CN112845563A - Modified fly ash and preparation method and application thereof - Google Patents
Modified fly ash and preparation method and application thereof Download PDFInfo
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- CN112845563A CN112845563A CN202011505245.1A CN202011505245A CN112845563A CN 112845563 A CN112845563 A CN 112845563A CN 202011505245 A CN202011505245 A CN 202011505245A CN 112845563 A CN112845563 A CN 112845563A
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- 239000010881 fly ash Substances 0.000 title claims abstract description 110
- 238000002360 preparation method Methods 0.000 title abstract description 19
- 239000002689 soil Substances 0.000 claims abstract description 45
- 229910001385 heavy metal Inorganic materials 0.000 claims abstract description 26
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 43
- 239000000243 solution Substances 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 238000000034 method Methods 0.000 claims description 22
- 239000011259 mixed solution Substances 0.000 claims description 20
- 239000012279 sodium borohydride Substances 0.000 claims description 16
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 16
- 239000000725 suspension Substances 0.000 claims description 13
- 239000007795 chemical reaction product Substances 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 11
- 229940044631 ferric chloride hexahydrate Drugs 0.000 claims description 10
- NQXWGWZJXJUMQB-UHFFFAOYSA-K iron trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].Cl[Fe+]Cl NQXWGWZJXJUMQB-UHFFFAOYSA-K 0.000 claims description 10
- 238000005067 remediation Methods 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 6
- 238000001291 vacuum drying Methods 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 22
- APAWRDGVSNYWSL-UHFFFAOYSA-N arsenic cadmium Chemical compound [As].[Cd] APAWRDGVSNYWSL-UHFFFAOYSA-N 0.000 abstract description 14
- 230000000694 effects Effects 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 5
- 230000004048 modification Effects 0.000 abstract description 4
- 238000012986 modification Methods 0.000 abstract description 4
- 230000003647 oxidation Effects 0.000 abstract description 2
- 238000007254 oxidation reaction Methods 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 25
- 239000008367 deionised water Substances 0.000 description 18
- 229910021641 deionized water Inorganic materials 0.000 description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 229910052757 nitrogen Inorganic materials 0.000 description 12
- 229910052785 arsenic Inorganic materials 0.000 description 11
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 11
- 229910052793 cadmium Inorganic materials 0.000 description 11
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 11
- 239000000203 mixture Substances 0.000 description 10
- 235000019441 ethanol Nutrition 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 238000001000 micrograph Methods 0.000 description 8
- 238000009210 therapy by ultrasound Methods 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 239000003344 environmental pollutant Substances 0.000 description 4
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 4
- 231100000719 pollutant Toxicity 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 2
- 239000011133 lead Substances 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- 244000005700 microbiome Species 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000003002 pH adjusting agent Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 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
- MKJXYGKVIBWPFZ-UHFFFAOYSA-L calcium lactate Chemical compound [Ca+2].CC(O)C([O-])=O.CC(O)C([O-])=O MKJXYGKVIBWPFZ-UHFFFAOYSA-L 0.000 description 1
- 239000001527 calcium lactate Substances 0.000 description 1
- 235000011086 calcium lactate Nutrition 0.000 description 1
- 229960002401 calcium lactate Drugs 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 231100000171 higher toxicity Toxicity 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 239000004310 lactic acid Substances 0.000 description 1
- 235000014655 lactic acid Nutrition 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000001369 metatartaric acid Substances 0.000 description 1
- 235000011042 metatartaric acid Nutrition 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000001508 potassium citrate Substances 0.000 description 1
- 229960002635 potassium citrate Drugs 0.000 description 1
- QEEAPRPFLLJWCF-UHFFFAOYSA-K potassium citrate (anhydrous) Chemical compound [K+].[K+].[K+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O QEEAPRPFLLJWCF-UHFFFAOYSA-K 0.000 description 1
- 235000011082 potassium citrates Nutrition 0.000 description 1
- 239000008213 purified water Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 239000008234 soft water Substances 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 230000004083 survival effect Effects 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention relates to the field of materials, and particularly discloses modified fly ash and a preparation method and application thereof4The solution is added to achieve a modification effect, and the modified fly ash loaded with the nano zero-valent iron is prepared, so that compared with common fly ash, the effective cadmium arsenic concentration of the soil can be obviously reduced, and the fly ash can prevent the nano zero-valent iron from agglomerating and inhibit the oxidation of the nano zero-valent iron, so that the stability of repairing the soil polluted by heavy metals is ensured, the problem that the effect of reducing the effective cadmium arsenic concentration of the soil is not obvious in the existing fly ash is solved, and the preparation method is simple and has a wide market prospect.
