CN105622290B - A kind of biochar soil heavy metal remediation agent and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of heavy metal contaminated soil conditioners, and particularly relates to a biomass charcoal soil heavy metal restoration agent and a preparation method and application thereof. The preparation method of the biomass charcoal soil heavy metal restoration agent comprises the following steps: (1) respectively drying the chicken manure or the oil tea shell to obtain dried chicken manure or oil tea shell; (2) crushing the chicken manure or the camellia oleifera shell dried in the step (1), heating to 450-550 ℃, then preserving heat for 1h +/-5 min, and cooling to obtain the biomass charcoal soil heavy metal restoration agent. The repairing agent can inhibit the bioavailability of heavy metals in soil, reduce the absorption amount of crops to the heavy metals in the soil, has rich nutrient substances, coordinated and lasting release of nutrient elements and high utilization efficiency of fertilizer nutrients, can effectively improve and fertilize the soil, improves the utilization rate of the fertilizer, increases the content of organic matters in the soil and improves the water and fertilizer retention capacity of the soil.

Description

A kind of biochar soil heavy metal remediation agent and preparation method and application thereof

technical field

The invention belongs to the technical field of heavy metal contaminated soil conditioners, and particularly relates to a biochar soil heavy metal repair agent and a preparation method and application thereof.

Background technique

In recent years, biomass carbonization is one of the research hotspots of biomass utilization and conversion technology. Biomass carbonization refers to the technology in which biomass (such as agricultural and forestry waste, livestock and poultry manure, etc.) is used as the target product under anoxic and certain temperature conditions. Biochar is mainly composed of aromatic hydrocarbons and elemental carbon or carbon with graphite structure, and contains more than 60% of carbon elements, including H, O, N, S and a small amount of trace elements. Biochar has a well-developed pore structure, large specific surface area, many negative charges, high aroma, strong adsorption characteristics and high stability.

Based on the characteristics of biomass charcoal and the idea of ecological circular agriculture, many scholars have proposed the idea of returning biomass charcoal to the field. Therefore, the effect of charcoal returning to the field on soil fertility, physicochemical properties and soil heavy metal adsorption has attracted increasing attention and has become a research hotspot.

Many studies have investigated the effect of returning biomass charcoal to the field, and preliminary progress has been made.

First of all, biomass char contains a large number of nutrients needed by plants, which is suitable for improving the fertility of poor soil. In addition to the high content of C, the content of N, P, K, Ca and Mg is also high in the biomass char. The nutrient content of the biomass char is higher than that of the agricultural and forestry biomass char, and it can be used as an alternative fertilizer.

Secondly, biochar can change the physical properties and structure of the soil, promote the interaction between soil biochemistry and physical chemistry, and improve soil fertility, thus playing a positive role in promoting crop growth. Biochar can reduce the bulk density and hardness of clay soil after returning to the field, thereby improving soil texture and farming performance; it can also promote the interaction of biochemistry and physicochemistry to improve soil fertility, and indirectly improve crop nutrient use efficiency, thereby improving crop nutrient use efficiency. Growth plays a positive role in promoting. The soil microbial biomass and organic carbon content can be significantly increased by returning biomass char to the field; the application of biomass char to the soil can increase the taproot length, root volume and root fresh weight of rice roots in the early stage of growth, and increase the total absorption area and activity of rice roots. Absorb the area, so as to achieve the effect of competing for production.

In addition, biochar has a significant adsorption effect on soil heavy metals (lead, cadmium, copper, etc.), reducing the availability of metals. Studies have shown that the soil treated with cotton stalk charcoal has a significant adsorption effect on cadmium. With the increase of the amount of cotton stalk charcoal added, the pH value of the soil increases, which weakens the competitiveness of H ⁺ , and the heavy metals are insoluble. exist in the form of hydroxides, carbonates or phosphates. Functional groups such as carboxylic acids in biomass char can promote the immobilization of heavy metals in the soil.

