CN113717731A - Efficient restoration agent for lead-cadmium combined polluted soil and preparation method thereof - Google Patents
Efficient restoration agent for lead-cadmium combined polluted soil and preparation method thereof Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 65
- 229910052793 cadmium Inorganic materials 0.000 title claims abstract description 45
- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 40
- 238000002360 preparation method Methods 0.000 title claims abstract description 25
- QJZYHAIUNVAGQP-UHFFFAOYSA-N 3-nitrobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid Chemical class C1C2C=CC1C(C(=O)O)C2(C(O)=O)[N+]([O-])=O QJZYHAIUNVAGQP-UHFFFAOYSA-N 0.000 claims abstract description 63
- 239000002734 clay mineral Substances 0.000 claims abstract description 48
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000002156 mixing Methods 0.000 claims abstract description 23
- 239000002131 composite material Substances 0.000 claims abstract description 19
- 239000000292 calcium oxide Substances 0.000 claims abstract description 16
- 235000012255 calcium oxide Nutrition 0.000 claims abstract description 16
- 239000002994 raw material Substances 0.000 claims abstract description 13
- 239000003381 stabilizer Substances 0.000 claims abstract description 11
- 239000012190 activator Substances 0.000 claims abstract description 7
- 238000005303 weighing Methods 0.000 claims abstract description 6
- 239000004021 humic acid Substances 0.000 claims description 36
- 239000000243 solution Substances 0.000 claims description 34
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 32
- 238000005406 washing Methods 0.000 claims description 28
- WQHONKDTTOGZPR-UHFFFAOYSA-N [O-2].[O-2].[Mn+2].[Fe+2] Chemical compound [O-2].[O-2].[Mn+2].[Fe+2] WQHONKDTTOGZPR-UHFFFAOYSA-N 0.000 claims description 24
- 239000000843 powder Substances 0.000 claims description 22
- 229910019142 PO4 Inorganic materials 0.000 claims description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical group OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 18
- 239000010452 phosphate Substances 0.000 claims description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 239000006228 supernatant Substances 0.000 claims description 15
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 14
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 14
- 230000004048 modification Effects 0.000 claims description 13
- 238000012986 modification Methods 0.000 claims description 13
- 238000003756 stirring Methods 0.000 claims description 12
- 230000003213 activating effect Effects 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 9
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 9
- 239000011259 mixed solution Substances 0.000 claims description 9
- 229910017604 nitric acid Inorganic materials 0.000 claims description 9
- 229910021536 Zeolite Inorganic materials 0.000 claims description 8
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims description 8
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- 229910052901 montmorillonite Inorganic materials 0.000 claims description 8
- 238000002791 soaking Methods 0.000 claims description 8
- 239000010457 zeolite Substances 0.000 claims description 8
- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 claims description 6
- 235000019691 monocalcium phosphate Nutrition 0.000 claims description 6
- 238000007873 sieving Methods 0.000 claims description 6
- 230000009471 action Effects 0.000 claims description 5
- 238000000975 co-precipitation Methods 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 230000007935 neutral effect Effects 0.000 claims description 5
- 230000033116 oxidation-reduction process Effects 0.000 claims description 5
- 239000012286 potassium permanganate Substances 0.000 claims description 5
- 239000010902 straw Substances 0.000 claims description 5
- 238000010298 pulverizing process Methods 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000011001 backwashing Methods 0.000 claims description 2
- 239000012530 fluid Substances 0.000 claims description 2
- 125000002467 phosphate group Chemical group [H]OP(=O)(O[H])O[*] 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 229940062672 calcium dihydrogen phosphate Drugs 0.000 claims 1
- 229910000389 calcium phosphate Inorganic materials 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 7
- 238000001179 sorption measurement Methods 0.000 abstract description 7
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 abstract description 6
- 230000006378 damage Effects 0.000 abstract description 4
- 229910001385 heavy metal Inorganic materials 0.000 description 7
- 238000005067 remediation Methods 0.000 description 6
- 239000001506 calcium phosphate Substances 0.000 description 5
- 239000003610 charcoal Substances 0.000 description 5
- 238000002386 leaching Methods 0.000 description 5
- 229910000150 monocalcium phosphate Inorganic materials 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 description 4
- 235000010755 mineral Nutrition 0.000 description 4
