Release promoting agent for heavy metals in plant attached roots and application of release promoting agent

Abstract

The invention discloses a release promoting agent for heavy metals in plant attached roots and application. The release promoting agent comprises 33.5-36 mmol / L of organic acid, 250-250.3 g / L of a plant growth regulator, 1-10 mg / L of a flocculating agent, 15-30 g / L of a chelating agent, 80-120 mg / L of a pH regulator and 10-1000 mg / L of modified combined aluminum oxide. Wherein the plant growth regulator is composed of indolebutyric acid, trans-zeatin nucleoside, ethephon, a seaweed extract and chitin, and the organic acid is composed of salicylic acid and tartaric acid. The release efficiency of heavy metals in plant attached roots is improved, and the remediation process of soil heavy metal pollution is accelerated.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil heavy metal pollution remediation, and particularly relates to a heavy metal release promoter in plant epiphytic roots and its application. Background Art

[0002] Heavy metals in soil primarily originate from natural sources and from human interference. With the modernization of industry and agriculture and urbanization, this interference has led to excessive levels of heavy metals in soil, resulting in heavy metal pollution, a serious environmental problem. Heavy metals in soil are generally difficult to leach into water and are not decomposed by soil microorganisms. They are easily accumulated by organisms, leading to their gradual accumulation in the soil. Some heavy metals can even be converted into more toxic methyl compounds in the soil. Others can accumulate in the human body at harmful concentrations through the food chain, seriously endangering human health. Furthermore, compared with water pollution, heavy metal pollution in the soil is more difficult to control and poses a greater risk.

[0003] Currently, the main methods for remediating heavy metal contaminated soil include physical remediation, chemical remediation, and bioremediation. Physical remediation includes soil replacement, imported soil, separation remediation, and isolation. Chemical remediation includes chemical solidification, chemical leaching, and electrokinetic remediation. Bioremediation includes microbial remediation and phytoremediation. Phytoremediation utilizes naturally occurring organisms to purify the environment, minimizing environmental disturbance and offering low-cost, environmentally friendly advantages. Therefore, it has garnered widespread attention in recent years.

[0004] For example, Indian mustard and vetiver can transform Pb from an available state to a residual state, reducing the effectiveness of Pb in the soil and alleviating the damage of heavy metal Pb to the soil; Callitriche stagnalis, Potamogetonnatans, and Potamogeton pectinatus can filter uranium from water; Pteris vittata L. can enrich As, and Solanum nigrum L. and Sedum alfredii Hance can enrich Cd. Chinese patent CN108746169B discloses a method for repairing heavy metal cadmium contamination in soil. The method involves planting grain amaranth in soil free of heavy metal cadmium contamination. When its main root grows to more than 7 cm, the above-ground part of the grain amaranth is mowed. The mowed grain amaranth plants are then moved to soil to be repaired that is contaminated with heavy metal cadmium. The plants are mowed once around the time they bloom, and the entire plants are harvested again before they bloom, effectively enriching the heavy metal cadmium in the soil.

[0005] Because some plants have clonal physiological integration characteristics, there is the phenomenon of material transfer between the connected ramets of the same base plant, which can be well adapted to heterogeneous ecological environment, therefore can be used for the repair of soil heavy metal pollution, utilize Zhu Wu taproot to absorb soil heavy metals, then transfer to the water body by the epiphytic root on the ramet, directly reclaim heavy metals in the water body, and realize green soil repair. As disclosed in CN111672901B, a method for utilizing Alternanthera philoxeroides to repair lead contaminated soil is disclosed, which will plant Alternanthera philoxeroides on the electroplating plant sediment, and build a reservoir 5cm away from the sediment pool, artificially regulate the growth of Alternanthera philoxeroides, so that it will extend towards the reservoir, due to physiological integration effect, Alternanthera philoxeroides will patent the water body and release lead ions, and finally after cultivating a certain period, Na is put into the water body PO Carry out precipitation recovery, complete the transfer and precipitation recovery of lead ions, and realize the repair of lead contaminated soil.