Livestock and poultry manure and agricultural and forestry waste are two major types of biomass carbon raw materials. At present, there are many studies on the preparation and application of biomass charcoal using crop straw as raw material in my country, and there are few studies on the preparation and application of biomass charcoal. Compared with agricultural and forestry biomass, livestock and poultry manure has little to do with seasons, and the scale of farms is conducive to the centralized utilization of manure. Keri et al. pointed out that the pyrolysis of animal feces can prepare biomass chars that are alkaline, contain a large amount of stable aromatic structures and are rich in inorganic minerals, and these biomass chars concentrate non-volatile minerals such as P and K, increasing the Soil nutrients and water retention. If the energy of livestock and poultry manure can be efficiently and fully converted into high-grade biomass charcoal, etc., it is of special significance for realizing the sustainable development of animal husbandry and alleviating the increasingly serious greenhouse effect.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies and shortcomings of the prior art, the primary purpose of the present invention is to provide a preparation method of a biochar soil heavy metal remediation agent.

Another object of the present invention is to provide a biochar soil heavy metal remediation agent prepared by the above preparation method.

Another object of the present invention is to provide the application of the above-mentioned biochar soil heavy metal remediation agent.

The object of the present invention is achieved through the following technical solutions:

A preparation method of a biochar soil heavy metal remediation agent, comprising the following steps:

(1) drying material chicken manure or camellia oleifera shell respectively, obtains dried chicken manure or camellia oleifera shell;

(2) pulverizing the dried chicken manure or Camellia oleifera shell in step (1), then heating to 450-550°C, keeping the temperature for 1h±5min, and cooling to obtain a biochar soil heavy metal remediation agent, namely chicken manure charcoal soil heavy metal remediation agent or Camellia oleifera shell charcoal soil heavy metal repair agent;

The drying temperature described in step (1) is preferably 40～65 ℃;

The drying time described in step (1) is preferably 20～28h;

The drying time described in the step (1) is further preferably 24h;

The moisture content of the dried chicken manure described in the step (1) is 3.84-6.25%;

The moisture content of the dried Camellia oleifera shell described in the step (1) is 7.54-8.23%;

The granule after the chicken manure described in the step (2) or Camellia oleifera shell is pulverized is no longer than 4mm long;

The heating rate of the heating described in step (2) is 16～18 ℃/min;

The biochar soil heavy metal remediation agent described in the step (2) contains the following moisture, volatile matter, ash, fixed carbon, C element, H element, N element, S element and O element by mass percentage:

In the above preparation method, the pyrolysis temperature and holding time are relatively critical, and have a greater impact on the final technical effect, such as the structure of carbon, industrial analysis, and elemental analysis;

Application of the biochar soil heavy metal remediation agent in the field of soil improvement;

The application of the biochar soil heavy metal repair agent in the field of soil improvement includes the application of the biochar soil heavy metal repair agent in potted soil and the application of the biochar soil heavy metal repair agent in field soil;

The application of the biochar soil heavy metal repair agent in potted soil comprises the following steps:

Planting in pots, the ratio of charcoal to soil is 20~110g/kg, and the biochar soil heavy metal remediation agent is applied to the soil, that is, 20g~110g biochar soil heavy metal remediation agent is added per kilogram of dry soil;

The application of the biochar soil heavy metal remediation agent in potted soil preferably comprises the following steps:

All the air-dried potted soil is sieved with 10 meshes, each pot is filled with 8.6kg soil (water content 12.8%, equivalent to 7.5kg dry soil weight), and the biomass charcoal soil heavy metal repair agent is 20～110g/kg according to the proportion of charcoal soil The standard is mixed into the soil, and the water is regularly replenished, and the plants are planted after aging for 14 to 30 days;

The application of the biochar soil heavy metal remediation agent in field soil comprises the following steps:

When the thickness of the soil ploughing layer (surface layer) is 0.30m, 0.48t-2.64t of biochar soil heavy metal remediation agent is applied to one mu of land;

