CN113828630A - Restoration method of hexavalent chromium contaminated soil - Google Patents
Restoration method of hexavalent chromium contaminated soil Download PDFInfo
- Publication number
- CN113828630A CN113828630A CN202111214328.XA CN202111214328A CN113828630A CN 113828630 A CN113828630 A CN 113828630A CN 202111214328 A CN202111214328 A CN 202111214328A CN 113828630 A CN113828630 A CN 113828630A
- Authority
- CN
- China
- Prior art keywords
- soil
- hexavalent chromium
- chromium
- soaking
- alkali
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000002689 soil Substances 0.000 title claims abstract description 114
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 title claims abstract description 84
- 238000000034 method Methods 0.000 title claims abstract description 71
- 239000003513 alkali Substances 0.000 claims abstract description 64
- 238000002791 soaking Methods 0.000 claims abstract description 48
- 239000011651 chromium Substances 0.000 claims abstract description 34
- 230000001603 reducing effect Effects 0.000 claims abstract description 32
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 28
- 238000006722 reduction reaction Methods 0.000 claims abstract description 19
- 230000009467 reduction Effects 0.000 claims abstract description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 42
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 24
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 16
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 13
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 12
- 239000008103 glucose Substances 0.000 claims description 12
- OWEGMIWEEQEYGQ-UHFFFAOYSA-N 100676-05-9 Natural products OC1C(O)C(O)C(CO)OC1OCC1C(O)C(O)C(O)C(OC2C(OC(O)C(O)C2O)CO)O1 OWEGMIWEEQEYGQ-UHFFFAOYSA-N 0.000 claims description 4
- 229930091371 Fructose Natural products 0.000 claims description 4
- RFSUNEUAIZKAJO-ARQDHWQXSA-N Fructose Chemical compound OC[C@H]1O[C@](O)(CO)[C@@H](O)[C@@H]1O RFSUNEUAIZKAJO-ARQDHWQXSA-N 0.000 claims description 4
- 239000005715 Fructose Substances 0.000 claims description 4
- GUBGYTABKSRVRQ-QKKXKWKRSA-N Lactose Natural products OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)C(O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O GUBGYTABKSRVRQ-QKKXKWKRSA-N 0.000 claims description 4
- GUBGYTABKSRVRQ-PICCSMPSSA-N Maltose Natural products O[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@@H]1[C@@H](CO)OC(O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-PICCSMPSSA-N 0.000 claims description 4
- 125000003172 aldehyde group Chemical group 0.000 claims description 4
- 229930182830 galactose Natural products 0.000 claims description 4
- 125000000468 ketone group Chemical group 0.000 claims description 4
- 239000008101 lactose Substances 0.000 claims description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 4
- GUBGYTABKSRVRQ-XLOQQCSPSA-N Alpha-Lactose Chemical compound O[C@@H]1[C@@H](O)[C@@H](O)[C@@H](CO)O[C@H]1O[C@@H]1[C@@H](CO)O[C@H](O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-XLOQQCSPSA-N 0.000 claims description 3
- WQZGKKKJIJFFOK-PHYPRBDBSA-N alpha-D-galactose Chemical compound OC[C@H]1O[C@H](O)[C@H](O)[C@@H](O)[C@H]1O WQZGKKKJIJFFOK-PHYPRBDBSA-N 0.000 claims description 3
- 239000002585 base Substances 0.000 claims description 3
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 3
- GUBGYTABKSRVRQ-QUYVBRFLSA-N beta-maltose Chemical compound OC[C@H]1O[C@H](O[C@H]2[C@H](O)[C@@H](O)[C@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@@H]1O GUBGYTABKSRVRQ-QUYVBRFLSA-N 0.000 claims description 3
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 2
- 239000003638 chemical reducing agent Substances 0.000 abstract description 20
- 238000001514 detection method Methods 0.000 abstract description 7
- 230000001988 toxicity Effects 0.000 abstract description 5
- 231100000419 toxicity Toxicity 0.000 abstract description 5
- 238000004162 soil erosion Methods 0.000 abstract description 4
- 238000010438 heat treatment Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 238000005067 remediation Methods 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 12
- 239000000243 solution Substances 0.000 description 12
- 230000007797 corrosion Effects 0.000 description 10
- 238000005260 corrosion Methods 0.000 description 10
- 239000002253 acid Substances 0.000 description 9
- RGHNJXZEOKUKBD-SQOUGZDYSA-M D-gluconate Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C([O-])=O RGHNJXZEOKUKBD-SQOUGZDYSA-M 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 229940050410 gluconate Drugs 0.000 description 8
- 229910052979 sodium sulfide Inorganic materials 0.000 description 7
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 7
- 230000008439 repair process Effects 0.000 description 6
- 238000004140 cleaning Methods 0.000 description 5
- 239000011247 coating layer Substances 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000004576 sand Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 244000005700 microbiome Species 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 230000036632 reaction speed Effects 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 239000002455 scale inhibitor Substances 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000011066 ex-situ storage Methods 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 238000005882 aldol condensation reaction Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 230000000711 cancerogenic effect Effects 0.000 description 2
