CN116283180A - Heavy metal curing agent and preparation method thereof - Google Patents
Heavy metal curing agent and preparation method thereof Download PDFInfo
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- CN116283180A CN116283180A CN202211535829.2A CN202211535829A CN116283180A CN 116283180 A CN116283180 A CN 116283180A CN 202211535829 A CN202211535829 A CN 202211535829A CN 116283180 A CN116283180 A CN 116283180A
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- heavy metal
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- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 88
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 229920001661 Chitosan Polymers 0.000 claims abstract description 81
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 55
- 239000004568 cement Substances 0.000 claims abstract description 25
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 20
- 239000002893 slag Substances 0.000 claims abstract description 20
- 239000010959 steel Substances 0.000 claims abstract description 20
- 239000000654 additive Substances 0.000 claims abstract description 18
- 230000000996 additive effect Effects 0.000 claims abstract description 18
- 239000000843 powder Substances 0.000 claims abstract description 16
- 239000002994 raw material Substances 0.000 claims abstract description 15
- 239000003463 adsorbent Substances 0.000 claims abstract description 14
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 claims abstract description 14
- 239000003349 gelling agent Substances 0.000 claims abstract description 12
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 9
- 239000011707 mineral Substances 0.000 claims abstract description 9
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 6
- 229920002401 polyacrylamide Polymers 0.000 claims abstract description 6
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims abstract description 4
- 238000001723 curing Methods 0.000 claims description 56
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 51
- 239000011259 mixed solution Substances 0.000 claims description 46
- 238000003756 stirring Methods 0.000 claims description 38
- 239000000243 solution Substances 0.000 claims description 33
- 239000011381 foam concrete Substances 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 24
- 239000011268 mixed slurry Substances 0.000 claims description 22
- 238000005187 foaming Methods 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 239000002245 particle Substances 0.000 claims description 16
- 230000008569 process Effects 0.000 claims description 15
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 claims description 14
- 238000002156 mixing Methods 0.000 claims description 13
- 239000004088 foaming agent Substances 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 11
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 9
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 claims description 9
- 239000011976 maleic acid Substances 0.000 claims description 9
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 claims description 9
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 8
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 238000007664 blowing Methods 0.000 claims description 4
- 229920003086 cellulose ether Polymers 0.000 claims description 4
- 239000010881 fly ash Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 239000002689 soil Substances 0.000 abstract description 40
- 238000002386 leaching Methods 0.000 abstract description 13
- 238000007789 sealing Methods 0.000 abstract description 11
- 238000001179 sorption measurement Methods 0.000 description 26
- 230000000052 comparative effect Effects 0.000 description 19
- 230000000694 effects Effects 0.000 description 14
- 239000011148 porous material Substances 0.000 description 14
- 238000006703 hydration reaction Methods 0.000 description 13
- 239000010802 sludge Substances 0.000 description 13
- 239000004567 concrete Substances 0.000 description 12
- 150000002500 ions Chemical class 0.000 description 12
- 239000000463 material Substances 0.000 description 9
- 229910021536 Zeolite Inorganic materials 0.000 description 8
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 8
- 230000036571 hydration Effects 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 239000010457 zeolite Substances 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 239000003431 cross linking reagent Substances 0.000 description 6
- 238000004132 cross linking Methods 0.000 description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 229910001653 ettringite Inorganic materials 0.000 description 4
- 238000007711 solidification Methods 0.000 description 4
- 230000008023 solidification Effects 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000000378 calcium silicate Substances 0.000 description 3
- 229910052918 calcium silicate Inorganic materials 0.000 description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 239000011133 lead Substances 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 238000003900 soil pollution Methods 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 239000003999 initiator Substances 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- -1 polydimethylsiloxane Polymers 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- RTBFRGCFXZNCOE-UHFFFAOYSA-N 1-methylsulfonylpiperidin-4-one Chemical compound CS(=O)(=O)N1CCC(=O)CC1 RTBFRGCFXZNCOE-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004113 Sepiolite Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000012271 agricultural production Methods 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- JFCQEDHGNNZCLN-UHFFFAOYSA-N anhydrous glutaric acid Natural products OC(=O)CCCC(O)=O JFCQEDHGNNZCLN-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229960000892 attapulgite Drugs 0.000 description 1
- 229910001570 bauxite Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000004205 dimethyl polysiloxane Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000004720 fertilization Effects 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000000051 modifying effect Effects 0.000 description 1
- 125000000962 organic group Chemical group 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 229910052625 palygorskite Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910052624 sepiolite Inorganic materials 0.000 description 1
- 235000019355 sepiolite Nutrition 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052902 vermiculite Inorganic materials 0.000 description 1
- 239000010455 vermiculite Substances 0.000 description 1
- 235000019354 vermiculite Nutrition 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/142—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing synthetic or waste calcium sulfate cements
- C04B28/143—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing synthetic or waste calcium sulfate cements the synthetic calcium sulfate being phosphogypsum
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/02—Agglomerated materials, e.g. artificial aggregates
- C04B18/027—Lightweight materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
- C04B40/0046—Premixtures of ingredients characterised by their processing, e.g. sequence of mixing the ingredients when preparing the premixtures
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Civil Engineering (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention discloses a heavy metal curing agent which comprises the following raw materials in parts by weight: 30-40 parts of adsorbent, 50-60 parts of gelatinizer and 0.1-10 parts of additive; wherein the adsorbent is porous micro aggregate loaded with modified chitosan; the gelling agent comprises the following raw materials in parts by weight: 10-20 parts of cement, 10-20 parts of mineral powder, 20-30 parts of steel slag, 20-30 parts of red mud and 20-30 parts of phosphogypsum; the additive comprises the following raw materials in parts by weight: 40-60 parts of polyacrylamide, 10-20 parts of polymethyl siloxane and 0.1-30 parts of polyaluminium sulfate. The invention discloses a preparation method of a heavy metal curing agent, which improves the durability of cured soil, further reduces leaching of heavy metals and realizes sealing and preserving treatment of the heavy metals.
