阅读说明：本技术 一种土壤重金属修复剂的制备方法 (Preparation method of soil heavy metal restoration agent ) 是由 陈俊阳 宫能领 向泽文 董惠 魏素君 于 2021-09-06 设计创作，主要内容包括：本发明公开了一种土壤重金属修复剂的制备方法,包括：S1、以巯基化试剂对纳米二氧化硅进行改性,得巯基改性纳米二氧化硅；S2、以巯基改性纳米二氧化硅为载体接枝单宁酸,即得土壤重金属修复剂。本发明所述土壤重金属修复剂能够用于修复被Cd～(2+)、Pb～(2+)、Hg～(2+)等重金属污染的土壤；土壤重金属修复剂与土壤中重金属牢固结合,避免重金属因再次浸出造成土壤再次污染。(The invention discloses a preparation method of a soil heavy metal restoration agent, which comprises the following steps: s1, modifying the nano-silica by using a sulfhydrylation reagent to obtain sulfhydrylation modified nano-silica; s2, grafting tannic acid by taking the sulfydryl modified nano silicon dioxide as a carrier to obtain the soil heavy metal restoration agent. The soil heavy metal restoration agent can be used for restoring quilt Cd 2+ 、Pb 2+ 、Hg 2+ Soil contaminated with heavy metals; the soil heavy metal restoration agent is firmly combined with heavy metals in the soil, so that the soil secondary pollution caused by secondary leaching of the heavy metals is avoided.)

1. A preparation method of a soil heavy metal restoration agent is characterized by comprising the following steps: s1, modifying the nano-silica by using a sulfhydrylation reagent to obtain sulfhydrylation modified nano-silica; s2, grafting tannic acid by taking the sulfydryl modified nano silicon dioxide as a carrier to obtain the soil heavy metal restoration agent.

2. The preparation method of the soil heavy metal restoration agent according to claim 1, wherein the nano-silica is prepared from power plant biomass ash serving as a raw material through acid treatment, alkali treatment and carbonization reaction.

3. The preparation method of the soil heavy metal restoration agent according to claim 2, wherein the carbonization reaction is specifically: introducing carbon dioxide into the water glass obtained by acid treatment and alkali treatment, reacting at 60-70 ℃ for 10-30min, and then reacting at 85-90 ℃ for 30-50 min.

4. The method for preparing a soil heavy metal restoration agent according to any one of claims 1 to 3, wherein in S1, nano silica is dispersed in ethanol, the pH is adjusted to 7-9, and a sulfhydrylation reagent is added to react at 50-65 ℃ for 1-2h to obtain sulfhydryl modified nano silica.

5. The method for preparing the soil heavy metal restoration agent according to claim 4, wherein the weight ratio of the nano silicon dioxide to the sulfhydrylation agent is 1: 5-10.

6. The method for preparing a soil heavy metal remediation agent as claimed in any one of claims 1 to 5, wherein in S1, the sulfhydrylation agent is mercaptosilane; preferably, the thiolating agent is mercaptopropyltrimethoxysilane.

7. The method for preparing the soil heavy metal restoration agent according to any one of claims 1 to 6, wherein in S2, the sulfhydryl modified nano-silica is added into a tannic acid solution, the pH is adjusted to 9 to 10, the reaction is carried out for 1 to 2 hours, and then the drying is carried out for 8 to 12 hours at the temperature of 40 to 60 ℃ to obtain the soil heavy metal restoration agent.

8. The method for preparing a soil heavy metal restoration agent according to claim 7, wherein the concentration of the tannic acid solution is 45-55 mg/mL.

Technical Field

The invention belongs to the technical field of soil remediation, and particularly relates to a preparation method of a soil heavy metal remediation agent.

