A kind of heavy metal cadmium, lead, arsenic combined contamination soil renovation agent and preparation method thereof
Technical field:
The invention belongs to soil pollution recovery technique field, be specifically related to a kind of heavy metal cadmium, lead, arsenic combined contamination soil renovation agent and preparation method thereof.
Background technology:
" whole nation Soil Pollution Investigation publication " display within 2014, is announced: whole nation soil environment situation totally allows of no optimist according to Environmental Protection Department and Ministry of Land and Resources; some areas soil pollution is heavier; arable soil environmental quality causes anxiety, industry and mining discarded ground soil environment outstanding problem.The human activity such as industry and mining, agricultural and Environmental Background Values of Soils height are to cause soil pollution or the main cause exceeded standard.The whole nation total exceeding standard rate of soil is 16.1%, the most slightly, slightly, moderate and serious pollution point position ratio be respectively 11.2%, 2.3%, 1.5% and 1.1%.Pollution type is based on inorganic type, and organic type takes second place, and compound pollution proportion is less, and an inorganic pollution figure place that exceeds standard accounts for the 82.8% of all super punctuation bits.
From polluting in terms of distribution situation, soils in south china pollutes and overweights the north;The subregion soil contamination problem such as Yangtze River Delta, the Delta of the Pearl River, Northeastern rust belt are the most prominent, southwest, variable charge soil heavy metals exceeding standard scope bigger;Cadmium, hydrargyrum, arsenic, 4 kinds of level of inorganic contaminants distributions of lead present the situation gradually risen from northwest to the southeast, from northeast to southwestward.
Major pollutants are cadmium, nickel, copper, arsenic, hydrargyrum, lead, clofenotane and polycyclic aromatic hydrocarbon.If being as the criterion with second national land investigation result, China's arable land latest data is 2,030,770,000 mu and calculates, and the cultivated area of middle serious pollution accounts for 2.9%, has reached 58,890,000 mu.
Administering method currently for heavy metal pollution of soil mainly has immobilization/stabilisation, elution method, washes local method, electromotion repairing technique method, chemical reduction method, phytoremediation, microorganism remediation, totally there is the problems such as remediation efficiency is low, processing cost is high.The quantities such as traditional restorative procedure such as landfill, drip washing, electrochemistry are big, and cost is high and frequently results in Soil structure and destroys and some nutrient loss.Therefore, exploitation one low cost, soil remediation medicament simple, efficient, eco-friendly are significant.
Chemical passivation renovation agent is the controlling area-source pollution technology of a kind of high-efficiency and economic, and this technology also complies with the needs of China's sustainable development.
Summary of the invention
The technical problem to be solved is to provide a kind of heavy metal cadmium, lead, arsenic combined contamination soil renovation agent and preparation method thereof, the present invention uses biomass carbon, kieselguhr, sodium bentonite, activated alumina, dithiocar-bamate, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate is mixed in proportion, make soil-repairing agent, add to by a certain percentage in heavy-metal contaminated soil according to pollution level, by absorption, ion exchanges, the synergism such as chelating react with the heavy metal in soil, heavy metal is made to form stable chemical form, stop its environmental transport and transfer and diffusion, reduce heavy metal murder by poisoning degree in the environment.
For solving above-mentioned technical problem, the invention provides a kind of heavy metal cadmium, lead, arsenic combined contamination soil renovation agent, its raw material is made up of biomass carbon, kieselguhr, sodium bentonite, activated alumina, dithiocar-bamate, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate, and the percentage by weight of each raw material of described soil-repairing agent is:
Biomass carbon 30-50%;
Kieselguhr 5-10%;
Sodium bentonite 5-10%;
Activated alumina 5-10%;
Dithiocar-bamate 10-20%;
Ethylenediaminetetraacetic acid 5-10%;
Tartaric acid 5-10%;
Polyacrylamide 5-10%;
Dodecyl sodium sulfate 5-10%;
The mass percent sum of each raw material is 100%.
Further, in described renovation agent, the mass percent of each raw material is:
Biomass carbon 50%;
Kieselguhr 5%;
Sodium bentonite 5%;
Activated alumina 5%;
Dithiocar-bamate 15%;
Ethylenediaminetetraacetic acid 5%;
Tartaric acid 5%;
Polyacrylamide 5%;
Dodecyl sodium sulfate 5%;
One heavy-metal contaminated soil renovation agent of the present invention, described biomass carbon is with the mixture of straw and calcium oxide as raw material, the mass ratio of described straw and calcium oxide is 20:1, system pressure be 20kPa, pyrolysis temperature be 500 DEG C under conditions of vacuum pyrolysis 30min, the pressed powder that particle diameter is below 3mm obtained by milled processed;
Described kieselguhr, activated alumina are respectively the pressed powder of below 2mm;
Described sodium bentonite be alkalescence coefficient more than 1, smectite content be 60-88%, particle diameter be the pressed powder of below 2mm;
Described ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate are the pressed powder of below 2mm.
