CN-121555203-B - Modifier for cadmium-polluted soil and preparation method thereof

CN121555203BCN 121555203 BCN121555203 BCN 121555203BCN-121555203-B

Abstract

The invention belongs to the technical field of soil pollution remediation, and particularly relates to a conditioner for cadmium-polluted soil and a preparation method thereof. The preparation method comprises the steps of S1 preparing modified bentonite, namely adding bentonite subjected to heat treatment into deionized water, adding ferric sulfate and manganese sulfate to obtain solution A, adding sodium carbonate and sodium phosphate into deionized water to obtain solution B, heating the solution A, adding the solution B, continuing heating reaction to obtain pretreated bentonite, adding the pretreated bentonite into ethanol water solution, adding a silane coupling agent to perform heating reaction to obtain bentonite modified by the silane coupling agent, mixing the bentonite with amino trimethylene phosphonic acid and urea to perform heating reaction to obtain modified bentonite, S2 preparing straw source soluble organic matters, S3 mixing and granulating, S4 coating, namely coating composite particles by taking the modified bentonite as a coating material, and drying to obtain the modified bentonite. The modifier has excellent slow release and soil restoration effects.

Inventors

LIU MINXIA
WANG JINCHAO
SHI MENGYAO
HAN ZHIQIANG
LIANG WENJUN

Assignees

山西农业大学

Dates

Publication Date: 20260508
Application Date: 20260121

Claims (5)

1. The preparation method of the modifier for the cadmium-polluted soil is characterized by comprising the following steps of: S1, preparing modified bentonite (1) Adding bentonite after heat treatment into deionized water, adding ferric sulfate and manganese sulfate, and uniformly stirring to obtain a solution A, adding sodium carbonate and sodium phosphate into deionized water, uniformly stirring to obtain a solution B, heating the solution A to 75-85 ℃, adding the solution B, continuously heating for reaction, and obtaining pretreated bentonite after the reaction is completed; (2) Adding the pretreated bentonite into an ethanol water solution, adding a silane coupling agent for heating reaction, and obtaining bentonite modified by the silane coupling agent after the reaction is completed; (3) Mixing the bentonite modified by the silane coupling agent, amino trimethylene phosphonic acid and urea, and carrying out heating reaction under the protection of inert gas to obtain modified bentonite after the reaction is completed; S2, preparing soluble organic matters of straw sources Adding the corn straw powder into deionized water, sealing and culturing under room temperature and dark conditions, centrifuging after culturing, filtering, and freeze-drying to obtain straw source soluble organic matters; S3, mixing and granulating Uniformly mixing the straw source soluble organic matters and calcium peroxide, and granulating to obtain composite particles; S4, coating film Coating the composite particles by taking the modified bentonite as a coating material, and drying to obtain the modifier for cadmium polluted soil; In the step (1), the mass ratio of bentonite to ferric sulfate to manganese sulfate after heat treatment is 1 (0.5-1.5) (1-2), the mass ratio of sodium carbonate to sodium phosphate is 0.1-0.2) (0.05-0.1), the mass ratio of bentonite to sodium carbonate after heat treatment is 1 (1.5-2), the temperature of heat treatment is 170-180 ℃ for 2-3h, the temperature of heating reaction is 75-85 ℃ for 5-6h; The dosage ratio of the pretreated bentonite to the silane coupling agent to the ethanol aqueous solution in the step (2) is 1g (0.2-0.5 g) (15-20) mL, the heating reaction temperature is 70-85 ℃ and the time is 22-26h, the silane coupling agent is gamma-aminopropyl triethoxysilane, and the concentration of the ethanol aqueous solution is 50-60wt%; the dosage ratio of the bentonite modified by the silane coupling agent, the amino trimethylene phosphonic acid and the urea in the step (3) is 1g (1-6) mL (1-5), the temperature of the heating reaction is 130-150 ℃ and the time is 3-5h.
2. The method for preparing the modifier for the cadmium-polluted soil according to claim 1, wherein in the step S2, the feed liquid ratio of the corn stalk powder to the deionized water is 1g (20-30) mL, and the time of the sealed culture is 25-35d.
3. The method for preparing the modifier for cadmium-polluted soil according to claim 1, wherein in the step S3, the mass ratio of the soluble organic matters of the straw source to the calcium peroxide is 1 (2-4).
4. The method for preparing the modifier for cadmium-polluted soil according to claim 1, wherein the mass ratio of the composite particles to the modified bentonite in the step S4 is 1 (0.1-0.3), and the drying temperature is 90-100 ℃.
5. An improvement agent for cadmium-contaminated soil, characterized by being prepared by the preparation method of any one of claims 1 to 4.