[0006] However, when plants with clonal physiological integration characteristics are used to repair soil heavy metal pollution, the release efficiency of heavy metals from epiphytic roots often directly affects the remediation efficiency. Therefore, how to improve the release efficiency of heavy metals from epiphytic roots is an important factor in improving the green and efficient in situ recovery efficiency of soil heavy metals. Summary of the Invention

[0007] In response to the above technical problems, the present invention provides a heavy metal release promoter in plant epiphytic roots and its application, which improves the release efficiency of heavy metals in plant epiphytic roots and accelerates the remediation process of soil heavy metal pollution.

[0008] In order to achieve the above object, the present invention provides a heavy metal release promoter in plant epiphytic roots, comprising 33.5-36 mmol / L of organic acid, 250-250.3 g / L of plant growth regulator, 1-10 mg / L of flocculant, 15-30 g / L of chelating agent, 80-120 mg / L of pH regulator, and 10-1000 mg / L of modified combined alumina.

[0009] Preferably, the preparation method of the modified combined alumina comprises the following steps: (1) Bauxite is mixed with additives and then pre-treated for sintering; (2) crushing the pretreated material, mixing and dissolving it with alkali solution, dissolving it under high pressure to obtain sodium aluminate solution, and filtering and retaining the filtrate; (3) adding aluminum hydroxide seed crystals to the filtrate, cooling and crystallizing to obtain aluminum hydroxide; (4) While calcining aluminum hydroxide, polyacrylic acid and polyvinyl alcohol are added in batches to prepare modified combined alumina.

[0010] Further preferably, the additives in step (1) are limestone and soda ash.

[0011] Further preferably, the alkali solution in step (2) is sodium hydroxide solution.

[0012] Further preferably, the volume ratio of the aluminum hydroxide to the polyacrylic acid and polyvinyl alcohol in step (4) is (40-42): (10-16): (20-25).

[0013] More preferably, the volume ratio of the aluminum hydroxide to the polyacrylic acid and polyvinyl alcohol is 4:1:2.

[0014] More preferably, the concentration of the polyacrylic acid is 3-8 mg / L, and the concentration of the polyvinyl alcohol is 0.2-0.8 mg / L.

[0015] Preferably, the plant growth regulator consists of indolebutyric acid, trans-zeatin riboside, ethephon, seaweed extract and chitin.

[0016] Further preferably, the concentration of indolebutyric acid in the release-promoting agent is 100~1000 μmol / L, the concentration of trans-zeatin riboside in the release-promoting agent is 3 nmol / L, the concentration of ethephon in the release-promoting agent is 100 μmol / L, the concentration of seaweed extract in the release-promoting agent is 150 g / L, and the concentration of chitin in the release-promoting agent is 100 g / L.

[0017] Preferably, the organic acid consists of salicylic acid and tartaric acid.

[0018] Further preferably, the concentration of salicylic acid in the release-promoting agent is 0.5-2 mmol / L, and the concentration of tartaric acid in the release-promoting agent is 33-34 mmol / L.

[0019] Preferably, the flocculant is polyacrylamide, the pH regulator is ammonia-ammonium chloride solution, and the chelating agent is disodium EDTA, any one of EDTA and DTPA.

[0020] The present invention also provides an application of a heavy metal release promoter in plant epiphytic roots in plant remediation of heavy metal contaminated soil.

[0021] Preferably, the application method is to plant the main root of the plant with clonal integration characteristics in heavy metal contaminated soil, and then soak the epiphytic roots in a release-promoting agent to promote the release of heavy metals from the epiphytic roots.

[0022] Further preferably, the plant having clonal integration characteristics is any one or more of Alternanthera philoxeroides, Epipremnum aureum, and Chlorophytum comosum.

[0023] The beneficial effects of the present invention are: a modified combined alumina is prepared by using the Bayer process and the sintering method, and polyacrylic acid solution and polyvinyl alcohol solution are added to modify the combined alumina during the sintering process, so that the modified combined alumina has a more dispersed particle size and a higher heavy metal adsorption efficiency.