- 231100000357 carcinogen Toxicity 0.000 description 2
- 239000003183 carcinogenic agent Substances 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 2
- 239000000084 colloidal system Substances 0.000 description 2
- 230000000536 complexating effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- -1 iron ions Chemical class 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011978 dissolution method Methods 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000002351 wastewater 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
Abstract
The invention relates to a restoration method of hexavalent chromium polluted soil, belonging to the technical field of chromium pollution restoration. The invention discloses a restoration method of hexavalent chromium contaminated soil, which comprises the steps of soaking chromium contaminated soil to be restored in alkali liquor, adding reducing sugar to carry out reduction reaction, and reducing hexavalent chromium in the soil into trivalent chromium, thereby reducing the toxicity of the soil. The restoration method of the invention improves the reduction efficiency of hexavalent chromium in an insoluble state through alkali soaking and heating reduction under an alkaline condition, and simultaneously avoids the problems of soil erosion, secondary pollution of residual reducing agent to soil and interference of soil hexavalent chromium detection.
Description
Technical Field
The invention belongs to the technical field of chromium pollution remediation, and relates to a remediation method of hexavalent chromium polluted soil.
Background
In natural environment, chromium is trivalent chromium (Cr)3+) Is present in the form of hexavalent chromium [ Cr (VI) ]which is not a carcinogen]From human industrial activity, with CrO4 2-The acid radical exists in the form of a carcinogen, the toxicity of the acid radical is nearly thousand times that of trivalent chromium. Therefore, the most commonly adopted technical route for remediation of chromium-contaminated soil is to reduce hexavalent chromium in the soil to trivalent chromium to reduce the toxicity of the contaminated soil.
The remediation method can be divided into in-situ remediation (without excavation) and ex-situ remediation (excavation) according to whether the contaminated soil is excavated in the remediation process. In the ex-situ remediation method, the chromium-polluted soil is conveyed to special equipment to be remedied according to a certain process flow. The existing ex-situ remediation method can be divided into a dry method (reducing hexavalent chromium into trivalent chromium by calcining in a special rotary kiln by taking coal powder as a reducing agent) and a wet method. The wet method is to mix the soil polluted by chromium into a solution containing a reducing agent, dissolve hexavalent chromium from the soil and then enter the solution containing the reducing agent, and carry out reduction reaction on the hexavalent chromium and the reducing agent to reduce the hexavalent chromium into trivalent chromium by the reducing agent.
The remediation effect of the wet method (not referring to the removal percentage, but referring to the residual hexavalent chromium content in the soil after remediation being a requirement to meet the remediation target value) is limited by the solubility of hexavalent chromium in the soil. The existing form of hexavalent chromium in soil can be divided into a soluble state and an insoluble state from the dissolution angle: the easily soluble hexavalent chromium is easy to be leached out, so the hexavalent chromium is usually leached out by a leaching process and then is independently reduced; the existing forms of the insoluble hexavalent chromium in the soil can be further divided into an adsorption state, a coating state and an insoluble chromate (such as PbCrO)4And BaCrO4) The surface of the soil particles can be contacted with a reducing agent in the solution in an adsorption state and can be easily reduced, and the coated hexavalent chromium is coated by various soil minerals, cannot be contacted with the reducing agent in the solution and cannot be reduced, so that the coating layer needs to be firstly damaged to expose the hexavalent chromium in the solution to treat the coated hexavalent chromium. The current method for destroying the coating layer adopts an acid dissolution method, and has the advantages of short reaction time and high efficiency, and the defects of serious soil erosion and even secondary environment problem caused by dissolution of other heavy metals if the pH value of the acid is too low. Therefore, the pH is usually controlled to 5 or more (pH) in engineering<5, carbonate in the soil is almost completely dissolved, the proportion of carbonate in the soil is usually more than 20%), but under the condition that the pH is more than 5, chromium pollutes some coating layers and insoluble chromate (PbCrO) in the soil4And BaCrO4) Can not be well dissolved, thereby influencing the restoration effect of the hexavalent chromium soil.