The application of the described biochar soil heavy metal remediation agent in field soil preferably comprises the following steps:

The area of one mu of arable land is 667m ² , the thickness of the crop ploughing layer is 0.30m, and the bulk density of the air-dried soil is 1.2t/m ³ . The weight of the air-dried soil to be fertilized for one mu of land is calculated to be 24t, and the proportion of charcoal soil applied to the planting plot is 20~ 110g/kg of biochar soil heavy metal remediation agent, apply 0.48-2.64t of biochar soil heavy metal remediation agent to one mu of land; and regularly replenish water, and plant crops after aging for 14 to 30 days;

Compared with the prior art, the present invention has the following advantages and effects:

(1) Chicken manure, one of the raw materials of biomass charcoal, is selected for this project. The total amount of resources is huge, but its resource utilization technology is relatively scarce. The annual production of chicken manure in the breeding industry in Guangdong Province is nearly 10 million tons. The resource utilization, especially the rapid treatment technology, is lacking. The energy utilization rate is only 5% to 10%. Most of them are directly discharged into the environment without treatment, causing water bodies. Eutrophication, pollution of the atmosphere, spread of diseases, direct or indirect pollution of soil, and poisoning of crops. Pyrolysis of livestock and poultry manure to prepare biomass charcoal can improve the economic benefits of livestock and poultry manure, and at the same time partially solve the problem of utilization of livestock and poultry waste.

(2) The biochar heavy metal soil conditioner of the present invention inhibits the bioavailability of heavy metals in the soil, reduces the absorption of heavy metals in the soil by crops, and is rich in nutrients, the release of nutrients is coordinated and lasting, the fertilizer nutrient utilization efficiency is high, and it can effectively Improve and fertilize soil, improve fertilizer utilization rate, increase soil organic matter content, and improve soil water and fertilizer retention capacity.

Description of drawings

Figure 1 is the SEM morphological diagram of the heavy metal repair agent in chicken manure charcoal soil and the heavy metal repair agent in camellia shell charcoal soil; wherein, CMC: heavy metal repair agent in chicken manure charcoal soil; COOSC: heavy metal repair agent in camellia shell charcoal soil.

Figure 2 is the infrared spectrum of the heavy metal remediation agent in chicken manure charcoal soil.

Figure 3 is the infrared spectrum of Camellia oleifera shell charcoal soil heavy metal remediation agent.

Figure 4 shows the XRD patterns of the chicken manure charcoal soil before and after the reaction between the heavy metal remediation agent and copper ions.

Figure 5 shows the XRD patterns of the Camellia oleifera shell charcoal soil heavy metal remediation agent before and after the reaction with copper ions.

Figure 6 is the result analysis diagram of the effect of different contents of CMC on the speciation of heavy metals in Cu-contaminated soil, wherein, EX: acid exchangeable; FMO: bound to Fe and Mn oxide; OM: Bound to organic matter; RES: Residual.

Figure 7 is the result analysis diagram of the effect of different contents of COOSC on the form of heavy metals in Cu-contaminated soil; wherein, EX: acid exchangeable; FMO: bound to Fe and Mn oxide; OM: Bound to organic matter; RES: Residual.

Figure 8 is an analysis diagram of the change of copper concentration in Chinese cabbage after the heavy metal remediation agent in the chicken manure charcoal soil remediates the contaminated soil.

Figure 9 is an analysis diagram of the change of copper concentration in Chinese cabbage after the oil-tea shell charcoal soil heavy metal remediation agent remediates the contaminated soil.

Fig. 10 is an analysis diagram of the yield change of cabbage planted in copper-contaminated soil improved by chicken manure charcoal soil heavy metal remediation agent.

Figure 11 is an analysis diagram of yield changes of cabbage planted in copper-contaminated soil improved by Camellia oleifera shell charcoal soil heavy metal remediation agent.