Description
Technical Field
The invention relates to the field of heavy metal solidification. More particularly, the invention relates to a heavy metal curing agent and a preparation method thereof.
Background
With the development of technology and economy, the influence of human activities on natural environment is increasing, such as heavy metals generated in the processes of agricultural production, industrial production and the like, are finally discharged into soil along with precipitation, mining, pollution discharge, fertilization and other approaches, are further enriched into plants and organisms, so that the pollution of the ecological environment is caused, and the heavy metals are transmitted through a food chain, so that the human health is finally and seriously threatened, and the treatment of the heavy metal polluted soil is a great environmental problem.
The chemical curing method is one of the most commonly used heavy metal polluted soil restoration methods at present because of better economy and quick treatment aging, the chemical curing method changes the physicochemical property of the soil by adding a specific curing agent material into the soil, and then passivates and seals heavy metal through the adsorption or coprecipitation of the heavy metal, thereby reducing the bioavailability and reducing the influence on ecological environment.
The traditional heavy metal curing agent is mainly used for wrapping heavy metal ions by utilizing the hydration reaction product of the cement-based cementing material, but the curing strength of the cement-based cementing material in soil is often lower, the heavy metal sealing effect is poor, the durability is poor, the later stage is easy to leach, and meanwhile, the alkalinity is high, so that secondary pollution is easy to cause; the porous materials such as sepiolite, vermiculite, attapulgite, zeolite and active carbon are utilized to realize the adsorption effect on heavy metals, but the porous materials need further treatment after adsorption, the operation is complex, and otherwise the desorption risk exists.
Disclosure of Invention
The invention also aims to provide a heavy metal curing agent for improving the durability of the cured soil, further reducing leaching of heavy metals and realizing the sealing treatment of the heavy metals and a preparation method thereof.
To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a heavy metal solidifying agent comprising the following raw materials in parts by weight:
30-40 parts of adsorbent, 50-60 parts of gelatinizer and 0.1-10 parts of additive;
wherein the adsorbent is porous micro aggregate loaded with modified chitosan;
the gelling agent comprises the following raw materials in parts by weight: 10-20 parts of cement, 10-20 parts of mineral powder, 20-30 parts of steel slag, 20-30 parts of red mud and 20-30 parts of phosphogypsum;
the additive comprises the following raw materials in parts by weight: 40-60 parts of polyacrylamide, 10-20 parts of polymethyl siloxane and 0.1-30 parts of polyaluminium sulfate.
Preferably, the preparation method of the porous micro aggregate loaded with the modified chitosan comprises the following steps:
step S1, crushing the microporous foamed concrete blocks to obtain porous micro aggregate for later use;
step S2, taking acetic acid solution as solute, dissolving chitosan into the acetic acid solution according to the proportion of 0.03-0.05 g/ml to obtain a first mixed solution, adding the porous micro aggregate of the step S1 into the first mixed solution according to the proportion of 0.03-0.08 g/ml, stirring to obtain a second mixed solution, adding glutaraldehyde into the second mixed solution in the stirring process to obtain a porous micro aggregate solution of the loaded chitosan, continuously stirring for 2 hours, filtering out the porous micro aggregate of the loaded chitosan from the porous micro aggregate solution of the loaded chitosan, and drying at 60 ℃ for later use;
and S3, mixing the chitosan-loaded porous micro aggregate obtained in the step S2 with water according to the proportion of 0.1g/ml to obtain a mixed solution III, adding maleic acid into the mixed solution III according to the proportion of 0.02-0.05 ml/ml to obtain a mixed solution IV, heating the mixed solution IV to 50 ℃, continuously stirring for 30min under the condition, adding potassium persulfate into the mixed solution IV to obtain a mixed solution V, continuously stirring for 1h, adding glutaraldehyde into the mixed solution V according to the proportion of 0.02-0.05 ml/ml to obtain a modified chitosan-loaded porous micro aggregate solution, continuously stirring for 2h, filtering the modified chitosan-loaded porous micro aggregate from the modified chitosan-loaded porous micro aggregate solution, and drying under the environment of 60 ℃ to obtain the modified chitosan-loaded porous micro aggregate.
Preferably, the microporous foamed concrete block in the step S1 is crushed to a particle size of less than 2.36mm, and then is elutriated in water, naturally dried and used as the porous micro aggregate.
