CN113481014A - Preparation and application methods of cadmium-polluted soil solid waste base passivator - Google Patents
Preparation and application methods of cadmium-polluted soil solid waste base passivator Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/40—Soil-conditioning materials or soil-stabilising materials containing mixtures of inorganic and organic compounds
Abstract
The invention relates to a cadmium-polluted soil solid waste base passivator which comprises modified blast furnace slag, modified fly ash and modified biochar. The modified blast furnace slag is prepared by modifying blast furnace slag through hydrochloric acid, the modified fly ash is prepared by modifying fly ash through NaOH, and the modified biochar is prepared by modifying biochar through chitosan. The invention also relates to a preparation method of the cadmium-polluted soil solid waste base passivator, which comprises the steps of uniformly mixing the modified blast furnace slag, the modified fly ash and the modified charcoal, adding water, stirring and drying to obtain the cadmium-polluted soil solid waste base passivator. The invention also relates to a method for repairing cadmium-polluted soil by applying the cadmium-polluted soil solid waste base passivator. The cadmium-polluted soil solid waste base passivator has the advantages that the cost is low, the specific surface areas of the modified blast furnace slag, the modified fly ash and the modified biochar formed after modification are increased, and the adsorption sites are increased, so that the contact area between the modified blast furnace slag, the modified fly ash and the modified biochar is increased, the adsorption effect is further improved, and the content of effective cadmium in the cadmium-polluted soil is reduced.
Description
Technical Field
The invention relates to the technical field of cadmium contaminated soil treatment and restoration, in particular to a preparation and application method of a cadmium contaminated soil solid waste base passivator.
Background
According to the national soil pollution condition survey bulletin published by the ministry of environmental protection and the ministry of national soil resources 2014, 4, 17, the total point location standard exceeding rate of the soil in China is 16.1% by the published date, wherein the point location standard exceeding rate of the farmland soil is as high as 19.4%, the point location standard exceeding rates are divided according to the pollution degrees, and the point location standard exceeding rates of slight, mild, moderate and severe pollution in the farmland soil are respectively 13.7%, 2.8%, 1.8% and 1.1%. The point location overproof rate represents the proportion of the number of the soil overproof point locations to the total number of survey point locations. At present, the cultivated land area in China is 20.27 hundred million mu, the contaminated cultivated land area reaches 3.9 hundred million mu, and the contaminated condition of the cultivated land soil is severe.
Pollutants in farmland soil are mainly heavy metals such as cadmium, and human beings can influence the metabolism of calcium and phosphorus after taking cadmium-containing food for a long time, so that the diseases of organs such as kidney and liver are caused, and diseases such as osteoporosis, osteomalacia and renal calculus are induced. Cadmium is a major environmental pollutant and food pollutant in research internationally due to its great harm to human body. Therefore, the task of repairing cadmium contaminated soil is urgent.
The existing soil pollution remediation technologies comprise a physical remediation technology and a chemical remediation technology, and because the physical remediation technology is high in cost, the chemical remediation technology with relatively low price is generally adopted for soil remediation at present. The chemical remediation techniques are classified into stabilization techniques and immobilization techniques according to whether or not a chemical reaction with a contaminant occurs. Among other things, stabilization techniques can convert contaminants into less soluble, mobile, or toxic forms to reduce the hazard of the contaminants. Curing techniques limit contaminant migration by enclosing the contaminant in an inert substrate or coating the contaminant with a low permeability material to reduce the leached area of the contaminant. Currently, a repair technology combining an immobilization technology and a stabilization technology is generally adopted to improve a stabilization effect.
Currently, the commonly used soil heavy metal fixing/stabilizing materials mainly include: lime and carbonate mineral repair materials, phosphorus-containing materials, silicon-containing materials, metal and metal oxide materials, novel materials, and the like. When the cadmium-polluted soil is repaired in a large area, the cost of repair is high due to the high price of the passivators.
In conclusion, the cadmium-polluted soil solid waste base passivator with lower cost and better protection effect is needed at present.
Disclosure of Invention
Technical problem to be solved
In view of the defects and shortcomings of the prior art, the invention provides a cadmium-polluted soil solid waste base passivator, a preparation method thereof and a method for repairing cadmium-polluted soil, which solve the technical problem that the repair cost of cadmium-polluted soil is high due to high price of the conventional passivator.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
in a first aspect, the embodiment of the invention provides a cadmium-polluted soil solid waste base passivator, which comprises modified blast furnace slag, modified fly ash and modified biochar;
the modified blast furnace slag is prepared by modifying blast furnace slag through hydrochloric acid, the modified fly ash is prepared by modifying fly ash through NaOH, and the modified biochar is prepared by modifying biochar through chitosan.
According to the invention, the particle size of the modified blast furnace slag is less than 150 um;
the particle size of the modified fly ash is less than 150 um.
According to the invention, the modified blast furnace slag is neutral;
the modified fly ash is neutral;
the modified biochar is neutral.
According to the invention, the mass ratio of the modified blast furnace slag, the modified fly ash and the modified biochar is 0.5-1: 1-2: 3-4.
In a second aspect, an embodiment of the present invention further provides a preparation method of a cadmium-contaminated soil solid waste base passivator, including the following steps:
s1: reacting the crushed blast furnace slag with hydrochloric acid, performing suction filtration, washing and drying to obtain modified blast furnace slag;
s2: uniformly mixing the fly ash and NaOH, roasting, grinding, sieving and washing to obtain modified fly ash;
s3: adding biochar into acetic acid solution of chitosan, stirring, adding NaOH for reaction, separating and washing to obtain modified biochar;
s4: and uniformly mixing the modified blast furnace slag, the modified fly ash and the modified charcoal, adding water, stirring and drying to obtain the cadmium-polluted soil solid waste base passivator.
According to the invention, in step S1:
washing with deionized water or distilled water;
the drying temperature is 60-105 ℃, and the drying time is 10-24 h.
