 2 3 parallel experiments were set up.
Test example 3
Blank control group (CK):
the test device selects a 500mL reagent bottle (with an effective volume of 400 mL) as an anaerobic digestion reactor. 115.51g of pig manure and inoculum were added to the reactor. Wherein 115.51g of pig manure is the fresh weight of pig manure, the dry basis of pig manure is 43.2g, and the carbon-nitrogen ratio of wet pig manure is less than 20:1. The inoculum suspension volume was 20% of the reactor effective volume, the inoculum was added 80mL, the inoculum density was calculated as 1, the total solids TS of the inoculum was 6%, and the inoculum dry basis was 4.8g. Pig manure and inoculum are used as total fermentation substrates, and the total solid mass of the total fermentation substrates is 48g.
After diluting the mixture of pig manure and inoculum with tap water to a volume of 400mL and stirring well, a mixed gas (volume ratio of 70% N) was blown into the reactor 2 And volume ratio of 30% CO 2 ) So as to discharge the air in the top of the reactor and ensure anaerobic environment. After sealing with a cover, the reactor was placed in a biochemical incubator, and anaerobic digestion was performed at a constant temperature of (37.+ -. 1) °c. Test example 3 1 parallel experiment was set up.
And measuring the methane yield by using a drainage method, and measuring the ammonia nitrogen concentration by using a Nahner reagent spectrophotometry. The cumulative methane yield results of test examples 1-3 are shown in Table 1 and FIG. 1, and the ammonia nitrogen concentration change results are shown in Table 2 and FIG. 2.
Table 1 cumulative methane yield (units: mL/gVS) for test examples 1-3
| Fermentation time (d) | Test example 3 (CK) | Test example 2 (BC) | Test example 1 (BC-PBA) |
| 0 | 0 | 0 | 0 |
| 2 | 0.41261 | 0.4 | 0.4 |
| 4 | 0.95285 | 0.99 | 1.21 |
| 6 | 2.11984 | 6.21 | 5.65 |
| 8 | 2.4012 | 6.98 | 6.34 |
| 10 | 2.5214 | 10 | 9.48 |
| 12 | 3.11984 | 10.87 | 11.02 |
| 14 | 4.06248 | 15.37 | 15.34 |
| 16 | 9.33099 | 30.15 | 37.28 |
| 18 | 19.58907 | 45.28 | 65.23 |
| 20 | 28.93769 | 74.34 | 103.52 |
| 22 | 37.19485 | 91.67 | 126.72 |
| 24 | 46.66332 | 110.25 | 150.85 |
| 26 | 50.19751 | 130.59 | 194.37 |
| 28 | 54.50778 | 144.36 | 217.68 |
| 30 | 64.274 | 154.36 | 246.94 |
| 32 | 75.68 | 180.74 | 268.11 |
| 34 | 101.78 | 208.56 | 300.42 |
| 36 | 125.46 | 234.22 | 322.71 |
| 38 | 154.29 | 261.35 | 335.63 |
| 40 | 182.69 | 275.69 | 351.61 |
| 42 | 200.65 | 297.56 | 355.44 |
| 44 | 211.67 | 310.48 | 358.55 |
| 46 | 221.36 | 323.47 | 360 |
| 48 | 240 | 324.25 | 364.28 |
| 50 | 250.99 | 326.4 | 367.46 |
| 52 | 253.26 | 327.68 | 369.12 |
| 54 | 255.95 | 328.82 | 370.55 |
| 56 | 257.48 | 329.68 | 372.35 |
| 58 | 258.99 | 330.88 | 376.19 |
| 60 | 261.53 | 331.2 | 377.24 |
Note that: BC represents biochar; BC-PBA represents a strong oxidant modified biochar loaded Prussian blue analog composite material, and the following is the same.
Table 2 shows the ammonia nitrogen concentration (unit: mg/L) of test examples 1 to 3
| Fermentation time (d) | Test example 1 (BC-PBA) | Test example 2 (BC) | Test example 3 (CK) |
| 5 | 1583.59896 | 1502.3694 | 1476.2354 |
| 15 | 1464.3598 | 1412.537 | 1335.1286 |
| 25 | 1640.15342 | 1598.2564 | 1500.458 |
| 35 | 1748.8891 | 1975.3567 | 2168.9435 |
| 45 | 1388.21357 | 1924.3572 | 2038.5695 |
| 60 | 1272.48039 | 1900.2865 | 2065.3665 |
According to tables 1 and 2 and fig. 1 and 2, it can be known that the strong oxidant modified biochar loaded Prussian blue analog composite material prepared by the invention can remarkably improve the yield of methane in anaerobic digestion and reduce the ammonia nitrogen concentration in digestive juice. And simultaneously, the anaerobic digestion methane production and the digestion liquid ammonia nitrogen removal are enhanced.
Test example 4
The Biochar (BC) and modified biochar (BC-modified) prepared in example 1 were subjected to fitting analysis by using xps software, and the results are shown in Table 3, FIG. 3 and FIG. 4.
