CN115889423A

CN115889423A - Method for enhancing biodegradability of micro-plastic through biochar

Info

Publication number: CN115889423A
Application number: CN202310014689.2A
Authority: CN
Inventors: 杨瑞; 王忆飞; 王欣媛; 孟阿晓; 张安洁; 梁园
Original assignee: Wuchang Institute of Technology
Current assignee: Wuchang Institute of Technology
Priority date: 2023-01-05
Filing date: 2023-01-05
Publication date: 2023-04-04

Abstract

The invention discloses a method for enhancing the biodegradability of a micro plastic by biochar, which relates to the field of the biodegradation of the micro plastic and solves the problems that the existing micro plastic is difficult to degrade and seriously affects and harms human health. The method has the characteristics that the micro-plastic can be effectively degraded by microorganisms, and the degradation efficiency is greatly improved.

Description

Method for enhancing biodegradability of micro-plastic through biochar

Technical Field

The invention relates to the field of microbial plastic biodegradation, in particular to a method for enhancing the biodegradability of a microbial plastic through biochar.

Background

The plastic is a synthetic long-chain high polymer material [1]. Since plastics have excellent physical and chemical properties such as strength, transparency, water resistance, etc., synthetic plastics have been widely used for packaging products such as foods, medicines, cosmetics, detergents, chemicals, etc. Plastics have become an integral part of human life, and there is currently about 30% of plastics used for packaging worldwide and still spread at rates up to 12% per year.

The micro plastic is a plastic particle with the diameter less than 5 mm and is a main carrier causing pollution. The microplastic is small, which means a higher specific surface area (specific surface area refers to the surface area per unit mass of porous solid material) and the greater the specific surface area, the greater the capacity for adsorbing contaminants.

Firstly, persistent organic pollutants such as polychlorinated biphenyl and bisphenol A (which are often hydrophobic, i.e., they are not readily soluble in water and are not readily diluted by water) already exist in the environment, and once the micro-plastics and the pollutants meet, they just aggregate to form an organically-polluted sphere. Micro-plastics correspond to a ride that becomes a contaminant, both of which can wander around in the environment.

With the widespread use of plastics, micro plastics are also continuously detected in various places, especially in soil, which further results in the transmission to animals including human body, affecting and endangering human health, and because of their chemical stability, the insoluble plastics are high molecular compounds polymerized by addition polymerization or polycondensation reaction, the main component of the micro plastics is resin, which is a high molecular compound not mixed with various additives, the basic properties of the plastics are mainly determined by the nature of the resin, the plastics are chemically stable, do not rust, have good impact resistance and strong corrosion resistance, do not react with acid and alkali, and are resistant to chemical corrosion, so that the plastics are difficult to degrade and are troublesome to treat. Thus, a method for enhancing the biodegradability of a micro plastic by means of biochar is proposed.

Disclosure of Invention

The invention aims to provide a method for enhancing the biodegradability of a micro plastic through biochar, and solves the problems that the existing micro plastic is difficult to degrade, seriously influences and harms human health.

In order to achieve the purpose, the invention provides the following technical scheme: a method for enhancing the biodegradability of a micro-plastic by means of biochar, comprising the following steps:

s1: mixing charcoal, corn straw balance biochar and plant ash according to the proportion of 2;

s2: removing surface soil in pollution-free soil for 10-20 cm, digging the soil with the surface removed, detecting soil humidity, and controlling the humidity to be 40-50%;

s3: mixing the biochar mixed in the S1 with the soil with the humidity of 40-50% in the S2 in a stirrer, controlling the rotating speed of the stirrer to be 60r/min,

stirring for 2-3h;

s4: after the stirring is finished in the S3, adding corn starch into the stirrer, continuously stirring for 30-60min, and introducing into a shading container;

s5: covering a shading container, standing at 25-35 deg.C for 1-2 weeks, opening the shading container, pouring out the soil mixture, stacking the soil mixture, and naturally drying at 25-35 deg.C to humidity of 20-30%;

s6: transferring the dried soil mixture to a soil ground containing micro-plastics, sowing, turning the soil while the soil of the soil block is sowed by a soil turning machine after sowing is finished, covering a layer of black shading plastic cloth on the ground surface, and standing for 3-6 months;

s7: removing the black shading plastic cloth in 3-6 months, and then naturally improving the soil for 12-18 months.

Preferably, in the S2, when the humidity is less than 40-50%, the water can be sprayed for wetting, and when the humidity is more than 40-50%, the air can be naturally dried.

Preferably, the mixing ratio of the biochar in S3 to the soil with the humidity of 40-50% in S2 is 1.

Preferably, the ratio of the addition amount of the corn starch in the S4 to the soil with the humidity of 40-50% is 1.

Preferably, in S5, after natural air drying, mixing is performed again to sufficiently mix the surface layer mixture and the inner layer mixture to ensure uniform humidity.

Compared with the related art, the method for enhancing the biodegradability of the micro-plastic through the biochar has the following beneficial effects:

1. the invention provides a method for enhancing the biodegradability of a micro plastic by biochar, one of the important reasons for improving the abundance of microorganisms by biochar is that the biochar provides a proper habitat for soil microorganisms by a porous structure and a rich specific surface area, and the biochar is applied to the decomposition of the microorganisms on the micro plastic by the microorganisms so as to improve the content of the microorganisms in the soil and improve the decomposition efficiency.