[0024] A release enhancer, formulated using modified alumina, plant growth regulators, and organic acids, can improve the release efficiency of heavy metals from plant epiphytic roots and accelerate the remediation of heavy metal-contaminated soils. The plant growth regulators contained in the release enhancer regulate hormones and the expression and activity of ABC transporters in plant cells, which are responsible for transporting heavy metal ions. The flocculants and chelating agents rapidly complex and precipitate heavy metals released into the water, reducing their concentration in the water and increasing the concentration difference between the root system and the surrounding area, thereby promoting the transfer of heavy metals from the epiphytic roots into the water.

[0025] The prepared release promoter is mainly used in plants with plant cloning and integration characteristics, including green ivy, water lily, spider plant, etc. The main roots of the plants are planted in heavy metal contaminated soil, and the epiphytic roots connected to them in a source-sink relationship are immersed in water. The heavy metals in the soil are enriched by the main roots of the plants, and then transmitted to the epiphytic roots through the source-sink relationship between the main roots and epiphytic roots. The epiphytic roots release them into the water in the form of root secretions, transferring the heavy metals in the soil to the water through the plant roots, thereby realizing soil heavy metal remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram of the repair status of experimental group 1 in Example 5.

[0027] Figure 2 This is a diagram of the repair status of control group 1 in Example 5.

[0028] Figure 3 This is a diagram showing the repair status of control group 2 in Example 5.

[0029] Figure 4 This is a diagram of the repair status of control group 3 in Example 5. DETAILED DESCRIPTION

[0030] The technical solutions of the present invention are further explained below with reference to the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be determined by the claims. Any modifications or substitutions made to the technical solutions of the present invention by those skilled in the art without creative effort shall fall within the scope of protection of the present invention.

[0031] Example 1 The modified combined alumina is prepared by the Bayer process and the sintering process in the following steps: (1) Bauxite (aluminum oxide content of 53%, impurities mainly silicon dioxide and iron oxide) is crushed to 60-100 mesh and then mixed with limestone and soda ash to form a spherical material (10-20 mesh), wherein the mass ratio of bauxite to limestone to soda ash is 10:2:1; (2) placing the spherical material in a rotary kiln, heating it to 1250°C and sintering it for 2.5 hours to obtain a pretreated material; (3) The pretreated material was crushed into 100 mesh, mixed with sodium hydroxide solution (concentration of 5 mol / L) and stirred to fully dissolve it to form a slurry; (4) The slurry is heated to 180°C and leached at 4 MPa to dissolve the alumina to form a sodium aluminate solution; (5) filtering the sodium aluminate solution to remove impurities and retaining the filtrate; (6) After the filtrate is cooled to 50°C, aluminum hydroxide seed crystals are added (the mass ratio of seed crystals to filtrate is 1:15), and aluminum hydroxide is obtained by crystallization and solid-liquid separation while stirring; (7) Aluminum hydroxide was placed in a calcining furnace and calcined at 1100°C for 4 h to prepare modified combined alumina, wherein 5 mL of polyacrylic acid solution (5 mg / L) and 10 mL of polyvinyl alcohol (0.5 mg / L) were added through a spray nozzle at 1 h, 2 h, and 3 h of calcination, respectively; and finally, the volume ratio of aluminum hydroxide to polyacrylic acid and polyvinyl alcohol was 4:1:2.

[0032] Example 2 The method and steps were the same as those in Example 1, except that step (7) was changed to adding 3.75 mL of polyacrylic acid solution (5 mg / L) and 8.6 mL of polyvinyl alcohol (0.5 mg / L) at 0.5 h, 1.5 h, 2.5 h, and 3.5 h of calcination, respectively, so that the final mass ratio of aluminum hydroxide to polyacrylic acid and polyvinyl alcohol was 40:10:23.