- 239000011707 mineral Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910052745 lead Inorganic materials 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000000813 microbial effect Effects 0.000 description 2
- 239000002910 solid waste Substances 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000005115 demineralization Methods 0.000 description 1
- 230000002328 demineralizing effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000005520 electrodynamics Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000002920 hazardous waste Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000003864 humus Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 150000002902 organometallic compounds Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/40—Soil-conditioning materials or soil-stabilising materials containing mixtures of inorganic and organic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
- C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
- C01B33/40—Clays
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/0018—Mixed oxides or hydroxides
- C01G49/0072—Mixed oxides or hydroxides containing manganese
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
- C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- Soil Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Health & Medical Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Biochemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Dispersion Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention discloses an efficient repairing agent for lead-cadmium combined polluted soil, which comprises the following raw materials in parts by weight: 40-60 parts of quicklime, 20-30 parts of modified humic acid, 20-30 parts of modified clay mineral, 5-15 parts of activator and 1-10 parts of stabilizer; the preparation method comprises the following steps: (1) weighing the raw materials; (2) mixing quicklime, modified humic acid, modified clay mineral, activator and stabilizer uniformly to obtain the product. The efficient restoration agent for lead-cadmium composite polluted soil has strong adsorption restoration effect on lead and cadmium in soil, is short in restoration period, does not damage soil structure and planting function, is free of secondary pollution, and is durable in restoration effect.
Description
Technical Field
The invention relates to the technical field of soil remediation, in particular to an efficient remediation agent for lead-cadmium combined polluted soil and a preparation method thereof.
Background
Soil is a loose layer of material on the earth surface, and is composed of mineral substances formed by weathering rocks, animals and plants, organic matters generated by decomposition of microbial residues, soil organisms (solid-phase substances), water (liquid-phase substances), air (gas-phase substances), oxidized humus and the like. With the development of industrialization, unreasonable exploitation of mineral resources and the use of a large amount of pesticides, a lot of soil is polluted, the pollution of cultivated land is particularly serious, and the pollution of lead and cadmium in the cultivated land especially troubles farmers.
The lead-cadmium pollution not only has negative influence on the degradation of organic matters in soil, soil ammoniation and nitrification, but also can be converted into metal-organic compounds with higher pollution, and has greater harm to the health of human bodies and the soil.
At present, the treatment method aiming at the lead and cadmium pollution of soil mainly comprises an immobilization/stabilization method, a leaching method, a soil washing method, an electrodynamic remediation method, a chemical reduction method, a plant remediation method and a microbial remediation method, but the overall remediation efficiency is low.
Therefore, how to develop a high-efficiency repairing agent for lead-cadmium combined polluted soil is a problem which needs to be solved urgently by the technical personnel in the field.
Disclosure of Invention
In view of the above, the present invention aims to provide an efficient repairing agent for lead-cadmium complex contaminated soil and a preparation method thereof, so as to solve the defects in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
an efficient repairing agent for lead-cadmium composite polluted soil comprises the following raw materials in parts by weight: 40-60 parts of quicklime, 20-30 parts of modified humic acid, 20-30 parts of modified clay mineral, 5-15 parts of activator and 1-10 parts of stabilizer;
preferably: 50 parts of quicklime, 25 parts of modified humic acid, 25 parts of modified clay mineral, 10 parts of activating agent and 5 parts of stabilizing agent.
In the invention, the quicklime has the functions of: on one hand, the method provides a relatively stable alkaline environment which is easy to react with Pb under alkaline conditions2+And Cd2+Forming insoluble compound, thereby reducing the bioavailability and the mobility of Pb and Cd; on the other hand, the quicklime can increase the pH value of the soil by about 0.2, but does not change the soil property and the tilth remarkably, and can also prevent the loss of soil nutrients.