Preferably, the microporous foamed concrete block is prepared by a chemical foaming method, and specifically comprises the following steps:
step a, uniformly stirring 10-20 parts of common silica cement, 30-40 parts of fly ash, 30-40 parts of steel slag micropowder and 5-10 parts of cellulose ether under the conditions of water-cement ratio of 0.6-0.8 and temperature of 40-50 ℃ to obtain mixed slurry I;
b, adding a foaming agent into the mixed slurry I in the step a, stirring uniformly to obtain mixed slurry II, quickly pouring the mixed slurry II into a mould, transferring the mould into a closed box with the temperature of 40-50 ℃ and the humidity of not less than 95%, blowing air to ensure that the pressure in the box reaches 110-130 kpa and keeps stable, and finishing the foaming process of the mixed slurry II in a positive pressure environment to obtain foamed concrete;
and c, curing the foamed concrete in the step b for 12-24 hours with a mold, removing the mold, and autoclaved curing for 4 hours at 200 ℃ to obtain the microporous foamed concrete block.
Preferably, in the step b, the foaming agent is aluminum powder or hydrogen peroxide, and the concentration of the foaming agent is 0.1-0.3%.
Preferably, the steel slag of the gelling agent is ground into powder with the particle size of 10-20 mu m.
Preferably, the particle size of the red mud is 20-50 mu m, and the specific surface area is 10-25 m 2 /g; the phosphogypsum is washed, dried and ground to 75-150 mu m in particle size.
Preferably, in the step S2, the concentration of the acetic acid solution is 2%.
A preparation method of the heavy metal curing agent comprises the step of uniformly mixing the adsorbent, the gelling agent and the additive in parts by weight to obtain the heavy metal curing agent.
The invention at least comprises the following beneficial effects:
1. the porous micro aggregate loaded with the modified chitosan is used as an adsorbent to realize the main adsorption of heavy metals in polluted soil and provide skeleton support for solidified soil; secondly, the steel slag, the red mud and the phosphogypsum are taken as main raw materials to form a gelatinizing agent, so that on one hand, the supplementary adsorption of heavy metals is realized, the treatment capacity of a solidifying agent on the heavy metals is improved, on the other hand, hydration products generated by hydration reaction of components in the gelatinizing agent and water in polluted soil realize sealing on the surface of porous micro-aggregate loaded with the modified chitosan, the adsorbed heavy metals are prevented from being leached again, meanwhile, the rest hydration products are taken as a tie, and the porous micro-aggregate loaded with the modified chitosan is taken as a core, so that a mutually embedded space network structure is formed in the polluted soil, the strength of the solidified soil is higher, the solidified soil is slightly alkaline, and the environment-friendly degree is high; the components of the additive are used for improving the action effect of the components of the gelling agent, improving the durability of the solidified soil, further reducing the leaching of heavy metals and realizing the sealing treatment of the heavy metals;
2. after chitosan is dissolved in acetic acid solution, porous micro aggregate is added and stirred uniformly, glutaraldehyde (C) is added 5 H 8 O 2 ) As a cross-linking agent, the chitosan is filtered to obtain the loaded chitosanPorous micro aggregate of (C) and partial-NH in cross-linking process 2 The active groups of-OH are consumed by the cross-linking agent, so as to further improve the adsorption performance of the porous micro aggregate loaded with chitosan on heavy metals, and the porous micro aggregate is prepared by the following steps of adding the potassium persulfate (K 2 S 2 O 4 ) As an initiator, glutaraldehyde is used as a cross-linking agent, maleic acid is added to ensure that the chitosan is not completely reacted with-NH 2 and-OH with maleic acid rich in-COOH (C 4 H 4 O 4 ) Performing cross-linking polymerization to obtain porous micro-aggregate loaded with modified chitosan, wherein the active sites are more, and the adsorption capacity of heavy metal ions is greatly improved;
3. the adoption of the chemical foaming method for preparing the microporous foaming concrete block can improve the occupation ratio of the communicated pores and the adsorption quantity; by coordinating the pressure value in the closed box and the addition amount of the foaming agent, the foamed body growing in the pressure environment is cultivated, the pore size of the foamed concrete can be regulated and controlled, the specific surface area of the porous micro aggregate is increased, the adsorption capacity is improved, and meanwhile, the overall strength of the foamed concrete can be improved due to the reduction of the pore diameter, so that the curing strength and the durability of the curing agent are improved.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Detailed Description
The present invention is described in further detail below to enable those skilled in the art to practice the invention by reference to the specification.
It should be noted that the experimental methods described in the following embodiments, unless otherwise specified, are all conventional methods, and the reagents and materials, unless otherwise specified, are all commercially available; in the description of the present invention, the terms "transverse," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience of description and to simplify the description, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.
The invention provides a heavy metal curing agent which comprises the following raw materials in parts by weight:
30-40 parts of adsorbent, 50-60 parts of gelatinizer and 0.1-10 parts of additive;
wherein the adsorbent is porous micro aggregate loaded with modified chitosan;
the gelling agent comprises the following raw materials in parts by weight: 10-20 parts of cement, 10-20 parts of mineral powder, 20-30 parts of steel slag, 20-30 parts of red mud and 20-30 parts of phosphogypsum;
the additive comprises the following raw materials in parts by weight: 40-60 parts of polyacrylamide, 10-20 parts of polymethyl siloxane and 0.1-30 parts of polyaluminium sulfate.