2. The invention provides a method for enhancing the biodegradability of a micro plastic by biochar, which is characterized in that firstly, a microorganism releases hydrolase to be specifically combined with a receptor on the surface of the plastic, so that the plastic is hydrolyzed into fatty acid or lipid substances with the molecular weight of less than 500; the second step is that the small molecule acid or lipid substance generated in the former process enters the microorganism to participate in the physiological metabolic process, thereby further decomposing into water and carbon dioxide and providing energy for cells.

The method has the characteristics that the micro-plastic can be effectively degraded by microorganisms, and the degradation efficiency is greatly improved.

Detailed Description

The technical solutions will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The first embodiment is as follows:

the invention provides a technical scheme that: a method for enhancing the biodegradability of a micro-plastic by means of biochar, comprising the following steps:

s1: mixing charcoal, corn straw balance biochar and plant ash according to the ratio of 2;

s3: mixing the biochar mixed in the S1 with the soil with the humidity of 40-50% in the S2 in a stirrer at the rotating speed of 60r/min,

stirring for 2-3h;

And in the S2, when the humidity is less than 40-50%, water spraying and wetting can be carried out, and when the humidity is more than 40-50%, air drying can be carried out naturally.

The mixing ratio of the biochar in S3 to the soil with the humidity of 40-50% in S2 is 1.

In S4, the proportion of the addition amount of the corn starch to the soil with the humidity of 40-50% is 1.

And S5, after natural air drying, mixing again to ensure that the surface layer mixture and the inner layer mixture are fully mixed and the humidity is consistent.

In the present embodiment:

the organic matter is composed of a variety of nitrogens including amino acids, amines, amino sugars, and the like. When the organic matter is pyrolyzed, these structures agglomerate to form heterocyclic nitrogen structures, and these inert N cannot be directly used for plant growth. Although some biochar (such as manure) has a high total N content of 6.4g/kg, its mineralized nitrogen (ammonia nitrogen and nitrate nitrogen) content is very low and can be ignored compared with the mineral N in soil. Thus, from an N supply perspective, biochar can increase soil organic nitrogen content and cannot directly provide plant growth mineral nitrogen. The method is mainly realized by changing the retention and conversion of the N element, on one hand, the N element substance is adsorbed and retained by utilizing the porous characteristic and the huge specific surface area of the charcoal applied to the soil, on the other hand, the physical and chemical properties of the soil are changed, the diversity, the abundance and the activity of microorganisms in the turnover process of the N element are directly or indirectly influenced, and then the circulation of the N element substance of the soil is influenced.

Biochar can provide a good environment for microorganisms, especially bacteria, to mineralize and dissolve organic and inorganic phosphorus, so that the P is utilized and absorbed by plants. It is presently believed that biochar may function by (1) the relatively high content of P in the ash of biochar; the content of effective P in the soil can be increased after the fertilizer is added into the soil; (2) CEC, the pH value of soil, surface charge, fe, al, ca and Mg contents and forms are changed by the biochar, and meanwhile, the chemical behavior and the effectiveness of P can be influenced by the abundant pore volume and the specific surface area of the biochar.

And also comparative experiments were made as follows:

taking the same amount of soil containing the micro-plastics, measuring the content of the micro-plastics to be 2941.3/kg, dividing the soil into five groups of A/B/C/D/E, each group of soil is 10kg, respectively mixing four groups of A/B/C/D with the local soil mixtures with different qualities, respectively, wherein the quality of the local soil mixtures added into the four groups of A/B/C/D is 1kg, 1.5kg, 2kg and 2.5kg, respectively, placing the four groups in a shading outdoor environment for 6 months, not adding the local soil mixtures into the group E, respectively measuring the content of the micro-plastics divided into the five groups of A/B/C/D/E again after 6 months, and respectively obtaining 2563.3/kg, 2411.3/kg and 3.2221 micro-plastics

2193.3/kg, 2918.4/kg;

from the above data, it is understood that the degradation processing ability for the micro plastic in the soil, for example, peaks when the ratio of the added own soil mixture to the treated soil containing the micro plastic is 1.

Claims

1. A method for enhancing the biodegradability of a micro plastic by using biochar is characterized by comprising the following steps:

s3: mixing the biochar mixed in the step S1 with the soil with the humidity of 40-50% in the step S2 in a stirrer, and controlling the rotating speed of the stirrer to be 60r/min for stirring for 2-3h;

s6: transferring the dried soil mixture to a soil ground containing micro-plastics, sowing, turning the soil while the soil is turned by a soil turning machine after the sowing is finished, covering a layer of black shading plastic cloth on the ground surface, and then placing for 3-6 months;

2. The method for enhancing the biodegradability of micro plastics through biochar as claimed in claim 1, wherein said S2 can be wetted by sprinkling water when the humidity is less than 40-50%, and can be dried by natural air when the humidity is more than 40-50%.

3. A method for enhancing the biodegradability of micro plastics through biochar as claimed in claim 1, said S3 mixing biochar with S2 soil with humidity between 40-50% in a ratio of 1.

4. The method for enhancing the biodegradability of micro plastics through biochar according to claim 1, wherein the ratio of the addition amount of corn starch to the soil with moisture content between 40-50% in S4 is 1.

5. The method for enhancing the biodegradability of micro plastics through biochar as claimed in claim 1, wherein after natural air drying in S5, mixing is performed again to make the surface layer mixture and the inner layer mixture mixed well to ensure the consistency of humidity.