CN114804972B - Method for regulating heavy metal activity by cooperation of biochar and soil humus - Google Patents

Method for regulating heavy metal activity by cooperation of biochar and soil humus Download PDF

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CN114804972B
CN114804972B CN202110114089.4A CN202110114089A CN114804972B CN 114804972 B CN114804972 B CN 114804972B CN 202110114089 A CN202110114089 A CN 202110114089A CN 114804972 B CN114804972 B CN 114804972B
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biochar
iron
soil
rich
humus
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CN114804972A (en
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王雷
席北斗
占金华
王小书
刘剑聪
檀文炳
崔东宇
李彤彤
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Chinese Research Academy of Environmental Sciences
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    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
    • C05G3/80—Soil conditioners
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/30—Active carbon
    • C01B32/312—Preparation
    • C01B32/318—Preparation characterised by the starting materials
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
    • C05D9/00—Other inorganic fertilisers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/40—Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Soil Sciences (AREA)
  • Pest Control & Pesticides (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The invention discloses a method for effectively regulating and controlling heavy metal activity by utilizing biochar to cooperate with soil humus, which is characterized in that an improver prepared from iron-rich biochar and soil humus is added into heavy metal polluted soil, the adsorption and conversion of the biochar to heavy metal ions are enhanced by utilizing the soil humus, so that the soil is improved, particularly the biochar is prepared from aquatic plants, the loaded iron content is high, the biochar is subjected to pyrolysis and laser scanning treatment, the specific surface area is large, a great effective contact area and reaction modification space are provided for loaded iron, atoms in the iron-rich biochar are regularly distributed, the active sites of the biochar are improved, the effect of the iron-rich biochar and the soil humus is fully exerted, the mediating efficiency of the biochar on microorganism electron transfer process is improved by 52-58 times, the microorganism amount reaches 10.5-12.0 lg CFU/g, and the technical method provided by the invention is simple to operate and low in cost.

Description

Method for regulating heavy metal activity by cooperation of biochar and soil humus
Technical Field
The invention belongs to the technical field of environmental preparation, and particularly relates to a method for regulating and controlling heavy metal activity by utilizing biochar and soil humus.
Background
Soil is fundamental to human survival, and largely carries the daily life of humans. However, with the rapid development of industrial technology, pesticide and fertilizer containing excessive heavy metals are continuously applied to soil, and industrial mineral resources are unreasonably smelted and discharged, so that the heavy metal pollution of soil in China is increasingly serious.
Heavy metal pollution not only can reduce the productivity of soil, but also can be accumulated in human bodies through food chains finally, thereby threatening the physical health of the human bodies. Therefore, the treatment of heavy metal pollution of soil is not necessary.
Because of the large population pressure in China, the contradiction between the shortage of high-quality cultivated land resources and the grain production demand is remarkable, and the contaminated soil cannot be subjected to large-scale leisure, non-grain crops can be planted or phytoremediation can be carried out; engineering measures are high in cost and difficult to implement, and heavy metal pollutants cannot be removed when the polluted soil is buried, so that repair measures which are feasible and can ensure safe production of crops are regulated and controlled by humus for farmland heavy metal polluted soil.
One of the most important functions and functions of soil humus is that the soil humus can interact with metal ions and organic compounds, and the main functions of the soil humus include influencing cation exchange capacity and soil pH value, adsorbing and forming coordination compounds so as to change the bioavailability and occurrence form of heavy metals and improve the amount of chelating peptides in a repaired plant body; promote the conversion of heavy metals from an unstable state to a stable state, namely, passivate deposit heavy metals and reduce the bioavailability thereof.
Heavy metal polluted soil is mostly acidic, while biochar is mostly alkaline, and the biochar is applied to the soil, so that the method has remarkable effects of improving the acidic soil, improving the pH value of the soil and relieving toxicity. Meanwhile, the biochar can improve the physical structure of soil, influence the microbial activity of the soil, reduce the loss of nutrient elements and regulate and control the circulation of the nutrient elements, so that in recent years, adding the biomass charcoal into the soil becomes an important technical approach for increasing the emission and reducing the emission of agriculture.
