阅读说明：本技术 一种负载杂原子的生物质炭材料及其应用 (Heteroatom-loaded biomass charcoal material and application thereof ) 是由 左静 杨琳 方国东 秦丰林 于 2020-12-09 设计创作，主要内容包括：本申请提供了一种负载杂原子的生物质炭材料及其应用,涉及环保领域；该生物质炭材料是由秸秆、氮源、磷源、硫源、硼源混合后,经马弗炉程序加热碳化获得；该生物质炭材料来源广泛,环境友好,在常温、自然条件下即可高效活化过硫酸盐进而修复土壤有机污染,生物质炭材料及其负载的杂原子不仅不会对土壤生态环境造成不利影响,还能显著提高土壤有机质等养分含量,进而对土壤起到改良作用,易于推广应用。(The application provides a heteroatom-loaded biomass charcoal material and application thereof, relating to the field of environmental protection; the biomass charcoal material is obtained by mixing straws, a nitrogen source, a phosphorus source, a sulfur source and a boron source and then heating and carbonizing the mixture by a muffle furnace program; the biomass charcoal material has wide sources and is environment-friendly, persulfate can be efficiently activated under normal temperature and natural conditions to restore soil organic pollution, the biomass charcoal material and the loaded heteroatoms thereof can not cause adverse effects on the soil ecological environment, the content of nutrients such as soil organic matters and the like can be obviously improved, the soil is further improved, and the biomass charcoal material is easy to popularize and apply.)

1. A heteroatom-loaded biomass charcoal material is characterized by being prepared by the following method:

1) uniformly mixing straws, a nitrogen source, a phosphorus source, a sulfur source and a boron source according to a mass ratio of 70:10:10:5:5 to obtain a mixture; wherein, the nitrogen source, the phosphorus source, the sulfur source and the boron source are respectively calculated according to the mass of nitrogen, phosphorus, sulfur and boron contained in the nitrogen source, the phosphorus source, the sulfur source and the boron source;

2) filling the mixture obtained in the step 1) into a reaction tank without oxygen;

3) putting the reaction tank into a muffle furnace, heating to 120 ℃, preserving heat for 15min, then heating to 180 ℃, preserving heat for 15min, then heating to 500 ℃, preserving heat for 15min, and raising the temperature in the whole process to 5 ℃/min;

4) and 3) after heating is finished, naturally cooling to room temperature, taking out the material, grinding and sieving by a 2mm sieve to obtain the heteroatom-loaded biomass charcoal-based material.

2. The heteroatom-laden biomass char material of claim 1, wherein the nitrogen source comprises one or more of urea, ammonium nitrate, ethylenediamine, indole, polyaniline; the phosphorus source is ammonium dihydrogen phosphate; the sulfur source is thiourea; the boron source is boric acid.

3. The heteroatom-laden biochar material of claim 1, wherein the straw is obtained from crop straw by drying and pulverizing to a diameter of 2-5 mm.

4. Use of the heteroatom-loaded biochar material of any one of claims 1-3 in activating persulfates.

5. Use of the heteroatom-loaded biochar material of any one of claims 1-3 in degrading organic-contaminated soil.

6. Use according to claim 5, characterized by the steps of: adding the biomass charcoal-based material loaded with the heteroatom into the soil polluted by the organic matters, uniformly mixing, and then applying persulfate to realize the degradation of the organic pollutants in the soil.

7. The use of claim 6, wherein the mass ratio of the heteroatom-loaded biomass charcoal-based material to the organic-contaminated soil is 1-5: 100.

8. The use of claim 6, wherein the mass ratio of the heteroatom-loaded biomass char-based material to the persulfate is 1: 3-5.

9. Use according to claim 6, wherein the persulfate salt is sodium persulfate.

10. The use of claim 7, wherein the mass ratio of the heteroatom-laden biochar-based material to the organic-contaminated soil is 1: 100.