In the technical scheme, the porous micro aggregate loaded with the modified chitosan is used as an adsorbent to realize main adsorption of heavy metals in polluted soil and provide skeleton support for solidified soil; secondly, the steel slag, the red mud and the phosphogypsum are taken as main raw materials to form a gelatinizing agent, so that on one hand, the supplementary adsorption of heavy metals is realized, the treatment capacity of a solidifying agent on the heavy metals is improved, on the other hand, hydration products generated by hydration reaction of components in the gelatinizing agent and water in polluted soil realize sealing on the surface of porous micro-aggregate loaded with the modified chitosan, the adsorbed heavy metals are prevented from being leached again, meanwhile, the rest hydration products are taken as a tie, and the porous micro-aggregate loaded with the modified chitosan is taken as a core, so that a mutually embedded space network structure is formed in the polluted soil, the strength of the solidified soil is higher, the solidified soil is slightly alkaline, and the environment-friendly degree is high; the components of the additive are used for improving the action effect of the components of the gelling agent, improving the durability of the solidified soil, further reducing the leaching of heavy metals and realizing the sealing treatment of the heavy metals.
In another technical scheme, the preparation method of the porous micro aggregate loaded with the modified chitosan comprises the following steps:
step S1, crushing the microporous foamed concrete blocks to obtain porous micro aggregate for later use;
step S2, taking acetic acid solution as solute, dissolving chitosan into the acetic acid solution according to the proportion of 0.03-0.05 g/ml to obtain a first mixed solution, adding the porous micro aggregate of the step S1 into the first mixed solution according to the proportion of 0.03-0.08 g/ml, stirring to obtain a second mixed solution, adding glutaraldehyde into the second mixed solution in the stirring process to obtain a porous micro aggregate solution of the loaded chitosan, continuously stirring for 2 hours, filtering out the porous micro aggregate of the loaded chitosan from the porous micro aggregate solution of the loaded chitosan, and drying at 60 ℃ for later use;
and S3, mixing the chitosan-loaded porous micro aggregate obtained in the step S2 with water according to the proportion of 0.1g/ml to obtain a mixed solution III, adding maleic acid into the mixed solution III according to the proportion of 0.02-0.05 ml/ml to obtain a mixed solution IV, heating the mixed solution IV to 50 ℃, continuously stirring for 30min under the condition, adding potassium persulfate into the mixed solution IV to obtain a mixed solution V, continuously stirring for 1h, adding glutaraldehyde into the mixed solution V according to the proportion of 0.02-0.05 ml/ml to obtain a modified chitosan-loaded porous micro aggregate solution, continuously stirring for 2h, filtering the modified chitosan-loaded porous micro aggregate from the modified chitosan-loaded porous micro aggregate solution, and drying under the environment of 60 ℃ to obtain the modified chitosan-loaded porous micro aggregate.
In the technical proposal, after chitosan is dissolved in acetic acid solution, porous micro aggregate is added and stirred evenly, glutaraldehyde (C) is added 5 H 8 O 2 ) As a cross-linking agent, filtering to obtain the chitosan-loaded porous micro-aggregate, wherein part of-NH is in the cross-linking process 2 The active groups of-OH are consumed by the cross-linking agent, so as to further improve the adsorption performance of the porous micro aggregate loaded with chitosan on heavy metals, and the porous micro aggregate is prepared by the following steps of adding the potassium persulfate (K 2 S 2 O 4 ) As an initiator, glutaraldehyde is used as a cross-linking agent, maleic acid is added to ensure that the chitosan is not completely reacted with-NH 2 and-OH with maleic acid rich in-COOH (C 4 H 4 O 4 ) Performing cross-linking polymerization to obtain porous micro-aggregate loaded with modified chitosan and active sitesThe number of the positions is more, and the adsorption capacity for heavy metal ions is greatly improved.
In another technical scheme, the microporous foamed concrete block in the step S1 is crushed until the particle size is below 2.36mm, then is elutriated in water, and is naturally dried to be used as porous micro aggregate for standby.
In the technical scheme, the microporous foaming concrete blocks are crushed, the parts with the particle sizes less than or equal to 2.36mm are screened as adsorption aggregates, the parts with the particle sizes greater than 2.36mm continue to be crushed until the requirements are met, and then the crushed parts are elutriated in water for 2 times, so that the powder content in the pores is reduced, and the adsorption capacity of the crushed parts is improved.
In another technical scheme, the microporous foamed concrete block is prepared by adopting a chemical foaming method, and specifically comprises the following steps of:
step a, uniformly stirring 10-20 parts of common silica cement, 30-40 parts of fly ash, 30-40 parts of steel slag micropowder and 5-10 parts of cellulose ether under the conditions of water-cement ratio of 0.6-0.8 and temperature of 40-50 ℃ to obtain mixed slurry I;
b, adding a foaming agent into the mixed slurry I in the step a, stirring uniformly to obtain mixed slurry II, quickly pouring the mixed slurry II into a mould, transferring the mould into a closed box with the temperature of 40-50 ℃ and the humidity of not less than 95%, blowing air to ensure that the pressure in the box reaches 110-130 kpa and keeps stable, and finishing the foaming process of the mixed slurry II in a positive pressure environment to obtain foamed concrete;
and c, curing the foamed concrete in the step b for 12-24 hours with a mold, removing the mold, and autoclaved curing for 4 hours at 200 ℃ to obtain the microporous foamed concrete block.