In the step S2:
the roasting temperature is 250 +/-10 ℃, and the roasting time is 2 +/-0.1 h;
washing with deionized water or distilled water.
According to the invention, in step S3:
the biochar is prepared by agricultural straws and/or wood chips in an anaerobic environment at the temperature of 400-;
stirring for 30 +/-5 min;
washing with deionized water or distilled water.
In the step S4:
the mass ratio of the modified blast furnace slag to the modified fly ash to the modified biochar is 0.5-1: 1-2: 3-4;
the mass of the water is 10-30% of the total mass of the mixture of the modified blast furnace slag, the modified fly ash and the modified biochar.
In a third aspect, the invention also provides a method for repairing cadmium-contaminated soil by applying the cadmium-contaminated soil solid waste base passivator, which comprises the following steps:
and uniformly mixing the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivator, and keeping the water content in the cadmium-polluted soil not lower than 60% of the maximum water holding capacity of the soil.
According to the invention, during mixing, the cadmium-polluted soil solid waste base passivating agent is uniformly scattered in the cadmium-polluted soil, and the cadmium-polluted soil is subjected to rotary tillage with the rotary tillage depth of 20-25 cm.
According to the invention, the spreading amount of the cadmium-polluted soil solid waste base passivator is 1-10% of the dry weight of the cadmium-polluted soil.
(III) advantageous effects
The invention has the beneficial effects that:
the cadmium-polluted soil solid waste base passivator, the preparation method thereof and the method for repairing cadmium-polluted soil have the following beneficial effects:
firstly, the modified blast furnace slag is prepared by modifying blast furnace slag, the modified fly ash is prepared by modifying fly ash, and the modified biochar is prepared by modifying biochar. The blast furnace slag, the fly ash and the biochar are all industrial and agricultural wastes.
The industrial and agricultural wastes are recycled, the industrial and agricultural wastes are used as raw materials to prepare the cadmium-polluted soil solid waste base passivator, the price is low, the production cost of the cadmium-polluted soil solid waste base passivator can be reduced, the utilization rate of the industrial wastes can be improved, and the environment and organisms are prevented from being polluted when the blast furnace slag and the fly ash are discharged.
And secondly, the blast furnace slag is of a net structure, the fly ash is of a porous honeycomb structure, the porosity reaches 50% -80%, and the biochar also has an abundant surface microporous structure, so that the adsorption performance of the three is high, and the three are high in corrosion resistance, durability, high temperature resistance and chemical stability and can exist in soil for a long time.
The surface properties of the blast furnace slag, the fly ash and the biochar are optimized through modification, and the method specifically comprises the following steps:
after the blast furnace slag is modified by hydrochloric acid, the micro-crack structure on the surface of the blast furnace slag is converted into a loose structure on the surface of the modified blast furnace slag, and the loose structure is beneficial to improving the adsorption and solidification performance of the modified blast furnace slag on cadmium ions in the cadmium-polluted soil.
After the fly ash is modified by NaOH, the smooth spherical structure on the surface of the fly ash is converted into a rough loose porous structure on the surface of the modified fly ash, and the specific surface area of the modified fly ash is increased to 21.77 times of that of the fly ash. The rough loose porous structure and the larger specific surface area on the surface of the modified fly ash can increase the contact area of the modified fly ash and cadmium ions in cadmium-polluted soil, so that the adsorption performance of the modified fly ash on the cadmium ions is improved.
After the biochar is modified by chitosan, hydroxyl functional groups are introduced to the surface of the biochar, and the hydroxyl functional groups can effectively improve the adsorption performance of the modified biochar on cadmium ions.
In conclusion, compared with the blast furnace slag, the fly ash and the biochar, after modification, the modified blast furnace slag, the modified fly ash and the modified biochar keep the original corrosion resistance, durability, high temperature resistance and chemical stability, and further improve the adsorption and solidification performance on cadmium ions, so as to reduce the mobility of the cadmium ions in the cadmium-polluted soil and reduce the effective cadmium content in the cadmium-polluted soil. The effective state represents a state that can be absorbed and utilized by plants.
And thirdly, the modified charcoal has rich surface microporous structures and higher adsorbability, and can effectively adsorb phytotoxin secreted by pathogens and weeds in soil so as to reduce the harm of the pathogens and the phytotoxin to crops, further reduce the dosage of pesticides and herbicides in the agricultural management process, and obtain win-win effect of economic benefit and environmental benefit.
And fourthly, the modified blast furnace slag, the modified fly ash and the modified charcoal contain rich organic matters and nutrient elements and can provide rich nutrient substances for the growth of plants in the cultivated land soil.
Fifthly, when the cadmium-polluted soil solid waste base passivator is used for repairing cadmium-polluted soil, the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivator are uniformly mixed, and the water content in the cadmium-polluted soil is kept to be not lower than 60% of the maximum water holding capacity of the soil.
Meanwhile, the cadmium-polluted soil solid waste base passivator disclosed by the invention is prepared by mixing the three modified blast furnace slag, the modified fly ash and the modified charcoal, so that the adsorption and solidification performances of cadmium ions in cadmium-polluted soil are improved, and the effective cadmium content in the repaired cadmium-polluted soil is reduced. Tests prove that the effective cadmium content in the cadmium-polluted soil after being repaired is reduced along with the increase of the quality of the cadmium-polluted soil solid waste base passivator added in the cadmium-polluted soil, and is reduced along with the increase of the action time of the cadmium-polluted soil solid waste base passivator. The pH value of the repaired cadmium-polluted soil is increased along with the increase of the action time of the cadmium-polluted soil solid waste base passivator, and the content of effective cadmium in the cadmium-polluted soil is reduced along with the increase of the action time.