Another method for destroying the coating layer is to soak in strong alkaline solution to destroy the crystal lattice structure of the coating layer mineral to a certain extent to make it relatively loose, so that the coated hexavalent chromium can contact with the solution, which has the advantages of not causing soil erosion and being capable of dissolving PbCrO when the pH is more than 124And BaCrO4Dissolving; the main disadvantages are: firstly, the time consumption is long, the time efficiency is low, and secondly, the pH value of the soil needs to be adjusted back in the subsequent hexavalent chromium reduction stageOtherwise, the reducing agents used in the existing chromium pollution remediation cannot be used, so that the consumption of acid in the treatment process is increased, and high-salt wastewater with very high treatment cost is generated, so that the remediation cost is greatly increased. In addition, some soil minerals that were not dissolved in acid without alkaline leaching also dissolve in acid due to the destruction of the crystal lattice, resulting in soil erosion. If sodium sulfide is used as a reducing agent without lowering the pH, high concentrations of sodium sulfide are required (when other strong bases are present, the reaction of sodium sulfide with hexavalent chromium is inhibited, and the concentration of sodium sulfide needs to be increased), which results in a severe excess of sodium sulfide being applied and secondary pollution. In addition, the excess sodium sulfide reduces iron in the soil, and the produced black FeS is retained in the soil and cannot be washed out. Elemental sulfur is the main oxidized product of sodium sulfide, and because it is insoluble in water, it can also be retained in soil, and these retained substances can cause serious secondary pollution and release odor. In addition, FeS and elemental sulfur can also seriously interfere the detection of soil hexavalent chromium, so that a qualified soil hexavalent chromium content detection result cannot be obtained. Due to the above disadvantages, the alkali soaking and the reduction process under the alkaline condition have not been studied and reported so far.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a method for remediating hexavalent chromium-contaminated soil.
In order to achieve the purpose, the invention provides the following technical scheme:
1. a method for remediating hexavalent chromium-contaminated soil, the method comprising the steps of:
(1) alkali soaking: adding the chromium-contaminated soil to be repaired into alkali liquor containing soluble carbonate, and soaking for not less than 1-12 h at the temperature of not more than 100 ℃;
(2) and (3) hexavalent chromium reduction: adding reducing sugar containing aldehyde group or ketone group into the mixed solution after soaking in the step (1), carrying out reduction reaction to reduce hexavalent chromium into trivalent chromium, and dehydrating to obtain the repaired soil.
Preferably, the concentration of the soluble carbonate in the alkali liquor containing the soluble carbonate in the step (1) is 0.02-3 mol/L, the concentration of the alkali is 0.05-2 mol/L, and the pH value of the alkali liquor is more than or equal to 10.
More preferably, the soluble carbonate is Na2CO3Or K2CO3At least one of (1).
Further preferably, the base is at least one of NaOH or KOH.
Preferably, the reducing sugar in step (2) is any one or more of glucose, fructose, galactose, lactose and maltose.
Further preferably, the mass ratio of the reducing sugar to the hexavalent chromium in the soil polluted by the chromium to be repaired in the step (2) is not less than 11: 1.
Preferably, the conditions of the reduction reaction in step (2) are: carrying out reduction reaction at the temperature of 30-100 ℃ for more than 0.5 min.