[0033] Example 3 The method and steps were the same as those in Example 1, except that step (7) was changed to adding 5 mL of polyacrylic acid solution (5 mg / L) and 7.8 mL of polyvinyl alcohol (0.5 mg / L) at 1 h, 2 h, and 3 h of calcination, respectively, so that the final mass ratio of aluminum hydroxide to polyacrylic acid and polyvinyl alcohol was 40:16:25.

[0034] Comparative Example 1 The method and steps are the same as those in Example 1, except that step (7) is changed to calcination at 1000°C for 4 hours to prepare the combined alumina.

[0035] Comparative Example 2 The method and steps were the same as those in Example 1, except that step (7) was changed to adding 5 mL of polyacrylic acid solution (5 mg / L) and 5 mL of polyvinyl alcohol (0.5 mg / L) three times during calcination (the total amount was the same as in Example 1) to prepare modified combined alumina.

[0036] Comparative Example 3 The method and steps were the same as those in Example 1, except that step (7) was changed to adding 5 mL of polyacrylic acid solution (5 mg / L) and 15 mL of polyvinyl alcohol (0.5 mg / L) three times during calcination to prepare modified combined alumina.

[0037] Results: The combined alumina prepared in the above examples and comparative examples was tested for adsorption performance using the activated carbon adsorption comparison method, and for flocculation performance using the beaker test. The results are shown in Table 1: Table 1 Physical and chemical properties of combined alumina

[0038] As can be seen from Table 1, the optimal volume ratio of aluminum hydroxide to polyacrylic acid solution and polyvinyl alcohol solution is 4:1:2. When the volume of polyacrylic acid or polyvinyl alcohol is significantly increased, the specific surface area of ​​the prepared combined alumina decreases significantly, the adsorption performance weakens, and the flocculation time also becomes longer. When only aluminum hydroxide is used for modification without using polyacrylic acid and polyvinyl alcohol, its specific surface area is very low, and the adsorption and flocculation properties deteriorate significantly, which is not conducive to the precipitation of heavy metals, thereby affecting the release of heavy metals from plant floating roots.

[0039] Example 4 Using Pothos as the experimental object, the soil contaminated by heavy metal Pb was repaired. The specific steps are as follows: (1) A Pb-contaminated test field to be remediated was selected in Xiling District, Yichang City, Hubei Province. The Pb content in the soil was 36.8 mg / kg. (2) Preparation of a release promoter: an organic acid, a plant growth regulator, a flocculant, the modified combined alumina prepared in Example 1, and a chelating agent were placed in water, and a pH regulator was added to adjust the pH value to 6.5 to prepare a release promoter, wherein the concentrations of the substances in the release promoter were salicylic acid 0.5 mmol / L, tartaric acid 5 g / L, ethephon 100 μmol / L, indolebutyric acid 100 μmol / L, trans-zeatin riboside 3 nmol / L, seaweed extract 150 g / L, chitin 100 g / L, polyacrylamide 1 mg / L, modified combined alumina 10 mg / L, Na2-EDTA 20 g / L, and the pH regulator was a 100 mg / L ammonia-ammonium chloride solution; (3) Preparation of aqueous solution: 120 g / L ammonium nitrate, 150 g / L potassium nitrate, 15 g / L calcium nitrate tetrahydrate, 15 g / L potassium chloride, 15 g / L magnesium sulfate heptahydrate, 10 g / L sodium dihydrogen phosphate, and 25 g / L ammonium ferric sulfate dodecahydrate are mixed to obtain a macroelement, which is then mixed with the release promoter prepared in step (2) while maintaining the final concentration constant, and the mixture is mixed to obtain an aqueous solution for epiphytic root growth; (4) The green radish was planted in the soil contaminated with Pb as described in step (1). One month later, the epiphytic roots of the green radish were placed in different aqueous solutions (with a depth of 5 cm). One week later, the water was collected to detect the concentration of heavy metals therein. The aqueous solutions were grouped as follows: Experimental group: the release enhancer in aqueous solution was prepared in step (2); Control group 1: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the combined alumina prepared in comparative example 1; Control group 2: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the modified combined alumina prepared in comparative example 2; Control group 3: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the modified combined alumina prepared in comparative example 3; Control group 4: the release-promoting agent in the aqueous solution is prepared in step (2), which only does not contain salicylic acid; Control group 5: the release-promoting agent in the aqueous solution is prepared in step (2), which does not contain salicylic acid and modified combined alumina; Control group 6: the release-promoting agent in the aqueous solution is prepared in step (2), but does not contain the modified combined alumina; Control group 7: the release-promoting agent in the aqueous solution was prepared in step (2), wherein only the concentration of the modified combined alumina was 1200 mg / L; Control group 8: The release enhancer in aqueous solution was prepared in step (2), except that the concentration of salicylic acid was changed to 2.3 mmol / L; Control group 9: the release-promoting agent in the aqueous solution is prepared in step (2), which does not contain seaweed extract and chitin; Blank control group: pure water.

