CN-122012111-A - Biochemistry composite soil heavy metal pollution fixing and repairing material and preparation method thereof

CN122012111ACN 122012111 ACN122012111 ACN 122012111ACN-122012111-A

Abstract

The invention provides a biochemical composite soil heavy metal pollution fixing and repairing material and a preparation method thereof, wherein the material comprises the following steps of carrying out acid treatment on biochar to obtain activated biochar; mixing calcium salt, ferric salt, aluminum salt and deionized water uniformly to obtain a mixed salt solution, adding urea to obtain a precursor solution, immersing activated biochar in the precursor solution, performing hydrothermal reaction to obtain loaded biochar, mixing oyster shell powder and dipotassium hydrogen phosphate, grinding and calcining at high temperature to obtain activated oyster shell powder, mixing bacillus subtilis bacterial liquid, activated oyster shell powder and trehalose, oscillating, centrifugally separating, freeze-drying to obtain a biological composite material, mixing the loaded biochar, the biological composite material and carboxymethyl cellulose solution uniformly, granulating, and drying wet granules to obtain the biochemical composite soil heavy metal pollution fixing and repairing material. The fixing and repairing material prepared by the invention improves the fixing efficiency and adaptability to various heavy metals in soil.

Inventors

LIU ZHIQIANG
ZHANG ZE
ZHANG FENG
ZHAO CHENG
YUAN HUI
LI FUGANG
LI JUNDA
LU XIU
DAI QIAN

Assignees

中新瑞美(天津)环保科技有限公司
中科瑞美(天津)环境技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260205

Claims (10)