Described dithiocar-bamate is the ammonia saline solution of polymerization dithiocarbonic acid, and mass concentration is 500mg/L.
One heavy-metal contaminated soil renovation agent of the present invention, by formation mixture that biomass carbon, kieselguhr, sodium bentonite, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate are stirred according to the above ratio, again the dithiocar-bamate of aforementioned proportion is added in mixture and stir, i.e. can obtain repairing medicament.
One heavy-metal contaminated soil renovation agent of the present invention, is obtained after mixture by said process, adds in heavy-metal contaminated soil, the 1-10% that reparations pharmaceutical quantities is contaminated soil weight added, then sprays a small amount of water and make Soil conservation moistening.
This medicament may be used for the improvement of single heavy metal contaminated soil, is also applied for the improvement of Compound Heavy Metals, it is adaptable to large area heavy-metal contaminated soil is repaired, and the mine including heavy metal pollution is repaired and heavy metal uses the reparation of manufacturing enterprise contaminated site.Compared with prior art, the medicament of repairing of the present invention has the advantage that preparation method is simple, feasible, regulation effect is good.
Relative to prior art, the beneficial effects of the present invention is:
Biomass carbon in renovation agent is obtained by vacuum pyrolysis biomass, and the biomass carbon porosity prepared under vacuum is high, and adsorptive value is high;With biomass such as straws as raw material, make full use of resource, it is to avoid because its burning causes environmental pollution.The yield promoting straw charcoal during vacuum pyrolysis by adding calcium oxide increases, and the biomass carbon obtained by vacuum pyrolysis has specific surface area big, and duct is enriched, and easily adsorbs all kinds of heavy metal ion, reduces the concentration of animal migration heavy metal ion in soil;Calcium oxide self in the biomass carbon prepared can make soil pH value improve soil surface negative charge to be increased, thus the affinity of soil heavy metal increases;On the other hand pH value raises, and is also beneficial to the existence of MOH+ and improves the adsorbance of heavy metal ion, promotes heavy metal in soil to form hydroxide or combined state precipitation or co-precipitation simultaneously.
Sodium bentonite is the clay mineral based on montmorillonite, and primary chemical formula is Nax (H2O)4(AI2-xMg0.83)Si4O10)(OH)2, its structure is pressed from both sides, by two silicon-oxy tetrahedrons, the crystal structure that one layer of alumina octahedral form.The layer structure that sodium bentonite structure cell is formed is primarily present sodium ion, easily by other cation replacements, has preferable ion exchangeable, can carry out ion exchange with the heavy metal in soil, reduce the bio-toxicity of heavy metal-polluted soil.
Activated alumina has many capillary channels, and specific surface area is big, has stronger affinity to water, oxide etc..
The heavy metal ion that aminodithioformic acid can effectively remove each metal ion species and various forms coexists.Dithiocarbamate-based strong complexation power can Direct precipitation chemical combination or the heavy metal ion of complexation, the stiff stability of complex avoids secondary pollution.During dithiocar-bamate and ethylenediaminetetraacetic acid, tartaric acid use simultaneously, ethylenediaminetetraacetic acid, tartaric acid are as compounding ingredient, form hydroxide precipitation with heavy metal to vie each other, promote aminodithioformic acid and heavy metal ion generation chelatropic reaction;In addition ethylenediaminetetraacetic acid, tartaric acid can be with heavy metal ion generation complex reaction.
The ammonia saline solution of polymerization dithiocarbonic acid, active group is dithiocarbonic acid, because the sulphur atom electronegativity in active group is little, radius has lost electronics more greatly, and easily polarization deformation produces negative electric field, thus can trapping positive ions tend to bonding, generate the dithiocar-bamate being insoluble in water.When it is combined with a certain metal ion, all forming four-membered ring by 2 sulphur atoms in its structure, the compound of formation is chelate.Dithiocar-bamate forms covalency chelate as trapping agent with heavy metal ion, cloth angle is joined to what electronics group space around central ion joined that cloth is decided by metal ion bonding orbital, dithiocar-bamate forms plane square structure with the metal ion of valence link track dsp2 type, four front three-dimensional-structures are formed with the metal ion of valence link track sp3 type, octahedral three-dimensional-structure is formed with the metal ion of valence link track ds2p3 type, owing to trapping agent forms, with the metal ion of different price bond orbital, the steric configuration that tension force is less, therefore what thing of Austria that dithiocar-bamate and metal ion generate has higher stability.