Technical Field

The application relates to the field of environmental protection, in particular to a heteroatom-loaded biomass charcoal material and application thereof in persulfate activation.

Background

With the acceleration of the urbanization process, a large amount of industrial pollutants related to industries such as coking, chemical engineering, petroleum and the like are discharged into soil, a large amount of organic polluted sites are generated, and how to quickly and effectively repair the organic polluted sites is a problem which needs to be solved at present. The chemical oxidation remediation technology has the advantages of high remediation efficiency, short period, low cost, insensitivity to pollutant types and concentrations and the like, and is one of common technologies for remedying the polluted soil.

Advanced Oxidation Processes (AOPs) are a general name of a series of reaction processes for oxidizing and degrading organic pollutants based on high oxidation potential of free radicals, and have the characteristics of wide application range, strong oxidizing capability and high reaction rate. Conventional AOPs use hydroxyl radical (. OH) as the main active species to degrade pollutants. HO · is a strong oxidizing agent having a high reduction potential, but HO · oxidation of pollutants is required to be performed under acidic conditions, and there is no selectivity for degradation of pollutants, and therefore, it is greatly affected by background substances (carbonates, bicarbonates, natural organic substances, and the like) at the time of application.

The activated persulfate oxidation technology is a new advanced oxidation process developed in recent years, using sulfate radicals (SO)₄ ^-Etc.) as the main active substance to degrade organic pollutants, and S has limited ability to oxidize pollutants by persulfate itself under the conditions of light, heat, sound, transition metal ions and the like₂O₈ ^2-Can be activated and decomposed into SO₄ ^-Has higher oxidation-reduction potential and can degrade most pollutants.

Methods of activating persulfates include thermal activation, ultraviolet light activation, ultrasonic activation, and the like. The traditional persulfate activation technology has large energy consumption and high cost, and the problem of secondary pollution caused by leaching of metal ions when the metal-based catalytic material activates persulfate. In order to reduce the risk of secondary pollution, researchers at home and abroad are working on developing novel heterogeneous catalysts, such as nano copper ferrite and nano Co₃O₄The cost of the material is too high, and the material is difficult to popularize and apply on a large scale; at the same time, CO²⁺It also has some toxicity that may cause potential harm to the operator, further limiting the application of this technique.

In addition, the existing biological carbon preparation technology is that the temperature is raised to 100 ℃ and kept for 2h, then the temperature is raised to 300 ℃, 400 ℃, 500 ℃, 600 ℃ and 700 ℃ respectively, the temperature gradient is 10 ℃/min, the temperature is kept for different time, and then the room temperature is recovered to obtain the biological carbon; however, the method is used for heating to the thermal cracking temperature of 100 ℃ in one step and then preserving the heat for 2 hours, the temperature is low, the thermal cracking process is not thorough, a good thermal cracking effect cannot be achieved, the subsequent heating is directly carried out to the designed temperature, the performance of a carbonized product is relatively poor, and the subsequent utilization of the biomass charcoal is not facilitated.

Therefore, an environment-friendly, efficient and cheap activating agent is urgently needed to be developed so as to improve the application range of persulfate in the field organic pollution scene restoration.

Disclosure of Invention

Aiming at the problems, the application provides an activating agent prepared by doping a biomass charcoal material with heteroatoms, which generates sulfate radicals through activating a persulfate system, so that organic pollutants are rapidly decomposed and eliminated, and the activating agent is environment-friendly and does not cause secondary pollution.