Further, the preparation method of the modified humic acid comprises the following steps:
(1) adding humic acid into a dilute hydrochloric acid solution, stirring and mixing, standing, and centrifuging to remove a supernatant to obtain primary washing humic acid;
(2) adding the primary washing humic acid into a dilute hydrochloric acid solution, stirring and mixing, standing, and centrifuging to remove a supernatant to obtain secondary washing humic acid;
(3) adding the rewashed humic acid into a mixed solution of dilute hydrochloric acid and hydrogen fluoride, mixing, reacting, then adding water for cleaning, and centrifuging to remove supernatant fluid to obtain the modified humic acid.
Furthermore, in the step (1), the molar concentration of the dilute hydrochloric acid solution is 0.5-1mol/L, and the mass ratio of the humic acid to the dilute hydrochloric acid solution is 1: (10-20); in the step (2), the molar concentration of the dilute hydrochloric acid solution is 0.3-0.5mol/L, and the mass ratio of the initial washing humic acid to the dilute hydrochloric acid solution is 1: (8-15); in the step (3), in the mixed solution of dilute hydrochloric acid and hydrogen fluoride, the molar concentration of the dilute hydrochloric acid solution is 0.3-0.5mol/L, and the molar concentration of the hydrogen fluoride is 3-8 mol/L; the mass ratio of the re-washing humic acid to the mixed solution of the dilute hydrochloric acid and the hydrogen fluoride is 1: (3-5); the reaction temperature is 40-50 ℃ and the reaction time is 8-12 h.
The further technical scheme has the beneficial effects that the humic acid is subjected to demineralization treatment, namely mineral impurities in the humic acid are removed, the organic carbon content and polar functional groups of the humic acid are increased, the specific surface area of the humic acid is increased, and the adsorption sites of the humic acid are increased. The modified humic acid has rich pore passages and is easy to adsorb various heavy metal ions, so that the adsorption performance of the modified humic acid is enhanced, the modified humic acid has good functions of absorption, complexation, exchange and the like, and also has a strong buffering effect on the pH value of soil, and the acid pickling modification can remove impurities such as minerals and the like in the soil, so that the risk of secondary pollution caused by the standard exceeding of heavy metals of a medicament is reduced.
Further, the preparation method of the modified clay mineral comprises the following steps:
(1) mixing zeolite and montmorillonite, pulverizing, and sieving to obtain clay mineral powder;
(2) adding clay mineral powder into dilute nitric acid solution for soaking, centrifuging and filtering, washing to be neutral, drying and activating to obtain acidified clay mineral powder;
(3) heating the acidified clay mineral powder for thermal modification, and cooling to obtain the modified clay mineral.
Furthermore, in the step (1), the mass ratio of the zeolite to the montmorillonite is 1: (1-2), the mesh number of the sieved screen is 100-200 meshes; in the step (2), the molar concentration of the dilute nitric acid solution is 1-2mol/L, and the mass ratio of the clay mineral powder to the dilute nitric acid solution is 1: (2-4), soaking at the temperature of 60-70 ℃ for 1-2 h; the temperature for drying and activating is 90-100 ℃, and the time is 2-3 h; in the step (3), the temperature of thermal modification is 300-500 ℃, and the time is 2-4 h.
The further technical scheme has the beneficial effects that the zeolite and the montmorillonite subjected to acid and thermal modification can be used for dissolving carbonate impurities and other cations adsorbed in pore channels with crystal structures, removing impurities distributed in the pore channels, dredging the pore channels and increasing the pore volume; the clay mineral can also lose surface water, hydration water and bound water in a structural framework, reduce the adsorption capacity of a water film on heavy metal pollutants, and enhance the adsorption performance of the clay mineral.
Further, the activator is phosphoric acid and/or monocalcium phosphate.
Further, the stabilizer is phosphate modified charcoal loaded iron-manganese oxide.
