CN108296276B

CN108296276B - Method for rapidly passivating soil cadmium based on amino acid complexation redistribution principle

Info

Publication number: CN108296276B
Application number: CN201810007510.XA
Authority: CN
Inventors: 李永涛; 何澍然; 柯美国; 张玉龙; 张振; 王进进; 周文迪
Original assignee: South China Agricultural University
Current assignee: South China Agricultural University
Priority date: 2018-01-04
Filing date: 2018-01-04
Publication date: 2020-10-09
Anticipated expiration: 2038-01-04
Also published as: CN108296276A

Abstract

The invention discloses a method for quickly passivating soil cadmium based on an amino acid complexing redistribution principle. The invention can effectively and quickly passivate heavy metal cadmium (Cd) in soil by singly applying glycine²⁺) While passing through glycine ingeniouslyComplexing and combining the complex to redistribute the solid phase and the liquid phase of the soil, so that more heavy metals are distributed to the soil solid, and finally the aim of quickly and efficiently passivating the heavy metals is fulfilled. The method for passivating the heavy metal cadmium provided by the invention is simple and low in cost, does not need complex material combination, does not need an energy-consuming production process, and does not need an external solid material as a precipitator. And no secondary pollution and negative influence on the environment exist, and the method is environment-friendly.

Description

Method for rapidly passivating soil cadmium based on amino acid complexation redistribution principle

Technical Field

The invention belongs to the field of environmental protection and soil heavy metal treatment, and particularly relates to a method for quickly passivating soil cadmium based on an amino acid complexing redistribution principle.

Background

The soil quality and food safety of China are on the trend of increasingly deteriorating, 3 hundred million acres of cultivated land in China are threatened by heavy metal pollution, wherein Cd pollution is the most serious, and the standard exceeding point is located at the top of the whole country. Cd element often goes into farmland soil along with mining, mine acid water irrigation, atmosphere subside, and the unreasonable use of chemical fertilizer and pesticide in the farmland also makes Cd constantly accumulate in farmland soil. This poses a great threat to the agricultural production and income increase and the grain safety in China.

The soil Cd has wide pollution range, strong mobility, concealment, various pollution types and great control difficulty, and after pollution, the Cd migrates into an underground water layer on the one hand, forms a toxic action on crops on the other hand, and even accumulates in the crops, and the Cd is poisoned by entering human bodies through agricultural products and drinking water, thereby affecting human health.

Once the soil is contaminated with Cd, it is difficult to completely eliminate it. Because Cd has the characteristics of easy migration, incapability of being decomposed by microorganisms, biological enrichment and the like, the commonly used restoration method for Cd pollution of farmland soil at present comprises a Cd element removal technology, a Cd element passivation technology, a phytoremediation technology and an agricultural regulation and control measure. In the existing treatment method, a modifying reagent or a method required by a Cd element removal technology is high in cost, inorganic and organic passivators adopted by a Cd element passivation technology can often damage the structure and the function of soil, a phytoremediation technology can be influenced by factors such as climate and soil type to cause that some high-enrichment plants cannot grow in a specific area, a large amount of inorganic fertilizer required by an agricultural regulation technology can cause soil hardening and acidification, and the physicochemical property of the soil is influenced, so that the growth of crops is finally hindered.

Although some of the above methods can alleviate the Cd pollution to a certain extent, all have their limitations, and the Cd pollution problem needs to be solved urgently.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of high cost and potential soil hardening and acidification caused by the fact that Cd-polluted farmland soil is repaired in the prior art, and provides the application of glycine in rapid passivation of cadmium in soil based on the principle of complex redistribution.

Another object of the present invention is to provide a method for rapidly passivating cadmium in soil based on the redistribution principle of amino acid (glycine) complexation. The method has the advantages of low cost of raw materials, good effect, quick response, simple and convenient operation, environmental friendliness, no secondary pollution and the like, and is suitable for large-area application of polluted farmland soil.

The purpose of the invention is realized by the following technical scheme:

the glycine is applied to quickly passivate cadmium in soil based on the principle of complex redistribution.

In the application, the rapid inactivation of cadmium (Cd) in soil can be realized by independently applying glycine²⁺) (ii) a The glycine is used as a cadmium passivator for quickly passivating cadmium in soil.

The complex redistribution principle refers to that: amino acid (glycine) reacts with Cd in soil²⁺While the complex is formed, the complex is redistributed in the solid-liquid two phases of the soil, so that more heavy metals are further addedDistributing the heavy metal to soil solids to finally achieve the purpose of passivating the heavy metal.