[0040] The results showed that the Pb concentration in the experimental group was 13.2 μg / L, the Pb concentration in the control group 1 was 12.9 μg / L, the Pb concentration in the control group 2 was 13.0 μg / L, the Pb concentration in the control group 3 was 11.5 μg / L, the Pb concentration in the control group 4 was 10.3 μg / L, the Pb concentration in the control group 5 was 7.5 μg / L, the Pb concentration in the control group 6 was 8.4 μg / L, the Pb concentration in the control group 7 was 14.1 μg / L, the Pb concentration in the control group 8 was 13.7 μg / L, the Pb concentration in the control group 9 was 13.1 μg / L, and the Pb concentration in the blank control group was 7.4 μg / L.

[0041] Example 5 Using Alternanthera philoxeroides as the experimental object, the soil contaminated by heavy metal Cd was repaired. The specific steps are as follows: (1) In the loess soil contaminated by heavy metal Cd in a mine in Enshi Prefecture, Hubei Province, the Cd content in the soil was 12.59 mg / kg; (2) Preparation of a release promoter: an organic acid, a plant growth regulator, a flocculant, the modified combined alumina prepared in Example 1, and a chelating agent were placed in water, and a pH regulator was added to adjust the pH value to 6.5 to prepare a release promoter, wherein the concentrations of the substances in the release promoter were salicylic acid 1.0 mmol / L, tartaric acid 5 g / L, ethephon 100 μmol / L, indolebutyric acid 600 μmol / L, trans-zeatin riboside 3 nmol / L, seaweed extract 150 g / L, chitin 100 g / L, polyacrylamide 5 mg / L, modified combined alumina 100 mg / L, Na2-EDTA 20 g / L, and the pH regulator was a 100 mg / L ammonia-ammonium chloride solution; (3) Preparation of aqueous solution: 120 g / L ammonium nitrate, 150 g / L potassium nitrate, 15 g / L calcium nitrate tetrahydrate, 15 g / L potassium chloride, 15 g / L magnesium sulfate heptahydrate, 10 g / L sodium dihydrogen phosphate, and 25 g / L ammonium ferric sulfate dodecahydrate are mixed to obtain a macroelement, which is then mixed with the release promoter prepared in step (2) while maintaining the final concentration constant, and the mixture is mixed to obtain an aqueous solution for epiphytic root growth; (4) The green radish was planted in the loess soil contaminated with heavy metal Cd as described in step (1). One month later, the epiphytic roots of the green radish were placed in different aqueous solutions (depth of 5 cm). One week later, the water was collected to detect the concentration of heavy metals therein. The aqueous solutions were grouped as follows: Experimental group: the release enhancer in aqueous solution was prepared in step (2); Control group 1: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the combined alumina prepared in comparative example 1; Control group 2: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the modified combined alumina prepared in comparative example 2; Control group 3: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the modified combined alumina prepared in comparative example 3; Control group 4: the release-promoting agent in the aqueous solution is prepared in step (2), which only does not contain salicylic acid; Control group 5: the release-promoting agent in the aqueous solution is prepared in step (2), which does not contain salicylic acid and modified combined alumina; Control group 6: the release-promoting agent in the aqueous solution is prepared in step (2), but does not contain the modified combined alumina; Control group 7: the release-promoting agent in the aqueous solution was prepared in step (2), wherein only the concentration of the modified combined alumina was 1200 mg / L; Control group 8: The release enhancer in aqueous solution was prepared in step (2), except that the concentration of salicylic acid was changed to 2.3 mmol / L; Control group 9: the release-promoting agent in the aqueous solution is prepared in step (2), which does not contain seaweed extract and chitin; Blank control group: pure water.

