CN115532225B

CN115532225B - Method for preparing zero-valent iron-loaded biochar by using waste soil as iron source and application of zero-valent iron-loaded biochar

Info

Publication number: CN115532225B
Application number: CN202211186474.0A
Authority: CN
Inventors: 赵楠; 杨再宽; 刘坤源; 印梓勤; 章卫华; 王诗忠; 汤叶涛; 仇荣亮
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2022-09-26
Filing date: 2022-09-26
Publication date: 2023-09-08
Anticipated expiration: 2042-09-26
Also published as: CN115532225A

Abstract

The invention relates to a method for preparing zero-valent iron-loaded biochar by using waste soil as an iron source and application thereof, belonging to the technical field of solid waste recycling. The method for preparing the zero-valent iron-loaded biochar by using the waste soil as an iron source comprises the following steps of: mixing a biomass raw material and an iron precursor, calcining in an inert atmosphere, cooling and grinding to obtain the biomass; the iron precursor is waste soil, wherein the waste soil contains 40% -50% of Fe element, 4% -5% of S element, 0.3% -0.5% of Zn element and 0.05% -0.1% of Mn element. The invention takes agricultural wastes as biomass raw materials, and prepares the zero-valent iron-loaded biochar composite material by fully mixing the agricultural wastes with the waste soil rich in iron and calcining the composite material at high temperature, the material is simple to prepare and good in stability, has high removal efficiency on heavy metals and antibiotic solutions, and can efficiently and synchronously remove the composite pollution of copper ions and tetracycline/terramycin.

Description

Method for preparing zero-valent iron-loaded biochar by using waste soil as iron source and application of zero-valent iron-loaded biochar

Technical Field

The invention belongs to the technical field of solid waste recycling, and particularly relates to a method for preparing zero-valent iron-loaded biochar by using waste soil as an iron source and application thereof.

Background

Biochar is one of the research hotspots in recent years. Biochar is prepared from biomass through a pyrolysis process under the condition of no oxygen or limited oxygen, and the pyrolysis temperature is generally 300-700 ℃, and the biochar is a porous, stable and carbon-rich solid material. The raw materials for producing the biochar have low cost and wide sources, and are mainly urban garbage and solid wastes produced by some industries, such as rice straw, durian shells, kitchen garbage and the like, so that the conversion of biomass into the biochar serving as an adsorbent is a way for carbon fixation, emission reduction, environmental protection and resource realization. The biochar has the characteristics of high cost benefit, wide application range, environmental friendliness and the like, and the application research on the biochar at present is mainly focused on the aspects of soil, water, pesticides, heavy metals and antibiotics, and has wide application prospects in the fields of agriculture, resources and environment.

Biochar has great application potential, but has some defects, such as uneven surface of the biochar can reduce some potential active sites on the surface, thereby reducing the adsorption capacity of the biochar, limiting the application of the biochar to a certain extent, and simultaneously, different biochar precursor types have great influence on the performance of the biochar. Many studies have been made on enhancing the adsorption capacity of biochar by modifying it, which can improve its surface properties such as surface area, pore volume, hydrophilic/hydrophobic properties, surface charge, etc., and can enhance the oxygen-containing functional groups of the surface so that it can effectively perform specific binding with contaminants such as hydrogen bonds, pi-pi electron donor-acceptor interactions, covalent binding, etc., thereby optimizing and enhancing the practical application of biochar. At present, the biochar is generally modified by adopting methods of acid or alkali treatment, oxidation, metal modification, nanoparticle loading and the like.

In the prior art, wu and the like utilize red mud and rice straw to carry out co-crackingThe solution is prepared under the high temperature condition to obtain the Fe-containing alloy ₃ O ₄ 、Fe ₂ O ₃ And FeO (OH) red mud modified biochar, which has significantly higher removal capacity for As (V) and As (III) than rice straw biochar, but which cannot effectively remove organic pollutants. The modified locust tree leaf biochar material is prepared by the Chinese patent document CN111729654A, zinc chloride and sodium hydroxide are adopted to carry out active modification on the biochar material, and the obtained modified biochar material has excellent adsorption performance and higher removal efficiency on bisphenol A, but the removal efficiency on heavy metals is not high.