The application is realized by the following technical scheme:

firstly, the application provides a biomass charcoal material loaded with heteroatoms, which is prepared by the following method:

1) mixing the straw biomass crushed material, a nitrogen source, a phosphorus source, a sulfur source and a boron source according to a mass ratio of 70:10:10:5:5, and then fully and uniformly mixing to obtain a mixture; wherein, the nitrogen source, the phosphorus source, the sulfur source and the boron source are respectively calculated according to the mass of the nitrogen element, the mass of the phosphorus element, the mass of the sulfur element and the mass of the boron element contained in the nitrogen source, the phosphorus source, the sulfur source and the boron source in sequence;

2) filling the mixture obtained in the step 1) into an oxygen-free reaction tank (preferably a stainless steel tank); e.g. by using an inert gas (preferably N)₂) Performing blowing treatment to remove oxygen in the reaction tank;

3) loading the filled reaction tank into a muffle furnace for oxygen-limited high-temperature thermal cracking; namely, a muffle furnace adopts programmed heating, the heating range is that the room temperature is raised to 120 ℃ and the temperature is preserved for 15min, then the room temperature is raised to 180 ℃ and the temperature is preserved for 15min, then the room temperature is raised to 500 ℃ and the temperature is preserved for 15min, and the whole heating range is 5 ℃/min;

4) and 3) after heating is finished, naturally cooling to room temperature, taking out the material, grinding and sieving by a 2mm sieve to obtain the heteroatom-loaded biomass charcoal-based material.

Further, the straw biomass crushed material is obtained by drying crop straws and crushing the crop straws into 2-5mm in diameter; the crops comprise at least one of rice, wheat and corn.

Further, the nitrogen source comprises one or more of urea, ammonium nitrate, ethylenediamine, indole and polyaniline; the phosphorus source is preferably monoammonium phosphate (i.e., monoammonium); the sulfur source is preferably thiourea and the boron source is preferably boric acid.

In the present application, the heteroatoms mainly include nitrogen, phosphorus, sulfur, boron.

Secondly, the application also provides the application of the biomass charcoal material loaded with the heteroatom in activating persulfate, namely the biomass charcoal material loaded with the heteroatom is mixed with persulfate, so that the persulfate can be activated.

Thirdly, the application also provides an application of the biomass charcoal material loaded with the heteroatom in the degradation of soil organic pollutants. The specific application steps are as follows: the biomass charcoal-based material loaded with the heteroatom is added into the organic matter contaminated soil, and after the biomass charcoal-based material is fully mixed, persulfate is applied (preferably sodium persulfate is fully reacted to achieve the effect of efficiently degrading organic pollutants in the organic matter contaminated soil.

Further, in the application of the heteroatom-loaded biomass charcoal material in activating persulfate, the mass ratio of the heteroatom-loaded biomass charcoal to the organic matter-contaminated soil is preferably 1-5: 100.

Further, in the application of the biomass charcoal material loaded with the heteroatom in activating persulfate, the mass ratio of the biomass charcoal material loaded with the heteroatom to organic matter-contaminated soil is preferably 1:100, and the mass ratio of the biomass charcoal material loaded with the heteroatom to persulfate (preferably sodium persulfate) is 1: 5-1: 3.

Further, in the application of the above-mentioned heteroatom-loaded biomass charcoal material in activating persulfate, the persulfate is an aqueous persulfate solution (preferably an aqueous sodium persulfate solution) so as to ensure sufficient contact between the persulfate and the soil.

The main reaction principle of the heteroatom-loaded biomass carbon material for activating persulfate is as follows: functional groups such as-OH, -OOH, -COOH, C-OH and the like in the biomass charcoal-based material loaded with heteroatoms can perform a metalloid catalytic reaction, and persulfate is activated to decompose and generate sulfate radicals, so that organic pollutants in soil are degraded, wherein the reaction equation is as follows: carbon surface-OH + S₂O₈ ^2-→Carbon surface-O·+SO₄·^-+HSO₄ ^-；

Carbon surface-OOH+S₂O₈ ^2-→Carbon surface-OO·+SO₄·^-+HSO₄ ^-；

C＝C＝O+HSO₅ ^-→SO₄·^-+C＝C-O++OH^-；

C＝C-O++HSO₅ ^-→C＝C＝O+SO₅·^-+H⁺。

The non-metal heteroatoms (N, P, S, B and the like) with the atomic radius, electronegativity and charge density similar to those of carbon atoms are introduced into the biomass charcoal material to obtain the biomass charcoal-based material loaded with the heteroatoms, so that the electron density in local carbon atoms can be changed, the electron mobility is improved, a new active center is introduced, and the catalytic electron transfer reaction is accelerated, so that the catalytic performance of the activated persulfate of the activated material for degrading organic pollutants in soil is enhanced.