[0042] The results showed that the Cd concentration in the experimental group was 8.9 μg / L, the Cd concentration in the control group 1 was 7.9 μg / L, the Cd concentration in the control group 2 was 8.2 μg / L, the Cd concentration in the control group 3 was 7.1 μg / L, the Cd concentration in the control group 4 was 7.8 μg / L, the Cd concentration in the control group 5 was 6.4 μg / L, the Cd concentration in the control group 6 was 6.9 μg / L, the Cd concentration in the control group 7 was 9.3 μg / L, the Cd concentration in the control group 8 was 9.1 μg / L, the Cd concentration in the control group 9 was 8.8 μg / L, and the Cd concentration in the blank control group was 6.2 μg / L.

[0043] Example 6 Using Chlorophytum as the experimental object, the soil contaminated by heavy metal Cu was repaired. The specific steps are as follows: (1) In the loess soil contaminated by heavy metal Cu at a large copper smelting enterprise in Huangshi City, Hubei Province, the Cd content in the soil was 350 mg / kg; (2) Preparation of a release promoter: an organic acid, a plant growth regulator, a flocculant, the modified combined alumina prepared in Example 1, and a chelating agent were placed in water, and a pH regulator was added to adjust the pH value to 6.0 to prepare a release promoter, wherein the concentrations of the substances in the release promoter were salicylic acid 2.0 mmol / L, tartaric acid 5 g / L, ethephon 100 μmol / L, indolebutyric acid 100 μmol / L, trans-zeatin riboside 3 nmol / L, seaweed extract 150 g / L, chitin 100 g / L, polyacrylamide 10 mg / L, modified combined alumina 1000 mg / L, Na2-EDTA 20 g / L, and the pH regulator was a 100 mg / L ammonia-ammonium chloride solution; (3) Preparation of aqueous solution: 120 g / L ammonium nitrate, 150 g / L potassium nitrate, 15 g / L calcium nitrate tetrahydrate, 15 g / L potassium chloride, 15 g / L magnesium sulfate heptahydrate, 10 g / L sodium dihydrogen phosphate, and 25 g / L ammonium ferric sulfate dodecahydrate were mixed to obtain a large number of elements, and then the release promoter prepared in step (2) was added and mixed to obtain an aqueous solution for epiphytic root growth; (4) The green radish was planted in the loess soil contaminated with the heavy metal Cu described in step (1). One month later, the epiphytic roots of the green radish were placed in different aqueous solutions. One week later, the water was collected to detect the concentration of heavy metals therein. The aqueous solutions were grouped as follows: Experimental group: the release enhancer in aqueous solution was prepared in step (2); Control group 1: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the combined alumina prepared in comparative example 1; Control group 2: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the modified combined alumina prepared in comparative example 2; Control group 3: the release-promoting agent in the aqueous solution is prepared in step (2), wherein the modified combined alumina is replaced by the modified combined alumina prepared in comparative example 3; Control group 4: the release-promoting agent in the aqueous solution is prepared in step (2), which only does not contain salicylic acid; Control group 5: the release-promoting agent in the aqueous solution is prepared in step (2), which does not contain salicylic acid and modified combined alumina; Control group 6: the release-promoting agent in the aqueous solution is prepared in step (2), but does not contain the modified combined alumina; Control group 7: the release-promoting agent in the aqueous solution was prepared in step (2), wherein only the concentration of the modified combined alumina was 1200 mg / L; Control group 8: The release enhancer in aqueous solution was prepared in step (2), except that the concentration of salicylic acid was changed to 2.3 mmol / L; Control group 9: the release-promoting agent in the aqueous solution is prepared in step (2), which does not contain seaweed extract and chitin; Blank control group: pure water.