Polyacrylamide is high molecular polymer, has a good water solublity, nontoxic, non-corrosiveness, can improve the physical property of soil, increase soil macro aggregate number, improve soil hydraulic and water content, slow down soil losses, soil can be allowed to be fully contacted with leacheate;Additionally, polyacrylamide has carboxyl and amide groups isoreactivity group, coordinate bond can be formed by the metal ion with soil particle surface, have the synergism making stable chromium ion;
Dodecyl sodium sulfate is a kind of efficient anion surfactant, and easily with various additive compounds, cost is relatively low, and synthesis technique is ripe, with the hydrophobicity in chelating agen complex treatment soil containing heavy metal substance, improves soil remediation effect.
Except the respective chelating of said components, complexation, flocculate, precipitate, in addition to adsorption, biomass carbon, kieselguhr, sodium bentonite, the addition of activated alumina can improve soil physico-chemical property well, are greatly enhanced the permeability of soil;Under the effect of dodecyl sodium sulfate, easily and biomass carbon, kieselguhr, sodium bentonite, activated alumina cooperate and heavy metal ion is reacted for dithiocar-bamate, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide has flocculation simultaneously, in the soil environment having water, promote that pollutant in soil matter is assembled and adsorb with biomass carbon, kieselguhr, sodium bentonite, activated alumina.
Play synergism by said components so that heavy metal leaching rate in soil is substantially reduced, reach and be better than the primary standard of country " standard of soil environment quality " (GB15618-1995).
Detailed description of the invention:
Embodiment 1
Test soil collecting content of beary metal in certain heavy metal pollution region, this regional soil top layer is higher than the grade III Standard of " standard of soil environment quality " (GB15618-1995).Practical situation according to polluting is repaired:
A (), sampling from soil, detect and use turnover oscillator that soil is carried out leaching test according to solid waste " Leaching leaching method sulfonitric method " (HJ/T299-2007), detect preprosthetic heavy metal-polluted soil concentration;
B prepared by (), soil-repairing agent: with the mixture of straw and calcium oxide as raw material, the mass ratio of described straw and calcium oxide is 20:1, system pressure be 20kPa, pyrolysis temperature be 500 DEG C under conditions of vacuum pyrolysis 30min, the biomass carbon powder that particle diameter is below 3mm obtained by milled processed;Obtain alkalescence coefficient more than 1, smectite content be 80%, the particle diameter sodium bentonite less than 2mm;Obtain particle diameter less than the kieselguhr of powder of 2mm, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate;Obtain the ammonia saline solution of the polymerization dithiocarbonic acid that mass concentration is 500mg/L.
The mass percent of each raw material is:
Biomass carbon 50%;
Kieselguhr 5%;
Sodium bentonite 5%;
Activated alumina 5%;
Dithiocar-bamate 15%;
Ethylenediaminetetraacetic acid 5%;
Tartaric acid 5%;
Polyacrylamide 5%;
Dodecyl sodium sulfate 5%;
By formation mixture that biomass carbon, kieselguhr, sodium bentonite, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate are stirred according to the above ratio, again the dithiocar-bamate of aforementioned proportion is added in mixture and stir, i.e. can obtain repairing medicament.
(c), the heavy-metal contaminated soil of 10kg is dug out, send into crusher in crushing, it is delivered to blender through belt, reparation medicament for soil quality 10% is sufficiently mixed with contaminated soil, in mixed process, spraying a small amount of water makes Soil conservation moisten, and stands 10 days after mixing, i.e. completes to repair.
(d), effect detection: sample the soil after repairing, detect and use turnover oscillator that soil is carried out leaching test according to solid waste " Leaching leaching method sulfonitric method " (HJ/T299-2007), heavy metal-polluted soil concentration after detection reparation, result is as shown in table 1:
Table 1
|
Cadmium (Cd) |
Lead (Pb) |
Arsenic (As) |
Before process (mg/kg) |
33.3 |
976 |
892 |
After process (mg/kg) |
0.009 |
0.06 |
0.5 |
Cadmium in Soil after reparation, lead, arsenic content meet the primary standard of " standard of soil environment quality " (GB15618-1995).
Embodiment 2
Test soil collecting content of beary metal in certain heavy metal pollution region, this regional soil top layer is higher than the grade III Standard of " standard of soil environment quality " (GB15618-1995).Practical situation according to polluting is repaired:
A (), sampling from soil, detect and use turnover oscillator that soil is carried out leaching test according to solid waste " Leaching leaching method sulfonitric method " (HJ/T299-2007), detect preprosthetic heavy metal-polluted soil concentration;
B prepared by (), soil-repairing agent: with the mixture of straw and calcium oxide as raw material, the mass ratio of described straw and calcium oxide is 20:1, system pressure be 20kPa, pyrolysis temperature be 500 DEG C under conditions of vacuum pyrolysis 30min, the biomass carbon powder that particle diameter is below 3mm obtained by milled processed;Obtain alkalescence coefficient more than 1, smectite content be 80%, the particle diameter sodium bentonite less than 2mm;Obtain particle diameter less than the kieselguhr of powder of 2mm, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate;Obtain the ammonia saline solution of the polymerization dithiocarbonic acid that mass concentration is 500mg/L.