Description
Technical Field
The invention relates to the field of materials, in particular to modified fly ash and a preparation method and application thereof.
Background
The soil is one of basic substances for human survival and has important significance for improving the living standard. However, with the development of industrial modernization in human society, heavy metal pollution of soil caused by human factors becomes an environmental problem that cannot be ignored.
The heavy metal pollution of the soil refers to the heavy metal contained in the soil by two ways of natural source and man-made interference input, so that the heavy metal polluted soil is formed, for example, the heavy metal pollution of the soil is caused by man-made factors such as mining, waste gas emission, sewage irrigation, and the use of products with heavy metal exceeding the standard. Heavy metal pollutants in the heavy metal polluted soil mainly comprise mercury, cadmium, lead, copper, chromium, arsenic, nickel, iron, manganese, zinc and the like, and can not be decomposed by soil microorganisms, so that the heavy metal pollutants can be accumulated in a human body at a harmful concentration through a food chain, and the human health is seriously harmed. Therefore, the heavy metal content in the soil needs to be reduced through the soil remediation agent, and then the soil remediation effect is achieved.
At present, the fly ash as a kind of tiny soot particles discharged from the combustion process of fuel (mainly coal) can play a certain role in reducing heavy metals in heavy metal contaminated soil. However, the above technical solutions have the following disadvantages: when the existing fly ash is used for restoring heavy metal contaminated soil, the problem that the effect of reducing the concentration of effective cadmium and arsenic in the soil is not obvious exists.
Disclosure of Invention
The embodiment of the invention aims to provide modified fly ash to solve the problem that the existing fly ash proposed in the background art has an unobvious effect of reducing the concentration of cadmium and arsenic in the soil in an effective state.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a modified fly ash, in particular to a fly ash material loaded with nano zero-valent iron, which comprises the following raw materials: chlorination of fly ash and hexahydrateIron (FeCl)3·6H2O), ethanol, NaBH4The solution and a proper amount of water.
Another object of an embodiment of the present invention is to provide a method for preparing modified fly ash, including the following steps:
1) weighing fly ash, adding the fly ash into water, and uniformly mixing to prepare stable suspension;
2) adding ferric chloride hexahydrate into the suspension, uniformly mixing, and adjusting the pH value to 2.5-4.0 to obtain a mixed solution;
3) adding ethanol (preferably absolute ethanol) into the mixed solution, stirring and mixing uniformly, and adding NaBH4And (3) reacting the solution, washing and drying a reaction product to obtain the modified fly ash, wherein the modified fly ash is loaded with nano zero-valent iron.
As a further scheme of the invention: the preparation method of the modified fly ash further comprises the step of carrying out ultrasonic treatment on the mixed solution before adding ethanol into the mixed solution.
As a still further scheme of the invention: in the preparation method of the modified fly ash, the stirring and mixing are uniform, and the reaction process is carried out in a protective atmosphere.
Another object of the embodiment of the present invention is to provide a modified fly ash prepared by the above preparation method of modified fly ash.
The embodiment of the invention also aims to provide application of the modified fly ash in heavy metal contaminated soil remediation.
Compared with the prior art, the invention has the beneficial effects that:
the modified fly ash provided by the embodiment of the invention takes fly ash as a raw material and is prepared by ferric chloride hexahydrate, ethanol and NaBH4The solution is added to achieve the modification effect, the modified fly ash loaded with the nano zero-valent iron is prepared, compared with the common fly ash, the effective cadmium arsenic concentration of the soil can be obviously reduced, and the fly ash can prevent the nano zero-valent iron from agglomerating and inhibit the nano zero-valent iron from being oxidized, so that the heavy weight is ensuredThe stability of the metal contaminated soil remediation solves the problem that the effect of reducing the effective cadmium arsenic concentration of the soil is not obvious in the existing fly ash, and the preparation method is simple and has wide market prospect.
Drawings
Fig. 1 is a scanning electron microscope image of fly ash provided in an embodiment of the present invention.
Fig. 2 is a scanning electron microscope image of the modified fly ash prepared in accordance with an embodiment of the present invention.
Fig. 3 is an X-ray energy spectrum image of the fly ash provided by an embodiment of the invention.