Drawings
FIG. 1 is a bar graph of effective cadmium content in cadmium-contaminated soil in comparative tests of blast furnace slag, fly ash and biochar in repairing cadmium-contaminated soil under different action times when the cadmium-contaminated soil solid waste base passivator of the invention is applied to repairing cadmium-contaminated soil;
FIG. 2 is a histogram of effective cadmium content in cadmium-contaminated soil in comparative experiments of repairing cadmium-contaminated soil by using modified blast furnace slag, modified fly ash and modified biochar under different action times when the cadmium-contaminated soil solid waste base passivator of the invention is applied to repairing cadmium-contaminated soil;
FIG. 3 is a bar graph of effective cadmium content in cadmium-contaminated soil in comparative tests of the modified blast furnace slag + modified biochar, modified fly ash + modified biochar and cadmium-contaminated soil solid waste base passivator for repairing cadmium-contaminated soil at different application rates when the cadmium-contaminated soil solid waste base passivator of the invention is applied to repairing cadmium-contaminated soil;
FIG. 4 is a histogram of the effective cadmium content in cadmium-contaminated soil in a comparative repair test in which the modified blast furnace slag + modified biochar, the modified fly ash + modified biochar and the cadmium-contaminated soil solid waste base passivator are mixed with cadmium-contaminated soil at different action times when the cadmium-contaminated soil solid waste base passivator of the invention is applied to repair cadmium-contaminated soil;
FIG. 5 is a histogram of effective cadmium content in cadmium-contaminated soil in comparative experiments on repair of cadmium-contaminated soil by using blast furnace slag, fly ash, biochar, modified blast furnace slag, modified fly ash, modified biochar, modified blast furnace slag + modified biochar, modified fly ash + modified biochar and the cadmium-contaminated soil solid waste base passivator in different action times when the cadmium-contaminated soil solid waste base passivator is used for repairing cadmium-contaminated soil.
Detailed Description
For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.
The invention provides a preparation method of a cadmium contaminated soil solid waste base passivator for the first time, which comprises the following steps:
s1: washing blast furnace slag with pure water, and drying at 60-105 deg.C for 10-24 hr. And sieving the crushed and dried blast furnace slag until the particle size is less than 150 mu m. Mixing the crushed blast furnace slag and hydrochloric acid with the concentration of 1mol/L according to the weight ratio of 1 g: mixing 10ml for reaction, stirring for 30 +/-5 min, performing suction filtration, washing with purified water to neutrality, and drying at 60-105 ℃ for 10-24h to obtain the modified blast furnace slag.
S2: mixing fly ash and NaOH in a ratio of 1 g: 1g of the modified fly ash is obtained by uniformly mixing, roasting for 2 +/-0.1 h at the temperature of 250 +/-10 ℃, grinding, sieving until the particle size is less than 150 mu m, and washing with purified water until the particle size is neutral.
S3: mixing chitosan and 2% acetic acid solution, stirring for 30 +/-5 min, adding biochar into the acetic acid solution of chitosan, stirring for 30 +/-5 min, adding 1.2% NaOH solution for reaction, keeping for 12 +/-0.1 h, performing centrifugal separation, and washing with purified water to be neutral to obtain the modified biochar.
Wherein, the biochar is prepared by agricultural straws and/or wood chips in an anaerobic environment at the temperature of 400-600 ℃.
The proportion of chitosan, 2% acetic acid solution, biochar and 1.2% NaOH solution is 1 g: 60 ml: 1 g: 36 ml.
S4: mixing 0.5-1g of modified blast furnace slag, modified fly ash and modified biochar: 1-2 g: and 3-4g of the passivating agent is uniformly mixed according to the proportion, water accounting for 10% -30% of the total mass of the mixture is added for stirring, and the obtained product is dried to obtain the cadmium-polluted soil solid waste base passivating agent.
Specifically, in the steps S1-S3, the purified water may be deionized water, distilled water, or other unpolluted water. Washing to neutrality to avoid acid and alkali substances used in the modification process from remaining in the modified blast furnace slag, the modified fly ash and the modified biochar.
In the step S2, a nickel crucible is preferably used to contain the mixture of fly ash and NaOH, and a muffle furnace is preferably used for calcination.
The cadmium-polluted soil solid waste base passivator prepared by the preparation method is a mixture of modified blast furnace slag, modified fly ash and modified biochar, and has the following advantages:
firstly, the modified blast furnace slag is prepared by modifying blast furnace slag, the modified fly ash is prepared by modifying fly ash, and the modified biochar is prepared by modifying biochar. The blast furnace slag, the fly ash and the biochar are all industrial and agricultural wastes.
The industrial and agricultural wastes are recycled, the industrial and agricultural wastes are used as raw materials to prepare the cadmium-polluted soil solid waste base passivator, the price is low, the production cost of the cadmium-polluted soil solid waste base passivator can be reduced, the utilization rate of the industrial wastes can be improved, and the environment and organisms are prevented from being polluted when the blast furnace slag and the fly ash are discharged.
And secondly, the blast furnace slag is of a net structure, the fly ash is of a porous honeycomb structure, the porosity reaches 50% -80%, and the biochar also has an abundant surface microporous structure, so that the adsorption performance of the three is high, and the three are high in corrosion resistance, durability, high temperature resistance and chemical stability and can exist in soil for a long time.
The surface properties of the blast furnace slag, the fly ash and the biochar are optimized through modification, and the method specifically comprises the following steps:
after the blast furnace slag is modified by hydrochloric acid, the micro-crack structure on the surface of the blast furnace slag is converted into a loose structure on the surface of the modified blast furnace slag, and the loose structure is beneficial to improving the adsorption and solidification performance of the modified blast furnace slag on cadmium ions in the cadmium-polluted soil.