The prior art also has research and proves that the biochar and humus can be combined to repair heavy metal polluted soil, and the addition of soil humus can obviously enhance the adsorption and conversion of the biochar to heavy metal ions, but the influence of the biochar on different types of biochar is different. And because the biochar and the soil humus have a certain risk in repairing the heavy metal polluted soil, for example, the biochar and the soil humus both have the possibility of improving the mobility of the heavy metal in the soil so as to increase the leaching possibility of the heavy metal, so that the research of jointly repairing the heavy metal polluted soil by the biochar and the humus cannot be developed.
For the above reasons, further research on biochar and humus is needed, and a method for effectively regulating and controlling the activity of heavy metals by combining the biochar with the soil humus is sought.
Disclosure of Invention
In order to overcome the problems, the inventor researches and researches a method for effectively regulating and controlling the activity of heavy metals by utilizing biochar to cooperate with soil humus, wherein an improver prepared from iron-rich biochar and soil humus is added into heavy metal polluted soil, the adsorption and conversion of the biochar to heavy metal ions are enhanced by utilizing the soil humus, the soil is further improved, particularly the biochar is prepared from aquatic plants, the loaded iron content is high, the specific surface area of the biochar is large through pyrolysis and laser scanning treatment, a great effective contact area and reaction modification space are provided for loaded iron, the atoms in the iron-rich biochar are regularly distributed, the active sites of the biochar are improved, the effect of the iron-rich biochar and the soil humus is fully exerted, the microbial biomass reaches 10.5-12.0 lg CFU/g, and the mediating efficiency of the microbial electron transfer process is at least improved by 1-2 orders of magnitude.
Specifically, the invention aims to provide a method for effectively regulating and controlling heavy metal activity by utilizing biochar to cooperate with soil humus, which comprises the following steps:
step 1, preparing iron-rich biochar;
and 2, preparing an improver by utilizing the iron-rich biochar prepared in the step 1 and soil humus.
Wherein, step 1 comprises the following steps:
step 1-1, culturing aquatic plants;
and step 1-2, preparing the iron-rich biochar by utilizing the aquatic plants in the step 1-1.
Wherein in step 1-1, the aquatic plants comprise any one or more of emergent aquatic plants, floating leaf plants, submerged plants and floating plants, preferably emergent aquatic plants, and more preferably calamus.
Wherein in step 1-1, an iron source is added to the culture broth of the aquatic plant, the iron source comprising an inorganic iron source, an organic iron source and/or a chelated iron, preferably a chelated iron, more preferably Fe-DTPA.
In the step 1-2, the aquatic plant in the step 1-1 is subjected to sectional sintering and laser scanning treatment.
Wherein, in step 1-2, the step of sintering comprises:
the first stage: the temperature is 200-300 ℃, the heating rate is 5-12 ℃/min, and the heat preservation time is 20-40 min;
and a second stage: the temperature is 350-600 ℃, the heating rate is 8-14 ℃/min, and the heat preservation time is 20-50 min;
and a third stage: the temperature is 620-1000 ℃, the temperature rising rate is 7-13 ℃/min, and the heat preservation time is 30-90 min.
Wherein the step of sintering includes:
the first stage: the temperature is 250-320 ℃, the heating rate is 7-10 ℃/min, and the heat preservation time is 25-35 min;
and a second stage: the temperature is 400-550 ℃, the heating rate is 9-12 ℃/min, and the heat preservation time is 25-40 min;
and a third stage: the temperature is 700-900 ℃, the heating rate is 9-12 ℃/min, and the heat preservation time is 50-80 min.
Wherein the step of sintering includes:
the first stage: the temperature is 280 ℃, the heating rate is 8 ℃/min, and the heat preservation time is 30min;
and a second stage: the temperature is 440 ℃, the heating rate is 11 ℃/min, and the heat preservation time is 25min;
and a third stage: the temperature is 800 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 60min.
In the step 2, the soil humus is obtained by decomposing any one or more raw materials of blue algae, livestock and poultry manure, straw, wood chips, rice hulls and plant wastes in soil by microorganisms.