In the technical scheme, the adoption of the chemical foaming method for preparing the microporous foaming concrete block can improve the ratio of the communicated pores, and the foaming agent and OH in the mixed slurry I - The chemical reaction is carried out to generate gas, on one hand, the generation and the escape of the gas can lead the mixed slurry II to generate volume expansion, a large number of communicated pores are formed in the slurry, and the adsorption capacity is improved; on the other hand, the pressure given by the foaming environment becomes resistance to the expansion of the slurry volume, and the foaming agent is added in the closed tank in a coordinated manner to thereby cultivate the foam growing in the pressure environmentThe body can realize the regulation and control of the pore size of the foaming concrete and improve the diameter<The number of the holes of 200 micrometers increases the specific surface area of the porous micro aggregate, improves the adsorption capacity, and simultaneously reduces the pore diameter to improve the integral strength of the foamed concrete, thereby being beneficial to improving the curing strength and durability of the curing agent.
In another technical scheme, in the step b, the foaming agent is aluminum powder or hydrogen peroxide, and the concentration of the foaming agent is 0.1-0.3%.
In another technical scheme, the steel slag of the gelling agent is ground into powder with the particle size of 10-20 mu m.
In the technical scheme, the steel slag is ground to form powder, the ground steel slag powder has certain gelatinization, the material cost of the curing agent can be further reduced as an auxiliary gelatinization material, the steel slag has loose and porous properties, and the ground steel slag powder has higher surface energy and larger specific surface area, thereby being beneficial to further absorbing heavy metals.
In another technical scheme, the grain diameter of the red mud is 20-50 mu m, and the specific surface area is 10-25 m 2 /g; the phosphogypsum is washed, dried and ground to 75-150 mu m in particle size.
In another embodiment, in the step S2, the concentration of the acetic acid solution is 2%.
A preparation method of the heavy metal curing agent comprises the step of uniformly mixing the adsorbent, the gelling agent and the additive in parts by weight to obtain the heavy metal curing agent.
In the technical scheme, when the modified chitosan porous micro-aggregate is used, the addition amount of the heavy metal curing agent is 10-30% of the mass of heavy metal polluted soil, so that the main adsorption of heavy metals in the polluted soil is realized, and meanwhile, a framework support is provided for the solidified soil; the gelatinizer can carry out hydration reaction with water in the sludge, form a mutually embedded netlike structure in the sludge to wrap, bond and fill pores of the sludge, and provide strength for the sludge; meanwhile, hydration products such as CSH, CAH, ettringite and the like generated by hydration can realize the adsorption, wrapping and passivation of heavy metal ions; on the other hand, the hydration product of the gelatinizer bonds together the porous micro-bones of the load modified chitosan dispersed in the sludge, a space network structure taking the porous micro-bones of the load modified chitosan as nodes is formed, the solidification strength is higher, the package and the cementation of the porous micro-bones of the load modified chitosan are synchronously realized, a large amount of heavy metal ions adsorbed by the porous micro-bones of the load modified chitosan are sealed, the heavy metal leaching is further reduced, and the gelatinizer has the following specific functions:
the cement is commercial P.O42.5 cement, and the cement reacts with water to generate hydrated calcium silicate CSH, hydrated calcium aluminate CAH and the like, is an amorphous porous material with very high specific surface area, can adsorb, wrap and passivate heavy metal ions in sludge, and simultaneously provides Ca (OH) for the cement 2 The silicon aluminum in the mineral powder, the red mud and the sludge also react to generate more CSH, CAH and the like, a meshed structure which is mutually embedded is formed in the sludge to wrap, bond and fill pores of the sludge, so that strength is generated;
the mineral powder is commercial S95-grade mineral powder which is used for improving the impermeability of the solidified soil, facilitating the increase of the later strength of the solidified soil, reducing the leaching of heavy metals, consuming calcium hydroxide generated by hydration of cement and reducing the alkalinity;
the steel slag provides a certain alkalinity for the reaction of mineral powder and red mud, and is used for further absorbing heavy metals;
the red mud has certain adsorption performance, attracts a part of heavy metal ions through electrostatic adsorption, and meanwhile, a small amount of hydroxyl and carboxyl remained on the surface of the red mud can carry out complex reaction with the heavy metal ions, so that the wrapping and passivation of the heavy metal ions are realized, and leaching is reduced; on the other hand, the activated silica and alumina in the red mud can be combined with Ca (OH) provided by cement 2 The reaction generates products such as hydrated calcium silicate, hydrated calcium aluminate and the like, reduces alkalinity and improves the strength of solidified soil;
SO provided by phosphogypsum 4 2- With Al in other materials 2 O 3 The CaO and the like react to generate ettringite crystals, so that the ettringite crystals have a micro-expansion effect, loose clay particles are extruded, gaps between the sludge and hydrated calcium silicate are filled, and the solidification strength is improved; at the same time, under alkaline condition, heavy metal ions are attached in the pore canal of ettringite in a precipitation form to obtainThe sealing is used for realizing the adsorption and the wrapping of heavy metals and reducing leaching; on the other hand, ca produced by phosphogypsum hydrolysis 2+ Substitution of K on the surface of organic matter in sludge by ion exchange + 、Na + The radius of hydrated ions is reduced, the thickness of an electric double layer is reduced, the influence of organic matters is inhibited, and the condensation process is promoted;