Background

Heavy metal means density of 5g/cm³The above metal elements are rapidly developed with economyIn the process, pollutants containing heavy metals enter soil through various ways to cause serious soil pollution, and the heavy metal pollution of the soil is absorbed by plants, enriched by livestock and finally enters human bodies through food chains to further induce various diseases and harm human health. For example, excessive cadmium can cause kidney injury, osteoporosis and other pathological changes; lead exceeding the standard will cause damage to the blood, central nervous system, reproductive system and other human organs and circulatory system. In China, about 1.5 hundred million acres of cultivated land are polluted by heavy metal, so that the yield reduction of grains is more than 1000 million tons per year, and the yield of the heavy metal overproof toxic grains is more than 1000 million tons per year. Therefore, the treatment and restoration of the heavy metal contaminated soil have important significance for protecting the ecological environment and guaranteeing the human health.

However, heavy metals are not degraded in soil and are easy to accumulate, and the improvement of the heavy metal contaminated soil is difficult and costly. The most effective method for preventing and treating soil pollution is to cut off the pollution source, to reduce the influence of heavy metals on plant growth and the pollution of food chains, to convert the heavy metals in the soil into relatively ineffective forms, and also to be the main target of treating the polluted soil. The immobilization of heavy metals in soil or the conversion of heavy metals into biologically ineffective forms by applying soil heavy metal remediation agents is a commonly used approach to the remediation of heavy metal contaminated soil.

The soil heavy metal restoration agents mainly adopted in the current market are mainly divided into two types: 1. an inorganic repair agent; 2. an organic repairing agent. Inorganic repair agents such as cement, lime, slag, modified cellulose, and the like; the organic repairing agent is organic clay, organic fertilizer and the like. Most of the existing repairing agents have the problems of poor curing effect, possibility of re-leaching of heavy metals under long-time and severe environment and re-pollution of the heavy metals. Therefore, the soil heavy metal restoration agent which can be stably and firmly combined with the heavy metal is of great significance.

Disclosure of Invention

Based on the technical problems, the invention provides a preparation method of a soil heavy metal restoration agent. The soil heavy metal restoration agent can be firmly combined with heavy metals in soil, so that the activity of the heavy metals is greatly reduced, the crops are prevented from absorbing the heavy metals, and secondary pollution to the soil caused by leaching of the heavy metals can be avoided.

The technical scheme of the invention is as follows:

the invention discloses a preparation method of a soil heavy metal restoration agent, which comprises the following steps: s1, modifying the nano-silica by using a sulfhydrylation reagent to obtain sulfhydrylation modified nano-silica; s2, grafting tannic acid by taking the sulfydryl modified nano silicon dioxide as a carrier to obtain the soil heavy metal restoration agent.

Preferably, the nano silicon dioxide is prepared by using power plant biomass ash as a raw material and performing acid treatment, alkali treatment and carbonization reaction.

The biomass ash of the power plant is ash which is formed by taking agricultural and forestry wastes such as straws, barks and rice hulls or waste wood such as wood building materials as biomass sources and remaining in a solid particle form after the biomass direct combustion power plant burns, and comprises fly ash and bottom ash, wherein the main components comprise Si, Ca, Mg, Al, K, P and the like.

Preferably, the carbonization reaction is specifically: introducing carbon dioxide into the water glass obtained by acid treatment and alkali treatment, reacting at 60-70 ℃ for 10-30min, and then reacting at 85-90 ℃ for 30-50 min.

Preferably, in S1, the nano-silica is dispersed in ethanol, the pH is adjusted to 7-9, and a sulfhydrylation reagent is added to react for 1-2h at 50-65 ℃ to obtain the sulfhydryl modified nano-silica.

Preferably, the weight ratio of the nano silicon dioxide to the sulfhydrylation agent is 1: 5-10.

Preferably, in S1, the thiolating agent is a mercaptosilane; preferably, the thiolating agent is mercaptopropyltrimethoxysilane.

Preferably, in S2, the sulfhydryl modified nano-silica is added into the tannic acid solution, the pH is adjusted to 9-10, the reaction is carried out for 1-2h, and then the drying is carried out for 12-24h at the temperature of 40-60 ℃, thus obtaining the product.

Preferably, the concentration of the tannic acid solution is 45-55 mg/mL.

The soil heavy metal restoration agent can be used alone or mixed with other fertilizers to be used asBase fertilizer or additional fertilizer is mainly used for repairing quilt Cd²⁺、Pb²⁺、Hg²⁺And (4) soil polluted by heavy metals. In practical use, the dosage of the soil heavy metal restoration agent is about 80kg per mu.