Wherein in the step 2, the weight ratio of the iron-rich biochar to the soil humus is (0.2-5): 1.
the invention has the beneficial effects that:
(1) The method for effectively regulating and controlling the activity of heavy metals by utilizing the biochar and the soil humus has the advantages that the aquatic plants are used as raw materials of the biochar, the self-properties of the aquatic plants are fully utilized, secondary pollution is avoided, and the method has certain economic value.
(2) According to the method for effectively regulating and controlling the activity of heavy metals by utilizing the biochar and the soil humus, the content of loaded iron in the biochar is high, the specific surface area of the biochar is large through pyrolysis and laser scanning treatment, a great effective contact area and a reaction modification space are provided for loaded iron, the atoms in the iron-rich biochar are regularly distributed, and the active sites of the biochar are improved.
(3) According to the method for effectively regulating and controlling the activity of heavy metals by utilizing the biochar and the soil humus, the adsorption and conversion of the biochar to heavy metal ions are enhanced by utilizing the soil humus, so that the soil is improved, and the synergistic effect of the iron-rich biochar and the soil humus is fully exerted.
(4) The method for effectively regulating and controlling the activity of heavy metals by utilizing the biochar to cooperate with soil humus is simple to operate, low in cost and environment-friendly.
(5) According to the method for effectively regulating and controlling the activity of heavy metals by utilizing the biochar and the soil humus, the nano iron is loaded in the biochar, and the zero-valent iron is coated in the biochar, so that the use reliability and durability are improved.
Detailed Description
The present invention will be described in further detail by way of examples. The features and advantages of the present invention will become more apparent from the description.
The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The invention aims to provide a method for effectively regulating and controlling heavy metal activity by utilizing biochar to cooperate with soil humus, which comprises the following steps:
and step 1, preparing the iron-rich biochar.
According to a preferred form, said step 1 comprises the steps of:
step 1-1, culturing aquatic plants.
In step 1, the aquatic plants include any one or more of emergent aquatic plants, floating leaf plants, submerged plants and floating plants, preferably emergent aquatic plants, and more preferably grasses.
According to the invention, roots, stems and leaves of the aquatic plants form complete and developed ventilation tissues, the oxygen requirement of organs and tissues is ensured, the developed root system tissues are ensured to absorb various nutrient substances and the like, the enrichment capability of crops is fully utilized, more particularly, the rhizome of the calamus is thick, the adaptability is strong, the cultivation is easy, the absorption effect on iron element is better, and the prepared biochar material has large specific surface area and high utilization efficiency.
In the step 1, the cultivation mode is preferably soilless cultivation, so that the land and biomass resources can be fully utilized, time and labor are saved, the concentration of ions is effectively controlled, and the influence of other ions such as copper ions on crops is reduced.
According to the invention, the culture solution for soilless culture is preferably Mo Lade nutrient solution, so that the growth requirement of aquatic plants can be met, and the use effect of the culture solution is exerted to the greatest extent.
In step 1, the aquatic plants are placed in an incubator with a culture broth and an iron source is added thereto, the iron source comprising an inorganic iron source, an organic iron source and/or a chelated iron, preferably a chelated iron.
The inventors found that the chelate iron is used as an iron source, the crops have higher enrichment of iron elements, and the inventors believe that the chelating agent can relieve the precipitation of trace elements combined with other ions in the nutrient solution, such as phosphate and carbonate ions, and overcome the problem of low absorption efficiency of the crops on the trace elements.
In a further preferred embodiment, the iron source is Fe-DTPA, and the Fe-DTPA has stable chemical property, is easily dissolved in water, has excellent chelating effect, can be absorbed by aquatic plants more easily, improves the utilization rate, and has better iron enrichment in crops.
The inventors found that the higher the Fe chelation value, the more favorable the plant to absorb and utilize fertilizer nutrients, and in order to achieve the use effect of the iron-rich biochar material, the concentration of iron element in the iron source compound is preferably 300-600 mg/mL, more preferably 360-500 mg/mL, for example 450mg/mL.