the addition of the additive is used for improving the durability of the solidified soil and reducing leaching of heavy metals, and the concrete steps are as follows:
the polyacrylamide realizes the granulation of the sludge through the processes of bridging, net repairing and flocculation of the polymer, and partial water is removed from the sludge for hydration reaction of the gelatinizer, so that secondary water addition is avoided; the oriented orientation of the organic groups in the polydimethylsiloxane can generate very low surface tension on the surface of the solidified soil, so that the infiltration of external water can be prevented, the effect of surface sealing is achieved, the durability of the solidified soil is improved, and the leaching of heavy metals is reduced; SO produced by hydrolysis of polyaluminium sulfate 4 2- And Ca (OH) in solution 2 And C 3 A reacts to promote the generation of hydrated calcium sulfoaluminate, improve the early strength of solidification and simultaneously hydrolyze the product Al (OH) 3 Too much OH-can be neutralized, and the alkalinity is reduced; on the other hand, hydroxyl provided by hydrolysis of the modified red mud can be attached to the surfaces of red mud, phosphogypsum and porous micro-aggregate, so that the adsorption capacity of heavy metals is enhanced; the adsorption and sealing effect of heavy metals are realized through the interaction of the adsorbent, the gelatinizing agent and the additive, the leaching of the heavy metals is reduced, and the sealing treatment of the heavy metals is realized;
the steel slag is a byproduct in the steelmaking process, the red mud is industrial waste residue discharged by extracting alumina from bauxite, and phosphogypsum is a byproduct in the wet-process phosphoric acid production; the curing agent disclosed by the invention takes solid waste as a main material to realize rapid curing treatment of heavy metal pollution medium, waste treatment by waste is realized, and meanwhile, the strength after curing is higher, so that the curing agent can be used for the scenes of roadbed construction, pit backfill, artificial rockery, landfill earthing and the like of non-risk areas, or is combined with a means of phytoremediation to realize long-term stability of the field.
Example 1 ]
The heavy metal curing agent comprises the following raw materials in parts by weight:
30 parts of porous micro aggregate loaded with modified chitosan, 60 parts of gelatinizer and 10 parts of additive;
the gelatinizer is prepared by mixing 20 parts of cement, 10 parts of mineral powder, 30 parts of steel slag, 20 parts of red mud and 20 parts of phosphogypsum;
the additive is prepared by mixing 60 parts of polyacrylamide, 20 parts of polymethylsiloxane and 20 parts of polyaluminum sulfate.
Preparing porous micro aggregate loaded with modified chitosan:
s1, crushing the microporous foaming concrete block until the particle size is below 2.36mm, washing the microporous foaming concrete block in water, and naturally airing the microporous foaming concrete block to serve as porous micro aggregate for standby;
step S2, taking acetic acid solution with the concentration of 2% as solute, dissolving chitosan in the acetic acid solution according to the proportion of 0.05g/ml to obtain a first mixed solution, adding the porous micro-aggregate of the step S1 into the first mixed solution according to the proportion of 0.08g/ml, stirring to obtain a second mixed solution, adding glutaraldehyde into the second mixed solution in the stirring process to obtain a porous micro-aggregate solution of the loaded chitosan, continuously stirring for 2 hours, filtering out the porous micro-aggregate of the loaded chitosan from the porous micro-aggregate solution of the loaded chitosan, and drying at 60 ℃ for later use;
and S3, mixing the chitosan-loaded porous micro aggregate obtained in the step S2 with water according to the proportion of 0.1g/ml to obtain a mixed solution III, adding maleic acid into the mixed solution III according to the proportion of 0.05ml/ml to obtain a mixed solution IV, heating the mixed solution IV to 50 ℃, continuously stirring for 30min under the condition, adding potassium persulfate into the mixed solution IV to obtain a mixed solution V, adding 0.05g/ml of potassium persulfate, continuously stirring for 1h, adding glutaraldehyde into the mixed solution V according to the proportion of 0.05ml/ml to obtain a modified chitosan-loaded porous micro aggregate solution, continuously stirring for 2h, and drying under the environment of 60 ℃ to obtain the modified chitosan-loaded porous micro aggregate.
Preparing the microporous foaming concrete block in the step S1:
step a, uniformly stirring 20 parts of common silica cement, 30 parts of fly ash, 40 parts of steel slag micropowder and 10 parts of cellulose ether at the temperature of 50 ℃ under the condition of a water-cement ratio of 0.6 to obtain mixed slurry I;
step b, adding aluminum powder into the mixed slurry I in the step a, stirring uniformly to obtain mixed slurry II, rapidly pouring the mixed slurry II into a mould, transferring the mould into a closed box with the temperature of 50 ℃ and the humidity of not less than 95%, blowing air to ensure that the pressure in the box reaches 130kpa and keeps stable, and completing the foaming process of the mixed slurry II in a positive pressure environment to obtain foamed concrete;
and c, curing the foamed concrete in the step b for 24 hours with a mold, removing the mold, and autoclaved curing for 4 hours at 200 ℃ to obtain the microporous foamed concrete block.
Preparing a curing agent: respectively weighing 30 parts of porous micro aggregate loaded with modified chitosan, 60 parts of gelatinizer and 10 parts of additive, and uniformly mixing to obtain the heavy metal curing agent.