Figure 12 is an infrared spectrum analysis diagram of the heavy metal remediation agent for chicken manure charcoal soil prepared at different pyrolysis temperatures.

Figure 13 is an infrared spectrum analysis diagram of the Camellia oleifera shell charcoal soil heavy metal remediation agent prepared at different pyrolysis temperatures.

Detailed ways

The present invention will be described in further detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

(1) Dry the chicken manure or Camellia oleifera shell at 65°C for 24 hours to obtain the dried chicken manure or Camellia oleifera shell; the moisture content of the dried chicken manure is 4.05%; the moisture content of the dried Camellia oleifera shell is 7.54%;

(2) pulverizing the dried chicken manure or camellia oleifera shells in step (1) with a pulverizer, so that the particles of the raw materials participating in the pyrolysis reaction are uniform, and the pulverized particles are no longer than 4 mm long; Put it into the biomass pyrolysis reaction device, heat it to 500°C, and the heating rate is 17°C/min; keep the temperature for 1 hour; then take it out when it is cooled to room temperature, and obtain the biochar soil heavy metal remediation agent, that is, chicken manure char soil heavy metal remediation agent or Camellia oleifera shell charcoal soil heavy metal repair agent;

(3) Perform industrial analysis, elemental analysis and nutrient analysis on the biochar soil heavy metal remediation agent prepared in step (2). The results are shown in Table 1 and Table 2.

Table 1 Industrial analysis and elemental analysis of soil heavy metal remediation agent prepared in Example 1

Table 2 Nutrient analysis of soil heavy metal remediation agent prepared in Example 1

(4) carry out the liquid phase adsorption characteristic analysis of the biochar soil heavy metal remediation agent prepared in step (2), wherein the methylene blue adsorption value of the chicken manure char soil heavy metal remediation agent is 24.7 mg/g, and the iodine adsorption value is 457.2 mg /g, and the copper ion adsorption value was 63.88 mg/g. The methylene blue adsorption value of Camellia oleifera shell charcoal soil heavy metal repair agent was 24.9 mg/g, the iodine adsorption value was 201.6 mg/g, and the copper ion adsorption value was 11.05 mg/g.

(5) As shown in Figure 1, the soil heavy metal remediation agent prepared in Example 1 is relatively smooth in appearance, has a scaly structure, has few openings on the surface, and causes part of the pore structure to collapse on the surface, which may be due to the pyrolysis process. It is caused by the boiling on the surface and the formation of bubbles before the middle volatiles leave the system.

(6) As shown in Table 3 and Figure 2, the heavy metal remediation agent of chicken manure charcoal soil has obvious absorption peaks near 1420cm ^-1 and 875cm ^-1 . The former is attributed to the antisymmetric stretching vibration of the CO bond, and the latter is the It is the out-of-plane deformation vibration of CO ₃ ^2- , and these two peaks are characteristic peaks of carbonate, indicating that there is a certain amount of CO ₃ ^2- . Chicken manure charcoal has a strong absorption peak near 1040cm ^-1 , which is attributed to the antisymmetric stretching vibration of PO bond, indicating that it contains a certain amount of phosphate.

Table 3 Infrared spectroscopy analysis of heavy metal remediation agent in chicken manure charcoal soil

Note: * in the table indicates the peak that can be identified, - indicates that the peak is not obvious or no peak here.

As shown in Table 4 and Figure 3, Camellia oleifera shell charcoal soil heavy metal remediation agent has a certain absorption peak near 1040cm ^-1 ~ 1007cm ^-1 , this peak is attributed to the antisymmetric stretching vibration of PO bond, indicating that it contains a certain amount of phosphoric acid salt, but the intensity of the peak is not as strong as that of the heavy metal remediation agent in chicken manure charcoal soil, indicating that the P content of the heavy metal remediation agent in camellia shell charcoal soil is not as strong as that of the heavy metal remediation agent in chicken manure charcoal soil.