1. The preparation method of the biochemical composite soil heavy metal pollution fixing and repairing material is characterized by comprising the following steps of: (I) Uniformly mixing calcium salt, ferric salt, aluminum salt and deionized water to obtain a mixed salt solution, adding urea into the mixed salt solution to obtain a precursor solution, soaking the activated biochar in the precursor solution, performing hydrothermal reaction, and filtering, washing and drying after the reaction is finished to obtain the loaded biochar; Mixing and grinding oyster shell powder and dipotassium hydrogen phosphate, and then calcining at high temperature to obtain activated oyster shell powder, mixing and vibrating bacillus subtilis bacterial liquid, the activated oyster shell powder and trehalose, and then carrying out centrifugal separation and freeze drying to obtain a biological composite material; (III) uniformly mixing the loaded biochar, the biocomposite and the carboxymethyl cellulose solution, granulating to obtain wet granules, and drying the wet granules to obtain the biochemical composite soil heavy metal pollution fixing and repairing material.
2. The method of claim 1, wherein in step (I), the activated biochar is prepared by: (1) Uniformly mixing bamboo powder and calcium carbonate, performing gradient pyrolysis under a nitrogen atmosphere, and then crushing, sieving and pickling to obtain bamboo-based biochar; (2) Dispersing the bamboo-based biochar in a mixed acid solution consisting of a nitric acid solution and a phosphoric acid solution for microwave activation, and then filtering, washing and drying to obtain the activated biochar.
3. The preparation method of claim 2, wherein in the step (1), the mass ratio of the bamboo powder to the calcium carbonate is 1 (0.8-1.2); The gradient pyrolysis comprises the following operation steps of low-temperature pyrolysis and high-temperature pyrolysis which are sequentially carried out; The temperature rising rate of the low-temperature pyrolysis is 3-5 ℃ per minute; The pyrolysis temperature of the low-temperature pyrolysis is 300-400 ℃; The heat preservation time of the low-temperature pyrolysis is 60-90 min; The heating rate of the high-temperature pyrolysis is 5-10 ℃ per minute; The pyrolysis temperature of the high-temperature pyrolysis is 600-700 ℃; The heat preservation time of the high-temperature pyrolysis is 60-90 min; The number of the screen meshes of the crushing and sieving is 100-120 meshes; the pickling process comprises the following steps: And adding the crushed and sieved biochar powder into a 2-3wt% dilute hydrochloric acid solution, stirring and washing for 1-2 hours at 60-80 ℃, filtering, washing with deionized water to be neutral, and drying to obtain the bamboo-based biochar.
4. The preparation method of claim 2, wherein in the step (2), the solid-to-liquid ratio of the bamboo-based biochar to the mixed acid solution is 1g (12-15) mL; The mixed acid solution is prepared by uniformly mixing a phosphoric acid solution and a nitric acid solution according to the volume ratio of (2-3): 1; the mass fraction of the phosphoric acid solution is 10-15wt%; The mass fraction of the nitric acid solution is 10-15wt%; the microwave power of the microwave activation is 300-400W; the treatment time of microwave activation is 10-15 min; the drying temperature is 100-110 ℃; And the drying time is 6-8 hours.
5. The method of claim 1, wherein in step (I), the calcium salt comprises calcium nitrate; The iron salt comprises ferric nitrate; The aluminum salt comprises aluminum nitrate; The molar ratio of Ca 2+ 、Fe 3+ to Al 3+ in the mixed salt solution is 3 (0.3-0.5) (0.5-0.7); The total concentration of Ca 2+ 、Fe 3+ and Al 3+ in the mixed salt solution is 0.4-0.6 mol/L; The total molar ratio of the urea to Ca 2+ 、Fe 3+ and Al 3+ in the mixed salt solution is (3-5) 1; the solid-to-liquid ratio of the activated biochar to the precursor solution is 1g (15-20) mL; The soaking time of the activated biochar in the precursor solution is 3-5 h; The temperature of the hydrothermal reaction is 100-150 ℃; the hydrothermal reaction time is 10-15 h; the drying temperature is 100-110 ℃; And the drying time is 6-8 hours.
6. The preparation method of claim 1, wherein in the step (II), the mass ratio of the oyster shell powder to the dipotassium hydrogen phosphate is 1 (0.1-0.2); The high-temperature calcination temperature of the oyster shell powder and the dipotassium hydrogen phosphate is 180-200 ℃; the high-temperature calcination time of the oyster shell powder and the dipotassium hydrogen phosphate is 2-3 hours.
7. The preparation method of claim 1, wherein in the step (II), the viable count of the bacillus subtilis liquid is not less than 10 9 CFU/mL; The solid-liquid ratio of the activated oyster shell powder to the bacillus subtilis bacterial liquid is 1g (2-3) mL; The consumption of the trehalose is 1.5-2wt% of the mass of the bacillus subtilis bacterial liquid; The rotation speed of the mixed oscillation of the bacillus subtilis bacterial liquid, the activated oyster shell powder and the trehalose is 150-200 rpm; the temperature of the mixed oscillation of the bacillus subtilis bacterial liquid, the activated oyster shell powder and the trehalose is 30-40 ℃; the mixing and oscillating time of the bacillus subtilis bacterial liquid, the activated oyster shell powder and the trehalose is 2-3 hours.
8. The method according to claim 1, wherein in the step (II), the rotational speed of the centrifugal separation is 4000 to 6000rpm; the centrifugal separation time is 10-15 min; the freeze drying process comprises pre-cooling and deep cooling which are sequentially carried out; The precooling temperature is 0-5 ℃; The pre-cooling time is 4-6 hours; The cryogenic temperature is-30 to-40 ℃; the time of the deep cooling is 12-24 hours.
9. The preparation method according to claim 1, wherein in the step (III), the mass ratio of the supported biochar to the biocomposite is 1 (1-1.5); the mass fraction of the carboxymethyl cellulose solution is 5-8wt%; The mass of the carboxymethyl cellulose in the carboxymethyl cellulose solution is 1-3wt% of the total mass of the loaded biochar and the biocomposite; the particle size of the wet granules is 3-5 mm; the drying process of the wet granules comprises the steps of hot air drying at 35-40 ℃ for 1-2 hours, and then airing in a ventilated shade place.
10. A biochemical composite soil heavy metal pollution immobilization and repair material prepared by the preparation method of any one of claims 1 to 9.