Description

Modifier for cadmium-polluted soil and preparation method thereof Technical Field The invention belongs to the technical field of soil pollution remediation, and particularly relates to a conditioner for cadmium-polluted soil and a preparation method thereof. Background Soil is a valuable resource for human survival, however, with the rapid development of industry and agriculture, heavy metal pollution has become a prominent environmental problem endangering global soil health and agricultural product safety. Among them, cadmium (Cd) is regarded as one of the most harmful heavy metals due to its high toxicity, strong mobility and easy enrichment in organisms through food chains. Cadmium pollution not only inhibits normal growth of crops, but also can be absorbed by crops and accumulated on edible parts, finally enters human bodies through dietary ways, and organs such as kidneys, bones and the like are seriously damaged after long-term intake, thus the cadmium pollution constitutes a continuous threat to public health. Currently, china faces the challenge of cadmium pollution of wide cultivated lands. The technology for treating the cadmium-polluted soil is various, but compared with physical engineering measures such as a soil-removing method and a leaching method which are high in cost and easy to damage soil, and a plant restoration technology which is long in period and unstable in efficiency, the in-situ chemical passivation restoration is regarded as a farmland cadmium pollution treatment strategy with great prospect because of low cost, simple operation, quick response and suitability for large-area popularization and application. The core of the technology is to add an improver to the polluted soil, and the bioavailability and mobility of cadmium are reduced by changing the existence form of the cadmium in the soil. The existing modifier, such as alkaline substances of quicklime, silicon-calcium-magnesium fertilizer and the like, can promote cadmium to form hydroxide or carbonate to precipitate by increasing the pH value of soil, and quickly reduces the content of effective cadmium, but the effect is often difficult to be long-acting. Under the condition of soil acidification caused by rainfall, irrigation or mass application of chemical fertilizers, the fixed cadmium electrode is easy to reactivate, and the phenomenon of 'disease return' is caused, so that the repairing effect is one-step short. Therefore, developing a novel functional material which can not only effectively passivate effective cadmium, but also can improve repairing capability for a long time becomes a hot spot and a difficult point of research in the field at present. Disclosure of Invention In order to overcome the defects of the prior art, the first aim of the invention is to provide a preparation method of a modifier for cadmium-polluted soil, which has simple process. The second object of the invention is to provide a modifier for cadmium-contaminated soil, which has excellent slow release and soil restoration effects. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: The preparation method of the modifier for the cadmium-polluted soil comprises the following steps: S1, preparing modified bentonite (1) Adding bentonite after heat treatment into deionized water, adding ferric sulfate and manganese sulfate, and uniformly stirring to obtain a solution A, adding sodium carbonate and sodium phosphate into deionized water, uniformly stirring to obtain a solution B, heating the solution A to 75-85 ℃, adding the solution B, continuously heating for reaction, and obtaining pretreated bentonite after the reaction is completed; (2) Adding the pretreated bentonite into an ethanol water solution, adding a silane coupling agent for heating reaction, and obtaining bentonite modified by the silane coupling agent after the reaction is completed; (3) Mixing the bentonite modified by the silane coupling agent, amino trimethylene phosphonic acid and urea, and carrying out heating reaction under the protection of inert gas to obtain modified bentonite after the reaction is completed; S2, preparing soluble organic matters of straw sources Adding the corn straw powder into deionized water, sealing and culturing under room temperature and dark conditions, centrifuging after culturing, filtering, and freeze-drying to obtain straw source soluble organic matters; S3, mixing and granulating Uniformly mixing the straw source soluble organic matters and calcium peroxide, and granulating to obtain composite particles; S4, coating film And taking the modified bentonite as a coating material, coating the composite particles, and drying to obtain the modifier for cadmium contaminated soil. Preferably, in the step (1), the mass ratio of the bentonite, the ferric sulfate and the manganese sulfate after heat treatment is 1 (0.5-1.5) (1-2), the mass ratio of the sodium carbonate and the sodium phosphate is 0.1-0.2