The invention has the beneficial effects that: the invention discloses a restoration method of hexavalent chromium contaminated soil, which comprises the steps of soaking chromium contaminated soil to be restored in alkali liquor, adding reducing sugar (comprising any one or more of glucose, fructose, galactose, lactose or maltose) for reduction reaction, and reducing hexavalent chromium in the soil into trivalent chromium, thereby reducing the toxicity of the soil. The invention has the following advantages:
(1) the corrosion phenomenon does not exist: because the repair method of the invention adopts the alkali liquor for soaking, the corrosion phenomenon existing in the acid-soluble treatment method does not exist;
(2) the restoration method of the invention carries out reduction reaction under alkaline condition, thus avoiding a series of problems caused by the need of adjusting pH value downwards in the chromium pollution treatment process;
(3) the restoration method adopts reducing sugar as a reducing agent, wherein reducing sugar molecules contain free aldehyde groups or ketone groups and have reducing property, and hexavalent chromium can be reduced into trivalent chromium by the reducing sugar under the catalysis of alkali;
(4) the reducing sugar and the oxidation product thereof used in the invention are harmless to human body and environment, and can be utilized by soil microorganisms in natural environment to promote the recovery of soil microorganism population;
(5) when the reducibility is used as a reducing agent, the oxidation product of the gluconate is an excellent scale inhibitor and corrosion inhibitor, for example, gluconate has strong complexing ability to calcium, magnesium and iron ions, and the gluconate is an excellent scale inhibitor, so that the problem of pipeline blockage in repair engineering can be remarkably reduced, in addition, the corrosion inhibition ability of the gluconate is enhanced along with the rise of temperature, and the corrosion to equipment and pipelines in the repair process can be further reduced;
(6) when reducing sugar is used as a reducing agent, the detection of hexavalent chromium in soil cannot be interfered, and the main reasons are as follows: firstly, because the sugar acid salt is soluble in water, it can be eliminated by washing with water before detection; secondly, after the hexavalent chromium is reduced, the residual reducing sugar is easily oxidized by dissolved oxygen or loses activity through aldol condensation reaction under the conditions of high temperature and strong alkali; experiments show that the standard recovery rate of hexavalent chromium can be very easily kept above 90% (standard requirement is more than 70%) by using reducing sugar as a reducing agent;
(7) the components of the alkali liquor for soaking in the repairing method do not participate in redox reaction, so that the consumption in the whole repairing process is limited, the alkali liquor can be directly recycled for supplementing new alkali liquor after being cleaned after being treated, the polluted soil is dry soil when being excavated in the whole repairing process, the water content is usually only a few percent, and the water content is usually between 20 and 40 percent after the whole repairing process and dehydration, so that the alkali soaking liquor is lost and must be supplemented in time;
(8) when the hexavalent chromium is soaked by the normal-temperature alkali, the hexavalent chromium is not expected to be reduced because of Cr (OH) generated by the reaction at the normal temperature3Most of the hexavalent chromium is in a colloid form, has relatively strong adsorbability, can be coated on the surface or in cracks of soil particles to prevent part of hexavalent chromium from contacting a reducing agent in the subsequent reduction stage, and is Cr (OH) at high temperature3The glucose is rapidly aged and crystallized, the adsorption coating effect is greatly reduced, the reaction speed of the glucose and the hexavalent chromium is extremely slow at normal temperature, and an obvious reaction phenomenon can be observed only when the temperature is heated to 40-50 ℃; when the temperature is heated to be close to 100 DEG CThe reaction speed is accelerated and can be finished within 1min, so that when the water in the last cleaning link is reused for preparing the front-end alkaline soak solution, the influence of residual glucose is not necessary to worry.
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. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a flow chart of a remediation process for hexavalent chromium-contaminated soil by the remediation method used in example 1;
FIG. 2 is a flow chart of the remediation process of the hexavalent chromium-contaminated soil remediation method employed in example 3.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Example 1
The method is characterized in that the polluted soil of the chromium slag yard (the soil is from the polluted soil of a certain chromium slag yard, the hexavalent chromium content of the polluted soil is 630mg/kg, the water content of the polluted soil is 4.1%) is repaired, the process flow in the repairing process is shown in figure 1, and the specific repairing method comprises the following steps:
(1) preparing alkali liquor containing soluble carbonate: adding sodium carbonate and sodium hydroxide into water to form alkali liquor containing 0.3mol/L of sodium carbonate and 0.5mol/L of sodium hydroxide, and respectively storing the alkali liquor in a normal-temperature alkali liquor tank and a high-temperature alkali liquor tank (the high-temperature alkali liquor tank is provided with a heating device);
(2) soaking the polluted soil in a soaking alkali liquor tank containing the alkali liquor in the step (1) for 5 days, and performing solid-liquid separation by using a dehydrator to obtain the alkali liquor (returned to the soaking alkali liquor tank for soaking of the next batch of soil to be repaired) and the dehydrated soil I;
(3) the soil I dehydrated in the step (2) enters a high-temperature alkali soaking reactor, is soaked for 1h at the temperature of 90 ℃, glucose is added according to the mass ratio of 20:1 (glucose: hexavalent chromium) after the high-temperature alkali soaking is finished, the reaction is carried out for 2min, the hexavalent chromium in the soil is reduced into trivalent chromium, and the dehydrated soil II is obtained after the reaction is finished;
(4) the dehydrated soil II enters a cleaning pool, is cleaned by clear water, and is dehydrated again after the pH value of the soil is reduced to be below 9 to obtain cleaning liquid (one part of the cleaning liquid is conveyed to an alkali liquid tank to be used for preparing alkali liquid lost in the step of alkali supplement soaking) and dehydrated soil III;
(5) and stacking and airing the dehydrated soil III to obtain repaired soil, and backfilling after the repaired soil is detected to be qualified.