Furthermore, the preparation method of the phosphate modified charcoal loaded iron-manganese oxide comprises the following steps: firstly, plant straws are soaked in phosphoric acid for modification and then pyrolyzed at high temperature to prepare biochar, and then the biochar is loaded with iron-manganese oxide under the action of potassium permanganate by adopting an oxidation-reduction coprecipitation method, so that the phosphate modified biochar loaded iron-manganese oxide is obtained.
The further technical scheme has the beneficial effects that the selected activating agent can effectively activate the carbonate binding state sensitive to acid-base conditions in the soil, lead and cadmium in free and unstable binding states react with the subsequently added stabilizing agent to form a more stable iron-manganese oxide binding state or residue state, so that the stability of the acid-base conditions and the redox environment of the soil is ensured, and the repairing effect is stable for a long time.
A preparation method of an efficient repairing agent for lead-cadmium composite polluted soil specifically comprises the following steps:
(1) weighing the raw materials according to the parts by weight of the efficient repairing agent for the lead-cadmium composite polluted soil;
(2) and uniformly mixing the quicklime, the modified humic acid, the modified clay mineral, the activator and the stabilizer to obtain the high-efficiency repairing agent for the lead-cadmium composite polluted soil.
According to the technical scheme, compared with the prior art, the invention has the following beneficial effects:
the efficient restoration agent for lead-cadmium composite polluted soil has strong adsorption restoration effect on lead and cadmium in soil, is short in restoration period, does not damage soil structure and planting function, is free of secondary pollution, and is durable in restoration effect.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The efficient repairing agent for lead-cadmium composite polluted soil comprises the following raw materials by weight: 50kg of quicklime, 25kg of modified humic acid, 25kg of modified clay mineral, 10kg of monocalcium phosphate and 5kg of phosphate modified biochar loaded iron-manganese oxide;
the preparation method of the modified humic acid comprises the following steps:
(1) adding 1kg of humic acid into 15kg of dilute hydrochloric acid solution with the molar concentration of 0.8mol/L, stirring and mixing, standing, and centrifuging to remove supernatant to obtain primary washing humic acid;
(2) adding 1kg of primary washing humic acid into 12kg of dilute hydrochloric acid solution with the molar concentration of 0.4mol/L, stirring and mixing, standing, and centrifuging to remove supernatant to obtain secondary washing humic acid;
(3) adding 1kg of re-washing humic acid into 4kg of mixed solution of dilute hydrochloric acid and hydrogen fluoride, heating to 45 ℃, reacting for 10 hours, adding water for washing, and centrifuging to remove supernatant to obtain modified humic acid, wherein the molar concentration of the dilute hydrochloric acid solution is 0.4mol/L and the molar concentration of the hydrogen fluoride is 5 mol/L;
the preparation method of the modified clay mineral comprises the following steps:
(1) mixing 1kg zeolite and 1.5kg montmorillonite, pulverizing, and sieving with 150 mesh sieve to obtain clay mineral powder;
(2) adding 1kg of clay mineral powder into 3kg of dilute nitric acid solution with the molar concentration of 1.5mol/L, heating to 65 ℃, soaking for 1.5h, centrifugally filtering, washing to be neutral, and drying and activating at the temperature of 95 ℃ for 2.5h to obtain acidified clay mineral powder;
(3) heating the acidified clay mineral powder to 400 ℃ for thermal modification for 3h, and cooling to obtain a modified clay mineral;
the preparation method of the phosphate modified charcoal loaded iron manganese oxide comprises the following steps: firstly, plant straws are soaked in phosphoric acid for modification and then pyrolyzed at high temperature to prepare biochar, and then the biochar is loaded with iron-manganese oxide under the action of potassium permanganate by adopting an oxidation-reduction coprecipitation method, so that the phosphate modified biochar loaded iron-manganese oxide is obtained.