After the fly ash is modified by NaOH, the smooth spherical structure on the surface of the fly ash is converted into a rough loose porous structure on the surface of the modified fly ash, and the specific surface area of the modified fly ash is increased to 21.77 times of that of the fly ash. The rough loose porous structure and the larger specific surface area on the surface of the modified fly ash can increase the contact area of the modified fly ash and cadmium ions in cadmium-polluted soil, so that the adsorption performance of the modified fly ash on the cadmium ions is improved.
After the biochar is modified by chitosan, hydroxyl functional groups are introduced to the surface of the biochar, and the hydroxyl functional groups can effectively improve the adsorption performance of the modified biochar on cadmium ions.
In conclusion, compared with the blast furnace slag, the fly ash and the biochar, after modification, the modified blast furnace slag, the modified fly ash and the modified biochar keep the original corrosion resistance, durability, high temperature resistance and chemical stability, and further improve the adsorption and solidification performance on cadmium ions, so as to reduce the mobility of the cadmium ions in the cadmium-polluted soil and reduce the effective cadmium content in the cadmium-polluted soil. The effective state represents a state that can be absorbed and utilized by plants.
And thirdly, the modified charcoal has rich surface microporous structures and higher adsorbability, and can effectively adsorb phytotoxin secreted by pathogens and weeds in soil so as to reduce the harm of the pathogens and the phytotoxin to crops, further reduce the dosage of pesticides and herbicides in the agricultural management process, and obtain win-win effect of economic benefit and environmental benefit.
And fourthly, the modified blast furnace slag, the modified fly ash and the modified charcoal contain rich organic matters and nutrient elements and can provide rich nutrient substances for the growth of plants in the cultivated land soil.
Fifthly, after modification, the particle sizes of the modified blast furnace slag and the modified fly ash are both smaller than 150 microns, and the reduction of the particle sizes can increase the contact area of the modified blast furnace slag and the modified fly ash with cadmium ions in the cadmium-polluted soil, so that the adsorption effect of the cadmium ion adsorption agent on the cadmium-polluted soil solid waste base is improved, and the content of effective cadmium in the cadmium-polluted soil is reduced.
For better explanation, the following are examples of the preparation method of the cadmium-contaminated soil solid waste base passivator of the invention:
example 1.1
S1: and washing the blast furnace slag by using deionized water or distilled water, and drying at 60 ℃ for 24 hours. And sieving the crushed and dried blast furnace slag until the particle size is less than 150 mu m. Mixing 5g of crushed blast furnace slag and 50ml of hydrochloric acid with the concentration of 1mol/L for reaction, stirring for 25min, performing suction filtration, washing with purified water to be neutral, and drying at 60 ℃ for 24h to obtain the modified blast furnace slag.
S2: uniformly mixing 5g of fly ash and 5g of NaOH, roasting for 1.9h at 240 ℃, grinding, sieving until the particle size is less than 150 mu m, and washing with purified water until the particle size is neutral to obtain the modified fly ash.
S3: mixing 25g of chitosan and 1500ml of 2% acetic acid solution, stirring for 25min, adding 25g of biochar into the acetic acid solution of chitosan, stirring for 25min, adding 900ml of 1.2% NaOH solution, reacting, keeping for 19.9h, performing centrifugal separation, and washing with deionized water or distilled water until the solution is neutral to obtain the modified biochar.
S4: mixing the modified blast furnace slag, the modified fly ash and the modified biochar in a proportion of 0.5 g: 1 g: and 3g of the passivator is uniformly mixed, added with water accounting for 10% of the total mass of the mixture, stirred and dried to obtain the cadmium-polluted soil solid waste base passivator.
Example 1.2
S1: and washing the blast furnace slag by using deionized water or distilled water, and drying at 80 ℃ for 12 hours. And sieving the crushed and dried blast furnace slag until the particle size is less than 150 mu m. Mixing 10g of crushed blast furnace slag and 100ml of hydrochloric acid with the concentration of 1mol/L for reaction, stirring for 30min, performing suction filtration, washing with purified water to be neutral, and drying at 80 ℃ for 12h to obtain the modified blast furnace slag.
S2: uniformly mixing 10g of fly ash and 10g of NaOH, roasting for 2h at 250 ℃, grinding, sieving until the particle size is less than 150 mu m, and washing with purified water until the particle size is neutral to obtain the modified fly ash.
S3: mixing 30g of chitosan and 1800ml of 2% acetic acid solution, stirring for 30min, adding 30g of biochar into the acetic acid solution of chitosan, stirring for 30min, adding 1080ml of 1.2% NaOH solution for reaction, keeping for 12h, performing centrifugal separation, and washing with deionized water or distilled water to neutrality to obtain the modified biochar.
S4: mixing the modified blast furnace slag, the modified fly ash and the modified biochar in a proportion of 0.8 g: 1.5 g: and 3.5g of the passivator is uniformly mixed according to the proportion, water accounting for 20% of the total mass of the mixture is added for stirring, and the passivator is dried to obtain the cadmium-polluted soil solid waste base passivator.
Example 1.3
S1: and washing the blast furnace slag by using deionized water or distilled water, and drying at 105 ℃ for 10 hours. And sieving the crushed and dried blast furnace slag until the particle size is less than 150 mu m. Mixing 15g of crushed blast furnace slag and 150ml of hydrochloric acid with the concentration of 1mol/L for reaction, stirring for 35min, performing suction filtration, washing with purified water to be neutral, and drying at 105 ℃ for 10h to obtain the modified blast furnace slag.
S2: uniformly mixing 15g of fly ash and 15g of NaOH, roasting for 2.1h at 260 ℃, grinding, sieving until the particle size is less than 150 mu m, and washing with purified water until the particle size is neutral to obtain the modified fly ash.
S3: mixing 35g of chitosan and 2100ml of 2% acetic acid solution, stirring for 30min, adding 35g of biochar into the chitosan acetic acid solution, stirring for 30min, adding 1260ml of 1.2% NaOH solution for reaction, keeping for 12.1h, performing centrifugal separation, and washing with deionized water or distilled water until the solution is neutral to obtain the modified biochar.