In step 1, the pH of the solution needs to be controlled to 4-7, preferably 5.5-6.5, more preferably 5.9-6.1 during the incubation; the pH-adjusting solvent is preferably a buffer solution of sodium carbonate/sodium bicarbonate and/or a buffer solution of sodium phosphate/sodium hydrogen phosphate, which is easy to control the pH and can provide trace elements.
And step 1-2, preparing the iron-rich biochar by utilizing the aquatic plants in the step 1-1.
According to a preferred mode, the aquatic plants in step 1-1 are subjected to staged sintering and laser scanning.
Preferably, the staged sintering comprises three stages of thermal decomposition, in particular:
the first stage: the temperature is 200-300 ℃, the heating rate is 5-12 ℃/min, and the heat preservation time is 20-40 min.
And a second stage: the temperature is 350-600 ℃, the heating rate is 8-14 ℃/min, and the heat preservation time is 20-50 min.
And a third stage: the temperature is 620-1000 ℃, the temperature rising rate is 7-13 ℃/min, and the heat preservation time is 30-90 min.
According to the invention, for the carbon element, as the sintering temperature is increased, the specific surface area and the total pore volume of the biochar are increased, the micropore volume is also increased, as the temperature is further increased, the branched carbon atom structure in the biochar is broken, and when the reaction continuously generates micropores, some micropores are expanded into mesopores and even macropores, and meanwhile, the micropore volume is slightly reduced along with collapse of the micropore wall. The temperature is too high, carbon is continuously ablated, and the yield of the biochar is reduced; for iron element, the iron-rich biochar prepared by the sintering method has good structural characteristics and electrochemical characteristics, the specific surface area is greatly increased, ferroferric oxide is generated at 500 ℃, martensite is generated by carbon reduction at 700 ℃, the martensite is gradually transformed into austenite at 900 ℃, and the particle size of zero-valent iron is about 80 nm.
The inventor researches and discovers that the carbon layer spacing is firstly reduced and then increased along with the increase of the temperature rising rate, and the mechanical strength of the corresponding carbon material is firstly increased and then reduced, so that the carbon material with higher mechanical property is preferably obtained, the temperature rising rate in the first stage is 5-12 ℃/min, the temperature rising rate in the second stage is 8-14 ℃/min, the temperature rising rate in the third stage is 7-13 ℃/min, and the durability of the biochar loaded with iron is the best; and too short or too long a holding time may also result in poor mechanical properties of the carbon material, and thus in low durability of the iron-loaded biochar.
In a further preferred manner, the first stage: the temperature is 250-320 ℃, the heating rate is 7-10 ℃/min, and the heat preservation time is 25-35 min; and a second stage: the temperature is 400-550 ℃, the heating rate is 9-12 ℃/min, and the heat preservation time is 25-40 min; and a third stage: the temperature is 700-900 ℃, the heating rate is 9-12 ℃/min, and the heat preservation time is 50-80 min.
In a still further preferred manner, the first stage: the temperature is 280 ℃, the heating rate is 8 ℃/min, and the heat preservation time is 30min; and a second stage: the temperature is 440 ℃, the heating rate is 11 ℃/min, and the heat preservation time is 25min; and a third stage: the temperature is 800 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 60min.
According to the invention, the laser scanning comprises scanning the sintered material by an infrared laser and/or an ultraviolet laser, and the scanned biochar material can better draw out electrons in the breathing process of microorganisms, and transfer the electrons to ionic heavy metal pollutants adsorbed on the surface of the biochar, so that the valence state of the biochar is reduced, the activity of the biochar is reduced, and finally the biochar is wrapped in the biochar iron oxide to realize solidification and stabilization of the biochar iron oxide.
According to the invention, in theory, the regular arrangement of atoms not only can improve the reactive sites, but also can improve the durability of the material, in order to ensure that the iron-rich biochar has higher activity, the invention carries out laser scanning treatment on the sintered iron-rich biochar, the mediating efficiency of the biochar obtained by laser scanning on the microbial electron transfer process is greatly improved by 52-58 times, the microbial biomass can reach 10.5-12.0 lg CFU/g, and the promotion is at least 1-2 orders of magnitude.