TABLE 3 fitting results of biochar and modified biochar
| BC | Initial binding energy | Peak position binding energy | Ending binding energy | Area (P) CPS.eV | Duty cycle (%) |
| Quinone | 546.3 | 531.2 | 526.3 | 10156.34 | 21.93 |
| C=O | 546.3 | 532.5 | 526.3 | 21299.37 | 46.01 |
| -OH | 546.3 | 533.7 | 526.3 | 13258.07 | 28.65 |
| -COOH | 546.3 | 535.05 | 526.3 | 1577.68 | 3.41 |
| BC-modification | Initial binding energy | Peak position binding energy | Ending binding energy | Area (P) CPS.eV | The ratio of% |
| Quinone | 545.4 | 531.2 | 525.4 | 6019.9 | 26.34 |
| C=O | 545.4 | 532.5 | 525.4 | 12076.35 | 52.87 |
| -OH | 545.4 | 533.7 | 525.4 | 3373.76 | 14.78 |
| -COOH | 545.4 | 534.9 | 525.4 | 1370.75 | 6.01 |
Note that: quinone represents a Quinone group.
As can be seen from table 3 and fig. 3 and 4, the relative content of oxygen-containing functional groups including quinone groups (a redox-active group) was analyzed using xps fitting, and after biochar modification, the content of quinone groups, -c=o, -COOH was significantly increased.
Although the foregoing embodiments have been described in some, but not all, embodiments of the invention, it should be understood that other embodiments may be devised in accordance with the present embodiments without departing from the spirit and scope of the invention.
Claims (9)
1. The strong oxidant modified biochar Prussian blue analog-loaded composite material is characterized by comprising a polymer carrier and Prussian blue analog loaded on the polymer carrier; the polymer carrier is formed by combining strong oxidant modified biochar and carboxymethyl cellulose;
the Prussian blue analogues are loaded in the lamellar layers and/or defect sites of the strong oxidant modified biochar; the Prussian blue analogue is Na 2 Zn 3 [Fe(CN) 6 ] 2 。
2. The composite material of claim 1, wherein the bonding means comprises physical bonding and/or chemical bonding.
3. A method of preparing a composite material according to claim 1 or 2, comprising the steps of:
firstly mixing strong oxidant modified biochar with carboxymethyl cellulose solution to obtain precursor solution;
second mixing the precursor solution and sodium ferrocyanide to obtain a first solution;
thirdly mixing the weak acid buffer solution with zinc chloride to obtain a second solution;
adding the first solution into the second solution to obtain a composite material;
the pH value of the weak acid buffer solution is 3.5-5.6.
4. The preparation method of claim 3, wherein the molar ratio of the mass of the strong oxidant modified biochar to the sodium ferrocyanide is 5-10 g: 1-2 mM.
5. The preparation method of claim 3, wherein the mass concentration of zinc chloride in the second solution is 10-25 g/L; the weak acidic buffer comprises a citric acid-sodium citrate buffer.
6. The preparation method according to claim 3, wherein the mass concentration of the carboxymethyl cellulose in the carboxymethyl cellulose solution is 0.25-0.5wt%.
7. A method for synchronously enhancing anaerobic digestion to produce methane and remove ammonia nitrogen in situ, which is characterized in that a composite material prepared by the method of claim 1 or 2 or any one of the preparation methods of claim 3-6, an inoculum, a fermentation substrate and water are mixed to obtain a fermentation system, and anaerobic fermentation is carried out;
the inoculum comprises anaerobic sludge granules and cow dung mixed culture.
8. The method according to claim 7, wherein when the total solid content of the fermentation substrate and the inoculum is 8.5% -10.5%, the composite material is added when the pH value of the fermentation system is more than 7.8 or less than 6.5, and the addition amount of the composite material accounts for 10% -15% of the total solid content of the fermentation substrate;
when the total solid content of the fermentation substrate and the inoculant is more than 10.5%, the addition amount of the composite material accounts for 5% of the total solid content of the fermentation substrate, and the composite material and the fermentation substrate are added simultaneously.
9. The composite material of claim 1 or 2 or the composite material prepared by the preparation method of any one of claims 3-6 or the application of the method of claim 7 or 8 in increasing anaerobic digestion methane yield and/or reducing ammonia nitrogen concentration in digestive juice.
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| CN112322665A (en) * | 2020-10-30 | 2021-02-05 | 江苏省农业科学院 | Anaerobic fermentation method for organic domestic garbage in villages and towns |
| CN112342694A (en) * | 2020-10-30 | 2021-02-09 | 江苏省农业科学院 | FeZn Prussian blue/polyacrylonitrile composite nanofiber membrane as well as preparation method and application thereof |
| CN113336329A (en) * | 2021-06-01 | 2021-09-03 | 中国农业科学院农业环境与可持续发展研究所 | Granular biochar, preparation method thereof and application thereof in anaerobic digestion for methane production |
| CN115207316A (en) * | 2022-08-03 | 2022-10-18 | 北京航空航天大学 | Preparation method and application of Prussian blue analogue cathode material |
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| CN112047590B (en) * | 2020-08-31 | 2021-05-11 | 同济大学 | Method for strengthening anaerobic digestion of sludge by utilizing pre-alcoholization of kitchen waste |
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| CN112322665A (en) * | 2020-10-30 | 2021-02-05 | 江苏省农业科学院 | Anaerobic fermentation method for organic domestic garbage in villages and towns |
| CN112342694A (en) * | 2020-10-30 | 2021-02-09 | 江苏省农业科学院 | FeZn Prussian blue/polyacrylonitrile composite nanofiber membrane as well as preparation method and application thereof |
| CN113336329A (en) * | 2021-06-01 | 2021-09-03 | 中国农业科学院农业环境与可持续发展研究所 | Granular biochar, preparation method thereof and application thereof in anaerobic digestion for methane production |
| CN115207316A (en) * | 2022-08-03 | 2022-10-18 | 北京航空航天大学 | Preparation method and application of Prussian blue analogue cathode material |
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