S4: mixing 1g of modified blast furnace slag, modified fly ash and modified biochar: 2 g: and 4g of the passivator is uniformly mixed, added with water accounting for 30% of the total mass of the mixture, stirred and dried to obtain the cadmium-polluted soil solid waste base passivator.
Furthermore, the invention also provides the application of the cadmium-polluted soil solid waste base passivator prepared by the preparation method of the cadmium-polluted soil solid waste base passivator in the aspect of repairing cadmium-polluted soil for the first time.
The application method comprises the following steps:
the cadmium-polluted soil solid waste base passivating agent is uniformly scattered in cadmium-polluted soil, the cadmium-polluted soil is subjected to rotary tillage to 20-25cm, the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivating agent are uniformly mixed, and the cadmium-polluted soil is irrigated until the water content in the cadmium-polluted soil is not less than 60% of the maximum water holding capacity of the farmland soil.
The application method is simple and quick.
Specifically, the spreading amount of the cadmium-polluted soil solid waste base passivator is 1% -10% of the dry weight of the cadmium-polluted soil.
Specifically, the cadmium-polluted soil solid waste base passivator disclosed by the invention can repair cadmium-polluted soil with the pH value not higher than 9.0, and is more suitable for the soil repair operation with the pH value of 5.5-7.0.
By way of example, the cadmium-contaminated soil selected by the method is taken from a contaminated farmland in Liaoning province, and the basic physicochemical properties are as follows: the pH value is 6.5, and the organic matter content is 15.04g kg-1The total nitrogen content is 0.83 g/kg-1The total phosphorus content is 0.46 g/kg-1The quick-acting potassium content is 93.05 g.kg-1The total sulfur content is 295 mg/kg-1Background value of heavy metal Cd is 0.22 mg-kg-1. The concentration of cadmium ions in the cadmium polluted soil is 10.45mg/kg, which exceeds the maximum allowable content of cadmium in the farmland soil of the secondary standard of the soil environmental quality of China by 0.6 mg/kg. The cadmium pollution passivator can be used for repairing any cadmium pollution soil.
For better explanation, the following application examples for repairing cadmium contaminated soil are given:
example 2.1
The cadmium-polluted soil solid waste base passivating agent is uniformly scattered in cadmium-polluted soil, the cadmium-polluted soil is subjected to rotary tillage to 20cm, the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivating agent are uniformly mixed, and the cadmium-polluted soil solid waste base passivating agent are irrigated until the water content in the cadmium-polluted soil is 60% of the maximum water holding capacity of the cultivated land soil.
Example 2.2
The cadmium-polluted soil solid waste base passivating agent is uniformly scattered in cadmium-polluted soil, the cadmium-polluted soil is subjected to rotary tillage to 22cm, the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivating agent are uniformly mixed, and the cadmium-polluted soil solid waste base passivating agent are irrigated until the water content in the cadmium-polluted soil is 70% of the maximum water holding capacity of the cultivated land soil.
Example 2.3
The cadmium-polluted soil solid waste base passivating agent is uniformly scattered in cadmium-polluted soil, the cadmium-polluted soil is subjected to rotary tillage to 25cm, the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivating agent are uniformly mixed, and the cadmium-polluted soil solid waste base passivating agent are irrigated until the water content in the cadmium-polluted soil is 80% of the maximum water holding capacity of the cultivated land soil.
Further, in order to better reflect the repairing effect of the cadmium-contaminated soil solid waste base passivator on cadmium-contaminated soil, a repairing contrast test of mixing different passivators on cadmium-contaminated soil, a repairing contrast test of mixing the cadmium-contaminated soil solid waste base passivator and cadmium-contaminated soil in different mass ratios, and a repairing contrast test of mixing the cadmium-contaminated soil solid waste base passivator and cadmium-contaminated soil under different action times are respectively performed as follows.
Specifically, the method adopts a standard substance method (BCR method) for sequentially extracting the heavy metal cadmium in the soil to extract the cadmium ions in the weak acid extraction state in the cadmium polluted soil, thereby obtaining the effective cadmium content in the cadmium polluted soil. The detection method comprises the following steps:
s5: and (3) placing 0.5000-0.5010g of air-dried cadmium contaminated soil with the particle size of less than 150um into a container cleaned by pickling.
S6: adding 45 plus or minus 5mL of 0.11mol/LCH3And (3) shaking the COOH solution at the temperature of 22 +/-5 ℃ at the rotating speed of 30 +/-10 rpm for 16 +/-0.5 h, standing for 3-5min, and then slightly shaking the container to ensure that attachments on the wall of the container completely enter the solution in the container.
S7: the vessel was centrifuged at 4000. + -.100 rpm for 15. + -.1 min. Transferring the supernatant into another container cleaned by acid soaking, and storing at 4 + -1 deg.C to form cadmium ion solution in weak acid extraction state.
S8: and detecting the content of the effective cadmium in the cadmium ion solution to obtain the content of the effective cadmium in the cadmium-polluted soil.
Preferably, in step S5, 50ml of bubble acid is used. In step S6, CH3The volume of the COOH solution was 40mL, and the solution was shaken for 16 h. In the step S7, in the step S,the rotation speed is 4000rpm, the centrifugation is carried out for 15min, the acid soaking volume is 10mL, and the storage condition is 4 ℃.
Preferably, the air-dried cadmium-contaminated soil is weighed by using an analytical balance with the accuracy of 0.0001g, so that the weighing accuracy is improved. And an inductive coupling plasma spectrometer is adopted to detect the effective cadmium content of the cadmium ion solution.
Test one: remediation contrast test for cadmium contaminated soil mixed by different passivators
Referring to FIGS. 1-3, the test conditions are: uniformly mixing the cadmium-polluted soil and a plurality of groups of passivators respectively in a mass ratio of 20:1, keeping the water content of the cadmium-polluted soil to be 60% of the maximum water holding capacity of the soil, and keeping for 60 days. And cadmium-contaminated soil which is not subjected to remediation treatment is used as a control group.