Example 2 ]
The difference between the heavy metal curing agent and the preparation method thereof is that the aluminum powder in the step b is hydrogen peroxide, and the rest conditions and parameters are the same as those in the embodiment 1.
Comparative example 1 ]
A cement lime curing agent and a preparation method thereof are provided, wherein the cement lime curing agent is prepared by mixing 70% of cement and 30% of lime according to the weight ratio of components.
Comparative example 2 ]
A cement-chitosan zeolite curing agent and its preparing process are disclosed, which are prepared from cement (60 wt.%) and zeolite aggregate (40 wt.%) loaded with chitosan through mixing.
Preparation of chitosan-loaded zeolite aggregate:
step A, dissolving chitosan in acetic acid solution (CH) with concentration of 2% at a ratio of 0.04g/ml with acetic acid solution with concentration of 2% as solute 3 COOH), then continuing to add zeolite in a proportion of 0.03g/ml and continuing to stir, adding glutaric acid during stirringAldehyde (C) 5 H 8 O 2 ) Obtaining a mixed solution, wherein the addition amount of glutaraldehyde is 0.01ml/ml, continuously stirring for 2 hours, filtering the zeolite loaded with chitosan from the mixed solution, and drying the zeolite loaded with chitosan in an environment of 60 ℃ to obtain the zeolite aggregate loaded with chitosan.
Comparative example 3 ]
The difference between the heavy metal curing agent and the preparation method thereof is that the porous micro aggregate loaded with the modified chitosan is prepared, and the rest conditions and parameters are the same as those in the embodiment 1;
preparing porous micro aggregate loaded with modified chitosan:
step a, crushing the microporous foaming concrete block until the particle size is below 2.36mm, washing the microporous foaming concrete block in water, and naturally airing the microporous foaming concrete block to serve as porous micro aggregate for standby;
and b, taking 2% acetic acid solution as solute, respectively dissolving the porous micro-aggregate and chitosan in the acetic acid solution according to the proportion of 0.08g/ml and 0.05g/ml, stirring, continuously adding water, 0.02ml/ml glutaraldehyde, 0.05ml cis-Ding Xier acid and 0.05g/ml potassium persulfate according to the proportion of 0.1g/ml in the stirring process, continuously stirring for 1h, and filtering to obtain the porous micro-aggregate loaded with the modified chitosan.
The method is characterized in that a certain contaminated soil in Zhejiang is taken as a treatment object, main pollutants of the contaminated soil are copper, nickel, chromium and lead, wherein the contents of the copper, the nickel and the total chromium are higher than the upper limit of a soil pollution risk screening value of an agricultural land in a soil environment quality agricultural land pollution risk management and control standard (trial) (GB 15618-2018), and the heavy metal types and leaching concentrations of the contaminated soil are shown in a table 1;
TABLE 1
| Species of type | pH | Total chromium (mg/kg) | Lead (mg/kg) | Nickel (mg/kg) | Copper (mg/kg) |
| Numerical value | 6.7 | 432 | 63.2 | 197.1 | 792 |
The contaminated soil was subjected to curing treatment with the curing agents of examples 1 to 2 and comparative examples 1 to 3, respectively, the amount of the curing agent added was 15% of the contaminated soil, and the curing agents were compared in terms of curing strength, softening coefficient, PH, heavy metal leaching concentration, etc., at 7d and 28d after treatment, and the results are shown in table 2;
TABLE 2
As can be seen from table 2: the curing agents 7d and 28d of examples 1 and 2 of the present invention had better curing strength and better removal rate of heavy metals than those of comparative examples 1 and 2; the curing agents of example 1 and example 2 of the present invention are superior to those of comparative example 1 and comparative example 2 in mechanical properties, durability and heavy metal removal effect, since the softening coefficients are lower than those of the curing agents of comparative example 1 and comparative example 2; the pH value of 28d of the solidified soil in the embodiment 1 and the embodiment 2 is 8.4, and the solidified soil is slightly alkaline and has higher environmental friendliness;
the curing agent of comparative example 3 has the same curing strength and pH value as those of the effects of the examples 1 and 2 of the present invention, but has a general softening coefficient effect, and the porous micro-aggregate of comparative example 3 loaded with modified chitosan is prepared by mixing all materials together, stirring and filtering, the loading and modification of chitosan are carried out simultaneously, and part of active groups of chitosan are consumed before the porous micro-aggregate is loaded, so that the loading efficiency of chitosan is reduced; at the same time-NH on chitosan 2 Reactive groups such as-OH and maleic acid (C) 4 H 4 O 4 ) The degree of crosslinking polymerization reaction was lowered, and the modifying effect was also greatly impaired, and the adsorption capacity for heavy metal ions was rather lowered, i.e., the adsorption capacity for heavy metal of the curing agent of comparative example 3 was far lower than that of the curing agents of examples 1 and 2 of the present invention.