Preferably, the iron-rich biochar is scanned by an infrared laser firstly and then scanned by an ultraviolet laser, the wavelength of infrared light is long, the wavelength of ultraviolet light is short, atoms of the iron-rich biochar can be regularly arranged, and in order to meet the requirement of energy obtaining of the atoms for releasing electrons, the laser pulse intensity is 10 12 ～10 16 W/cm 2 Preferably 10 13 ～10 14 W/cm 2 More preferably 10 14 W/cm 2 。
According to the invention, the prepared iron-rich biochar has diffraction peaks of zero-valent iron at 44.8 degrees and ferricarbon compounds CFe at 43.1 degrees and 73.9 degrees 15.1 Diffraction peak, the specific surface area of the carbon material reaches 2300m 2 And/g.
And 2, preparing an improver by utilizing the iron-rich biochar prepared in the step 1 and soil humus.
In the step 2, the soil humus is obtained by decomposing any one or more raw materials of blue algae, livestock manure, straw, wood chips, rice hulls and plant wastes in soil through microorganisms.
According to the invention, as the soil humus possibly contains various harmful substances such as ova, fungi imperial, ascomycetes and the like, the fungi need to be sterilized before use, and the bactericide is not limited to any one of substances which can sterilize in the market, preferably carbendazim, and can effectively prevent and treat crop diseases caused by the fungi.
In the step 2, the weight ratio of the iron-rich biochar to the soil humus is (0.2-5): 1, preferably (0.8 to 3): 1, more preferably (1 to 2): 1.
according to the invention, as the iron-rich biochar and the soil humus both play a certain role in adsorbing and migrating heavy metals in the soil, in order to prevent the possibility of excessively increasing heavy metal leaching of the weight of the iron-rich biochar and/or the soil humus, the inventor researches and discovers that the weight ratio of the iron-rich biochar to the soil humus is (0.2-5): 1, in particular (1-2): 1, the adsorption and conversion effects of the soil humus synergistic biochar on heavy metal ions are most remarkable, the soil cation exchange capacity and the soil water holding capacity are effectively improved, and nutrient elements such as nitrogen and phosphorus of the soil are enriched.
According to the invention, optionally, the modifier obtained in the step 2 is ploughed to the heavy metal soil, thereby modifying the heavy metal soil. Wherein, the weight of the modifier used per kilogram of heavy metal soil is 100-600 mg, preferably 150-500 mg, more preferably 200-400 mg, at the moment, the heavy metal leaching can be prevented, and the soil quality can be effectively improved.
Examples
The invention is further described below by means of specific examples, which are however only exemplary and do not constitute any limitation on the scope of protection of the invention.
EXAMPLE 1 preparation of modifier
(1) Preparation of iron-rich biochar
Washing the incubator with clear water, placing Mo Lade culture solution and rhizoma Acori Calami in the incubator, and standing for 5 days until the concentration of iron element is 450mg.L -1 The Fe-DTPA solution in the incubator is added into the incubator for culturing for 80 days, the culture solution in the incubator is replaced in a period of 8 days in order to ensure the concentration of iron ions, the pH value of the aqueous solution in the incubator is kept in the range of 5.9-6.1 during the experiment, the roots, stems and leaves of plants are treated separately after the experiment is finished, and the plants are dried and ground to pass through a 100-mesh sieve to obtain the iron-rich biomass.
Placing the dried iron-rich biomass into a crucible, and placing the crucible into a tubular muffle furnace for sintering:
the first stage: the temperature is 280 ℃, the heating rate is 8 ℃/min, and the heat preservation time is 30min;
and a second stage: the temperature is 440 ℃, the heating rate is 11 ℃/min, and the heat preservation time is 25min;
and a third stage: the temperature is 800 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 60min.