The plurality of groups of passivators are blast furnace slag, fly ash, biochar, modified blast furnace slag, modified fly ash, modified biochar, modified blast furnace slag + modified biochar, modified fly ash + modified biochar and cadmium-polluted soil solid waste base passivators respectively.
After 60 days, according to the arrangement sequence of the passivators, the effective cadmium content in the cadmium polluted soil is as follows: 4.48mg/kg, 3.88mg/kg, 3.58mg/kg, 3.15mg/kg, 2.06mg/kg, 2.02mg/kg, 2.84mg/kg, 2.01mg/kg, 1.22 mg/kg; the effective cadmium content in the cadmium polluted soil without restoration treatment is as follows: 3.85 plus or minus 0.5 mg/kg.
Compared with the unrepaired cadmium-polluted soil, the content of the effective cadmium in the cadmium-polluted soil is reduced to different degrees after the cadmium-polluted soil is restored by other passivators except the blast furnace slag and the fly ash. The reasons for this are: the blast furnace slag and the fly ash contain cadmium ions, the cadmium ions are easily introduced into the cadmium-polluted soil in the process of repairing the cadmium-polluted soil, the effective cadmium content in the repaired cadmium-polluted soil is increased, and the cadmium ions are removed after the blast furnace slag and the fly ash are modified, so that the cadmium ions are effectively prevented from being introduced into the cadmium-polluted soil.
Specifically, the cadmium-polluted soil and cadmium-polluted soil solid waste base passivator is prepared by mixing the following components in percentage by weight of 20:1, and after the cadmium-polluted soil is acted for 60 days, compared with cadmium-polluted soil which is not subjected to restoration treatment, the effective cadmium content in the cadmium-polluted soil restored by the cadmium-polluted soil solid waste base passivator is reduced by about 68 percent, so that the requirements of efficient and rapid restoration and restoration of the cadmium-polluted soil can be met.
After 60 days, the passivators corresponding to the effective cadmium content in the cadmium polluted soil from low to high sequentially comprise:
cadmium-polluted soil solid waste base passivator modified fly ash and modified biochar, modified fly ash, modified blast furnace slag and modified biochar, modified blast furnace slag, biochar, fly ash and blast furnace slag.
According to the arrangement sequence, the effective cadmium content in the cadmium-polluted soil treated by the modified passivator is lower than that in the cadmium-polluted soil treated by the unmodified passivator, so that the curing effect of the passivator on cadmium in the cadmium-polluted soil can be effectively improved by modifying the passivator. Compared with blast furnace slag, fly ash and biochar, the modified blast furnace slag, the modified fly ash and the modified biochar formed by modification have larger specific surface areas and more adsorption sites, and have larger contact areas with cadmium ions in cadmium-polluted soil, so that the adsorption effect on the cadmium ions in the cadmium-polluted soil is improved.
Meanwhile, compared with a single passivator and a passivator used in a mixed mode, the cadmium-polluted soil solid waste base passivator disclosed by the invention has lower effective cadmium content in the repaired cadmium-polluted soil, so that after three modified blast furnace slag, modified fly ash and modified biochar are mixed, the cadmium-polluted soil solid waste base passivator disclosed by the invention can improve the stable curing effect on cadmium ions in the cadmium-polluted soil, further reduce the effective cadmium content in the cadmium-polluted soil and improve the repairing effect on the cadmium-polluted soil.
And (2) test II: remediation contrast test for mixing cadmium-contaminated soil solid waste base passivator and cadmium-contaminated soil in different mass ratios
Referring to fig. 3, the test conditions are: respectively mixing a cadmium-polluted soil and a cadmium-polluted soil solid waste base passivator in a proportion of 50: 1. 20:1 and 10: 1, keeping the water content in the cadmium-polluted soil to be 60% of the maximum water holding capacity of the soil, and keeping for 30 days. And cadmium-contaminated soil which is not subjected to remediation treatment is used as a control group.
In the initial state, the effective cadmium content in the cadmium-polluted soil to be repaired is as follows: 3.85 plus or minus 0.5 mg/kg.
After 30 days, according to the sequence of the mass ratio, the effective cadmium content in the cadmium polluted soil is respectively as follows: 2.35 plus or minus 0.25mg/kg, 1.21 plus or minus 0.20mg/kg, 0.92 plus or minus 0.11 mg/kg; the effective cadmium content in the cadmium polluted soil without restoration treatment is as follows: 3.31 +/-0.03 mg/kg.
After 60 days, the mass ratio of the effective cadmium content in the cadmium polluted soil from low to high is as follows: 10: 1> 20: 1> 50: 1.
therefore, the content of the effective cadmium in the cadmium polluted soil after being repaired by different mass ratios is reduced to different degrees.
From the above sequence and fig. 3, it can be seen that the effective cadmium content in the cadmium-contaminated soil after the remediation decreases with the decrease of the mass ratio of the cadmium-contaminated soil to the cadmium-contaminated soil solid waste base passivator, that is, the effective cadmium content in the cadmium-contaminated soil after the remediation decreases with the increase of the mass of the cadmium-contaminated soil solid waste base passivator added in the cadmium-contaminated soil. The more the content of the cadmium-polluted soil solid waste base passivator in the cadmium-polluted soil is, the more the contact area between cadmium ions in the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivator is, so that cadmium can be better adsorbed and fixed by gaps or a net structure of the cadmium-polluted soil solid waste base passivator, more cadmium ions can be bonded by surface groups of the cadmium-polluted soil solid waste base passivator, and the effective cadmium content in the cadmium-polluted soil is further reduced.