(1) The activated material is mainly biomass charcoal, the raw materials of the activated material are rich, the cost is relatively low, and the activated material is easier to popularize and apply practically.

(2) Compared with the prior art, the method has the advantages that the nitrogen blowing treatment is carried out before the thermal cracking, so that better oxygen insulation conditions can be achieved; the heating process is that the room temperature is raised to 120 ℃ and the temperature is preserved for 15min, then raised to 180 ℃ and preserved for 15min, finally raised to 500 ℃ and preserved for 15min, and the temperature raising amplitude is 5 ℃/min; the temperature programming is divided into two stages from room temperature to 120 ℃, belongs to preliminary thermal cracking, ensures the inherent appearance of raw materials, shapes better carbon plasticity, further raises the temperature to 180 ℃, carries out slow pyrolysis, is beneficial to improving the pore and surface properties of carbonized products, reduces the ash content and is convenient for the application of subsequent heteroatom loading.

(3) Compared with the traditional metal catalytic material, the heteroatom loaded by the biochar comprises N, P, S, B, so that the secondary pollution cannot be caused, and meanwhile, due to the introduction of the nonmetal heteroatoms, the network inertia of the carbon-based material can be broken, the conductivity can be improved, the reaction active sites can be increased, and the degradation efficiency of persulfate on organic pollutants in soil can be remarkably improved; however, the metal ions or organic compounds (hydroquinone, phenol, catechol) used in the prior art are significantly different from the non-metal atoms in the scheme in terms of chemical composition, and the technical effects of changing the electron density in local carbon atoms, improving the electron mobility, introducing new active centers and accelerating the catalytic electron transfer reaction in the application cannot be achieved.

(4) The biomass charcoal material is environment-friendly, persulfate can be efficiently activated under normal temperature and natural conditions to restore organic pollution of soil, the biomass charcoal material cannot cause adverse effect on the ecological environment of the soil, the content of nutrients such as organic matters in the soil can be remarkably increased, and the soil is further improved.

(5) The heteroatom-loaded biomass carbon material provided by the application releases SO4 DEG-through activating sodium persulfate in the activated persulfate, SO as to oxidize and degrade organic pollutants, not only can degrade polychlorinated biphenyl, but also can degrade other organic pollutants (such as organic matters of polycyclic aromatic hydrocarbon, organic chlorine, petroleum hydrocarbon and the like).

Drawings

FIG. 1 is a diagram showing dynamic results of PCBs content at different repair times.

Detailed Description

Example 1: preparation of heteroatom-loaded biomass charcoal material

The method comprises the following specific steps:

s1: drying rice straws and then crushing the rice straws to 2-5mm to obtain straw biomass crushed materials;

then mixing the materials prepared in advance according to the following parts by weight respectively: crushing straw biomass: urea: an ammonium: thiourea: mixing boric acid 70:10:10:5:5, and then fully and uniformly mixing; wherein, the mass of the urea, the monoammonium, the thiourea and the boric acid is calculated according to the nitrogen element, the phosphorus element, the sulfur element and the boron element contained in the urea, the monoammonium, the thiourea and the boric acid respectively.

S2 filling the above prepared materials into a stainless steel can and using N₂Blowing, and sealing the stainless steel tank after air in the tank is exhausted;

s3: and then loading the filled stainless steel can into a muffle furnace for oxygen-limited high-temperature thermal cracking, wherein the muffle furnace adopts programmed heating, the heating range is room temperature rise to 120 ℃ and heat preservation for 15min, then the heating range is room temperature rise to 180 ℃ and heat preservation for 15min, then the heating range is 500 ℃ and heat preservation for 15min, and the whole heating range is 5 ℃/min.