Fig. 4 is an X-ray energy spectrum image of the modified fly ash provided by an embodiment of the invention.
Fig. 5 is an X-ray diffraction image of the modified fly ash provided by an embodiment of the invention.
Fig. 6 is a graph showing the results of the effective cadmium arsenic content of the modified fly ash before and after the treatment of the soil polluted by cadmium arsenic in accordance with an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
The embodiment of the invention provides modified fly ash, in particular to a fly ash material loaded with nano zero-valent iron, which comprises the following raw materials: fly ash, ferric chloride hexahydrate (FeCl)3·6H2O), ethanol, NaBH4The solution and a proper amount of water.
As another preferred embodiment of the present invention, the NaBH is4The concentration of the solution is 0.5-2.0mol/L, and specifically, a proper amount of NaBH is added4Adding into water for dissolving.
As another preferred embodiment of the present invention, the NaBH is4The concentration of the solution is0.9-1.2mol/L。
The embodiment of the invention also provides a preparation method of the modified fly ash, which comprises the following steps:
1) weighing fly ash, adding the fly ash into water, and uniformly mixing to prepare stable suspension;
2) adding ferric chloride hexahydrate into the suspension, uniformly mixing, and adjusting the pH value to 2.5-4.0 to obtain a mixed solution;
3) adding ethanol (preferably absolute ethanol) into the mixed solution, stirring and mixing uniformly, and adding NaBH4And (3) reacting the solution, washing and drying a reaction product to obtain the modified fly ash, wherein the modified fly ash is loaded with nano zero-valent iron.
As another preferred embodiment of the invention, in the preparation method of the modified fly ash, the pH is adjusted to 3.0-3.5.
As another preferred embodiment of the present invention, in the suspension, the weight ratio of the fly ash to water is 1: 10-1: 15.
in another preferred embodiment of the present invention, the concentration of ferric chloride hexahydrate in the mixed solution is 0.1 to 0.6 mol/L.
In another preferred embodiment of the present invention, the concentration of ferric chloride hexahydrate in the mixed solution is 0.2 to 0.4 mol/L.
As another preferred embodiment of the present invention, in the preparation method of the modified fly ash, the weight ratio of ethanol to water is 1: 10-2: 10.
as another preferred embodiment of the invention, in the preparation method of the modified fly ash, the NaBH is4The weight ratio of the solution to water is 1: 1-2: 1.
as another preferred embodiment of the present invention, the method for preparing the modified fly ash further comprises the step of subjecting the mixed solution to ultrasonic treatment before adding ethanol into the mixed solution, specifically, subjecting the mixed solution to ultrasonic energy to change and accelerate the treatment process for changing certain physical, chemical, biological characteristics or states of the substances, generally 10 to 15 minutes.
In another preferred embodiment of the present invention, the stirring and mixing are performed under a protective atmosphere, which may be performed by introducing nitrogen and inert gases such as argon and helium.
Preferably, after adding the ethanol, stable nitrogen is continuously introduced, and the mixture is stirred for 30 minutes by a magnetic stirrer at the speed of 600-; while adding NaBH4Before the solution, nitrogen is introduced, the rotating speed of a stirrer is adjusted to 400-4Solution, guaranteed Fe3+After the dropwise addition is finished, the rotating speed of the stirrer is adjusted to be 200-400r/mim, and the reaction is continued for 45-60min until NaBH is added4The mixture after solution turned black.
In another preferred embodiment of the present invention, in the method for preparing the modified fly ash, the water may be any one selected from purified water, mineral water, distilled water, deionized water and soft water, and is not limited thereto and may be selected as needed.
Preferably, the water is deionized water.
As another preferred embodiment of the present invention, in the preparation method of the modified fly ash, the pH adjustment is performed by adding a pH adjuster, wherein the pH adjuster may be selected from existing products such as sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium citrate, potassium citrate, calcium sulfate, calcium lactate, calcium hydroxide, potassium hydroxide, meta-tartaric acid, citric acid, lactic acid, hydrochloric acid, and the like, and is not limited herein, as long as the pH of the mixed solution can reach 2.5 to 4.0 (preferably 3.0 to 3.5) by adding a certain amount.
Preferably, the pH regulator is NaOH with the concentration of 0.1 mol/L.
As another preferred embodiment of the invention, in the preparation method of the modified fly ash, the washing is to wash the material with deionized water 3 times, and then wash with absolute ethyl alcohol to remove residual chlorine and borohydride.