The sintered carbon material is subjected to laser scanning,the method comprises the steps of firstly scanning by an infrared laser for one time, and then scanning by an ultraviolet laser for one time to obtain the iron-rich biochar, wherein the laser pulse intensity is 10 14 W/cm 2 。
XRD characterization of iron-rich biochar, wherein the iron-rich biochar has diffraction peak of zero-valent iron at 44.8 degrees, and has ferricarbon compound CFe at 43.1 degrees and 73.9 degrees 15.1 Diffraction peaks.
XPS characterization was performed on the iron-rich biochar with zero-valent nano-iron contents of 1.90%, 9.95% and 19.06 at the surface, 40nm depth and 80nm depth, respectively.
(2) Homemade soil humus
Collecting autumn fallen leaves, shearing the fallen leaves, mixing the fallen leaves with black soil, pouring rice washing water, covering the black soil on the fallen leaves, standing for half a year, turning and tamping for several times, sterilizing by using carbendazim before use to obtain humus soil, and purifying the humus of the soil, wherein the following steps are as follows:
placing a soil sample in a beaker, adding a hydrochloric acid solution with the concentration of 1M into the beaker, stirring the mixture for 20 hours at normal temperature, centrifugally filtering the mixture, removing supernatant, washing precipitate to be neutral, then carrying out treatment by using a sodium hydroxide solution with the concentration of 0.1M, stirring the mixture for 20 hours at normal temperature, centrifugally filtering the mixture, separating the supernatant, collecting supernatant, adding the hydrochloric acid solution with the concentration of 7M into the supernatant until the pH is 1, standing the mixture for 6 hours, and centrifugally separating the supernatant to obtain a lower layer of substance which is soil humus required by a subsequent modifier preparation.
(3) Preparation of modifier
And mixing the iron-rich biochar and soil humus in a weight ratio of 1.2:1 to obtain the modifier.
EXAMPLE 2 preparation of modifier
The method for preparing the modifier of this example is the same as that of example 1, except that:
and mixing the iron-rich biochar with soil humus in a weight ratio of 1.5:1 to obtain the modifier.
Comparative example
Preparation of modifier of comparative example 1
Comparative example 1 the procedure for preparing the modifier was the same as in example 1, except that: the preparation process of the iron-rich biochar does not carry out laser scanning.
Experimental example
Experimental example 1 heavy metal soil restoration ability detection
Drying loess soil (10 m×10m for sampling with sampling depth of 50 cm) in test field, rolling, naturally air drying, and sieving with 100 mesh sieve. Adding CuSO 4 、CrCl 3 、ZnSO 4 Aqueous solution, wherein copper addition amount was 400mg/kg soil (in Cu 2+ Calculated by the weight of the chromium, the dosage of the chromium is 200mg/kg of soil (Cr 3+ Calculated by the weight of Zn, the dosage of Zn is 300mg/kg of soil (calculated by Zn) 2+ Meter), stirring uniformly, aging for one week, naturally air-drying, crushing, sieving with 100 sieves, simulating polluted soil samples, and backfilling into an experimental field.
The modifiers obtained in examples 1 to 2 were each blended into the soil in an amount of 250mg/Kg of soil. After 30 days, planting magnolia multiflora at a plant row spacing of 15cm multiplied by 15cm, watering suitably after cutting, harvesting plants after 100 days, and culturing Cu in the simulated polluted soil sample 2+ 、Cr 3+ And Zn 2+ The content measurement pair of (2) is shown in Table 1.
Experimental example 2 heavy metal soil restoration ability detection
The experimental example has the same steps as the experimental example, and the difference is that: copper addition amount 500mg/kg soil (Cu 2+ Calculated by the weight, the chromium addition amount is 300mg/kg of soil (Cr 3+ Calculated by the weight of Zn, the dosage of Zn is 400mg/kg of soil (calculated by Zn) 2+ Meter), culture of Cu in simulated polluted soil sample 2+ 、Cr 3+ And Zn 2+ The content measurement pair of (2) is shown in Table 1.
Table 1 heavy metal soil remediation capability detection
Experimental example 3 Effect of modifier on microorganisms
The farmland soil used in this experimental example was from a corn cultivation layer of a long-term positioning test in Tongzhou area of Beijing city, the pH of the soil was 5.7, and the microbial biomass in the soil was measured to be 8.3lg CFU/g.