Table 4 Infrared spectroscopy analysis of heavy metal remediation agent in Camellia oleifera shell charcoal soil

Note: * in the table indicates the peak that can be identified, - indicates that the peak is not obvious or no peak here.

(7) Crystal structure of biomass carbon - XRD

As shown in Figure 4, the heavy metal remediation agent in chicken manure charcoal soil before reacting with copper ions has a diffraction peak with high intensity near 28° and 41°. It is a characteristic peak of white phosphate rock ((Ca, Mg) ₃ (PO ₄ ) ₂ ). Compared with the heavy metal remediation agent in chicken manure charcoal soil before reacting with copper ions, the white phosphate rock ((Ca, Mg) ₃ (PO ₄ ) ₂ ) characteristic peaks weaken or disappear. Chicken manure charcoal soil heavy metal remediation agent has a certain amount of negatively charged phosphate groups and polyphosphates generated by pyrolysis, which participate in the adsorption reaction of carbon to metal ions, thus improving the composite ability of carbon to metal ions.

As shown in Fig. 5, compared with the heavy metal remediation agent of chicken manure charcoal soil, the heavy metal remediation agent of Camellia oleifera shell charcoal soil before the reaction with copper ions was at 2θ=28° and 2θ=41° of white phosphate rock ((Ca, Mg) ₃ (PO ₄ ) ₂ ) characteristic peak intensity was significantly weakened. After reacting with copper ions, the characteristic peaks of white phosphate rock ((Ca,Mg) ₃ (PO ₄ ) ₂ ) at 2θ=28° and 2θ=41° are also insignificant.

Example 2

(1) drying the chicken manure or Camellia oleifera shell at 40°C for 28h to obtain the dried chicken manure or Camellia oleifera shell; the moisture content of the dried chicken manure is 6.25%; the moisture content of the dried Camellia oleifera shell is 8.05%;

(2) pulverizing the dried chicken manure or camellia oleifera shells in step (1) with a pulverizer, so that the particles of the raw materials participating in the pyrolysis reaction are uniform, and the pulverized particles are no longer than 4 mm long; Put it into the biomass pyrolysis reaction device, heat it to 450°C, and the heating rate is 16°C/min; keep the temperature for 1 hour; then take it out when it cools to room temperature to obtain the biochar soil heavy metal remediation agent, that is, chicken manure char soil heavy metal remediation agent or Camellia oleifera shell charcoal soil heavy metal repair agent;

(3) Perform industrial analysis, elemental analysis and nutrient analysis on the biochar soil heavy metal remediation agent prepared in step (2). The results are shown in Table 5 and Table 6.

Table 5 Industrial analysis and elemental analysis of soil heavy metal remediation agent prepared in Example 2

Table 6 Nutrient analysis of soil heavy metal remediation agent prepared in Example 2

(4) carry out the liquid phase adsorption characteristic analysis of the biochar soil heavy metal remediation agent prepared in step (2), wherein the methylene blue adsorption value of the chicken manure charcoal soil heavy metal remediation agent is 24.7 mg/g, and the iodine adsorption value is 308.3 mg /g, and the copper ion adsorption value was 47.77 mg/g. The methylene blue adsorption value of Camellia oleifera shell charcoal soil heavy metal remediation agent was 22.3 mg/g, the iodine adsorption value was 190.6 mg/g, and the copper ion adsorption value was 8.87 mg/g.

Example 3

(1) drying the chicken manure or Camellia oleifera shell at 60°C for 20h to obtain the dried chicken manure or Camellia oleifera shell; the moisture content of the dried chicken manure is 4.80%; the moisture content of the dried Camellia oleifera shell is 7.85%;

(2) pulverizing the dried chicken manure or camellia oleifera shells in step (1) with a pulverizer, so that the particles of the raw materials participating in the pyrolysis reaction are uniform, and the pulverized particles are no longer than 4 mm long; Put it into the biomass pyrolysis reaction device, heat it to 550 °C, and the heating rate is 18 °C/min; keep it for 1 hour; then take it out when it is cooled to room temperature, and obtain the biochar soil heavy metal remediation agent, that is, chicken manure char soil heavy metal remediation agent or Camellia oleifera shell charcoal soil heavy metal repair agent;

(3) Perform industrial analysis, elemental analysis and nutrient analysis on the biochar soil heavy metal remediation agent prepared in step (2). The results are shown in Tables 7 and 8.