As another preferred embodiment of the invention, in the preparation method of the modified fly ash, the drying is vacuum drying at 60-80 ℃ for 6-12 h.
As another preferred embodiment of the invention, the drying specifically comprises the steps of performing vacuum drying on the obtained reaction product at 60-80 ℃ for 6-12h, and grinding the dried reaction product to obtain the modified fly ash loaded with nano zero-valent iron.
Preferably, the preparation method of the modified fly ash comprises the following steps:
(1) adding deionized water into the fly ash to prepare a stable suspension (the weight ratio of the fly ash to the deionized water is 1: 10-1: 15).
(2) FeCl is added3·6H2Adding O solid into the suspension liquid in the step (1), and adjusting the pH value of the suspension liquid to 3.0-3.5 by using 0.1mol/L NaOH to obtain a mixed liquid (FeCl in the mixed liquid)3·6H2The concentration of O is 0.2-0.4 mol/L).
(3) And (3) carrying out ultrasonic treatment on the mixed solution obtained in the step (2) for 10-15 minutes, then adding absolute ethyl alcohol, continuously introducing stable nitrogen, and stirring for 30 minutes by using a magnetic stirrer at the speed of 600-.
(4) Introducing nitrogen, adjusting the rotating speed of the stirrer to 400-4Solution, guaranteed Fe3+By full reduction (NaBH)4The weight ratio of the solution to the deionized water is 1: 1-2: 1).
(5) After the dropping is finished, forming a mixture, adjusting the rotation speed of the stirrer to be 200-400r/mim, and continuing the reaction for 45-60min until the mixture turns black.
(6) Then washing the reaction product with deionized water for 3 times, and then washing with absolute ethyl alcohol to remove residual chlorine and borohydride.
(7) And (4) carrying out vacuum drying on the reaction product obtained in the step (6) at the temperature of 60-80 ℃ for 6-12h, and grinding the dried reaction product to obtain the modified fly ash loaded with the nano zero-valent iron.
The embodiment of the invention also provides the modified fly ash prepared by the preparation method of the modified fly ash.
The embodiment of the invention also provides application of the modified fly ash in heavy metal contaminated soil remediation.
As another preferred embodiment of the present invention, the heavy metal contaminated soil contains heavy metals through two ways of natural sources and man-made interference input, and the heavy metals are not decomposed by soil microorganisms, so that the heavy metals are easy to accumulate and are converted into methyl compounds with higher toxicity, and even some of the heavy metals are accumulated in a human body through a food chain at harmful concentrations, which seriously harm human health; the heavy metal pollutants in the heavy metal polluted soil mainly comprise mercury, cadmium, lead, copper, chromium, arsenic, nickel, iron, manganese, zinc and the like; the modified fly ash provided by the invention can obviously reduce heavy metal pollutants in heavy metal polluted soil, especially for cadmium arsenic polluted soil, the content of effective cadmium arsenic in the cadmium arsenic polluted soil can be obviously reduced by adding 1-3 wt% of the modified fly ash, so that the absorption of crops to cadmium arsenic can be reduced, and the soil remediation effect is achieved.
The technical effects of the modified fly ash of the present invention will be further described below by referring to specific examples.
Example 1
A preparation method of modified fly ash comprises the following steps:
(1) deionized water is added into the fly ash to prepare a stable suspension (the weight ratio of the fly ash to the deionized water is 1: 12.5).
(2) FeCl is added3·6H2Adding O solid into the suspension liquid in the step (1), and adjusting the pH value of the suspension liquid to 3.0-3.5 by using 0.1mol/L NaOH to obtain a mixed liquid (FeCl in the mixed liquid)3·6H2The O concentration was 0.3 mol/L).
(3) And (3) carrying out ultrasonic treatment on the mixed solution obtained in the step (2) for 12.5 minutes, then adding absolute ethyl alcohol, continuously introducing stable nitrogen, and stirring for 30 minutes at the speed of 800 r/min by using a magnetic stirrer (the weight ratio of the absolute ethyl alcohol to the deionized water is 1.5: 10).
(4) Introducing nitrogen, adjusting the rotating speed of a stirrer to be 500 r/mim, and slowly adding 1.05mol/L NaBH while stirring4Solution, guaranteed Fe3+By full reduction (NaBH)4The weight ratio of the solution to the deionized water is 1.5: 1).