Specifically, cadmium contaminated soil and a plurality of groups of passivators are respectively mixed in a proportion of 10: 1, and after the treatment for 30 days, compared with the cadmium-polluted soil which is not subjected to remediation treatment, the effective cadmium content in the cadmium-polluted soil which is remediated by the cadmium-polluted soil solid waste base passivator is reduced by 71.00%, so that the requirements of efficient and rapid remediation and remediation of the cadmium-polluted soil can be met.
And (3) test III: comparative test for repairing cadmium-polluted soil solid waste base passivator and cadmium-polluted soil under different action times
Referring to fig. 4, the test conditions are: the cadmium-polluted soil and cadmium-polluted soil solid waste base passivator is prepared by mixing the following components in parts by weight: 1, keeping the water content in the cadmium-polluted soil to be 60% of the maximum water holding capacity of the soil, and respectively acting for 15 days, 30 days and 60 days. And cadmium-contaminated soil which is not subjected to remediation treatment is used as a control group.
In the initial state, the effective cadmium content in the cadmium-polluted soil to be repaired is as follows: 3.85 plus or minus 0.5 mg/kg.
After 15 days, the effective cadmium content in the repaired cadmium polluted soil is as follows: 1.76 plus or minus 0.15 mg/kg; the pH value is 7.30 +/-0.02; the effective cadmium content in the cadmium polluted soil without restoration treatment is as follows: 3.96 +/-0.06 mg/kg.
After 30 days, the effective cadmium content in the repaired cadmium polluted soil is as follows: 1.75 plus or minus 0.36mg/kg, and the pH is 7.37 plus or minus 0.03; the content of the effective cadmium in the cadmium polluted soil without restoration treatment is 4.53 +/-0.14 mg/kg.
After 60 days, the effective cadmium content in the repaired cadmium polluted soil is as follows: 1.22 plus or minus 0.11mg/kg, and the pH is 7.38 plus or minus 0.03; the effective cadmium content in the cadmium polluted soil without restoration treatment is as follows: 4.13. + -. 0.02 mg/kg.
Specifically, the cadmium-polluted soil and cadmium-polluted soil solid waste base passivator is prepared by mixing the following components in percentage by weight of 20:1, and after the cadmium-polluted soil is acted for 60 days, compared with cadmium-polluted soil which is not subjected to restoration treatment, the effective cadmium content in the cadmium-polluted soil restored by the cadmium-polluted soil solid waste base passivator is reduced by 70.00 percent, so that the requirements of efficient and rapid restoration and restoration of the cadmium-polluted soil can be met.
From the data sorting and fig. 4, it can be seen that the effective cadmium content in the cadmium-contaminated soil after the remediation is reduced to different degrees under different action times, and the effective cadmium content in the cadmium-contaminated soil after the remediation is reduced along with the increase of the effective cadmium content in the cadmium-contaminated soil along with the action time. The cadmium-polluted soil solid waste base passivator can fully contact with cadmium ions in cadmium-polluted soil along with the extension of action time, so that cadmium ions can be better adsorbed and fixed by gaps or a net structure of the cadmium-polluted soil solid waste base passivator, and surface groups of the cadmium-polluted soil solid waste base passivator can be bonded with more cadmium ions, thereby reducing the effective cadmium content in the cadmium-polluted soil.
From the change of the pH value, the pH value of the cadmium-polluted soil is increased along with the increase of the action time, which is opposite to the change condition of the effective cadmium content in the cadmium-polluted soil, namely, the higher the pH value of the cadmium-polluted soil is, the lower the effective cadmium content in the cadmium-polluted soil is. The reason is that the cadmium-polluted soil is more acidic when the pH value of the cadmium-polluted soil is lower, cadmium ions in the cadmium-polluted soil are easily extracted and converted into an effective state, and the concentration of the effective cadmium ions in the soil is increased.
In conclusion, the cadmium-polluted soil solid waste base passivator disclosed by the invention is prepared by mixing three modified blast furnace slag, modified fly ash and modified biochar, so that the adsorption and solidification performances of cadmium ions in cadmium-polluted soil are improved, and the effective cadmium content in the cadmium-polluted soil after remediation is reduced. Tests prove that the effective cadmium content in the cadmium-polluted soil after being repaired is reduced along with the increase of the quality of the cadmium-polluted soil solid waste base passivator added in the cadmium-polluted soil, and is reduced along with the increase of the action time of the cadmium-polluted soil solid waste base passivator. The pH value of the repaired cadmium-polluted soil is increased along with the increase of the action time of the cadmium-polluted soil solid waste base passivator, and the content of effective cadmium in the cadmium-polluted soil is reduced along with the increase of the action time.
Although embodiments of the present invention have been shown and described, it is understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that modifications, alterations, substitutions and variations of the above embodiments may be made by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. The cadmium-polluted soil solid waste base passivator is characterized by comprising modified blast furnace slag, modified fly ash and modified biochar;
the modified blast furnace slag is prepared by modifying blast furnace slag through hydrochloric acid, the modified fly ash is prepared by modifying fly ash through NaOH, and the modified biochar is prepared by modifying biochar through chitosan.
2. The cadmium-contaminated soil solid waste base passivator of claim 1, wherein:
the particle size of the modified blast furnace slag is less than 150 um;
the particle size of the modified fly ash is less than 150 um.
3. The cadmium-contaminated soil solid waste base passivator of claim 1, wherein:
the modified blast furnace slag is neutral;
the modified fly ash is neutral;
the modified biochar is neutral.
4. The cadmium-contaminated soil solid waste base passivator of claim 1, wherein the mass ratio of the modified blast furnace slag, the modified fly ash and the modified biochar is 0.5-1: 1-2: 3-4.