A method for rapidly passivating cadmium in soil based on glycine complexation redistribution principle comprises the following steps:

glycine is added to the soil contaminated with heavy metals and the treatment is carried out for at least 3 hours.

The concentration of the glycine added into the soil is preferably 700-800 mg N/kg; more preferably 750 mgN/kg.

The glycine is preferably glycine in a solution state.

The addition amount of the glycine solution is preferably 1: 60-3: 40 of the volume-to-mass ratio (mL/g) of the glycine solution to the soil; further preferably, the volume-to-mass ratio is 1: 15.

The concentration of the glycine solution is preferably 10-45 mg N/mL; further preferably 10-25 mg N/mL; more preferably 11.25mg N/mL.

The time of said treatment is preferably at least 24 hours.

The temperature of the treatment is preferably 25. + -. 5 ℃.

The treatment is preferably constant temperature treatment; the isothermal treatment is preferably carried out in an isothermal biological incubator.

The soil moisture content of the soil is preferably 60 +/-10% of the field moisture capacity.

The soil is preferably plough layer soil; further preferably, the thickness of the layer soil is 20 cm.

The action mechanism of the invention is as follows: the invention creatively utilizes the glycine to react the glycine with Cd in the soil²⁺Complexing to form an organometallic compound; meanwhile, the invention skillfully and effectively takes the soil as a complex adsorbent, so that the complex is redistributed in the solid-liquid two phases of the soil, further more heavy metals are distributed on the soil solid, and the aim of passivating the heavy metals is finally achieved.

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

1. the invention provides a brand-new idea for passivating heavy metal cadmium (Cd)

The research team of the invention finds that the heavy metal cadmium (Cd) in the soil can be effectively and quickly passivated by singly using the glycine²⁺). The invention skillfully complexes and redistributes the solid-liquid two phases of the soil by combining the glycine and the complex, so that more heavy metals are distributed on the soil solid, and finally the aim of passivating the heavy metals quickly and efficiently is achieved.

2. The method for passivating heavy metal provided by the invention is simple and low in cost

The heavy metal passivation method does not need complex material combination, does not need energy-consuming production process, does not need an exogenous solid material as a precipitator, and directly ensures that the heavy metal is adsorbed on the soil solid through complex redistribution.

3. The technical scheme of the invention is environment-friendly, rapid and efficient

According to the invention, glycine is added into the farmland soil polluted by typical Cd, the Cd passivating effect is obvious and the speed is high, and Cd is treated for 48 hours²⁺The reduction is 67%. Different from other heavy metal pollution treatment methods, the method is simple to operate, high in passivation speed and practical in the aspect of treating the soil pollution problem. The invention is convenient to use and friendly to the environment. The amino acids themselves are not toxic and the degradation rate in soil decreases with time, reaching 78.38% completion in the first 24 hours, at which time the reaction tends to stabilize. Basically, no secondary pollution exists and no negative influence is caused to the environment.

Drawings

FIG. 1 is a structural diagram of glycine.

FIG. 2 is a result analysis diagram of different time periods of action of available Cd after glycine is added to soil.

Fig. 3 is a graph analyzing the results of the release rate of carbon dioxide release after glycine was added to the soil.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Example 1

Glycine (structure shown in fig. 1, available from alatin reagent) was formulated as a glycine solution and added to soil contaminated with Cd. The physicochemical properties of the soil are shown in Table 1.

TABLE 1 basic physicochemical Properties of the soil tested

And (4) rapidly (3h) passivating Cd in typical polluted farmland soil by adding amino acid.

Two treatments, CK (control) and TA (glycine), were provided, each in 12 replicates. Fresh soil to be tested (said soil to be tested is sampled from the soil of the plough layer with the thickness of 20 cm) which is equivalent to the weight of air-dried soil is weighed and put into a 100mL polytetrafluoroethylene beaker. The glycine concentration is 750mg N kg^-1Adding soil, and adjusting the water content to 60% of the maximum water capacity of the soil field by using deionized water; control treatment was the addition of an equal amount of deionized water. Culturing in a constant temperature biological incubator at 25 ℃. After the experiment is started, sampling is carried out for 0 hour and 3 hours respectively, 3 times of treatment are randomly selected and repeated each time, the samples are put into a polyethylene plastic bag, and the content of Cd in an effective state is measured, wherein the method mainly comprises the following steps: drying a soil sample in a vacuum freeze dryer, rapidly grinding under ice bath condition, sieving by a 1mm sieve, weighing 1.000g, placing in a 50mL plastic centrifuge tube, adding 15mL of 0.1mol L^-1In (C) is₂Covering the solution, shaking at 25 deg.C and 200rpm for 1h, centrifuging at 6000rpm for 10min, filtering with whatman No. 42 filter paper, collecting supernatant, and measuring Cd²⁺The content (namely the content of Cd in an effective state) is determined by the following method: shuran He, Qin Lu, Wenyan Li, et al, fans controlling cadmium and lead activities in differential material-derived sources from the Pearl River Basin, Chemosphere,182 (2017): 509 + 516, doi: chemosphere.2017.05.007.

Results As shown in Table 2 and FIG. 2, CaCl was obtained 3 hours after the soil samples were treated₂The reduction in-Cd was 11%. CaCl in soil₂The concentration of-Cd decreases with the addition time of glycine, and is different from other heavy metal pollution treatment methodsThe method is characterized in that the method can rapidly and effectively passivate Cd in the soil.

TABLE 2 passivation effect of soil samples after 3 hours treatment

Time (h)	CaCl₂-Cd(mg kg^-1)	CaCl₂-Cd passivation rate (%)
			3	0.1352	11

Example 2

This example further examines the extent of inactivation of Cd contamination in typical farmland soils by glycine addition.

3 repeats of CK (control) and TA (glycine) treatment groups related to the method in the embodiment 1 are selected, sampling is carried out for 6 h and 12h after the experiment begins respectively, and the other operation steps are the same as those in the embodiment 1.

The results are shown in Table 3 and FIG. 2, with CaCl after 6 hours and 12 hours of glycine addition₂the-Cd reduction was 16%, 27%, respectively.

TABLE 3 passivating Effect of Glycine on contaminated soil after treatment

Time (h)	CaCl₂-Cd(mg kg^-1)	CaCl₂-Cd passivation rate (%)
			6	0.1271	16
12	0.1100	27

Example 3

This example further examines the extent of inactivation of Cd contamination in typical field soils by the glycine addition referred to in example 2.

3 replicates of the two treatment groups CK (control) and TA (glycine) referred to in example 1 were selected and sampled 24 and 48 hours after the start of the experiment to determine the content of Cd in the available state.

The results are shown in Table 4, CaCl 24 and 48 hours after the addition of glycine₂the-Cd is reduced by 30% and 65% respectively.

TABLE 4 passivating Effect of Glycine on contaminated soil after treatment

Time (h)	CaCl₂-Cd(mg kg^-1)	CaCl₂-Cd passivation rate (%)
			24	0.1068	30
48	0.0532	65

Example 4

This example examines the degradation rate of glycine in typical farmland soil to which example 1 relates.

The degradation rate of glycine in soil was characterized by measuring the carbon dioxide release from soil by selecting 3 replicates of the two treatment groups CK (control) and TA (glycine) referred to in example 1. The carbon dioxide release amount of the soil is measured by an alkali liquor absorption titration method (store escape, Haomingde, Zhanqiong and the like, 2015, influence of long-term fertilization in 26 years on carbon and nitrogen of soil microorganisms and soil respiration, ecology, 5: 1445-.

The result is shown in figure 3, glycine is also rapidly converted into carbon dioxide in the soil along with the addition time, the mineralization rate is reduced along with the time, the reaction is completed in the first 24 hours to reach 78.38%, the reaction tends to be stable, and the influence on the release amount of carbon dioxide in the soil is minimal, so that the method is convenient to use and environment-friendly.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The application of glycine in quickly passivating cadmium in soil based on the complexing redistribution principle is characterized in that: the glycine is used as a cadmium passivator for quickly passivating cadmium in soil; the complex redistribution principle refers to that: glycine and Cd in soil²⁺When the complex is formed, the complex is redistributed in the solid-liquid two phases of the soil, further more heavy metals are distributed on the soil solid, and finally the purpose of passivating the heavy metals is achievedIn (1).

2. A method for rapidly passivating cadmium in soil based on glycine complexation redistribution principle is characterized by comprising the following steps:

separately adding glycine into the soil polluted by the heavy metal, and treating for at least 3 hours;

the concentration of the glycine added into the soil is 700-800 mg N/kg;

the treatment temperature is 25 +/-5 ℃; the soil water content of the soil is 60 +/-10% of the field water capacity;

the soil is plough layer soil.

3. The method for rapidly passivating cadmium in soil based on glycine complexation redistribution principle according to claim 2, wherein:

the glycine is in a solution state.

4. The method for rapidly passivating cadmium in soil based on glycine complexation redistribution principle according to claim 2, wherein:

the treatment is constant temperature treatment.