CN-121972501-A - Method for efficiently removing heavy metals in soil based on magnetic removal technology and application

Abstract

The invention relates to the technical field of soil heavy metal removal, in particular to a method for efficiently removing soil heavy metal based on a magnetic removal technology and application thereof. The invention provides an innovative method for combining soil heavy metal activation and magnetic removal technology. By applying one of the activators EDDS, RLs, caCl 2 , the indissolvable heavy metals in the soil can be converted into a soluble form and transferred into the soil solution, so that the content of the heavy metals in the soil solution is remarkably improved, and the high-efficiency removal is realized by utilizing the adsorption effect of the magnetic material on the heavy metals. The method solves the problem of dependence on heavy metal morphology in the traditional magnetic removal technology through the preposed activation step, and remarkably improves the utilization efficiency of the magnetic material and the overall removal efficiency of the heavy metal. The method has important practical application value and popularization prospect for rapidly repairing heavy metal polluted farmlands and guaranteeing farmland safety and grain sustainable production.

Inventors

• YI XIAOJUN
• WANG HENG
• FU YUANQI
• LI JIANGNAN
• GAO LIYANG
• ZENG LIJUAN
• YANG ZHENYU
• LU GUINING
• DANG ZHI

Assignees

• 华南理工大学
• 广东省地质局清远地质调查中心

Dates

Publication Date

20260505

Application Date

20260204

Claims (10)

1. 1. The method for efficiently removing the heavy metals in the soil based on the magnetic material is characterized by comprising the following steps of: Adding polluted soil into a centrifuge tube, adding an activating agent, adding a CEOS magnetic material, putting the centrifuge tube into a shaking table for shaking, pouring the centrifuge tube into a beaker after the reaction is finished, recycling CEOS in the soil by using a strong magnet, repeating the above treatment process for a plurality of times, taking out the reacted soil, naturally airing the reacted soil, grinding and sieving the soil, and testing the total cadmium content of the soil.
2. 2. The method for efficiently removing heavy metals from soil based on magnetic materials according to claim 1, wherein the contaminated soil is cadmium-contaminated soil and the cadmium content is at least 0.3 mg/kg.
3. 3. The method for efficiently removing heavy metals from soil based on magnetic materials according to claim 1, wherein said activator comprises at least one of ethylenediamine disuccinate EDDS, rhamnolipid, and calcium chloride CaCl 2 .
4. 4. The method for efficiently removing heavy metals from soil based on magnetic material according to claim 1, wherein said activator is 0.002M CaCl 2 .
5. 5. The method for efficiently removing heavy metals from soil based on magnetic materials according to claim 1, wherein said activator is 1mM EDDS.
6. 6. The method for efficiently removing heavy metals from soil based on magnetic materials according to claim 1, wherein said activator is 1.0% RLs solution.
7. 7. The method for efficiently removing heavy metals in soil based on magnetic materials according to claim 1, wherein the amount of the CEOS magnetic material is 1-8wt%.
8. 8. The method for efficiently removing heavy metals from soil based on magnetic materials according to claim 1, wherein the centrifugal oscillation time is 3 h.
9. 9. The method for efficiently removing heavy metals in soil based on the magnetic material according to claim 1, wherein the cooperative repair times are repeated 1-3 times.
10. 10. The method for efficiently removing heavy metals from soil based on magnetic materials according to any one of claims 1 to 9, wherein the method reduces the total cadmium content of the soil by 58.4% -67.9%.

Description

Method for efficiently removing heavy metals in soil based on magnetic removal technology and application Technical Field The invention belongs to the technical field of soil heavy metal removal, and particularly relates to a method for efficiently removing soil heavy metal based on a magnetic removal technology and application thereof. Background In recent years, with the rapid development of industry and agriculture in China, the problem of heavy metal pollution of soil is increasingly serious. Soil is an important carrier for the circulation of biosphere substances and the energy flow as a key environmental element for maintaining the earth life system, and is also a core foundation for the stabilization of the land ecological system. The environmental quality is directly related to the safety and quality of agricultural products and further affects human health through the food chain. In 2014, the first system of national soil pollution condition investigation publication issued by the environmental protection department and the national resource department together reveals the overall condition of the soil environment in China. The report indicates that the soil environment quality is not optimistic in the whole country, the total soil overstandard rate reaches 16.1%, the problem of cultivated land pollution is particularly remarkable, and about one fifth of cultivated lands in China are polluted by heavy metals such as cadmium, arsenic, chromium, lead and the like. The population base of China is large, the grain demand is vigorous, and therefore, the safe and efficient restoration of heavy metal polluted farmlands becomes an urgent environmental and social task. Currently, the remediation technology of soil heavy metal pollution mainly comprises a leaching method, a bioremediation technology, a passivation technology, a magnetic removal technology and the like. The magnetic removal technology adsorbs heavy metals in the soil solution by means of magnetic materials, and then the heavy metals are rapidly separated by an external magnetic field. The technology not only can thoroughly remove pollutants, but also can avoid the common secondary pollution problem in the traditional repair method, and is widely focused because the technology has the advantages of being free from time limitation in operation, being capable of realizing permanent removal of heavy metals and the like. However, in the practical application of the technology, the magnetic material mainly plays a role in adsorbing and removing cadmium in a water-soluble state and an exchangeable state, and the part of cadmium occupies a relatively low total amount of heavy metals in soil, so that the overall repair efficiency of the magnetic material is obviously limited. Therefore, how to break through the technical bottleneck becomes a key for improving the repairing effect of the magnetic material. The soil heavy metal activator is a functional reagent capable of regulating heavy metal form through chemical or biochemical action, and the action mechanism comprises dissolution, coordination desorption, form conversion, interface modification and the like, so that the combination between heavy metal and soil particles can be destroyed, and the heavy metal is promoted to be transferred from a solid phase to a liquid phase, so that the heavy metal enters a soil solution. This process creates favorable conditions for subsequent efficient adsorption and removal of the magnetic material. Therefore, the activator and the magnetic material are combined to form a synergistic restoration technology, and the restoration effect of the heavy metal polluted soil is expected to be remarkably improved. CN113546952B discloses a magnetic biochar soil restoration agent for soil heavy metal pollution and application thereof, and the magnetic biochar is prepared by the invention and is used for adsorbing and removing soil heavy metal, and the magnetic biochar can effectively remove soil heavy metal. However, the removal amount of the heavy metals in the soil is low, mainly because the heavy metals in the soil have different forms, and the magnetic material can only remove the forms (Wang et al, 2024; gong et al, 2021) which are easy to adsorb, such as water-soluble forms, exchangeable forms and the like, so that the removal effect of the magnetic material on the heavy metals in the soil is limited. Disclosure of Invention The invention mainly aims to solve the problem that the magnetic removal technology is limited by the occurrence form of the technology when removing the heavy metals in soil, so that the removal efficiency is limited. To achieve this objective, the present invention proposes improvements and innovations of the prior art process, combining soil heavy metal activation with magnetic removal technology. By applying the activating agent, the indissolvable heavy metal in the soil can be converted into a soluble form and transferred into the soil solutio