And (3) detecting hexavalent chromium in the soil of the batch of soil after the soil is repaired by the process, wherein the content of the hexavalent chromium is 12 mg/kg.
Example 2
The operation flow of the embodiment is the same as that of the embodiment 1 except that the time of the normal temperature alkali soaking and the time of the high temperature alkali soaking are different:
(1) the time of the alkali soaking at the normal temperature is 20 days,
(2) the high temperature alkaline soaking time is 5 min.
And (3) detecting hexavalent chromium in the soil of the batch of soil repaired by the process, wherein the content of the hexavalent chromium is 9 mg/kg.
Example 3
For the polluted soil (hexavalent chromium from an industrial pollution site) of a chromium slag storage yardThe content is 1250mg/kg, and the formula amount is only 98m3) Repairing, wherein the technological process in the repairing process is shown in figure 2, and the specific repairing method comprises the following steps:
(1) preparing alkali liquor containing soluble carbonate: adding sodium carbonate and sodium hydroxide into water to form an alkali liquor containing 1.0mol/L of sodium carbonate and 1.0mol/L of sodium hydroxide;
(2) soaking 1000kg of chromium-contaminated soil to be repaired in a soaking tank containing 1000L of high-temperature alkali liquor with the temperature of 90 ℃ in the step (1) for 3 hours;
(3) and after soaking, adding 27.5kg of glucose into the soaking tank, stirring at 50 ℃ for reaction for 10min, naturally cooling, and dehydrating in a sand filter to obtain the repaired soil.
And (3) detecting hexavalent chromium in the soil of the batch of soil after the soil is repaired by the process, wherein the content of the hexavalent chromium is 22 mg/kg.
Example 4
For the polluted soil (from an industrial pollution site, the hexavalent chromium content is 1250mg/kg, and the amount of the hexavalent chromium is only 98 m)3) Repairing, wherein the specific repairing method comprises the following steps:
(1) preparing alkali liquor containing soluble carbonate: adding sodium carbonate and sodium hydroxide into water to form an alkali liquor containing 3.0mol/L of sodium carbonate and 2.0mol/L of sodium hydroxide;
(2) soaking 1000kg of chromium-contaminated soil to be repaired in a soaking tank containing 1000L of high-temperature alkali liquor with the temperature of 100 ℃ in the step (1) for 1 h;
(3) and after soaking, adding 15.2kg of fructose into the soaking tank, stirring at 30 ℃ for reaction for 80min, naturally cooling, and dehydrating in a sand filter to obtain the repaired soil.
And (3) detecting hexavalent chromium in the soil of the batch of soil after the soil is repaired by the process, wherein the content of the hexavalent chromium is 26 mg/kg.
Example 5
For the polluted soil (from an industrial pollution site, the hexavalent chromium content is 1250mg/kg, and the amount of the hexavalent chromium is only 98 m)3) Repairing, wherein the specific repairing method comprises the following steps:
(1) preparing alkali liquor containing soluble carbonate: adding potassium carbonate and sodium hydroxide into water to form an alkali solution containing 1.0mol/L of sodium carbonate and 1.0mol/L of sodium hydroxide;
(2) soaking 1000kg of chromium-contaminated soil to be repaired in a soaking tank containing 1000L of high-temperature alkali liquor with the temperature of 50 ℃ in the step (1) for 3 hours;
(3) and after soaking, adding 25kg of lactose into the soaking tank, stirring at 100 ℃ for reaction for 0.5min, naturally cooling, and dehydrating in a sand filter to obtain the repaired soil.
And (3) detecting hexavalent chromium in the soil of the batch of soil repaired by the process, wherein the content of the hexavalent chromium is 47 mg/kg.
Example 6
For the polluted soil (from an industrial pollution site, the hexavalent chromium content is 1250mg/kg, and the amount of the hexavalent chromium is only 98 m)3) Repairing, wherein the specific repairing method comprises the following steps:
(1) preparing alkali liquor containing soluble carbonate: adding sodium carbonate and sodium hydroxide into water to form an alkali liquor containing 3.0mol/L of sodium carbonate and 2.0mol/L of sodium hydroxide;
(2) soaking 1000kg of chromium-contaminated soil to be repaired in a soaking tank containing 1000L of high-temperature alkali liquor with the temperature of 100 ℃ in the step (1) for 1 h;
(3) and after soaking, adding 15.2kg of galactose into the soaking tank, stirring at 30 ℃ for reaction for 30min, naturally cooling, and dehydrating in a sand filter to obtain the repaired soil.