[0044] The results showed that the Cu concentration in the experimental group was 24.3 μg / L, the Cu concentration in the control group 1 was 20.8 μg / L, the Cu concentration in the control group 2 was 21.3 μg / L, the Cu concentration in the control group 3 was 18.6 μg / L, the Cu concentration in the control group 4 was 17.9 μg / L, the Cu concentration in the control group 5 was 15.6 μg / L, the Cu concentration in the control group 6 was 16.2 μg / L, the Cu concentration in the control group 7 was 25.7 μg / L, the Cu concentration in the control group 8 was 24.4 μg / L, the Cu concentration in the control group 9 was 22.5 μg / L, and the Cu concentration in the blank control group was 14.8 μg / L.

Claims

1. A heavy metal release promoter in plant epiphytic roots, characterized by: Including organic acid 33.5-36mmol / L, plant growth regulator 250-250.3g / L, flocculant 1-10mg / L, chelating agent 15-30 g / L, pH regulator 80-120 mg / L, modified combined alumina 10-1000 mg / L.

2. The heavy metal release accelerating agent in plant floating roots according to claim 1, characterized in that: The preparation method of the modified combined alumina comprises the following steps: (1) Bauxite is mixed with additives and then pre-treated for sintering; (2) crushing the pretreated material, mixing and dissolving it with alkali solution, dissolving it under high pressure to obtain sodium aluminate solution, and filtering and retaining the filtrate; (3) adding aluminum hydroxide seed crystals to the filtrate, cooling and crystallizing to obtain aluminum hydroxide; (4) While calcining aluminum hydroxide, polyacrylic acid and polyvinyl alcohol are added in batches to prepare modified combined alumina.

3. The heavy metal release accelerating agent in plant floating roots according to claim 2, characterized in that: The volume ratio of the aluminum hydroxide to the polyacrylic acid and polyvinyl alcohol in step (4) is (40-42): (10-16): (20-25).

4. The heavy metal release accelerating agent in plant floating roots according to claim 3, characterized in that: The concentration of the polyacrylic acid is 3-8 mg / L, and the concentration of the polyvinyl alcohol is 0.2-0.8 mg / L.

5. The heavy metal release accelerating agent in plant floating roots according to claim 1, characterized in that: The plant growth regulator consists of indolebutyric acid, trans-zeatin riboside, ethephon, seaweed extract and chitin.

6. The heavy metal release accelerating agent in plant floating roots according to claim 1, characterized in that: The concentration of indolebutyric acid in the release-promoting agent is 100-1000 μmol / L, the concentration of trans-zeatin riboside in the release-promoting agent is 3 nmol / L, the concentration of ethephon in the release-promoting agent is 100 μmol / L, the concentration of seaweed extract in the release-promoting agent is 150 g / L, and the concentration of chitin in the release-promoting agent is 100 g / L.

7. The heavy metal release accelerating agent in plant floating roots according to claim 6, characterized in that: The organic acid consists of salicylic acid and tartaric acid.

8. The heavy metal release accelerating agent in plant floating roots according to claim 7, characterized in that: The concentration of salicylic acid in the release-promoting agent is 0.5-2 mmol / L, and the concentration of tartaric acid in the release-promoting agent is 33-34 mmol / L.

9. The heavy metal release accelerating agent in plant floating roots according to claim 1, characterized in that: The flocculant is polyacrylamide, the pH regulator is ammonia-ammonium chloride solution, and the chelating agent is any one of disodium EDTA, EDTA and DTPA.

10. Use of the heavy metal release promoter in plant epiphytic roots according to any one of claims 1 to 9 in phytoremediation of heavy metal contaminated soil.

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