300g of farmland soil was mixed with 75mg of the modifier prepared in example 1, the moisture was adjusted to 40% of the field water holding capacity, and this was placed in a thermostatic incubator at 25℃for cultivation, the water was weighed weekly for replenishment, and samples were taken on day 50 during the cultivation experiment. Soil microbiological load was determined to be 11.6lg CFU/g and soil respiration was determined by the following method:
weighing 50g of the mixture of the cultivated farmland soil and the modifier into a 100mL brown wide-mouth bottle, regulating the water content of the soil to 60% of the field water-holding capacity, and sucking 0.l mol.L -1 10mL of NaOH solution was cultured in a brown jar at 25℃for 18h in a constant temperature incubator. After the completion of the culture, a phenolphthalein solution was added dropwise thereto with 0.l mol.L -1 The hydrochloric acid solution titrates until red color disappears, and the respiration rate of the soil is improved by 56% compared with that of farmland soil which is not subjected to any treatment.
300g of farmland soil was mixed with 75mg of the modifier prepared in comparative example 1, the water content was adjusted to 40% of the field water holding capacity, sealed with a preservative film, placed in a constant temperature incubator at 25℃9 for cultivation, weighed weekly for water replenishment, and sampled on day 50 during the cultivation experiment. Soil microbial biomass was determined to be 9.8lg CFU/g.
The invention has been described in detail with reference to preferred embodiments and illustrative examples. It should be noted, however, that these embodiments are merely illustrative of the present invention and do not limit the scope of the present invention in any way. Various improvements, equivalent substitutions or modifications can be made to the technical content of the present invention and its embodiments without departing from the spirit and scope of the present invention, which all fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims (1)

1. The method for effectively regulating and controlling the activity of heavy metals by utilizing biochar and soil humus is characterized by comprising the following steps of:
step 1, preparing iron-rich biochar;
washing the incubator with clear water, placing Mo Lade culture solution and rhizoma Acori Calami in the incubator, and maintaining the concentration of Fe element at 450 mg.L after 5 days -1 Adding Fe-DTPA solution into an incubator, culturing for 80 days, replacing the culture solution in the incubator with a period of 8 days in order to ensure the concentration of iron ions, keeping the pH value of the aqueous solution in the incubator within the range of 5.9-6.1 during the experiment, separately treating roots, stems and leaves of plants after the experiment is finished, drying and grinding the roots, stems and leaves, and sieving the stems and leaves with a 100-mesh sieve to obtain iron-rich biomass;
placing the dried iron-rich biomass into a crucible, and placing the crucible into a tubular muffle furnace for sintering:
the first stage: the temperature is 280 ℃, the heating rate is 8 ℃/min, and the heat preservation time is 30min;
and a second stage: the temperature is 440 ℃, the heating rate is 11 ℃/min, and the heat preservation time is 25min;
and a third stage: the temperature is 800 ℃, the heating rate is 10 ℃/min, and the heat preservation time is 60min;
the sintered charcoal material is scanned by laser, the infrared laser is scanned once, and then the ultraviolet laser is scanned once, so that the iron-rich biochar is obtained, wherein the laser pulse intensity is 10 14 W/cm 2 ；
XRD characterization of iron-rich biochar, wherein the iron-rich biochar has diffraction peak of zero-valent iron at 44.8 degrees, and has ferricarbon compound CFe at 43.1 degrees and 73.9 degrees 15.1 Diffraction peaks;
XPS characterization is carried out on the iron-rich biochar, wherein the zero-valent nano iron content at the surface, the 40nm depth and the 80nm depth of the iron-rich biochar are respectively 1.90%, 9.95% and 19.06%;
step 2, preparing an improver by utilizing the iron-rich biochar prepared in the step 1 and soil humus,
the soil humus is obtained by decomposing any one or more raw materials of blue algae, livestock manure, straw, wood dust and rice husk in soil by microorganisms,
the weight ratio of the iron-rich biochar to the soil humus is 1.2:1 or 1.5:1.
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