Method for repairing heavy metal contaminated soil based on carboxylated carbon nano-sol reinforced plants

Abstract

The invention relates to a method for enhancing phytoremediation of heavy metal contaminated soil on the basis of carboxylated carbon nanosol (CCN), in particular to a method for enhancing phytoremediation of heavy metal contaminated soil on the basis of CCN. The carboxylated carbon nano sol is only composed of carbon, hydrogen and oxygen. The carboxylated carbon nano sol synthesized under the low-voltage and low-energy preparation conditions has excellent nano characteristics, can enhance the stress resistance of plants, and can enhance the heavy metals enriched in the soil by the plants, so that the heavy metal contaminated soil is repaired.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation and application thereof, and specifically relates to a method for strengthening phytoremediation of heavy metal contaminated soil based on carboxylated carbon nanosol. Background Art

[0002] With the development of society and industry, soil pollution has become an important issue that seriously endangers the global environmental quality and human survival and development. Heavy metal pollution is the focus of soil pollution prevention and control. It is widely derived from non-point source pollution such as agricultural production, domestic waste and industrial waste, and has the characteristics of concealment, latency, irreversibility and long-term nature. For example, cadmium (Cd) and lead (Pb) are highly toxic whether in elemental or soluble form. Therefore, the treatment and remediation of heavy metal contaminated soil is a hot research topic in the scientific community.

[0003] Conventional remediation methods, such as soil replacement, soil leaching, chemical fixation, and electrochemical treatment, have limitations such as large engineering workload, high cost, and easy secondary pollution. Plant extraction technology, through the absorption, extraction, and transportation of heavy metals by hyperaccumulators, enriches the effective heavy metals in the environment in the roots, stems, and leaves of plants. It can not only extract heavy metals from the soil for reuse, but also repair large areas of contaminated sites through plant community models. It is an important ecological means of in-situ purification of heavy metal contaminated sites that is economical, eco-friendly, and highly sustainable.

[0004] Nanomaterials are widely used in the environmental field due to their unique nano properties, high adsorption performance and biological functionality. Carboxylated carbon nanosol (CCN) is small in size, high in oxygen content, and has a large number of surface active sites. It can capture heavy metals in the soil through ion exchange, electrostatic attraction and complexation reaction, and drive the migration of heavy metals into the plant body as a carrier, which can improve the rhizosphere microenvironment and soil nutrient structure, thereby promoting plant growth, stress resistance and the ability to repair soil heavy metals. Therefore, the nano-plant coupling remediation technology based on functional carbon nanosol-enhanced plant remediation can break through the bottleneck problem of low efficiency of plant extraction technology, which is of great significance for the ecological restoration of soil heavy metal pollution. Summary of the invention

[0005] The purpose of the present invention is to provide a method for strengthening plant repair of heavy metal contaminated soil based on carboxylated carbon nanosol. Using graphite plates as electrodes and acid solution as electrolyte, carboxylated carbon nanosol is synthesized by low-voltage electrolysis. The material preparation process is economical and simple, environmentally friendly, and the material has high biosafety and is suitable for environmental applications. The material is used for coupling plants to remove heavy metals in soil.

[0006] The technical solution of the present invention is as follows: A method for strengthening phytoremediation of heavy metal contaminated soil by carboxylated carbon nanosol, the preparation method of the carboxylated carbon nanosol comprises the following steps: (1) Using 15*18 cm graphite plates as electrodes, nitric acid and water in a ratio of 0.1:1 were added as electrolyte solution, the pH was adjusted, and carboxylated carbon nanosols were prepared by low-voltage direct current electrolysis. The reaction lasted for 5 days.

[0007] (2) The resulting solution was allowed to stand overnight, the supernatant was collected, and the solution was centrifuged at 10,000 r / min for 15 min. The supernatant was collected to synthesize a carboxylated carbon nanosol.

[0008] in: The purity of graphite involved in step (1) is >85%.

[0009] The DC power supply voltage involved in step (1) is 15V.

[0010] The beneficial effects of the present invention are: The carboxylated carbon nanosol of the technical solution has low production cost, simple operation, large output, and is composed of a variety of combinations of only three elements of carbon, hydrogen, and oxygen, with carbon as the skeleton, and covers various forms of organic functional groups. Carboxylated carbon nanosol is rich in organic functional groups such as carboxyl and hydroxyl, has a large specific surface area, has good heavy metal adsorption and activation performance, ion regulation performance and biological affinity, and can thus improve the efficiency of plant repair of lead. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the physical and chemical properties of soil after carboxylated carbon nanoremediation; Figure 2 is the repair efficiency diagram of carboxylated carbon nanotubes; Figure 3 is the IR graph of carboxylated carbon nanosol; Figure 4 is the Raman graph of carboxylated carbon nanosol; Figure 5A This is the full XPS spectrum of carboxylated carbon nanosol; Figure 5B is the C1s XPS spectrum of carboxylated carbon nanosol; Figure 5C is the O1s XPS spectrum of carboxylated carbon nanosol; Figure 6 This is a graph of the plant adsorption lead content of carboxylated carbon nanosol; Figure 7 is the plant fresh weight graph of carboxylated carbon nanosol; Figure 8 This is a graph showing the efficiency of soil zinc restoration by plants using carboxylated carbon nanosol; DETAILED DESCRIPTION