And (3) detecting hexavalent chromium in the soil of the batch of soil repaired by the process, wherein the content of the hexavalent chromium is 38 mg/kg.
Example 7
For the polluted soil (from an industrial pollution site, the hexavalent chromium content is 1250mg/kg, and the amount of the hexavalent chromium is only 98 m)3) Repairing, wherein the specific repairing method comprises the following steps:
(1) preparing alkali liquor containing soluble carbonate: adding sodium carbonate and sodium hydroxide into water to form an alkali liquor containing 1.0mol/L of sodium carbonate and 1.0mol/L of sodium hydroxide;
(2) soaking 1000kg of chromium-contaminated soil to be repaired in a soaking tank containing 1000L of high-temperature alkali liquor with the temperature of 90 ℃ in the step (1) for 3 hours;
(3) and after soaking, adding 13.75kg of maltose into the soaking tank, stirring for reaction for 10min, naturally cooling, and dehydrating in a sand filter to obtain the repaired soil.
And (3) detecting hexavalent chromium in the soil of the batch of soil repaired by the process, wherein the content of the hexavalent chromium is 48 mg/kg.
In summary, the invention discloses a restoration method of hexavalent chromium contaminated soil, which comprises the steps of soaking chromium contaminated soil to be restored in alkali liquor, adding reducing sugar to carry out reduction reaction, and reducing hexavalent chromium in the soil into trivalent chromium, thereby reducing the toxicity of the soil. The invention has the following advantages:
(1) the corrosion phenomenon does not exist: because the repair method of the invention adopts the alkali liquor for soaking, the corrosion phenomenon existing in the acid-soluble treatment method does not exist;
(2) the restoration method of the invention carries out reduction reaction under alkaline condition, thus avoiding a series of problems caused by the need of adjusting pH value downwards in the chromium pollution treatment process;
(3) the restoration method adopts reducing sugar as a reducing agent, wherein reducing sugar molecules contain free aldehyde groups or ketone groups and have reducing property, and hexavalent chromium can be reduced into trivalent chromium by the reducing sugar under the catalysis of alkali;
(4) the reducing sugar and the oxidation product thereof used in the invention are harmless to human body and environment, and can be utilized by soil microorganisms in natural environment to promote the recovery of soil microorganism population;
(5) when the reducibility is used as a reducing agent, the oxidation product of the gluconate is an excellent scale inhibitor and corrosion inhibitor, for example, gluconate has strong complexing ability to calcium, magnesium and iron ions, and the gluconate is an excellent scale inhibitor, so that the problem of pipeline blockage in repair engineering can be remarkably reduced, in addition, the corrosion inhibition ability of the gluconate is enhanced along with the rise of temperature, and the corrosion to equipment and pipelines in the repair process can be further reduced;
(6) when reducing sugar is used as a reducing agent, the detection of hexavalent chromium in soil cannot be interfered, and the main reasons are as follows: firstly, because the sugar acid salt is soluble in water, it can be eliminated by washing with water before detection; secondly, after the hexavalent chromium is reduced, the residual reducing sugar is easily oxidized by dissolved oxygen or loses activity through aldol condensation reaction under the conditions of high temperature and strong alkali; experiments show that the standard recovery rate of hexavalent chromium can be very easily kept above 90% (standard requirement is more than 70%) by using reducing sugar as a reducing agent;
(7) the components of the alkali liquor for soaking in the repairing method do not participate in redox reaction, so that the consumption in the whole repairing process is limited, the alkali liquor can be directly recycled for supplementing new alkali liquor after being cleaned after being treated, the polluted soil is dry soil when being excavated in the whole repairing process, the water content is usually only a few percent, and the water content is usually between 20 and 40 percent after the whole repairing process and dehydration, so that the alkali soaking liquor is lost and must be supplemented in time;
(8) when the hexavalent chromium is soaked by the normal-temperature alkali, the hexavalent chromium is not expected to be reduced because of Cr (OH) generated by the reaction at the normal temperature3Most of the hexavalent chromium is in a colloid form, has relatively strong adsorbability, can be coated on the surface or in cracks of soil particles to prevent part of hexavalent chromium from contacting a reducing agent in the subsequent reduction stage, and is Cr (OH) at high temperature3The glucose is rapidly aged and crystallized, the adsorption coating effect is greatly reduced, the reaction speed of the glucose and the hexavalent chromium is extremely slow at normal temperature, and an obvious reaction phenomenon can be observed only when the temperature is heated to 40-50 ℃; when the temperature is heated to be close to 100 ℃, the reaction speed is accelerated and can be finished within 1min, so that when the water in the last cleaning link is reused for preparing the front-end alkaline soak solution, the influence of residual glucose does not need to be worried about.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (7)
1. A restoration method of hexavalent chromium contaminated soil is characterized by comprising the following steps:
(1) alkali soaking: adding the chromium-contaminated soil to be repaired into alkali liquor containing soluble carbonate, and soaking for not less than 1h at the temperature of not more than 100 ℃;
(2) and (3) hexavalent chromium reduction: adding reducing sugar containing aldehyde group or ketone group into the mixed solution after soaking in the step (1), carrying out reduction reaction to reduce hexavalent chromium into trivalent chromium, and dehydrating to obtain the repaired soil.