The invention has the beneficial effects that:

the soil heavy metal restoration agent takes sulfydryl modified nano silicon dioxide as a carrier to load tannic acid, and the tannic acid contains a large number of hydroxyl groups which can be bonded with heavy metals in soil through coordination bonds; in addition, the surface of the mercapto-modified nano-silica has a large number of hydroxyl groups and mercapto groups, and the mercapto-modified nano-silica can be combined with hydroxyl groups on tannic acid in a hydrogen bond mode, so that the modified nano-silica can be firmly combined with tannic acid. The hydrogen bonds among a plurality of molecules are crosslinked to form a network, and the tannic acid loaded with heavy metals is surrounded, so that the heavy metals can be firmly loaded on the repairing agent, are not easy to run off, and the problem of heavy metal pollution caused by secondary leaching of the heavy metals is avoided.

In the preferred scheme, power plant biomass ash is used as a raw material, and the power plant ash contains a large amount of silicon and is prepared into nano silicon dioxide, so that the cost is reduced, an effective way is provided for solid waste treatment of a biomass power plant, and the cyclic utilization of resources is realized.

Detailed Description

Hereinafter, the technical solution of the present invention will be described in detail by specific examples, but these examples should be explicitly proposed for illustration, but should not be construed as limiting the scope of the present invention.

Example 1

A preparation method of a soil heavy metal restoration agent comprises the following steps:

preparing nano silicon dioxide: pretreating biomass ash of a power plant to remove impurities and scum; soaking the pretreated power plant biomass ash with acid liquor, filtering, separating, drying, boiling in alkali liquor, filtering, and separating to obtain water glass; putting water glass into a reaction kettle, heating the temperature of the reaction kettle to 60 ℃, introducing carbon dioxide gas, stirring and reacting for 10min, then heating the temperature to 90 ℃, continuously introducing the carbon dioxide gas, stirring and reacting for 50min, filtering and washing the obtained slurry, and purifying to obtain nano silicon dioxide;

mercapto-modified nano-silica: dispersing the prepared nano-silica in ethanol, adjusting the pH value to 7, adding mercaptopropyl trimethoxy silane into the ethanol in which the nano-silica is dispersed, reacting for 2 hours at 50 ℃, cooling to room temperature, filtering, washing and drying to obtain mercapto-modified nano-silica; wherein the weight ratio of the nano silicon dioxide to the mercaptopropyltrimethoxysilane is 1: 10;

grafting tannic acid: and adding the sulfydryl modified silicon dioxide into a tannic acid solution with the concentration of 45mg/mL, adjusting the pH value to 10, reacting at room temperature for 1.5h, filtering, washing, and drying at 60 ℃ for 8h to obtain the soil heavy metal restoration agent.

Example 2

A preparation method of a soil heavy metal restoration agent comprises the following steps:

preparing nano silicon dioxide: pretreating biomass ash of a power plant to remove impurities and scum; soaking the pretreated power plant biomass ash with acid liquor, filtering, separating, drying, boiling in alkali liquor, filtering, and separating to obtain water glass; putting water glass into a reaction kettle, heating the temperature of the reaction kettle to 70 ℃, introducing carbon dioxide gas, stirring and reacting for 30min, then heating the temperature to 85 ℃, continuously introducing the carbon dioxide gas, stirring and reacting for 40min, filtering and washing the obtained slurry, and purifying to obtain nano silicon dioxide;

mercapto-modified nano-silica: dispersing the prepared nano-silica in ethanol, adjusting the pH value to 8, adding mercaptopropyl trimethoxy silane into the ethanol in which the nano-silica is dispersed, reacting at 60 ℃ for 1.5h, cooling to room temperature, filtering, washing and drying to obtain mercapto-modified nano-silica; wherein the weight ratio of the nano silicon dioxide to the mercaptopropyltrimethoxysilane is 1: 6;

grafting tannic acid: and adding the sulfydryl modified nano silicon dioxide into a tannic acid solution with the concentration of 50mg/mL, adjusting the pH value to 9, reacting for 2 hours at room temperature, filtering, washing, and drying for 12 hours at 40 ℃ to obtain the soil heavy metal restoration agent.