[0012] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention. Example

[0013] (1) A 15*20 cm graphite plate was used as an electrode, and a 10% nitric acid solution was added as an electrolyte solution. The low-voltage direct current electrolysis method was continued for 5 days to prepare a carboxylated carbon nano-sol. (2) The obtained solution was filtered and the supernatant was taken to obtain a carboxylated carbon nano-sol. (3) Marigold was transplanted into Cd-contaminated soil with a Cd content of 12 mg / kg, and CCN was irrigated with 30 mg / kg of soil. After 45 days of remediation, the soil was harvested and the remediation effect was evaluated. (4) The Cd concentration in the soil and the physical and chemical properties of the soil were measured by inductively coupled plasma mass spectrometry. (5) The results showed that the addition of CCN promoted the absorption of nutrients by plants, and the Cd removal rate reached 48.96%, an increase of 15.89%. Example

[0014] (1) A 15*20 cm graphite plate was used as an electrode, and a 10% nitric acid solution was added as an electrolyte solution. The low-voltage direct current electrolysis reaction lasted for 5 days to prepare a carboxylated carbon nanosol. (2) The obtained solution was filtered and the supernatant was taken to obtain a carboxylated carbon nanosol. 1 mL of the solution was dried and its mass was measured. (3) Sunflowers that had been cultivated for 60 days were transplanted into soil with a lead concentration of 940 mg / kg, and CCN with a concentration of 5 mg / kg was added. After 30 days of cultivation, the sunflowers were harvested and soil samples were collected. (4) The lead concentration in the soil was measured by inductively coupled plasma mass spectrometry, and the amount of Pb adsorbed by the plant was 0.48 g. Example

[0015] (1) A 15*20 cm graphite plate was used as an electrode, and a 10% nitric acid solution was added as an electrolyte solution. The low-voltage direct current electrolysis reaction lasted for 5 days to prepare a carboxylated carbon nanosol. (2) The obtained solution was filtered and the supernatant was taken to obtain a carboxylated carbon nanosol. 1 mL of the solution was dried and its mass was measured. (3) Sunflowers that had been cultivated for 60 days were transplanted into soil with a lead concentration of 940 mg / kg, and CCN with a concentration of 15 mg / kg was added. After 30 days of cultivation, the sunflowers were harvested and soil samples were collected. (4) The lead concentration in the soil was measured by inductively coupled plasma mass spectrometry, and the amount of Pb adsorbed by the plant was 0.29 g. Example

[0016] (1) A 15*20 cm graphite plate was used as an electrode, and a 10% nitric acid solution was added as an electrolyte solution. The low-voltage direct current electrolysis reaction lasted for 5 days to prepare a carboxylated carbon nanosol. (2) The obtained solution was filtered and the supernatant was taken to obtain a carboxylated carbon nanosol. 1 mL of the solution was dried and its mass was measured. (3) Sunflowers that had been cultivated for 60 days were transplanted into soil with a lead concentration of 940 mg / kg, and CCN with a concentration of 5 mg / kg was added. After 30 days of cultivation, the sunflowers were harvested and soil samples were collected. (4) The lead concentration in the soil was measured by inductively coupled plasma mass spectrometry, and the amount of Pb adsorbed by the plant was 0.40 g. Example

[0017] (1) A 15*20 cm graphite plate was used as an electrode, and a 10% nitric acid solution was added as an electrolyte solution. The low-voltage direct current electrolysis reaction lasted for 5 days to prepare a carboxylated carbon nanosol. (2) The obtained solution was filtered and the supernatant was taken to obtain a carboxylated carbon nanosol. 1 mL of the solution was dried and its mass was measured. (3) Sunflowers that had been cultivated for 60 days were transplanted into soil with a zinc concentration of 114 mg / kg, and the leaves were sprayed with CCN at a concentration of 8 mg / kg. After 30 days of cultivation, the sunflowers were harvested, the fresh weight of the plants was measured, and soil samples were collected. (4) The zinc concentration in the soil was measured by inductively coupled plasma mass spectrometry. The zinc removal rate of the plants reached 56.42%, an increase of 28.79%. And the fresh weight of the plants increased by 84.14%.

Claims

1. A method for preparing a carboxylated carbon nanosol, characterized in that: The material that can provide carbon, hydrogen and oxygen is used as raw material, and is synthesized in one step under the condition of low-pressure electrolysis. After impurities are separated, the powder is obtained by drying.

2. The method for preparing a carboxylated carbon nanosol according to claim 1, wherein: The material providing the carbon source is natural graphite or artificial graphite with a purity of >85%; the oxygen source and hydrogen source are derived from low-concentration acid aqueous solutions, including nitric acid, hydrochloric acid or sulfuric acid aqueous solutions in a concentration range of 0.1%-25%.

3. The method for preparing a carboxylated carbon nanosol according to claim 1, wherein the electrolysis range of the low-voltage electrolysis is 1-20 V.

4. The method for preparing a carboxylated carbon nanosol according to claim 1, characterized in that: The carboxylated carbon nanosol should include three elements of carbon, hydrogen and oxygen, and at least include active functional groups or ions such as hydroxyl, carboxyl and carbonyl.

5. The carboxyl carbon nanosol according to claim 1, characterized in that: The carboxylated carbon nanosol includes an aqueous solution or a powder; the powder can be directly prepared into an aqueous solution by adding water.

6. A carboxylated carbon nanosol according to claim 3, characterized in that: The carboxylated carbon nanosol has a carbon skeleton of sp2 graphite structure, and a large number of carboxyl groups and other functional groups exist on the surface and / or edge of the carbon skeleton.

7. A method for strengthening phytoremediation of heavy metal contaminated soil based on carboxylated carbon nanosol, characterized in that: The carboxylated carbon nanosol described in any one of claims 1 to 5 is applied to plant leaves for spraying or rhizosphere application to improve the efficiency of plant repair of heavy metal contaminated soil.

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