Table 7 Industrial analysis and elemental analysis of soil heavy metal remediation agent prepared in Example 3

Table 8 Nutrient analysis of soil heavy metal remediation agent prepared in Example 3

(4) carry out the liquid phase adsorption characteristic analysis of the biochar soil heavy metal remediation agent prepared in step (2), wherein, the methylene blue adsorption value of the chicken manure charcoal soil heavy metal remediation agent is 24.7 mg/g, and the iodine adsorption value is 320.34 mg /g, and the copper ion adsorption value was 50.72 mg/g. The methylene blue adsorption value of Camellia oleifera shell charcoal soil heavy metal repair agent was 22.6 mg/g, the iodine adsorption value was 198.4 mg/g, and the copper ion adsorption value was 10.81 mg/g.

Example 4 The effect of biochar soil heavy metal remediation agent on heavy metal contaminated soil remediation

(1) The adsorption of copper to the soil treated by the biochar soil heavy metal remediation agent is the coexistence of physical and chemical adsorption, and the desorption efficiency after adsorbing heavy metals is low. Heavy metal remediation agents were applied to the soil to study the changes of Cu ions in the polluted soil.

The biochar soil heavy metal remediation agent prepared in Example 1 was applied to the soil according to different proportions of charcoal soil; the field water capacity was maintained at 65% for 14 days; the experimental design is shown in Table 9:

Table 9 Experimental design of the adsorption of heavy metals in polluted soil by biochar soil heavy metal remediation agent

Note: CMC, chicken manure charcoal soil heavy metal repair agent; COOSC, Camellia oleifera shell charcoal soil heavy metal repair agent.

(2) Analysis of the changes in the occurrence of Cu in the polluted soil by applying different amounts of biochar to the soil

Among the forms of heavy metals in soil, the bioavailability of metals is in the order of acid extractable state > iron and manganese bound state > organic bound state > residue state;

As shown in Figure 6, the acid extractable state of copper decreased by 3.35%-12.39% compared with the control group (CK) after 14 days of soil culture with different contents of chicken manure charcoal soil heavy metal remediator (CMC). The oxidatively bound state of iron and manganese decreased by 7.86%-41.68%; the organic bound state increased by 24.10%-54.66%; except for CMC-110, which increased the copper residue state by 3.17%, other additions of CMC reduced the copper residue state content. 1.51%～10.59%.

As shown in Figure 7, adding different contents of Camellia oleifera shell charcoal soil heavy metal remediation agent (COOSC), compared with the control group, the acid extractable state of soil Cu decreased by 1.39%-3.78%; 7.08%～33.11%; the organic combined state increased by 15.13%～29.68%; except COOSC-20 which increased the residual state by 5.86%, other additions of COOSC decreased the copper residual state content by 2.64%～6.08%.

Therefore, chicken manure charcoal soil heavy metal remediation agent or Camellia oleifera shell charcoal soil heavy metal remediation agent is applied to the soil, providing a large amount of organic matter to the soil, promoting the formation of organically bound copper in the soil, and reducing the bioavailability of copper in the soil.

