PH-responsive nano-iron-based sustained-release material, preparation method and application

Abstract

The invention belongs to the technical field of uranium-polluted underground water remediation, and discloses a pH-responsive nano-iron-based sustained-release material, a preparation method and application, and the preparation method of the pH-responsive nano-iron-based sustained-release material comprises the following steps: preparing a nano-iron-based material; preparing a cross-linked chitosan solution with pH response; the cross-linked chitosan wraps the nano iron-based material; and carrying out solid-liquid separation, washing and drying on the obtained precipitate to obtain the pH response type nano-iron-based slow-release material for repairing the uranium-polluted underground water of the acid-process in-situ leaching mine. The prepared nano slow-release material can slowly release the nano iron-based material under the acidic condition, and the released nano iron-based material can improve the pH of acidic uranium polluted underground water on one hand and fix uranium in the underground water through adsorption and chemical reduction effects on the other hand. The nano sustained-release material is small in particle size (20-100nm) and good in migration and diffusion performance, and has the advantages of long action period, stable structure, low cost, environmental friendliness and the like.

Description

technical field [0001] The invention belongs to the technical field of remediation of uranium-contaminated groundwater, in particular to a pH-responsive nano-iron-based slow-release material, a preparation method and an application. Background technique [0002] Foreign countries have always respected the natural purification method in the treatment of groundwater in mines by acid method in-situ leaching. The natural purification method mainly reduces the concentration of pollutants through the flow of natural groundwater and the adsorption and precipitation of pollutants by sediments. The flow speed is limited, the processing cycle of this method is long, and the processing effect is not good. In addition, domestic and foreign scholars have also explored the use of chemical precipitation, osmotic reaction wall technology and extraction-retreatment method to repair the groundwater of acid-based in-situ leaching mines, but the repair effect is not satisfactory. The chemical ...

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Problems solved by technology

[0005] (1) The natural purification method mainly reduces the concentration of pollutants through the flow of natural groundwater and the adsorption and precipitation of pollutants by sediments. Due to the limitation of the pore structure of the mine layer and the velocity of groundwater flow, this method has a long treatment cycle and poor treatment effect. good

[0006] (2) Using chemical precipitation method, osmotic reaction wall technology and extraction-retreatment method to restore the groundwater of acid leaching mines is not satisfactory; chemical precipitation method needs to add chemical reagents, which is expensive and the repair range is limited; osmotic reaction wall The cost of technical restoration is relatively high, and it is suitable for treating shallow groundwater; the effectiveness and sustainability of the restoration-retreatment method will gradually weaken as the restoration time prolongs

[0007] (3) In the method of using microbial in-situ reduction and in-situ mineralization to repair uranium-contaminated groundwater, the microbial community structure in the sediment sample after long-term acid leaching is single, the biological activity is weak, and the sulfates related to U reduction in the sediment Reducing bacteria and Fe-reducing bacteria are difficult to be activated, and it is difficult to achieve the desired effect

[0008] (4) nZVI has the problems of easy agglomeration, passivation, loss and poor electron selectivity in water, so it still has limitations in in-situ restoration and storage of groundwater.

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