(5) After the completion of the dropwise addition, a mixture was formed, the rotation speed of the stirrer was adjusted to 300r/mim, and the reaction was continued for 52.5min until the mixture became black.
(6) Then washing the reaction product with deionized water for 3 times, and then washing with absolute ethyl alcohol to remove residual chlorine and borohydride.
(7) And (4) carrying out vacuum drying on the reaction product obtained in the step (6) at 70 ℃ for 9h, and grinding the dried reaction product to obtain the modified fly ash loaded with the nano zero-valent iron.
Example 2
Respectively performing Scanning Electron Microscope (SEM) characterization on the conventional common fly ash and the modified fly ash prepared in example 1, wherein specific results are shown in fig. 1 and 2; wherein, FIG. 1 is a scanning electron microscope image of fly ash, in FIG. 1, a is a scanning electron microscope image of fly ash with a scale of 50 μm, b is a scanning electron microscope image of fly ash with a scale of 10 μm; FIG. 2 is a scanning electron microscope image of the modified fly ash, in FIG. 2, a is a scanning electron microscope image of the modified fly ash with a scale of 50 μm, and b is a scanning electron microscope image of the modified fly ash with a scale of 20 μm. It can be seen that in the modified fly ash prepared in example 1, nano zero-valent iron was successfully loaded on the surface of the fly ash.
Example 3
Respectively performing X-ray energy spectrum (EDS) characterization on the conventional common fly ash and the modified fly ash prepared in example 1, wherein specific results are shown in FIGS. 3 and 4; wherein, FIG. 3 is an X-ray energy spectrum image of fly ash; fig. 4 is an X-ray energy spectrum image of the modified fly ash. As can be seen by combining the figure 1 and the figure 2, the fly ash can prevent the agglomeration of the nano zero-valent iron and is successfully loaded on the surface of the fly ash.
Example 4
Respectively carrying out X-ray diffraction (XRD) characterization on the existing common fly ash and the modified fly ash prepared in the example 1, wherein the specific result is shown in an X-ray diffraction image shown in figure 5; wherein 44.7 degrees is a characteristic diffraction peak of the nano zero-valent iron, the characteristic peak of the nano zero-valent iron is obvious, and the fly ash inhibits the oxidation of the nano zero-valent iron.
Example 5
The method comprises the following steps of respectively carrying out cadmium-arsenic polluted soil remediation effect detection on the existing common fly ash and the modified fly ash prepared in the embodiment 1:
(1) in the cadmium-arsenic contaminated soil, 1wt% -3wt% of modified fly ash is added according to the soil contamination concentration for treatment (in the embodiment, the soil cadmium concentration is 0.55mg/kg, the arsenic concentration is 139.45mg/kg, and 1wt% of modified fly ash of the soil weight is added);
(2) adding water to the treated soil to submerge the soil;
(3) and (4) measuring the content of available cadmium and arsenic in the soil.
In this example, the soil cadmium concentration is 0.55mg/kg, the arsenic concentration is 139.45mg/kg, 1wt% of modified fly ash based on the soil weight is added, and the results of measuring the effective cadmium arsenic content before and after the treatment of the cadmium arsenic contaminated soil are shown in fig. 6. The modified fly ash can obviously reduce the concentration of the cadmium and arsenic in the soil in the effective state, the cadmium in the effective state is reduced by 48.39%, and the arsenic in the effective state is reduced by 46.20%, so that the cadmium and arsenic in the soil can be obviously reduced by the modified fly ash, and the absorption of crops to the cadmium and arsenic can be reduced.
Example 6
The procedure was as in example 1 except that the pH was adjusted to 3.0 as compared with example 1.
Example 7
The procedure was as in example 1 except that the pH was adjusted to 3.5 as compared with example 1.
Example 8
The procedure was as in example 1 except that the pH was adjusted to 2.5 as compared with example 1.
Example 9
The procedure was as in example 1 except that the pH was adjusted to 4.0 as compared with example 1.
Example 10
Compared with example 1, except that NaBH4The solution was the same as in example 1 except that the concentration of the solution was 0.5 mol/L.
Example 11
Compared with example 1, except that NaBH4The solution was the same as in example 1 except that the concentration of the solution was 2.0 mol/L.
Example 12
Compared with example 1, except that NaBH4The solution was the same as in example 1 except that the concentration of the solution was 0.9 mol/L.
Example 13
Compared with example 1, except that NaBH4The solution was the same as in example 1 except that the concentration of the solution was 1.2 mol/L.