The preparation method of the efficient repairing agent for the lead-cadmium composite polluted soil specifically comprises the following steps:
(1) weighing the raw materials according to the weight;
(2) and uniformly mixing the quicklime, the modified humic acid, the modified clay mineral, the monocalcium phosphate and the phosphate modified biochar loaded iron-manganese oxide to obtain the efficient repairing agent for the lead-cadmium composite polluted soil.
Example 2
The efficient repairing agent for lead-cadmium composite polluted soil comprises the following raw materials by weight: 40kg of quicklime, 20kg of modified humic acid, 30kg of modified clay mineral, 15kg of phosphoric acid and 10kg of phosphate modified biochar loaded iron-manganese oxide;
the preparation method of the modified humic acid comprises the following steps:
(1) adding 1kg of humic acid into 10kg of dilute hydrochloric acid solution with the molar concentration of 1mol/L, stirring and mixing, standing, and centrifuging to remove supernatant to obtain primary washing humic acid;
(2) adding 1kg of primary washing humic acid into 8kg of dilute hydrochloric acid solution with the molar concentration of 0.5mol/L, stirring and mixing, standing, and centrifuging to remove supernatant to obtain secondary washing humic acid;
(3) adding 1kg of re-washing humic acid into 3kg of mixed solution of dilute hydrochloric acid and hydrogen fluoride, heating to 40 ℃, reacting for 12 hours, adding water for washing, and centrifuging to remove supernatant to obtain modified humic acid, wherein the molar concentration of the dilute hydrochloric acid solution is 0.3mol/L and the molar concentration of the hydrogen fluoride is 8 mol/L;
the preparation method of the modified clay mineral comprises the following steps:
(1) mixing 1kg of zeolite and 1kg of montmorillonite, pulverizing, and sieving with 100 mesh sieve to obtain clay mineral powder;
(2) adding 1kg of clay mineral powder into 2kg of dilute nitric acid solution with the molar concentration of 2mol/L, heating to 60 ℃, soaking for 2h, centrifugally filtering, washing to be neutral, drying and activating for 3h at the temperature of 90 ℃ to obtain acidified clay mineral powder;
(3) heating the acidified clay mineral powder to 300 ℃, thermally modifying for 4h, and cooling to obtain a modified clay mineral;
the preparation method of the phosphate modified charcoal loaded iron manganese oxide comprises the following steps: firstly, plant straws are soaked in phosphoric acid for modification and then pyrolyzed at high temperature to prepare biochar, and then the biochar is loaded with iron-manganese oxide under the action of potassium permanganate by adopting an oxidation-reduction coprecipitation method, so that the phosphate modified biochar loaded iron-manganese oxide is obtained.
The preparation method of the efficient repairing agent for the lead-cadmium composite polluted soil specifically comprises the following steps:
(1) weighing the raw materials according to the weight;
(2) and uniformly mixing the quicklime, the modified humic acid, the modified clay mineral, the phosphoric acid and the phosphate modified biochar loaded iron-manganese oxide to obtain the high-efficiency repairing agent for the lead-cadmium composite polluted soil.