Example 5 Effect of biochar soil heavy metal remediation agent on Cu absorption value of Chinese cabbage

(1) after applying the biochar soil heavy metal remediation agent to the soil for 14 days by different charcoal soil ratios (Embodiment 4), plant pakchoi, and harvest after 60 days:

(2) Changes of copper concentration in pakchoi after remediation of contaminated soil with biochar soil heavy metal remediation agent

As can be seen from Figure 8, cabbage was planted 14 days after the application of chicken manure charcoal soil heavy metal remediation agent. From the perspective of the Cu absorbed by cabbage, as the amount of chicken manure charcoal applied per pot of 1kg of soil increased, the amount of cabbage absorbed per kilogram of cabbage increased. The Cu also decreased gradually, and the total amount of Cu absorbed by each pot also decreased gradually. The mass ratio of heavy metal remediation agent to soil in chicken manure charcoal soil increased from 2% to 14%, the absorption per kilogram of Chinese cabbage decreased from 41.91 mg/kg to 26.40 mg/kg, and the total absorption per pot of Chinese cabbage decreased from 0.17 mg/kg. pot decreased to 0.04mg/pot, indicating that in the case of copper-contaminated vegetable field soil, the amount of heavy metal remediation agent used for repairing chicken manure charcoal soil gradually increased, and the effect of inhibiting the absorption of copper by pakchoi was more obvious. The main reason is that with the increase of the amount of heavy metal remediation agent added in chicken manure charcoal soil, the acid extractable state and iron and manganese oxidation state of copper in the soil are reduced, and the organic binding state of copper is improved. absorbed. Therefore, chicken manure charcoal soil heavy metal remediation agent can improve copper-contaminated vegetable field soil and inhibit the bioavailability of copper.

It can be seen from Figure 9 that the Cu concentration of the upper part of the root of the pakchoi after 14 days of application of the Camellia oleifera shell charcoal soil remediation agent did not decrease significantly compared with the control. When the soil ratio increased from 2% to 14%, the Cu adsorption value per kilogram of Chinese cabbage was 70.4%, 66.6%, 76.3%, 14.7% and 13.5% higher than that of the control without carbon addition; at 2% When the addition amount is 5%, the total amount of Cu adsorption per pot of Chinese cabbage is higher than the comparison value, and when the addition amount is 8% to 14%, the total amount of Cu adsorption per pot of Chinese cabbage is lower than the comparison value. It shows that under this pollution condition, the heavy metal remediation agent of Camellia oleifera shell charcoal soil can inhibit the absorption of Cu in the soil by cabbage when the addition amount is 8% to 14%.

(3) The effect of biochar soil heavy metal remediation agent on the harvest of Chinese cabbage

It can be seen from Figure 10 that the chicken manure charcoal soil heavy metal remediation agent was applied to the copper-contaminated vegetable field soil remediation after 14 days to plant pakchoi, and 60 days to harvest. Except for the addition of 2% CMC (CMC-20), which increased the total harvest of pakchoi by 4.21%, other additions of 5% to 14% CMC all decreased the total amount of pakchoi, and the decline range was 20.62% to 63.20%.

It can be seen from Figure 11 that the Camellia oleifera shell charcoal soil heavy metal remediation agent was applied to the copper-contaminated vegetable field soil remediation after 14 days to plant pakchoi, and 60 days to harvest. Except for the addition of 2% COOSC (COOSC-20), the total harvest of pakchoi increased by 15.52%, and the addition of 5% to 14% COOSC reduced the total amount of pakchoi, and the decline range was 5.54% to 33.04%.

To sum up, adding an appropriate amount of biochar soil heavy metal repair agent can promote the growth of plants and provide trace elements, but excessive addition of biochar soil heavy metal repair agent will inhibit the growth of plants. From the perspective of the effect of biochar on soil nutrients, it is further explained that the biochar soil heavy metal remediation agent is used as a heavy metal contaminated soil remediation agent. The source, input and proportion of biomass char materials are adjusted according to soil nutrients and crop fertilizer requirements. The comprehensive application of biochar soil heavy metal remediation agent and appropriate farming management measures is the fundamental way to solve the increase of trace elements in heavy metal soil repaired by biochar soil heavy metal remediation agent.