2. The method according to claim 1, wherein the alkali liquor containing the soluble carbonate in the step (1) has a concentration of 0.02-3 mol/L of the soluble carbonate, a concentration of 0.05-2 mol/L of alkali, and a pH value of the alkali liquor is not less than 10.
3. The method of claim 2, wherein the soluble carbonate is Na2CO3Or K2CO3At least one of (1).
4. The method of claim 2, wherein the base is at least one of NaOH or KOH.
5. The method according to claim 1, wherein the reducing sugar in step (2) is any one or more of glucose, fructose, galactose, lactose and maltose.
6. The method according to claim 5, wherein the mass ratio of the reducing sugar to hexavalent chromium in the chromium-contaminated soil to be remediated in step (2) is not less than 11: 1.
7. The method according to claim 1, wherein the reduction reaction in step (2) is carried out under the following conditions: carrying out reduction reaction at the temperature of 30-100 ℃ for more than 0.5 min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111214328.XA CN113828630B (en) | 2021-10-19 | 2021-10-19 | Restoration method of hexavalent chromium contaminated soil |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111214328.XA CN113828630B (en) | 2021-10-19 | 2021-10-19 | Restoration method of hexavalent chromium contaminated soil |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113828630A true CN113828630A (en) | 2021-12-24 |
| CN113828630B CN113828630B (en) | 2022-09-09 |
Family
ID=78965396
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111214328.XA Active CN113828630B (en) | 2021-10-19 | 2021-10-19 | Restoration method of hexavalent chromium contaminated soil |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113828630B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116086931A (en) * | 2022-12-12 | 2023-05-09 | 浙江大学 | Soil hexavalent chromium determination method for eliminating interference of chalcogenide reducing agent |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6221002B1 (en) * | 1997-06-26 | 2001-04-24 | Chemical Land Holdings, Inc. | Method to reduce hexavalent chromium in soils, sediments, industrial wastes and other contaminated materials using ascorbic acid |
| WO2003022744A2 (en) * | 2001-09-06 | 2003-03-20 | Gannett Fleming, Inc. | In-situ process for detoxifying hexavalent chromium in soil and groundwater |
| CN103602819A (en) * | 2013-11-29 | 2014-02-26 | 中南大学 | Comprehensive recovery method of vanadate-chromate-containing solution |
| CN104609529A (en) * | 2014-05-26 | 2015-05-13 | 尹景启 | Complexing reducing agent for hexavalent chromium |
| CN104959369A (en) * | 2015-05-20 | 2015-10-07 | 湖南永清环保研究院有限责任公司 | Method used for recycling chromium from chromium-polluted soil |
| CN105127190A (en) * | 2015-08-11 | 2015-12-09 | 青海省环境科学研究设计院 | Method for repairing hexavalent chromium in chromium polluted soil |
| CN109796984A (en) * | 2017-11-16 | 2019-05-24 | 永清环保股份有限公司 | A kind of reduction stabilization agent for chromium-polluted soil |
| CN110452706A (en) * | 2019-08-21 | 2019-11-15 | 湖南科臣环境科技有限公司 | A kind of agent of stable composition chemical drug and its application of hexavalent chromium polluted soil |
| CN112453048A (en) * | 2020-11-06 | 2021-03-09 | 天津水泥工业设计研究院有限公司 | Electric in-situ remediation method for chromium-contaminated soil |
-
2021
- 2021-10-19 CN CN202111214328.XA patent/CN113828630B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6221002B1 (en) * | 1997-06-26 | 2001-04-24 | Chemical Land Holdings, Inc. | Method to reduce hexavalent chromium in soils, sediments, industrial wastes and other contaminated materials using ascorbic acid |
| WO2003022744A2 (en) * | 2001-09-06 | 2003-03-20 | Gannett Fleming, Inc. | In-situ process for detoxifying hexavalent chromium in soil and groundwater |
| CN103602819A (en) * | 2013-11-29 | 2014-02-26 | 中南大学 | Comprehensive recovery method of vanadate-chromate-containing solution |