Description

Biochemistry composite soil heavy metal pollution fixing and repairing material and preparation method thereof Technical Field The invention belongs to the technical field of soil remediation, and relates to a biochemical composite soil heavy metal pollution fixing and remediating material and a preparation method thereof. Background With the rapid development of industry and agriculture, soil heavy metal pollution has become a serious global environmental challenge. At present, the technology for repairing heavy metal contaminated soil is mainly based on two strategies, namely, separating and removing heavy metal from the soil, and changing the existing form of the heavy metal in the soil to reduce the bioavailability and mobility of the heavy metal. Among many restoration methods, the in-situ passivation restoration technology is considered to have good application prospect because of relatively low cost, simple and convenient operation and higher restoration efficiency of the medium and light polluted soil. The core of the technology is to add passivation materials into soil and fix heavy metals through adsorption, precipitation, complexation and other actions. The traditional modifier has a plurality of kinds, including inorganic materials such as lime, zeolite, bentonite and the like, and organic materials such as compost and the like. However, these materials have limitations such as lime-based passivating agents to repair pollution by increasing the pH of the soil, but the effect may be difficult to last due to the self-cleaning ability of the soil, with the risk of reactivation, while some organic curing agents may have problems with general repair effects or secondary pollution. In recent years, biochar has been receiving attention because of its advantages such as wide sources of raw materials, good environmental compatibility, etc. However, biochar prepared by simple pyrolysis tends to be limited in adsorption fixing ability for heavy metals in terms of pore structure and surface chemical characteristics. At the same time, biochemical composite materials combining chemical passivation with bioremediation show great potential. The material aims to comprehensively utilize the stability of inorganic materials, the improvement of organic materials and the degradation and conversion capability of microorganisms to realize synergistic restoration. Therefore, there is a need to develop a repair material which is efficient, stable, free of secondary pollution and suitable for a complex polluted site. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a biochemical composite soil heavy metal pollution fixing and repairing material and a preparation method thereof. To achieve the purpose, the invention adopts the following technical scheme: in a first aspect, the invention provides a preparation method of a biochemical composite soil heavy metal pollution fixing and repairing material, which comprises the following steps: (I) Uniformly mixing calcium salt, ferric salt, aluminum salt and deionized water to obtain a mixed salt solution, adding urea into the mixed salt solution to obtain a precursor solution, soaking the activated biochar in the precursor solution, performing hydrothermal reaction, and filtering, washing and drying after the reaction is finished to obtain the loaded biochar; Mixing and grinding oyster shell powder and dipotassium hydrogen phosphate, and then calcining at high temperature to obtain activated oyster shell powder, mixing and vibrating bacillus subtilis bacterial liquid, the activated oyster shell powder and trehalose, and then carrying out centrifugal separation and freeze drying to obtain a biological composite material; (III) uniformly mixing the loaded biochar, the biocomposite and the carboxymethyl cellulose solution, granulating to obtain wet granules, and drying the wet granules to obtain the biochemical composite soil heavy metal pollution fixing and repairing material. The preparation method comprises the steps of firstly carrying out acid activation and hydrothermal reaction on the activated charcoal, loading calcium, iron and aluminum Layered Double Hydroxide (LDH) on the activated charcoal, then calcining and activating oyster shell powder, then compounding the activated oyster shell powder with bacillus subtilis to prepare a biological composite material, and finally mixing and granulating the activated oyster shell powder and a carboxymethyl cellulose solution, thereby realizing multiple effects of physical adsorption, chemical precipitation and bioremediation. The supported biochar can rapidly capture heavy metal ions by utilizing the developed pore structure and the ion exchange capability of LDH, and the biocomposite provides long-term stabilization through microbial metabolism and phosphate precipitation, so that the fixing efficiency and adaptability to various heavy metals (such as lead, cadmium and arsenic)