Example 3
The efficient repairing agent for lead-cadmium composite polluted soil comprises the following raw materials by weight: 60kg of quicklime, 30kg of modified humic acid, 20kg of modified clay mineral, 5kg of monocalcium phosphate and 1kg of phosphate modified biochar loaded iron-manganese oxide;
the preparation method of the modified humic acid comprises the following steps:
(1) adding 1kg of humic acid into 20kg of dilute hydrochloric acid solution with the molar concentration of 0.5mol/L, stirring and mixing, standing, and centrifuging to remove supernatant to obtain primary washing humic acid;
(2) adding 1kg of primary washing humic acid into 15kg of dilute hydrochloric acid solution with the molar concentration of 0.3mol/L, stirring and mixing, standing, and centrifuging to remove supernatant to obtain secondary washing humic acid;
(3) adding 1kg of backwashing humic acid into a mixed solution of 5kg of dilute hydrochloric acid and hydrogen fluoride, heating to 50 ℃ for reaction for 8 hours, adding water for cleaning, and centrifuging to remove supernatant to obtain modified humic acid, wherein the molar concentration of the dilute hydrochloric acid solution is 0.5mol/L and the molar concentration of the hydrogen fluoride is 3 mol/L;
the preparation method of the modified clay mineral comprises the following steps:
(1) mixing 1kg of zeolite and 2kg of montmorillonite, crushing, and sieving with a 200-mesh sieve to obtain clay mineral powder;
(2) adding 1kg of clay mineral powder into 4kg of dilute nitric acid solution with the molar concentration of 1mol/L, heating to 70 ℃, soaking for 1h, centrifugally filtering, washing to be neutral, and drying and activating for 2h at the temperature of 100 ℃ to obtain acidified clay mineral powder;
(3) heating the acidified clay mineral powder to 500 ℃, thermally modifying for 2h, and cooling to obtain a modified clay mineral;
the preparation method of the phosphate modified charcoal loaded iron manganese oxide comprises the following steps: firstly, plant straws are soaked in phosphoric acid for modification and then pyrolyzed at high temperature to prepare biochar, and then the biochar is loaded with iron-manganese oxide under the action of potassium permanganate by adopting an oxidation-reduction coprecipitation method, so that the phosphate modified biochar loaded iron-manganese oxide is obtained.
The preparation method of the efficient repairing agent for the lead-cadmium composite polluted soil specifically comprises the following steps:
(1) weighing the raw materials according to the weight;
(2) and uniformly mixing the quicklime, the modified humic acid, the modified clay mineral, the monocalcium phosphate and the phosphate modified biochar loaded iron-manganese oxide to obtain the efficient repairing agent for the lead-cadmium composite polluted soil.
Performance testing
Selecting a certain lead-cadmium polluted site in suburbs of a new country, collecting soil with the surface layer of 1-20cm by using a spiral soil sampler, selecting large-particle solid waste materials such as stones, gravels, branches and the like, naturally drying the soil, and sieving the soil by using a 1 mm-aperture sieve after grinding.
2000g of soil is accurately weighed and evenly divided into four parts, each 500g of soil is respectively placed in a 2L beaker, the 1 st part to the 3 rd part of the high-efficiency repairing agent prepared in the examples 1 to 3 are respectively added and evenly mixed, and the 1 st part is not treated and is used as a blank control. Then adding pure water respectively, stirring uniformly to keep the soil moisture content at about 30%, stirring the sample once every 24h, and stabilizing for 10 days at 20 ℃.
And after the maintenance is finished, putting the four parts of soil in a cool and dry place for airing, and measuring the pH value of the leachate and the contents of heavy metals Cd and Pb. Wherein the leaching solution is executed according to the industrial standard GB5086.1-1997 of solid waste leaching toxicity leaching method, and the heavy metal detection analysis method is executed according to appendix A in GB5085.3-2007 of hazardous waste identification standard leaching toxicity identification. The results are shown in Table 1.
TABLE 1 pH value of leachate and heavy metal content test results
As can be seen from Table 1, the treatment with the high-efficiency repairing agent prepared in the examples 1-3 can improve the pH value of soil, remarkably reduce the contents of Cd and Pb in heavy metals, and meet the IV-class standard requirements of underground water. Among them, example 1 is the most preferable example.
The tests show that the efficient repairing agent for the lead-cadmium composite polluted soil has strong adsorption repairing effect on lead and cadmium in the soil, is short in repairing period, does not damage the soil structure and planting function, is free of secondary pollution, and is durable in repairing effect.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The efficient repairing agent for lead-cadmium composite polluted soil is characterized by comprising the following raw materials in parts by weight: 40-60 parts of quicklime, 20-30 parts of modified humic acid, 20-30 parts of modified clay mineral, 5-15 parts of activator and 1-10 parts of stabilizer.
2. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 1, which is characterized by comprising the following raw materials in parts by weight: 50 parts of quicklime, 25 parts of modified humic acid, 25 parts of modified clay mineral, 10 parts of activating agent and 5 parts of stabilizing agent.
3. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 1, wherein the preparation method of the modified humic acid is as follows:
(1) adding humic acid into a dilute hydrochloric acid solution, stirring and mixing, standing, and centrifuging to remove a supernatant to obtain primary washing humic acid;
(2) adding the primary washing humic acid into a dilute hydrochloric acid solution, stirring and mixing, standing, and centrifuging to remove a supernatant to obtain secondary washing humic acid;
(3) adding the rewashed humic acid into a mixed solution of dilute hydrochloric acid and hydrogen fluoride, mixing, reacting, then adding water for cleaning, and centrifuging to remove supernatant fluid to obtain the modified humic acid.
4. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 3, wherein in the step (1), the molar concentration of the dilute hydrochloric acid solution is 0.5-1mol/L, and the mass ratio of the humic acid to the dilute hydrochloric acid solution is 1: (10-20);
in the step (2), the molar concentration of the dilute hydrochloric acid solution is 0.3-0.5mol/L, and the mass ratio of the primary washing humic acid to the dilute hydrochloric acid solution is 1: (8-15);
in the step (3), in the mixed solution of the dilute hydrochloric acid and the hydrogen fluoride, the molar concentration of the dilute hydrochloric acid solution is 0.3-0.5mol/L, and the molar concentration of the hydrogen fluoride is 3-8 mol/L; the mass ratio of the mixed solution of the backwashing humic acid, the dilute hydrochloric acid and the hydrogen fluoride is 1: (3-5); the reaction temperature is 40-50 ℃ and the reaction time is 8-12 h.
5. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 1, wherein the preparation method of the modified clay mineral comprises the following steps:
(1) mixing zeolite and montmorillonite, pulverizing, and sieving to obtain clay mineral powder;
(2) adding clay mineral powder into dilute nitric acid solution for soaking, centrifuging and filtering, washing to be neutral, drying and activating to obtain acidified clay mineral powder;
(3) heating the acidified clay mineral powder for thermal modification, and cooling to obtain the modified clay mineral.
6. The high-efficiency repairing agent for lead-cadmium combined polluted soil according to claim 5, wherein in the step (1), the mass ratio of the zeolite to the montmorillonite is 1: (1-2), the mesh number of the sieved screen is 100-200 meshes;
in the step (2), the molar concentration of the dilute nitric acid solution is 1-2mol/L, and the mass ratio of the clay mineral powder to the dilute nitric acid solution is 1: (2-4), wherein the soaking temperature is 60-70 ℃, and the soaking time is 1-2 h; the temperature of drying and activating is 90-100 ℃, and the time is 2-3 h;
in the step (3), the temperature of the thermal modification is 300-500 ℃, and the time is 2-4 h.
7. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 1, wherein the activating agent is phosphoric acid and/or calcium dihydrogen phosphate.
8. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 1, wherein the stabilizing agent is phosphate modified biochar loaded iron-manganese oxide.
9. The efficient repairing agent for lead-cadmium combined polluted soil according to claim 8, wherein the preparation method of the phosphate modified biochar loaded iron-manganese oxide comprises the following steps:
firstly, plant straws are soaked in phosphoric acid for modification and then pyrolyzed at high temperature to prepare biochar, and then the biochar is loaded with iron-manganese oxide under the action of potassium permanganate by adopting an oxidation-reduction coprecipitation method, so that the phosphate modified biochar loaded iron-manganese oxide is obtained.
10. The preparation method of the efficient repairing agent for the lead-cadmium composite polluted soil is characterized by comprising the following steps:
(1) weighing the raw materials according to the parts by weight of the efficient repairing agent for the lead-cadmium combined polluted soil of any one of claims 1 to 9;
(2) and uniformly mixing the quicklime, the modified humic acid, the modified clay mineral, the activator and the stabilizer to obtain the high-efficiency repairing agent for the lead-cadmium composite polluted soil.
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