Comparative Example

(1) Dry the chicken manure or Camellia oleifera shell at 65°C for 24 hours to obtain the dried chicken manure or Camellia oleifera shell; the moisture content of the dried chicken manure is 4.05%; the moisture content of the dried Camellia oleifera shell is 7.54%;

(2) pulverizing the dried chicken manure or camellia oleifera shells in step (1) with a pulverizer, so that the particles of the raw materials participating in the pyrolysis reaction are uniform, and the pulverized particles are no longer than 4 mm long; Put it into the biomass pyrolysis reaction device, heat it to 350 °C or 650 °C, and the heating rate is 17 °C/min; keep the temperature for 1 hour; then take it out when it is cooled to room temperature, and obtain the biochar soil heavy metal remediation agent, namely chicken manure carbon soil Heavy metal repair agent or Camellia oleifera shell carbon soil heavy metal repair agent.

As can be seen from Figure 12 and Figure 13, the biochar soil heavy metal remediation agent prepared at the pyrolysis temperature of 500 °C in Example 1 is compared to the biochar prepared at the pyrolysis temperature of 350 °C or 650 °C in the comparative example. Biochar soil heavy metal remediation agent, the biochar soil heavy metal remediation agent obtained in Example 1 with a pyrolysis temperature of 500 ° C has a strong absorption peak near 1040cm ^-1 , indicating that there is a lot of phosphate here, and its peak It is obviously stronger than the absorption peak of biomass char pyrolyzed at 350 °C or 650 °C. These oxygen-containing functional groups make the surface of biomass charcoal exhibit hydrophilic, hydrophobic and acid-base buffering capabilities, which determine the function of biomass charcoal in liquid phase adsorption.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (6)

1. The application of the biomass charcoal soil heavy metal restoration agent in the field of soil improvement is characterized in that:

The biomass charcoal soil heavy metal restoration agent is prepared by the following method:

(1) Respectively drying the chicken manure or the oil tea shell to obtain dried chicken manure or oil tea shell;

(2) Crushing the chicken manure or the camellia oleifera shells dried in the step (1), heating to 450-550 ℃, preserving heat for 1h +/-5 min, and cooling to obtain a biomass charcoal soil heavy metal restoration agent, namely a chicken manure charcoal soil heavy metal restoration agent or a camellia oleifera shell charcoal soil heavy metal restoration agent;

The water content of the dried chicken manure in the step (1) is 3.84-6.25%; the water content of the dried oil tea shells is 7.54-8.23%;

The biomass charcoal soil heavy metal restoration agent in the step (2) comprises the following water, volatile matters, ash, fixed carbon, C elements, H elements, N elements, S elements and O elements in percentage by mass:

2. The application of the biomass charcoal soil heavy metal restoration agent in the field of soil improvement is characterized in that:

The drying temperature in the step (1) is 40-65 ℃; the drying time is 20-28 h.

3. The application of the biomass charcoal soil heavy metal restoration agent in the field of soil improvement is characterized in that:

The heating rate in the step (2) is 16-18 ℃/min.

4. The application of the biomass charcoal soil heavy metal restoration agent in the field of soil improvement is characterized in that: the method comprises the application of the biomass charcoal soil heavy metal restoration agent in potting soil and the application of the biomass charcoal soil heavy metal restoration agent in field soil.

5. The application of the biomass charcoal soil heavy metal restoration agent in the field of soil improvement is characterized in that:

The application of the biomass charcoal soil heavy metal restoration agent in potting soil comprises the following steps:

The method is characterized in that potted planting is adopted, and a biomass charcoal soil heavy metal restoration agent is applied to soil according to the carbon soil proportion of 20-110 g/kg.

6. The application of the biomass charcoal soil heavy metal restoration agent in the field of soil improvement is characterized in that:

The application of the biomass charcoal soil heavy metal restoration agent in field soil comprises the following steps:

When the thickness of the cultivated soil layer is 0.30m, 0.48 t-2.64 t of the biomass charcoal soil heavy metal restoration agent is applied to one mu of land.

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