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Cadmium-contaminated farmland soil remediation method based on magnetic biochar

A soil remediation and biochar technology, applied in the field of cadmium-contaminated farmland soil remediation, can solve the problems of high energy consumption and cumbersome operation steps, and achieve the effect of light texture

Pending Publication Date: 2020-03-24
POWERCHINA ZHONGNAN ENG +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method also has the effect of reducing heavy metals in the soil, but there are some problems in it. Taking out the soil for ex-situ treatment, high-pressure washing and screening is accompanied by huge energy consumption. At the same time, the separation system is multi-gradient sorting, and the operation steps are cumbersome.

Method used

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  • Cadmium-contaminated farmland soil remediation method based on magnetic biochar
  • Cadmium-contaminated farmland soil remediation method based on magnetic biochar
  • Cadmium-contaminated farmland soil remediation method based on magnetic biochar

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] Take 50 g of corn stalks with a crushed particle size of 2-8 mm in 1 L FeSO 4 ·7H 2 Soak in O solution (50 mM), stir magnetically for 0.5 h, add 2.51 g hydroxyapatite nanoparticles to form hydroxyapatite solution (5 mM), continue magnetic stirring for 1 h to make it evenly dispersed, suction filter, and place in Dry in a blast oven at 75°C. The dried corn stalks were placed in a silicon carbide reactor, covered with a lid and placed in a muffle furnace, nitrogen was continuously passed through the muffle furnace for 5 min, pyrolyzed at 600 °C for 1 h under anaerobic conditions, and cooled to obtain magnetic biological carbon. Figure 1 is the SEM-EDS image of the prepared magnetic biochar, Figure 1(a) shows a uniform pore structure, Figure 1(b) shows the loading of hydroxyapatite and magnetic iron oxide particles, Figure 1(c) and 1(d) is the elemental and content analysis of the particles in Fig. 1(b), showing that hydroxyapatite and magnetic iron oxide are indeed loa...

Embodiment 2

[0053] To investigate the effect of different reaction times, 200 g of soil passed through a 2 mm mesh sieve was weighed and poured into a 1 L beaker. Add 400 mL of deionized water at a water-to-soil ratio of 2:1. After standing for 1 h, 6 g of magnetic biochar was added at 3% of the soil mass, stirred for 30 min, and two parallel experiments were set up. After standing for 12 h, 24 h, 36 h and 48 h respectively, the magnetic biochar with adsorbed Cd was recovered with a magnet, and the removal rate of total cadmium in the soil was measured and calculated as follows: Figure 4 shown.

[0054] The effect of different dosages, weighed 3 parts of 200 g soil that passed through a 2 mm mesh sieve, and poured it into a 1 L beaker. Add 400 mL of deionized water at a water-to-soil ratio of 2:1. After standing for 1 h, 2 g, 6 g and 10 g of HMBC were added to the beaker at 1%, 3% and 5% of the soil mass, respectively, and stirred for 30 min to set up two parallel experiments. After ...

Embodiment 3

[0056] The air-dried soil passed through a 2mm sieve was subjected to particle size classification, the Cd content in different particle sizes was measured, and the distribution of Cd content in different particle sizes was calculated. Clay particle size Figure 6 As shown, the content of Cd in clay, silt and sand are 1.75, 1.37, 0.63 mg kg, respectively –1 , it can be seen that the Cd concentration in the clay is the highest. Therefore, removing a small part of the clay can reduce the total amount of Cd in the soil.

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Abstract

The invention discloses a cadmium-contaminated farmland soil remediation method based on magnetic biochar. The method mainly comprises the following steps: irrigating soil, adding biochar accounting for 0.5-5% of the mass of the soil, performing sufficient stirring until uniformity to make the magnetic biochar and the soil form a muddy water mixture, standing the mixture, adding water, performingstirring to make the magnetic biochar float out of the water surface, and recovering the magnetic biochar enriched with free Cd and soil clay particles so as to achieve the purpose of reducing the total Cd of the soil. The free Cd and clay particles with a small particle size (smaller than or equal to 2 [mu]m) and a high Cd concentration are enriched by means of the magnetism, floatability and other properties of the magnetic biochar, so the Cd content of the soil is reduced; and the application of the magnetic biochar also has an improvement effect on soil. The magnetic biochar prepared in the invention has floating capacity, and can be magnetically recycled, and the remediation method has the advantages of simple flow, high operability, greenness and environmental friendliness, and is anenvironmentally-friendly remediation technology.

Description

technical field [0001] The invention relates to a method for remediating cadmium-contaminated farmland soil based on magnetic biochar, and belongs to the technical field of soil pollution remediation for environmental protection. Background technique [0002] In heavy metal pollution, cadmium (Cd) is one of the most potentially harmful metal pollutants to human health. In 2014, the Ministry of Environmental Protection and the The point exceeding standard rate is as high as 7%. Therefore, it is urgent to remediate Cd-contaminated soil and reduce soil Cd. [0003] At present, there are many remediation methods for soil Cd reduction, such as phytoremediation technology and chemical leaching technology, and each method has its own advantages and disadvantages. Phytoremediation technology is environmentally safe and has economic advantages. However, most hyperaccumulator plants are small in size, slow in growth, and difficult to select and cultivate. Therefore, phytoremediation...

Claims

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Application Information

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IPC IPC(8): B09C1/02B09C1/08
CPCB09C1/02B09C1/08
Inventor 肖劲光刘喜王薇王琳玲钟怡肖武杜成琼
Owner POWERCHINA ZHONGNAN ENG
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