And S4, naturally cooling to room temperature after the steps are finished, taking out the material, grinding the material properly, and sieving the ground material by a 2mm sieve to obtain the heteroatom-loaded biomass carbon-based material. Namely the activating agent 1;

further, it will:

in the step S1, replacing boric acid with clean water with equal mass, and keeping the subsequent steps unchanged to obtain an activator 2;

replacing monoammonium and boric acid in the step S1 with equal amount of clear water, and keeping the subsequent steps unchanged to obtain an activator 3;

replacing the boric acid, the monoammonium and the thiourea in the step S1 with the same amount of clear water, and obtaining an activator 4 without changing the subsequent steps; the urea, monoammonium, boric acid and thiourea in the step S1 are replaced by the same amount of clear water, and the subsequent steps are not changed to obtain the activator 5 (namely pure biomass charcoal).

Example 2 soil remediation experiment

The soil tested in this example was polycyclic aromatic hydrocarbon contaminated soil sampled in the field, and the total amount of polychlorinated biphenyls (PCBs) in the soil was 177.68 mg/kg.

The experimental procedure was as follows: the activating agents 1-5 prepared in the embodiment 1 are respectively and uniformly mixed with soil according to the proportion, then sodium persulfate aqueous solution (mass fraction is 20%) is respectively and proportionally added, and the mixture is uniformly mixed under the condition of normal temperature and then is kept stand for reaction. Then detecting the content of polychlorinated biphenyl (PCB) in the soil according to the method disclosed by the national standard HJ 99-2017, wherein the total content of the polychlorinated biphenyl is calculated by the sum of twelve contents of PCB77, PCB81, PCB105, PCB114, PCB118, PCB123, PCB126, PCB156, PCB157, PCB167, PCB169 and PCB 179.

Experiment 1: activator 1: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:3: 100; detecting the total amount of the PCB before and after the reaction;

experiment 2: activator 1: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:4: 100; detecting the total amount of the PCB before and after the reaction;

experiment 3: activator 1: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:5: 100; detecting the total amount of the PCB before and after the reaction;

experiment 4: activator 4: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:4: 100; detecting the total amount of the PCB before and after the reaction;

experiment 5: activator 1: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:3: 100; detecting the total amount of the PCB before and after the reaction;

experiment 6: activator 2: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:3: 100; detecting the total amount of the PCB before and after the reaction;

experiment 7: activator 3: sodium persulfate: reacting for one week, wherein the mass ratio of the soil is 1:3: 100; the total amount of PCB before and after the reaction was measured.

The PCB detection results before and after the above repair reaction are shown in table 1 below:

TABLE 1 detection results of the activated persulfate test

Meanwhile, samples were taken every 24 hours from the start of the reaction within 7 days of the repair reaction, and the content of polychlorinated biphenyl in the samples was measured, respectively, and the results of the dynamic detection within 7 days are shown in fig. 1.

As shown in fig. 1 and table 1, in experiment 2 (the activating agent is mixed with sodium persulfate according to the mass ratio of 1: 4), the content of PCB in soil can be effectively removed by more than 60% within 24h, and after 7 days, the degradation rate is further increased to 87.55%, which proves that the biomass charcoal can rapidly and efficiently activate persulfate at normal temperature, and further realize the remediation of organic matter contaminated soil. In the specific implementation, the biomass charcoal-based material loaded with the heteroatom is added into the soil polluted by the organic matter, the persulfate is applied after the biomass charcoal-based material and the persulfate are fully mixed, the mass ratio of the added biomass charcoal loaded with the heteroatom to the soil polluted by the organic matter is within the range of 1% -5%, and the mass ratio of the biomass charcoal material loaded with the heteroatom to the persulfate is within the range of 1: 5-1: 3, so that the aim of the invention can be achieved.

The above embodiments are only specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.