Example 14
Compared to example 1, except that the weight ratio of fly ash to deionized water was 1: 10, the weight ratio of the absolute ethyl alcohol to the deionized water is 1: 10, NaBH4The weight ratio of the solution to the deionized water is 1: 1, and in the mixed solution, FeCl3·6H2The procedure of example 1 was repeated except that the O concentration was 0.1 mol/L.
Example 15
Compared to example 1, except that the weight ratio of fly ash to deionized water was 1: 15, the weight ratio of the absolute ethyl alcohol to the deionized water is 2: 10, NaBH4The weight ratio of the solution to the deionized water is 2: 1, and in the mixed solution, FeCl3·6H2The procedure of example 1 was repeated except that the O concentration was 0.6 mol/L.
Example 16
Compared to example 1 except that in the mixed liquor, FeCl3·6H2The procedure of example 1 was repeated except that the O concentration was 0.2 mol/L.
Example 17
Compared to example 1 except that in the mixed liquor, FeCl3·6H2The procedure of example 1 was repeated except that the O concentration was 0.4 mol/L.
Example 18
The same as example 1 except that the ultrasonic treatment time was 10 minutes as compared with example 1.
Example 19
The same as example 1 except that the ultrasonic treatment time was 15 minutes as compared with example 1.
Example 20
The same as example 1 except that the nitrogen gas was replaced with argon gas as compared with example 1.
Example 21
The same as example 1 except that helium was used instead of nitrogen, as compared with example 1.
Example 22
Compared with the example 1, except that after the absolute ethyl alcohol is added, stable nitrogen is continuously introduced, and the mixture is stirred for 30 minutes at 600 r/min by a magnetic stirrer; while adding NaBH4Before the solution, nitrogen is introduced, the rotating speed of a stirrer is adjusted to 400r/mim, and NaBH is slowly added while stirring4After the solution is added, the rotating speed of a stirrer is adjusted to be 200r/mim, and the reaction is continued for 45min until NaBH is added4The mixture after the solution was blackened, and the other steps were the same as in example 1.
Example 23
Compared with the example 1, except that after the absolute ethyl alcohol is added, stable nitrogen is continuously introduced, and the mixture is stirred for 30 minutes at 1000 r/min by a magnetic stirrer; while adding NaBH4Before the solution, nitrogen is introduced, the rotating speed of a stirrer is adjusted to 600 r/mim, and NaBH is slowly added while stirring4After the solution is added, the rotating speed of a stirrer is adjusted to 400r/mim, and the reaction is continued for 60min until NaBH is added4The mixture after the solution was blackened, and the other steps were the same as in example 1.
While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (10)
1. Modified fly ashThe modified fly ash is characterized by comprising the following raw materials: fly ash, ferric chloride hexahydrate, ethanol and NaBH4The solution and a proper amount of water.
2. The modified fly ash of claim 1, wherein the NaBH is4The concentration of the solution is 0.5-2.0 mol/L.
3. A method of preparing a modified fly ash as claimed in any one of claims 1 to 2, comprising the steps of:
1) adding the fly ash into water, and uniformly mixing to prepare a suspension;
2) adding ferric chloride hexahydrate into the suspension, uniformly mixing, and adjusting the pH value to 2.5-4.0 to obtain a mixed solution;
3) adding ethanol into the mixed solution, stirring and mixing uniformly, and adding NaBH4And (3) reacting the solution, and washing and drying a reaction product to obtain the modified fly ash.
4. The method for preparing modified fly ash according to claim 3, wherein the pH is adjusted to 3.0-3.5 in the method for preparing modified fly ash.
5. The method according to claim 3, wherein the concentration of ferric chloride hexahydrate in the mixed solution is 0.1 to 0.6 mol/L.
6. The method according to claim 3, wherein the concentration of ferric chloride hexahydrate in the mixed solution is 0.2-0.4 mol/L.
7. The method for preparing modified fly ash according to claim 3, wherein the stirring process and the reaction process are performed under a protective atmosphere.
8. The method for preparing modified fly ash according to claim 3, wherein the drying is vacuum drying at 60-80 ℃ for 6-12 h.
9. A modified fly ash prepared by the method for preparing modified fly ash according to claim 3, 4, 5, 6, 7 or 8.
10. Use of the modified fly ash of claim 1 or 2 or 9 for remediation of heavy metal contaminated soil.
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