An acidic cadmium-contaminated soil cadmium control and selenium-increasing soil modifier and a preparation method thereof

Abstract

The present application relates to a kind of acidic cadmium-contaminated soil control cadmium selenium-enriched soil modifier and its preparation method, relate to the field of agricultural technology.The soil modifier raw material includes the following mass parts of components: modified diatomite 45-60 parts, wood ash 25-35 parts, slaked lime 10-15 parts, chitin 1-2 parts and allantoin 4-5 parts.The cadmium control selenium-enriched modifier of the present application can effectively capture cadmium ions in soil, inhibit its migration to the surrounding environment, reduce the harm of soil cadmium;It can also reduce the fixation of selenium in soil, increase the effective selenium content in soil, and comprehensively achieve the effect of cadmium control and selenium enrichment, and is easy to use, has great application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural technology, in particular to an acid cadmium-contaminated soil cadmium control and selenium-increasing soil conditioner and a preparation method thereof. BACKGROUND

[0002] Cadmium is a toxic metal element, and cadmium pollution can cause soil dysfunction and soil degradation, and also has different degrees of adverse effects on the growth and development of plants, seriously threatening the normal growth and metabolism of plants. Cadmium is absorbed by plants, enriched and transferred into the food chain to harm human life and health. The cadmium-contaminated soil needs extremely long time to be repaired by nature, and the treatment by artificial soil replacement and soil improvement has significant effect, but the engineering quantity is extremely large and it is difficult to realize large-area popularization. Therefore, it is of great significance to realize cadmium control in cadmium-contaminated areas and avoid cadmium content exceeding the standard in crops to ensure food safety.

[0003] Selenium is an essential trace element for human body, and has many effects such as peroxide scavenging, anti-aging and prevention of cardiovascular and cerebrovascular diseases. Deficiency of selenium can cause many diseases in human body. Studies have shown that eating biological selenium is the safest and most effective way to supplement selenium. Selenium-rich crops have great development potential, broad market prospects and good economic benefits. However, the phenomenon of associated heavy metal cadmium often occurs in selenium-rich soil, which leads to the phenomenon that the selenium-rich soil is seriously over-standard in heavy metal cadmium, so that the agricultural products planted in the selenium-rich soil resources appear cadmium pollution, which brings significant safety risk of agricultural products for eating and greatly limits the development and utilization of natural selenium-rich soil resources. Therefore, how to efficiently and safely utilize the natural selenium-rich soil resources to plant selenium-rich crops is a practical problem to be solved. Especially in acid soil, the activity of cadmium is relatively high, while the activity of selenium is low, which makes the cadmium content in crops exceed the standard and the selenium content difficult to be improved, not only difficult to meet the nutritional needs of people for selenium, but also poses a great threat to human health.

[0004] Therefore, it is a technical problem to be solved at present to repair cadmium-contaminated soil to realize cadmium control and selenium increase, and then effectively control the cadmium content and improve the selenium content in crops. Based on the above technical status, it is of great significance for agricultural food safety to provide an acid cadmium-contaminated soil cadmium control and selenium-increasing soil conditioner. SUMMARY

[0005] The purpose of the present application is to provide an acid cadmium-contaminated soil cadmium control and selenium-increasing soil conditioner and a preparation method thereof, so as to solve the problems existing in the prior art and realize the repair of cadmium-contaminated soil, efficient cadmium control and selenium increase.

[0006] To achieve the above purpose, the present application provides the following solutions.

[0007] The application provides a cadmium-controlling and selenium-increasing soil modifier, and raw materials of the soil modifier comprise the following components in mass parts:

[0008] Modified diatomite 45-60 parts, wood ash 25-35 parts, slaked lime 10-15 parts, chitosan 1-2 parts and allantoin 4-5 parts.

[0009] Further, the modified diatomite is prepared through the following steps:

[0010] The diatomite subjected to the nitric acid pre-modification treatment is soaked in a mixed solution of ferric chloride and magnesium chloride, the obtained precipitate is dried, then mixed with aluminum oxide, and subjected to heat treatment in a protective atmosphere to obtain the modified diatomite.

[0011] Further, the nitric acid pre-modification treatment is that the diatomite is subjected to soaking treatment with nitric acid.

[0012] Preferably, the diatomite is soaked in 6 mol / L nitric acid for 1-1.5 h.

[0013] Further, in the mixed solution of ferric chloride and magnesium chloride, the concentration of ferric chloride is 0.8-1.2 mol / L, and the concentration of magnesium chloride is 0.3-0.7 mol / L.

[0014] Under the preferred concentrations of ferric chloride and magnesium chloride, the more preferred soaking time is 1-1.5 h. During the soaking process, the pH of the solution is controlled to be less than 7.

[0015] Further, the heat treatment is two-step heat treatment: first heat treatment at 65-70 DEG C for 8-12 h, and then heat treatment at 180-250 DEG C for 5-10 min.

[0016] Further, the added amount of aluminum oxide is 10-15% of the mass of the dried precipitate.

[0017] The application further provides a preparation method of the cadmium-controlling and selenium-increasing soil modifier.

[0018] The modified diatomite, wood ash, slaked lime, chitosan and allantoin are mechanically mixed according to the formula amount to obtain the cadmium-controlling and selenium-increasing soil modifier.

[0019] The wood ash can adjust the pH value of the soil, improve the soil texture, increase the soil aeration and water retention, and is beneficial to the growth of crops; and the wood ash also contains a large amount of mineral substances such as potassium, calcium and magnesium, and can provide nutrient elements for the growth of crops.

[0020] The soil improver of the present application adds wood ash and lime components, which can regulate the acidic environment of the soil, so that selenium is efficiently precipitated from the soil in a soluble inorganic state, which is beneficial for the absorption and conversion of crops, and on this basis, the addition of chitosan and allantoin further promotes the absorption of selenium, promoting the absorption of selenium by crops.

[0021] The modified diatomite material of the present application can provide a large number of adsorption sites for heavy metal cadmium, and realize efficient and stable cadmium.

[0022] The present application discloses the following technical effects:

[0023] The cadmium control and selenium increasing improver of the present application can effectively capture cadmium ions in the soil, inhibit their migration to the surrounding environment, and reduce the harm of cadmium in the soil; at the same time, it can also reduce the fixation of selenium in the soil, increase the content of effective selenium in the soil, and comprehensively realize the effect of cadmium control and selenium increase.

[0024] The soil conditioner of the present application can effectively regulate the soil quality, so that the products of crops meet the relevant requirements of cadmium content and selenium content; the soil conditioner is convenient to apply, and can be applied once before the planting of crops, without affecting the normal production of crops, and has remarkable effect of cadmium control and selenium increase, and great application and promotion value. DETAILED DESCRIPTION

[0025] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0026] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the stated range, and any other stated value or intermediate value in the stated range, is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0027] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present application. All documents mentioned in the specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict between the content of the specification and any incorporated document, the content of the specification shall prevail.

[0028] Many modifications and variations to the illustrative embodiments described herein will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. Additional embodiments of the technology will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. The specification and examples provided should be considered exemplary only.

[0029] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," and the like are open-ended terms that are intended to mean including, but not limited to.

[0030] Example 1

[0031] An acidic cadmium-contaminated soil cadmium control and selenium-increasing soil amendment, the raw material mass fraction ratio is as follows:

[0032] Modified diatomite 60 parts, wood ash 30 parts, lime 15 parts, chitin 2 parts and allantoin 5 parts.

[0033] The preparation process of the modified diatomite is as follows:

[0034] (1) The diatomite is added to deionized water, ultrasonic treated and filtered, and dried;

[0035] (2) The diatomite obtained in step (1) is soaked in 6 mol / L nitric acid for 3 hours to realize the pre-modification of the diatomite;

[0036] (3) The pre-modified diatomite is placed in a mixed solution of ferric chloride (1.0 mol / L) and magnesium chloride (0.7 mol / L), soaked for 1.5 hours, and the pH of the solution is controlled to be less than 7 during the soaking process;

[0037] (4) The obtained precipitate is filtered and dried, and then mixed with aluminum oxide. The mixture is heat treated at 70°C for 8 hours under a protective atmosphere, and then heat treated at 220°C for 10 minutes to obtain the modified diatomite. The addition amount of aluminum oxide is 15% of the mass of the dried precipitate.

[0038] The preparation process of the cadmium control and selenium-increasing soil amendment is as follows:

[0039] The modified diatomite, wood ash, lime, chitin and allantoin are mechanically mixed according to the formula amount to obtain the cadmium control and selenium-increasing soil amendment.

[0040] Comparative Example 1

[0041] The difference between Example 1 is only that the diatomite is not modified.

[0042] Comparative Example 2

[0043] The difference between Example 1 is only that the diatomite modification process does not include the modification process of aluminum oxide.

[0044] Comparative Example 3

[0045] The difference from Example 1 is that no allantoin is added.

[0046] Example 2

[0047] An acidic cadmium-contaminated soil cadmium control and selenium-increasing soil modifier, the raw material mass fraction ratio is as follows:

[0048] Modified diatomite 55 parts, wood ash 25 parts, lime 10 parts, chitosan 1.8 parts and allantoin 4 parts.

[0049] The preparation process of the modified diatomite is as follows:

[0050] (1) The diatomite is added to deionized water, ultrasonic treated, filtered and dried;

[0051] (2) The diatomite obtained in step (1) is soaked in 6 mol / L nitric acid for 4 h to realize the pre-modification of the diatomite;

[0052] (3) The pre-modified diatomite is placed in a mixed solution of ferric chloride (1.2 mol / L) and magnesium chloride (0.5 mol / L), soaked for 1 h, and the pH of the solution is controlled to be less than 7 during the soaking process;

[0053] (4) The obtained precipitate is dried, then mixed with aluminum oxide, and heat treated at 65°C for 8 h and at 250°C for 5 min under a protective atmosphere to obtain the modified diatomite. The addition amount of aluminum oxide is 12% of the mass of the dried precipitate.

[0054] The preparation process of the cadmium control and selenium-increasing soil modifier is as follows:

[0055] The modified diatomite, wood ash, lime, chitosan and allantoin are mechanically mixed according to the formula amount to obtain the cadmium control and selenium-increasing soil modifier.

[0056] Example 3

[0057] An acidic cadmium-contaminated soil cadmium control and selenium-increasing soil modifier, the raw material mass fraction ratio is as follows:

[0058] Modified diatomite 45 parts, wood ash 32 parts, lime 12 parts, chitosan 1.5 parts and allantoin 4 parts.

[0059] The preparation process of the modified diatomite is as follows:

[0060] (1) The diatomite is added to deionized water, ultrasonic treated, filtered and dried;

[0061] (2) using 6 mol / L nitric acid to soak the diatomite obtained in step (1) for 5 h to realize pre-modification of the diatomite;

[0062] (3) placing the pre-modified diatomite in a mixed solution of ferric chloride (1.0 mol / L) and magnesium chloride (0.3 mol / L), soaking for 1-1.5 h, and controlling the pH of the solution to be less than 7 during the soaking process;

[0063] (4) filtering, drying the obtained precipitate, then mixing with aluminum oxide, heat treating under a protective atmosphere at 65°C for 10 h, and then heat treating at 180°C for 10 min to obtain the modified diatomite. The addition amount of aluminum oxide is 14% of the mass of the dried precipitate.

[0064] The preparation process of the cadmium-controlled and selenium-increased soil conditioner is as follows:

[0065] The cadmium-controlled and selenium-increased soil conditioner is obtained by mechanically mixing the modified diatomite, wood ash, slaked lime, chitosan, and allantoin according to the formula amount.

[0066] Example 4

[0067] A cadmium-controlled and selenium-increased soil conditioner for acidic cadmium-contaminated soil, and the raw material mass ratio is as follows:

[0068] Modified diatomite 40 parts, wood ash 28 parts, slaked lime 13 parts, chitosan 1.3 parts, and allantoin 5 parts.

[0069] The preparation process of the modified diatomite is as follows:

[0070] (1) adding diatomite into deionized water, ultrasonic treating, filtering, and drying;

[0071] (2) using 6 mol / L nitric acid to soak the diatomite obtained in step (1) for 3-5 h to realize pre-modification of the diatomite;

[0072] (3) placing the pre-modified diatomite in a mixed solution of ferric chloride (0.8 mol / L) and magnesium chloride (0.6 mol / L), soaking for 1 h, and controlling the pH of the solution to be less than 7 during the soaking process;

[0073] (4) filtering, drying the obtained precipitate, then mixing with aluminum oxide, heat treating under a protective atmosphere at 70°C for 10 h, and then heat treating at 180°C for 8 min to obtain the modified diatomite. The addition amount of aluminum oxide is 12% of the mass of the dried precipitate.

[0074] The preparation process of the cadmium-controlled and selenium-increased soil conditioner is as follows:

[0075] The modified diatomite, wood ash, slaked lime, chitosan and allantoin are mechanically mixed according to the formula amount to obtain the cadmium control and selenium increasing soil modifier.

[0076] Rice has the habit of enriching metal cadmium, and is the most powerful bulk grain to absorb cadmium, and the present application takes rice as the research object to carry out field effect test of soil conditioning modifier:

[0077] Field test:

[0078] 1. Test plot: the soil pH is 4.8, the cadmium content is 1.7 mg / kg, and the selenium content is 0.6 mg / kg;

[0079] 2. Plot division: the test plot is divided into 8 equal area plots to verify the effect of the soil modifier;

[0080] 3. Soil conditioning agent application: 3 days before rice (Yixiangyou 2115) transplanting, the soil conditioning agent is mixed into the soil according to the application amount of 60 kg / mu;

[0081] 4. Test grouping:

[0082] Test group: the soil conditioning agents prepared by the present application examples 1-4 and comparative examples 1-3 are respectively applied to the corresponding plots, which are respectively recorded as test groups 1-4 and comparative test groups 1-3;

[0083] Control group: no soil conditioning agent is applied.

[0084] 5. Field management:

[0085] During the test period, each group adopts the same water and fertilizer management mode as the existing conventional mode, after the rice is harvested, the cadmium and selenium contents in brown rice are measured, and the results are shown in table 1.

[0086] Table 1

[0087]

[0088]

[0089] It can be seen that the cadmium control and selenium increasing soil modifier of the present application can significantly reduce the cadmium content in rice crops, not only meets the <0.4 mg / kg specified in the international CODEX STAN193-1995 standard, but also can reach the limit standard of 0.2 mg / kg of cadmium content in rice in the "GB2762-2022 food safety national standard for food contaminants" limit; at the same time, the selenium content of rice is significantly increased, which can meet the requirement of selenium content in selenium-rich rice in "GBT22499-2008 selenium-rich rice".

[0090] The above-described embodiments are merely intended to describe the preferred modes of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements of the present application made by those skilled in the art based on the above-described embodiments should fall within the scope of the present application defined by the claims.

Claims

1. An acidic cadmium-contaminated soil cadmium control and selenium-increasing soil improver, characterized in that, The raw material comprises the following components by mass fraction: modified diatomite 45-60 parts, wood ash 25-35 parts, slaked lime 10-15 parts, chitin 1-2 parts and allantoin 4-5 parts; The modified diatomite is prepared by the following steps: The diatomite after pre-modification treatment by nitric acid is soaked in a mixed solution of ferric chloride and magnesium chloride, filtered, and the obtained precipitate is dried, then mixed with aluminum oxide, and heat treated under a protective atmosphere to obtain the modified diatomite; The pre-modification treatment by nitric acid is that the diatomite is soaked by nitric acid; In the mixed solution of ferric chloride and magnesium chloride, the concentration of ferric chloride is 0.8-1.2 mol / L, and the concentration of magnesium chloride is 0.3-0.7 mol / L; The heat treatment is two-step heat treatment: first heat treatment at 65-70℃ for 8-12h, and then heat treatment at 180-250℃ for 5-10min; The amount of aluminum oxide added is 10-15% of the mass of the dried precipitate.

2. The preparation method of the cadmium-controlled and selenium-enhancing soil conditioner as described in claim 1, characterized in that, comprises the following steps: The modified diatomite, wood ash, slaked lime, chitin and allantoin are mechanically mixed according to the formula amount to obtain the cadmium-controlled and selenium-increased soil modifier.

3. The application of the cadmium-controlled and selenium-increased soil modifier of claim 1 in rice cadmium control and selenium increase.

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