The above examples 1-2 and comparative examples 1-3 were compared in terms of cost, and the comparison results are shown in Table 3:
TABLE 3 Table 3
| Example 1 | Example 2 | Comparative example 1 | Comparative example 2 | Comparative example 3 | |
| Cost (Yuan/square) | 120 | 121 | 90 | 225 | 121 |
As can be seen from tables 2 and 3, under the same amount of the curing agent, the comparative example 1 has the lowest cost, but has poor strength, softening coefficient and environmental protection performance, and the removal effect of the heavy metal copper does not meet the requirement of agricultural soil pollution risk screening value in the soil environment quality agricultural soil pollution risk management and control standard (trial) (GB 15618-2018); the cost of comparative example 2 is highest, the cost of comparative example 3 is the same as that of inventive example 2, but the softening coefficient and the effect of removing heavy metal are general, so that the heavy metal curing agent prepared by the preparation methods of inventive examples 1 and 2 has better application effect and higher economical efficiency in combination.
Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.
Claims (9)
1. The heavy metal curing agent is characterized by comprising the following raw materials in parts by weight:
30-40 parts of adsorbent, 50-60 parts of gelatinizer and 0.1-10 parts of additive;
wherein the adsorbent is porous micro aggregate loaded with modified chitosan;
the gelling agent comprises the following raw materials in parts by weight: 10-20 parts of cement, 10-20 parts of mineral powder, 20-30 parts of steel slag, 20-30 parts of red mud and 20-30 parts of phosphogypsum;
the additive comprises the following raw materials in parts by weight: 40-60 parts of polyacrylamide, 10-20 parts of polymethyl siloxane and 0.1-30 parts of polyaluminium sulfate.
2. The heavy metal solidifying agent according to claim 1, wherein the preparation method of the porous micro aggregate loaded with the modified chitosan comprises the following steps:
step S1, crushing the microporous foamed concrete blocks to obtain porous micro aggregate for later use;
step S2, taking acetic acid solution as solute, dissolving chitosan into the acetic acid solution according to the proportion of 0.03-0.05 g/ml to obtain a first mixed solution, adding the porous micro aggregate of the step S1 into the first mixed solution according to the proportion of 0.03-0.08 g/ml, stirring to obtain a second mixed solution, adding glutaraldehyde into the second mixed solution in the stirring process to obtain a porous micro aggregate solution of the loaded chitosan, continuously stirring for 2 hours, filtering out the porous micro aggregate of the loaded chitosan from the porous micro aggregate solution of the loaded chitosan, and drying at 60 ℃ for later use;
and S3, mixing the chitosan-loaded porous micro aggregate obtained in the step S2 with water according to the proportion of 0.1g/ml to obtain a mixed solution III, adding maleic acid into the mixed solution III according to the proportion of 0.02-0.05 ml/ml to obtain a mixed solution IV, heating the mixed solution IV to 50 ℃, continuously stirring for 30min under the condition, adding potassium persulfate into the mixed solution IV to obtain a mixed solution V, continuously stirring for 1h, adding glutaraldehyde into the mixed solution V according to the proportion of 0.02-0.05 ml/ml to obtain a modified chitosan-loaded porous micro aggregate solution, continuously stirring for 2h, filtering the modified chitosan-loaded porous micro aggregate from the modified chitosan-loaded porous micro aggregate solution, and drying under the environment of 60 ℃ to obtain the modified chitosan-loaded porous micro aggregate.
3. The heavy metal solidifying agent according to claim 2, wherein the microporous foamed concrete block of step S1 is crushed to a particle size of 2.36mm or less, and then is elutriated in water, naturally dried, and used as a porous micro aggregate.
4. The heavy metal curing agent according to claim 2, wherein the microporous foamed concrete block is prepared by a chemical foaming method, and specifically comprises the following steps:
step a, uniformly stirring 10-20 parts of common silica cement, 30-40 parts of fly ash, 30-40 parts of steel slag micropowder and 5-10 parts of cellulose ether under the conditions of water-cement ratio of 0.6-0.8 and temperature of 40-50 ℃ to obtain mixed slurry I;
b, adding a foaming agent into the mixed slurry I in the step a, stirring uniformly to obtain mixed slurry II, quickly pouring the mixed slurry II into a mould, transferring the mould into a closed box with the temperature of 40-50 ℃ and the humidity of not less than 95%, blowing air to ensure that the pressure in the box reaches 110-130 kpa and keeps stable, and finishing the foaming process of the mixed slurry II in a positive pressure environment to obtain foamed concrete;
and c, curing the foamed concrete in the step b for 12-24 hours with a mold, removing the mold, and autoclaved curing for 4 hours at 200 ℃ to obtain the microporous foamed concrete block.
5. The heavy metal solidifying agent according to claim 4, wherein in the step b, the foaming agent is aluminum powder or hydrogen peroxide, and the concentration of the foaming agent is 0.1-0.3%.
6. The heavy metal solidifying agent according to claim 1, wherein the steel slag of the gelling agent is ground into powder with a particle size of 10-20 μm.
7. The heavy metal solidifying agent according to claim 1, wherein the particle size of the red mud is 20-50 μm and the specific surface area is 10-25 m 2 /g; the phosphogypsum is washed, dried and ground to 75-150 mu m in particle size.
8. The heavy metal solidifying agent according to claim 2, wherein in the step S2, the concentration of the acetic acid solution is 2%.
9. A method for preparing the heavy metal solidifying agent according to claims 1-8, wherein the heavy metal solidifying agent is obtained by uniformly mixing the adsorbent, the gelling agent and the additive in parts by weight.
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