5. The preparation method of the cadmium-polluted soil solid waste base passivator as defined in any one of claims 1 to 4, comprising the following steps:
s1: reacting the crushed blast furnace slag with hydrochloric acid, performing suction filtration, washing and drying to obtain modified blast furnace slag;
s2: uniformly mixing the fly ash and NaOH, roasting, grinding, sieving and washing to obtain modified fly ash;
s3: adding biochar into acetic acid solution of chitosan, stirring, adding NaOH for reaction, separating and washing to obtain modified biochar;
s4: and uniformly mixing the modified blast furnace slag, the modified fly ash and the modified charcoal, adding water, stirring and drying to obtain the cadmium-polluted soil solid waste base passivator.
6. The preparation method of the solid waste base passivator for cadmium contaminated soil as claimed in claim 5, wherein:
in the step S1:
washing with deionized water or distilled water;
the drying temperature is 60-105 ℃, and the drying time is 10-24 h.
In the step S2:
the roasting temperature is 250 +/-10 ℃, and the roasting time is 2 +/-0.1 h;
washing with deionized water or distilled water.
7. The preparation method of the solid waste base passivator for cadmium contaminated soil as claimed in claim 5, wherein:
in the step S3:
the biochar is prepared by agricultural straws and/or wood chips in an anaerobic environment at the temperature of 400-;
stirring for 30 +/-5 min;
washing with deionized water or distilled water.
In the step S4:
the mass ratio of the modified blast furnace slag to the modified fly ash to the modified biochar is 0.5-1: 1-2: 3-4;
the mass of the water is 10-30% of the total mass of the mixture of the modified blast furnace slag, the modified fly ash and the modified biochar.
8. A method for repairing cadmium-contaminated soil by using the cadmium-contaminated soil solid waste base passivator as defined in any one of claims 1 to 4, which comprises the following steps:
and uniformly mixing the cadmium-polluted soil and the cadmium-polluted soil solid waste base passivator, and keeping the water content in the cadmium-polluted soil not lower than 60% of the maximum water holding capacity of the soil.
9. The method for remediating cadmium-contaminated soil by using the cadmium-contaminated soil solid waste base passivating agent as claimed in claim 8, wherein the cadmium-contaminated soil solid waste base passivating agent is uniformly scattered in the cadmium-contaminated soil during mixing, and the cadmium-contaminated soil is subjected to rotary tillage with the rotary tillage depth of 20-25 cm.
10. The method for remediating cadmium-contaminated soil by using the cadmium-contaminated soil solid waste base passivator as claimed in claim 9, wherein the spreading amount of the cadmium-contaminated soil solid waste base passivator is 1% -10% of the dry weight of the cadmium-contaminated soil.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115404084A (en) * | 2022-09-20 | 2022-11-29 | 江西中江环保集团股份有限公司 | Green fertilizing and pollution-reducing matrix for improving polluted farmland soil |
| CN116212825A (en) * | 2023-03-10 | 2023-06-06 | 山东交通学院 | Modified waste coffee grounds biochar adsorption material and preparation method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102174325A (en) * | 2011-03-11 | 2011-09-07 | 中国科学院亚热带农业生态研究所 | Composite passivant for soil polluted by heavy metal and preparation method |
| CN104560046A (en) * | 2015-01-27 | 2015-04-29 | 上海绿强新材料有限公司 | Contaminated soil passivator and preparation method and application thereof |
| CN105347907A (en) * | 2015-10-19 | 2016-02-24 | 福建金土地生物科技有限公司 | Biochar-based fertilizer for restoration of heavy metal contamination of arable soil |
| CN107116097A (en) * | 2017-06-21 | 2017-09-01 | 郑州航空工业管理学院 | A kind of method for repairing As polluted soil |
| CN108774531A (en) * | 2018-05-15 | 2018-11-09 | 环保桥（湖南）生态环境修复有限公司 | A kind of renovation agent and preparation method thereof for administering alkaline cadmium pollution soil |
| CN108865157A (en) * | 2018-06-14 | 2018-11-23 | 中国恩菲工程技术有限公司 | The reparation medicament and restorative procedure of heavy-metal contaminated soil |
-
2021
- 2021-07-15 CN CN202110802000.3A patent/CN113481014A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102174325A (en) * | 2011-03-11 | 2011-09-07 | 中国科学院亚热带农业生态研究所 | Composite passivant for soil polluted by heavy metal and preparation method |
| CN104560046A (en) * | 2015-01-27 | 2015-04-29 | 上海绿强新材料有限公司 | Contaminated soil passivator and preparation method and application thereof |
| CN105347907A (en) * | 2015-10-19 | 2016-02-24 | 福建金土地生物科技有限公司 | Biochar-based fertilizer for restoration of heavy metal contamination of arable soil |
| CN107116097A (en) * | 2017-06-21 | 2017-09-01 | 郑州航空工业管理学院 | A kind of method for repairing As polluted soil |
| CN108774531A (en) * | 2018-05-15 | 2018-11-09 | 环保桥（湖南）生态环境修复有限公司 | A kind of renovation agent and preparation method thereof for administering alkaline cadmium pollution soil |
| CN108865157A (en) * | 2018-06-14 | 2018-11-23 | 中国恩菲工程技术有限公司 | The reparation medicament and restorative procedure of heavy-metal contaminated soil |
Non-Patent Citations (3)
| Title |
|---|
| 周夏芝: "高炉渣改性及其吸附La3+/Ce3+性能研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑(月刊)》 * |
| 徐姝颖等: "氢氧化钠改性粉煤灰处理含铬废水的研究", 《精细石油化工进展》 * |
| 项江欣: "生物炭-壳聚糖复合材料对Cd的吸附特性及对Cd污染土壤的修复效应与机理研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑(月刊)》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115404084A (en) * | 2022-09-20 | 2022-11-29 | 江西中江环保集团股份有限公司 | Green fertilizing and pollution-reducing matrix for improving polluted farmland soil |
| CN116212825A (en) * | 2023-03-10 | 2023-06-06 | 山东交通学院 | Modified waste coffee grounds biochar adsorption material and preparation method thereof |
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