| CN104609529A (en) * | 2014-05-26 | 2015-05-13 | 尹景启 | Complexing reducing agent for hexavalent chromium |
| CN104959369A (en) * | 2015-05-20 | 2015-10-07 | 湖南永清环保研究院有限责任公司 | Method used for recycling chromium from chromium-polluted soil |
| CN105127190A (en) * | 2015-08-11 | 2015-12-09 | 青海省环境科学研究设计院 | Method for repairing hexavalent chromium in chromium polluted soil |
| CN109796984A (en) * | 2017-11-16 | 2019-05-24 | 永清环保股份有限公司 | A kind of reduction stabilization agent for chromium-polluted soil |
| CN110452706A (en) * | 2019-08-21 | 2019-11-15 | 湖南科臣环境科技有限公司 | A kind of agent of stable composition chemical drug and its application of hexavalent chromium polluted soil |
| CN112453048A (en) * | 2020-11-06 | 2021-03-09 | 天津水泥工业设计研究院有限公司 | Electric in-situ remediation method for chromium-contaminated soil |
Non-Patent Citations (4)
| Title |
|---|
| 丁井井: "Method 3060A——碱消解法提取六价铬的影响因素分析", 《标准科学》 * |
| 丹东市轻化工研究所: "《制革化工材料手册》", 31 December 1986, 中国轻工业出版社 * |
| 蒋世伟: "碱性条件下肼还原六价铬动力学研究", 《工程科技I辑》 * |
| 陈政: "还原稳定化技术在铬污染土壤修复中的应用", 《化工设计通讯》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116086931A (en) * | 2022-12-12 | 2023-05-09 | 浙江大学 | Soil hexavalent chromium determination method for eliminating interference of chalcogenide reducing agent |
| CN116086931B (en) * | 2022-12-12 | 2023-08-11 | 浙江大学 | Soil hexavalent chromium determination method for eliminating interference of chalcogenide reducing agent |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113828630B (en) | 2022-09-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105873644B (en) | Metal treatment method | |
| CN102240667B (en) | Electric remediation and reducing detoxication method for chromium contaminated soil and underground water | |
| CN107096789B (en) | Soil and sediment remediation | |
| CN113828630B (en) | Restoration method of hexavalent chromium contaminated soil | |
| PL182477B1 (en) | Method of treating sewage sludges | |
| CN113667825B (en) | Ferronickel wet processing method and application thereof | |
| CN108579669A (en) | For the regenerated regenerative agent of heavy-metal contaminated soil ring waste and preparation method and application | |
| CN113502394A (en) | Method for recovering cobalt or nickel intermediate product | |
| CN112456620A (en) | Method for treating wastewater after ore leaching and closing of ionic rare earth ore | |
| CN109622583A (en) | A kind of method heavy-metal contaminated soil ring waste regeneration and recycled | |
| JP6260332B2 (en) | Method and apparatus for treating waste-based combustion ash used in cement production | |
| CN206089294U (en) | Steel industry hydrochloric acid pickling liquid waste's processing recovery system | |
| CN111977919A (en) | Method for treating heavy metal polluted bottom mud by utilizing ultrasonic wave-composite acid extraction-chemical precipitation | |
| CN108950581B (en) | Regeneration method of stainless steel mixed pickling waste acid | |
| CN110550776A (en) | Fenton oxidation-reduction integrated method for treating chromium-containing wastewater | |
| US4978457A (en) | Method of filtering a brine | |
| JPS5829111B2 (en) | Oxidation and cleaning methods for contaminated soil | |
| CN112899483B (en) | Method for selectively extracting and separating vanadium from vanadium-molybdenum waste residues | |
| CN111072123B (en) | Method for removing complex lead by ferrous phosphate under anoxic condition | |
| GB2567655A (en) | Polyferric sulphate solution | |
| CN108408960B (en) | Method for recycling and treating iron-containing pickling newspaper waste liquid | |
| CN110846520A (en) | Method for removing iron in laterite-nickel ore leaching solution by using laterite-nickel ore nickel cobalt-depositing waste liquid slag | |
| US3865580A (en) | Copper recovery process | |
| RU2714309C1 (en) | Method for purification of oil-contaminated soils from natural radionuclides | |
| CN108249721B (en) | Method for removing zinc in phosphating solid dangerous waste |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |