Slow-release compound agent for reducing cadmium and arsenic in rice as well as preparation and application of slow-release compound agent

Abstract

The invention relates to the field of rice cadmium and arsenic reduction, and provides a slow-release compound for rice cadmium and arsenic reduction, preparation and application. The slow-release compounding agent comprises a selenium-based material, a calcium-based material and a silicon-based material, the mass ratio of the silicon-based material to the calcium-based material to the selenium-based material is (19-53): (13-47): (0.053-0.213), calcium selenite is selected as the selenium-based material, calcium oxide or calcium hydroxide is selected as the calcium-based material, and kieselguhr is selected as the silicon-based material. Wherein the calcium selenite is insoluble in water. The calcium oxide reacts with water to form water-insoluble calcium hydroxide, or directly comprises calcium hydroxide. In addition, the diatomite contains a large number of gaps and can adsorb calcium selenite, calcium hydroxide and selenium, calcium, silicon and other effective components dissolved out of the calcium selenite and the calcium hydroxide, so that the release speed of the effective components is further reduced, the diatomite can stably exist in the soil for a long time, and the long-term effect of reducing cadmium and arsenic is kept.

Description

Technical Field

[0001] The invention relates to the field of cadmium and arsenic reduction in rice, and in particular to a slow-release compound for reducing cadmium and arsenic in rice, and its preparation and application. Background Art

[0002] Wastewater, waste gas and waste residue generated during the mining and smelting of mineral resources lead to serious heavy metal pollution in farmland, with cadmium and arsenic compound pollution being the most prominent. Rice is an important food crop that has a significant enrichment effect on cadmium and arsenic. The human body will ingest a large amount of cadmium and arsenic during the process of eating rice. Long-term intake of cadmium can lead to "Itai-itai disease", and long-term intake of arsenic can lead to various cancers. Rice cadmium and arsenic pollution poses a serious threat to human health and food safety. Therefore, how to reduce the cadmium and arsenic content of rice and ensure food safety is a major problem that my country urgently needs to solve.

[0003] Compared with other existing technologies for reducing cadmium and arsenic in rice, nutrient regulation technology has the advantages of low cost, small amount of addition, and little damage to the soil, and has been widely studied and applied. However, due to the different chemical properties of cadmium and arsenic, it is still difficult to achieve the simultaneous reduction of cadmium and arsenic in rice through a single regulating material.

[0004] In view of this, it is necessary to provide a slow-release compound for reducing cadmium and arsenic in rice, a preparation method, an application and a cadmium and arsenic reduction treatment method to solve or at least alleviate the above-mentioned defects of high cost, poor long-term effect of reducing cadmium and arsenic, and difficulty in dual control of cadmium and arsenic. Summary of the invention

[0005] The main purpose of the present invention is to provide a slow-release compound for reducing cadmium and arsenic in rice, and its preparation and application, so as to solve the technical problem of rice absorbing soil cadmium.

[0006] To achieve the above-mentioned purpose, the present invention provides a sustained-release compound for reducing cadmium and arsenic in rice, comprising a selenium-based material, a calcium-based material and a silicon-based material, wherein the mass ratio of the silicon-based material, the calcium-based material and the selenium-based material is (19-53):(13-47):(0.053-0.213), the selenium-based material is calcium selenite, the calcium-based material is calcium oxide or calcium hydroxide, and the silicon-based material is diatomaceous earth.

[0007] According to an embodiment of the present application, the mass ratio of the silicon-based material, the calcium-based material and the selenium-based material is (22-44): (22-44): (0.053-0.106).

[0008] According to an embodiment of the present application, the calcium-based material is calcium oxide.

[0009] The present application also provides a method for preparing the above-mentioned sustained-release compound for reducing cadmium and arsenic in rice, comprising the following steps:

[0010] Selenium-based materials, calcium-based materials and silicon-based materials are mixed to obtain a sustained-release compound for reducing cadmium and arsenic in rice; wherein the mass ratio of the selenium-based material, the calcium-based material and the silicon-based material is (19-53):(13-47):(0.053-0.213), the selenium-based material is calcium selenite, the calcium-based material is calcium oxide, and the silicon-based material is diatomaceous earth.

[0011] According to an embodiment of the present application, the preparation method of calcium selenite comprises:

[0012] The calcium selenite is prepared by mixing a selenium dioxide solution and a calcium hydroxide suspension, wherein the mass ratio of Se to Ca is 1:0.7-0.75.

[0013] The present application also provides the use of the above-mentioned slow-release compound for reducing cadmium and arsenic in rice in reducing cadmium in rice, and the slow-release compound is applied to the soil in the rice-growing area.

[0014] According to the implementation mode of the present application, the application amount of the sustained-release compound meets the following requirements: the addition amount of silicon-based material is 0.19-0.53 g / kg soil, the addition amount of calcium-based material is 0.13-0.47 g / kg soil, and the addition amount of selenium-based material is: 0.53-2.13 mg / kg soil.

[0015] According to an embodiment of the present application, the step of applying the slow-release compound to the soil in the rice-growing area comprises:

[0016] Mixing the sustained-release compound with water to form a suspension;

[0017] The suspension is sprayed onto the soil.

[0018] According to an embodiment of the present application, in the step of spraying the suspension into the soil, the soil is tilled.

[0019] According to an embodiment of the present application, the step of applying the slow-release compound to the soil in the rice-growing area comprises:

[0020] The slow-release compound is directly applied on the soil, and the soil is ploughed before and after the application of the slow-release compound.

[0021] The above-mentioned slow-release compound for reducing cadmium and arsenic in rice includes a large number of active ingredients. Among them, calcium selenite is poorly soluble in water. Calcium oxide reacts with water to form calcium hydroxide that is poorly soluble in water, or directly includes calcium hydroxide. In addition, diatomaceous earth contains a large number of voids, which can absorb calcium selenite and calcium hydroxide, as well as the dissolved selenium, calcium, silicon and other effective ingredients, thereby further reducing the release rate of the above-mentioned effective ingredients, so that it can be stably present in the soil for a long time, maintaining the long-term effect of reducing cadmium and arsenic. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 The figures are data comparison diagrams of cadmium and arsenic content in the first crop of rice in Example 1 and Comparative Example 1; wherein (a) is a data comparison diagram of cadmium content; (b) is a data comparison diagram of arsenic content;

[0024] Figure 2 The figures are data comparison diagrams of cadmium and arsenic content in the second rice crop planted in Example 2; wherein (a) is a data comparison diagram of cadmium content; and (b) is a data comparison diagram of arsenic content.

[0025] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0029] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] The present application provides a sustained-release compound for reducing cadmium and arsenic in rice, comprising a selenium-based material, a calcium-based material and a silicon-based material, wherein the mass ratio of the silicon-based material, the calcium-based material and the selenium-based material is (19-53):(13-47):(0.053-0.213), the selenium-based material is calcium selenite, the calcium-based material is calcium oxide or calcium hydroxide, and the silicon-based material is diatomaceous earth.

[0031] Selenium is an essential trace element for plants and animals, and plays an important role in their growth and development. Plants can absorb selenium through their roots or leaves. Appropriate concentrations of selenium can also enhance plants' tolerance to heavy metal stress. The mechanisms by which selenium enhances plant heavy metal stress mainly include enhancing plant photosynthesis and antioxidant enzyme activity, promoting ROS clearance in the body, and inhibiting the absorption and accumulation of heavy metals.

[0032] The invention uses calcium selenite, which is easy to obtain, as a source of insoluble selenium, and can prepare materials efficiently and quickly. In addition, while reducing the cadmium content in rice, the selenium content in rice can also be increased to obtain selenium-enriched rice, further increasing the economic value of rice.

[0033] Calcium-based materials are selected from calcium oxide or calcium hydroxide. Calcium oxide reacts with water to form calcium hydroxide, such as adding water to the slow-release compound to prepare a suspension and reacting with water, or directly applying it to the soil and reacting with environmental water such as rainwater or moisture in the soil. Calcium hydroxide has a low solubility in water and is difficult to dissolve.

[0034] Diatomaceous earth is a natural substance formed from the remains of diatoms. It has a large number of pores inside, so it has the characteristics of large specific surface area and good adsorption performance. Therefore, it can not only absorb part of calcium selenite and calcium hydroxide, but also absorb the selenium and calcium components produced by calcium selenite and calcium hydroxide dissolved in water.

[0035] Calcium selenite, diatomaceous earth and calcium oxide ensure the continuous release of active ingredients without losing effectiveness due to the seepage and flow of water in the rice fields.

[0036] In the relevant technology, the single application of silicon, selenium and calcium elements can effectively reduce the enrichment of cadmium in rice. However, no research has been conducted on how to improve the long-term cadmium and arsenic reduction effects on rice, thereby further reducing the cadmium and arsenic content in rice, and how to control the cost of cadmium and arsenic reduction.

[0037] The above-mentioned slow-release compound for reducing cadmium and arsenic in rice includes a large number of active ingredients. Among them, calcium selenite is insoluble in water. Calcium oxide reacts with water to form calcium hydroxide, which is insoluble in water, or directly includes calcium hydroxide. In addition, diatomaceous earth contains a large number of voids, which can adsorb calcium selenite and calcium hydroxide, as well as the dissolved selenium, calcium, silicon and other effective ingredients, thereby further reducing the release rate of the above-mentioned effective ingredients. Therefore, it can be stably present in the soil for a long time, maintaining the long-term effect of reducing cadmium and arsenic. The slow-release compound can increase the calcium, silicon and selenium content in the soil, thereby increasing the soil pH, and further increase the iron film content in the rice roots, so as to achieve efficient reduction of the cadmium and arsenic content in the rice grains.

[0038] Moreover, the slow-release compound used for reducing cadmium and arsenic in rice in the present invention adopts relatively common raw materials, which has low cost. While reducing cadmium and arsenic, the selenium content in rice can also be increased to obtain selenium-enriched rice that is beneficial to the human body. Compared with other repair agents, the slow-release compound prepared by the present invention can not only reduce cadmium, arsenic and selenium, but also increase the calcium content in the soil, alleviating the serious acidification problem of soil in the south to a certain extent.

[0039] In some embodiments, the mass ratio of the silicon-based material, the calcium-based material and the selenium-based material is (22-44): (22-44): (0.053-0.106).

[0040] In this embodiment, the cadmium and arsenic reducing effects of the sustained-release compound are more obvious.

[0041] In some embodiments, the calcium-based material is calcium oxide.

[0042] The present application also provides a method for preparing the above-mentioned sustained-release compound for reducing cadmium and arsenic in rice, comprising the following steps:

[0043] Selenium-based materials, calcium-based materials and silicon-based materials are mixed to obtain a sustained-release compound for reducing cadmium and arsenic in rice; wherein the mass ratio of the selenium-based material, the calcium-based material and the silicon-based material is (19-53):(13-47):(0.053-0.213), the selenium-based material is calcium selenite, the calcium-based material is calcium oxide, and the silicon-based material is diatomaceous earth.

[0044] During the preparation process, a certain proportion of calcium selenite, diatomaceous earth and calcium oxide are physically mixed to obtain the sustained-release compound for reducing cadmium and arsenic in rice. This preparation method is simple and reduces the cost. Among them, calcium selenite can be prepared by itself or purchased commercially.

[0045] The invention can obtain the sustained-release compound for reducing cadmium and arsenic in rice by simple physical mixing, and after being applied to the rice planting process, the sustained-release compound for reducing cadmium and arsenic in rice can significantly reduce the enrichment of cadmium and arsenic in rice, thereby ensuring the dietary health of residents.

[0046] In some embodiments, the method for preparing calcium selenite comprises:

[0047] The calcium selenite is prepared by mixing a selenium dioxide solution and a calcium hydroxide suspension, wherein the mass ratio of Se to Ca is 1:0.7-0.75.

[0048] In this embodiment, the prepared calcium selenite is in the form of a suspension. The preparation method of the selenious acid solution may be: SeO 2 The calcium hydroxide suspension can be prepared by dissolving CaO in water to obtain the calcium hydroxide suspension.

[0049] The present application also provides the use of the above-mentioned slow-release compound for reducing cadmium and arsenic in rice in reducing cadmium in rice, and the slow-release compound is applied to the soil in the rice-growing area.

[0050] The compound described in any one of the above is used in the process of rice planting to obtain rice with low cadmium and arsenic content. It should be noted that the rice planting process can refer to the existing planting method, and the main difference is that the slow-release compound for reducing cadmium and arsenic in rice is applied during the rice planting in the present invention.

[0051] The synthesis method adopted in the present invention is simple and can be applied to the soil simultaneously with fertilizers, thus saving a lot of human resources and having low costs. The obtained slow-release compound for reducing cadmium and arsenic in rice can be applied to cadmium-contaminated rice fields, arsenic-contaminated rice fields, and cadmium-arsenic-contaminated rice fields, and has a wide range of applications.

[0052] In some embodiments, the application amount of the sustained-release compound satisfies: the addition amount of silicon-based material is 0.19-0.53 g / kg soil, the addition amount of calcium-based material is 0.13-0.47 g / kg soil, and the addition amount of selenium-based material is: 0.53-2.13 mg / kg soil.

[0053] In some more specific embodiments, the amount of silicon-based material added is 0.22-0.44 g / kg soil, the amount of calcium-based material added is 0.22-0.44 g / kg soil, and the amount of selenium-based material added is 0.53-1.06 mg / kg soil. Under this application amount, the effect of reducing cadmium and arsenic is better.

[0054] In some embodiments, the step of applying the slow-release compound to the soil in the rice-growing area comprises:

[0055] Mixing the sustained-release compound with water to form a suspension;

[0056] The suspension is sprayed onto the soil.

[0057] For example, the specific process of the treatment method for reducing the cadmium and arsenic content in rice can be: before planting rice, applying the slow-release compound for reducing cadmium and arsenic in rice to the soil in the planting area. Adding the slow-release compound for reducing cadmium and arsenic in rice to water to form a suspension, and then spraying it into the soil. The concentration of the suspension is not specifically limited.

[0058] In some embodiments, in the step of spraying the suspension into the soil, the soil is tilled.

[0059] This method allows the soil to be tilled during the spraying process so that the slow-release compound is fully mixed with the soil.

[0060] In some embodiments, the step of applying the slow-release compound to the soil in the rice-growing area comprises:

[0061] The slow-release compound is directly applied on the soil, and the soil is ploughed before and after the application of the slow-release compound.

[0062] The slow-release compound for reducing cadmium and arsenic in rice exists in a solid form and is directly applied to the soil in the solid form.

[0063] For example, before planting rice, basal fertilizer (urea and potassium chloride, etc.) and slow-release compound are mixed and applied to the soil in the rice planting area. By applying it to the soil together with basal fertilizer, the burden of secondary spraying of pesticides by farmers is reduced, and the simple application method is also easy to promote.

[0064] The solid of the slow-release compound comes into contact with the water in the soil and slowly dissolves. For example, before and after the application of the slow-release compound, the soil is kept flooded for two days. Under this condition, the compound can more evenly penetrate into the soil to achieve a better cadmium reduction effect.

[0065] In order to facilitate further understanding of the present invention, examples are given below:

[0066] Example 1

[0067] In this embodiment, paddy soil taken from Beishan Town, Changsha County, Changsha City, Hunan Province was used for potted plant experiments. 5 kg of naturally dried soil was placed in pots. A total of 12 groups of experiments were conducted, with 3 replicates in each group. The compounding method is shown in Table 1 below:

[0068] Table 1 Grouping of each group

[0069]

[0070] Note: Si:Ca=2:1 means the mass ratio of diatomaceous earth to calcium oxide in the compound is 2:1.

[0071] Se0.25 means that after calcium selenite in the compound agent is added to the soil, the amount of selenium added to the soil is 0.25 mg / kg soil.

[0072] Both single and double groups were used as control groups.

[0073] Among them, the single group preparation method includes:

[0074] Calcium selenite was added to 1L of aqueous solution to prepare a suspension, which was then sprayed into each pot of soil for physical mixing, with the pot containing 5kg of soil. The specific addition amount is shown in Table 2 below, and the other steps and treatments were the same as the steps and treatments of the following three combinations.

[0075] Table 2 Addition amount of each component in a single group

[0076]

[0077] The two-group matching method, namely the silicon-calcium group, includes:

[0078] According to the proportion, a certain amount of diatomaceous earth and calcium oxide are taken and physically mixed, and then added to each pot of soil without calcium selenite for physical mixing, and the pot contains 5kg of soil. The specific proportion is shown in Table 3 below, and the other steps and treatments are the same as the steps and treatments of the following three groups.

[0079] Table 3 Addition amount of each component in two groups

[0080]

[0081] The preparation and application of the three-group combination includes the following specific steps:

[0082] (1) According to the proportion, a certain amount of calcium selenite, diatomaceous earth and calcium oxide are taken and physically mixed, and then added to 1L of water to prepare a suspension, and then sprayed into each pot of soil for physical mixing, and the pot contains 5kg of soil. The specific ratio is shown in Table 4 below:

[0083] Table 4 Ratios of each group and corresponding arsenic and cadmium contents in rice

[0084]

[0085] (2) The mixture was allowed to stabilize for 7 days after completion, and then the potted plant experiment was carried out after flooding.

[0086] (3) After the rice matures, the cadmium and arsenic contents in the rice are measured.

[0087] (4) After testing: In this embodiment, after applying the slow-release compound for reducing cadmium and arsenic in rice, the cadmium and arsenic in rice were effectively reduced. For details, see Figure 1 .

[0088] By comparing with the control group, it can be seen that the cadmium and arsenic content in rice decreased from 0.37 mg / kg and 1.19 mg / kg to 0.16 mg / kg and 0.19 mg / kg, respectively, a decrease of 56.76% and 84.03%.

[0089] Reference Figure 1 As shown, after testing: 1. In this comparative example, the effect of single calcium selenite on reducing cadmium and arsenic in rice is general; 2. The silicon calcium group reduces the content of cadmium and arsenic in rice; 3. The Si:Ca=1:2+0.5Se group in Example 1 with the same silicon calcium ratio further reduces the content of cadmium and arsenic in rice compared with the silicon calcium group. It shows that the slow-release compound for reducing cadmium and arsenic in rice has better cadmium and arsenic reduction effects than the single calcium selenite and silicon calcium compound.

[0090] Example 2

[0091] This example was carried out under the original soil conditions of Example 1 without additional soil treatment. After the rice was harvested in Example 1, the second crop of rice was planted without adding a compound agent, and the rice was cultivated in the same conventional rice water management method as the first crop of rice.

[0092] Tested: See Figure 2 In this embodiment, after applying the compound agent of silicon, selenium and calcium to reduce arsenic, the cadmium and arsenic in rice were effectively reduced, and the effect was still there in the second crop. After the compound agent of silicon, selenium and calcium to reduce arsenic was applied during the planting of the first crop of rice, the cadmium and arsenic contents in the rice were reduced from 0.37 mg / kg and 1.19 mg / kg in the control treatment to 0.16 mg / kg and 0.19 mg / kg, respectively, and the cadmium and arsenic contents in the second crop of rice were still as low as 0.16 mg / kg and 0.20 mg / kg. See Table 5 below for details:

[0093] Table 5 Arsenic and cadmium contents in each group of rice in the second crop of rice

[0094]

[0095] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A sustained-release compound for reducing cadmium and arsenic in rice, characterized in that: The invention comprises selenium-based material, calcium-based material and silicon-based material, wherein the mass ratio of the silicon-based material, the calcium-based material and the selenium-based material is (19-53):(13-47):(0.053-0.213), the selenium-based material is calcium selenite, the calcium-based material is calcium oxide or calcium hydroxide, and the silicon-based material is diatomaceous earth.

2. The sustained-release compound for reducing cadmium and arsenic in rice according to claim 1, characterized in that: The mass ratio of the silicon-based material, the calcium-based material and the selenium-based material is (22-44): (22-44): (0.053-0.106).

3. The sustained-release compound for reducing cadmium and arsenic in rice according to claim 1 or 2, characterized in that: The calcium-based material is calcium oxide.

4. A method for preparing a sustained-release compound for reducing cadmium and arsenic in rice as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: Selenium-based materials, calcium-based materials and silicon-based materials are mixed to obtain a sustained-release compound for reducing cadmium and arsenic in rice; wherein the mass ratio of the selenium-based material, the calcium-based material and the silicon-based material is (19-53):(13-47):(0.053-0.213), the selenium-based material is calcium selenite, the calcium-based material is calcium oxide, and the silicon-based material is diatomaceous earth.

5. The method for preparing the sustained-release compound for reducing cadmium and arsenic in rice according to claim 4, characterized in that: The preparation method of calcium selenite comprises: The calcium selenite is prepared by mixing a selenium dioxide solution and a calcium hydroxide suspension, wherein the mass ratio of Se to Ca is 1:0.7-0.

75.

6. Use of a sustained-release compound for reducing cadmium and arsenic in rice as claimed in any one of claims 1 to 3 in reducing cadmium in rice, characterized in that: The slow-release compound is applied to the soil in the rice-growing area.

7. The use according to claim 6, characterized in that: The application amount of the slow-release compound meets the following requirements: the addition amount of silicon-based material is 0.19-0.53 g / kg soil, the addition amount of calcium-based material is 0.13-0.47 g / kg soil, and the addition amount of selenium-based material is 0.53-2.13 mg / kg soil.

8. The use according to claim 7, characterized in that: The step of applying the slow-release compound to the soil in the rice planting area comprises: Mixing the sustained-release compound with water to form a suspension; The suspension is sprayed onto the soil.

9. The use according to claim 8, characterized in that: In the step of spraying the suspension onto the soil, the soil is tilled.

10. The use according to claim 7, characterized in that: The step of applying the slow-release compound to the soil in the rice planting area comprises: The slow-release compound is directly applied on the soil, and the soil is ploughed before and after the application of the slow-release compound.

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