The mass percent of each raw material is:
Biomass carbon 30%;
Kieselguhr 10%;
Sodium bentonite 10%;
Activated alumina 10%;
Dithiocar-bamate 10%;
Ethylenediaminetetraacetic acid 10%;
Tartaric acid 10%;
Polyacrylamide 5%;
Dodecyl sodium sulfate 5%;
By formation mixture that biomass carbon, kieselguhr, sodium bentonite, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate are stirred according to the above ratio, again the dithiocar-bamate of aforementioned proportion is added in mixture and stir, i.e. can obtain repairing medicament.
(c), the heavy-metal contaminated soil of 10kg is dug out, send into crusher in crushing, it is delivered to blender through belt, reparation medicament for soil quality 10% is sufficiently mixed with contaminated soil, in mixed process, spraying a small amount of water makes Soil conservation moisten, and stands 10 days after mixing, i.e. completes to repair.
(d), effect detection: sample the soil after repairing, detect and use turnover oscillator that soil is carried out leaching test according to solid waste " Leaching leaching method sulfonitric method " (HJ/T299-2007), heavy metal-polluted soil concentration after detection reparation, result is as shown in table 2:
Table 2
|
Cadmium (Cd) |
Lead (Pb) |
Arsenic (As) |
Before process (mg/kg) |
29.1 |
931 |
653 |
After process (mg/kg) |
0.01 |
0.2 |
0.9 |
Cadmium in Soil after reparation, lead, zinc, mercury content meet the primary standard of " standard of soil environment quality " (GB15618-1995).
Embodiment 3
Test soil collecting content of beary metal in certain heavy metal pollution region, this regional soil top layer is higher than the grade III Standard of " standard of soil environment quality " (GB15618-1995).Practical situation according to polluting is repaired:
A (), sampling from soil, detect and use turnover oscillator that soil is carried out leaching test according to solid waste " Leaching leaching method sulfonitric method " (HJ/T299-2007), detect preprosthetic heavy metal-polluted soil concentration;
B prepared by (), soil-repairing agent: with the mixture of straw and calcium oxide as raw material, the mass ratio of described straw and calcium oxide is 20:1, system pressure be 20kPa, pyrolysis temperature be 500 DEG C under conditions of vacuum pyrolysis 30min, the biomass carbon powder that particle diameter is below 3mm obtained by milled processed;Obtain alkalescence coefficient more than 1, smectite content be 80%, the particle diameter sodium bentonite less than 2mm;Obtain particle diameter less than the kieselguhr of powder of 2mm, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate;Obtain the ammonia saline solution of the polymerization dithiocarbonic acid that mass concentration is 500mg/L.
The mass percent of each raw material is:
Biomass carbon 5%;
Kieselguhr 5%;
Sodium bentonite 5%;
Activated alumina 5%;
Dithiocar-bamate 20%;
Ethylenediaminetetraacetic acid 5%;
Tartaric acid 5%;
Polyacrylamide 10%;
Dodecyl sodium sulfate 10%;
By formation mixture that biomass carbon, kieselguhr, sodium bentonite, activated alumina, ethylenediaminetetraacetic acid, tartaric acid, polyacrylamide, dodecyl sodium sulfate are stirred according to the above ratio, again the dithiocar-bamate of aforementioned proportion is added in mixture and stir, i.e. can obtain repairing medicament.
(c), the heavy-metal contaminated soil of 10kg is dug out, send into crusher in crushing, it is delivered to blender through belt, reparation medicament for soil quality 10% is sufficiently mixed with contaminated soil, in mixed process, spraying a small amount of water makes Soil conservation moisten, and stands 10 days after mixing, i.e. completes to repair.
(d), effect detection: sample the soil after repairing, detect and use turnover oscillator that soil is carried out leaching test according to solid waste " Leaching leaching method sulfonitric method " (HJ/T299-2007), heavy metal-polluted soil concentration after detection reparation, result is as shown in table 3:
Table 3
|
Cadmium (Cd) |
Lead (Pb) |
Arsenic (As) |
Before process (mg/kg) |
32.1 |
965 |
757 |
After process (mg/kg) |
0.008 |
0.1 |
0.8 |
Cadmium in Soil after reparation, lead, zinc, mercury content meet the primary standard of " standard of soil environment quality " (GB15618-1995).