Example 3

A preparation method of a soil heavy metal restoration agent comprises the following steps:

preparing nano silicon dioxide: pretreating biomass ash of a power plant to remove impurities and scum; soaking the pretreated power plant biomass ash with acid liquor, filtering, separating, drying, boiling in alkali liquor, filtering, and separating to obtain water glass; putting water glass into a reaction kettle, heating the temperature of the reaction kettle to 70 ℃, introducing carbon dioxide gas, stirring and reacting for 15min, then heating the temperature to 90 ℃, continuously introducing the carbon dioxide gas, stirring and reacting for 30min, filtering and washing the obtained slurry, and purifying to obtain nano silicon dioxide;

mercapto-modified nano-silica: dispersing the prepared nano-silica in ethanol, adjusting the pH value to 9, adding mercaptopropyl trimethoxy silane into the ethanol in which the nano-silica is dispersed, reacting at 65 ℃ for 1h, cooling to room temperature, filtering, washing and drying to obtain mercapto-modified nano-silica; wherein the weight ratio of the nano silicon dioxide to the mercaptopropyltrimethoxysilane is 1: 5;

grafting tannic acid: and adding the sulfydryl modified nano silicon dioxide into a tannic acid solution with the concentration of 55mg/mL, adjusting the pH value to 10, reacting for 1h at room temperature, filtering, washing, and drying for 10h at 55 ℃ to obtain the soil heavy metal restoration agent.

Effect test 1:

preparation of Cd²⁺Indoor pot experiment was performed on contaminated soil at a concentration of 1mg/kg, the soil remediation agent described in example 1 was applied at 5% of the dry weight of the soil, pakchoi was planted (growth cycle: 35 days), harvested, air-dried, digested with microwaves, and Cd in roots and leaves was determined by ICP-AES²⁺Content (c); for comparison purposes, no soil remediation agent was applied.

The results show that: in the soil planted pakchoi applied with the soil remediation agent of example 1, compared with the pakchoi without the soil remediation agent, Cd in the roots and leaves²⁺The content is respectively reduced by 82.05% and 80.47%.

Effect test 2:

preparation of Pb²⁺An indoor pot experiment was performed on contaminated soil at a concentration of 1mg/kg, the soil remediation agent described in example 2 was applied at 5% of the dry weight of the soil, pakchoi was planted (growth cycle: 30 days), harvested, air-dried, digested with microwaves, and Pb in roots and leaves was measured by ICP-AES²⁺Content (c); for comparison purposes, no soil remediation agent was applied.

The results show that: the roots and leaves of the pakchoi planted in the soil to which the soil conditioner described in example 2 was applied contained Pb compared to those without the soil conditioner²⁺The content is reduced by 83.33 percent and 81.72 percent respectively.

Effect test 3:

preparation of Hg²⁺An indoor pot experiment is carried out on polluted soil with the concentration of 1mg/kg, the soil remediation agent described in the example 1 is applied according to 5% of the dry weight of the soil, lettuce is planted (the growth cycle is 90 days), the lettuce is dried after being harvested and is digested by microwaves, and Hg in lettuce leaves is measured by ICP-AES²⁺Content (c); for comparison purposes, no soil remediation agent was applied.

The results show that: hg in leaves of soil-planted lettuce to which the soil conditioner described in example 1 was applied, compared with lettuce which had not been applied²⁺The content is reduced by 81.72%.

The effect tests show that the soil remediation agent provided by the invention can treat heavy metal (Cd)²⁺、Pb²⁺、Hg²⁺) The remediation effect of the polluted soil is obvious; moreover, the soil repairing agent can be used for repairing the pakchoi with a relatively short growth cycle (about 30 days) or the lettuce with a relatively long growth cycle (about 90 days), so that the influence of heavy metals on vegetables can be greatly reduced, and the soil repairing agent has good stability, and the heavy metals can be firmly loaded on the repairing agent and are not easy to lose.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.