At present, more environment pollution is caused by compounding heavy metals and organic pollutants, the treatment of the heavy metals and organic pollutants is more difficult than the treatment of single components, the removal mechanism of the biochar material on the pollutants is complex, and the currently reported composite material can not effectively and synchronously remove the heavy metals and the organic pollutants, so that the preparation of the composite material capable of solving the problem of the heavy metals and the organic pollutants has great significance.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide a method for preparing zero-valent iron-loaded biochar by using waste soil as an iron source and application thereof.

The invention is realized by the following technical scheme:

the invention provides a method for preparing zero-valent iron-loaded biochar by using waste soil as an iron source, which comprises the following steps: mixing a biomass raw material and an iron precursor, calcining in an inert atmosphere, cooling and grinding to obtain the biomass; the iron precursor is waste soil, wherein the waste soil contains 40% -50% of Fe element, 4% -5% of S element, 0.3% -0.5% of Zn element and 0.05% -0.1% of Mn element.

The invention takes agricultural wastes as biomass raw materials, and the zero-valent iron loaded biochar composite material obtained by fully mixing the agricultural wastes with special waste soil iron precursors and calcining the mixture at high temperature is prepared by utilizing the wastes, has simple preparation and good stability, has high removal efficiency on heavy metals and antibiotic solutions, and can efficiently and synchronously remove the composite pollution of copper and tetracycline/terramycin. The material also has higher stability, and zero-valent iron is still stably existing in the material after pollutant treatment.

As a preferred embodiment of the preparation method of the present invention, the mass ratio of the biomass raw material to the iron precursor is 1: (1-3). Preferably, the mass ratio of the biomass feedstock to the iron precursor is 1: (1.6-2).

According to the invention, biomass raw materials and an iron precursor are properly proportioned, and the prepared zero-valent iron-loaded biochar composite material has excellent stability and the capability of degrading heavy metals and organic pollutant antibiotics.

As a preferred embodiment of the preparation method of the invention, the biomass raw material is at least one of straw, durian shell, miscanthus and rice hull. Preferably, the biomass feedstock is durian shells.

As a preferred embodiment of the preparation method of the invention, the pH value of the waste soil is 2-3.

The structure of biomass from which the biochar is derived has great influence on the performance of the prepared biochar material, the biomass raw material is agricultural waste, preferably at least one of straw, durian shell, miscanthus and rice husk, and the iron precursor is waste soil rich in iron, and the pH value is 2-3; the invention calcines the agricultural waste and the iron-containing waste soil to prepare the zero-valent iron-loaded biochar composite material with excellent heavy metal and organic pollutant removal effect, and can fully utilize the agricultural solid waste and the iron-rich solid waste to recycle the waste.

As a preferred embodiment of the preparation process according to the invention, the calcination temperature is 500℃to 900 ℃. Preferably, the calcination temperature is 750 ℃ and the incubation time is 1h.

The zero-valent iron loaded biochar composite material can be obtained at a lower calcination temperature, so that the energy consumption can be effectively reduced, and the prepared composite material still has better stability and the performance of removing heavy metals and organic pollutants.

As a preferred embodiment of the production method of the present invention, the biomass raw material and the iron precursor are separately ground, sieved, stirred in a solvent, and dried before the mixing.

As a preferred embodiment of the preparation method of the invention, the stirring time is 12-24 hours. Preferably, the stirring time is 20 hours.

Preferably, the preparation method of the invention comprises the following steps: before mixing, crushing, grinding and drying the biomass raw materials, and sieving the crushed, ground and dried biomass raw materials with a 100-mesh sieve to obtain powdery biomass raw materials; before the mixing, grinding the iron precursor through a 20-mesh sieve (removing impurities), grinding again, and passing through a 100-mesh sieve; respectively stirring the sieved biomass raw material and the iron precursor in a solvent (preferably water) for 12-24 hours, and drying; mixing the dried biomass raw material and the iron precursor in a mass ratio of 1: (1-3) mixing, calcining at 500-900 ℃ in an inert atmosphere (preferably nitrogen), heating at a rate of 10 ℃/min, preserving heat for 1h, cooling, grinding, and sieving by a 100-mesh sieve to obtain the zero-valent iron-loaded biochar composite material.

The invention also aims to provide the zero-valent iron-loaded biochar composite material prepared by the preparation method.

In the zero-valent iron-loaded biochar composite material, the nano-grade zero-valent iron is a reducing agent with colloid effect and large specific surface area, has high activity, can capture heavy metals through the reduction or coprecipitation effect, can remove various organic matters in the chemical reduction process, has high removal efficiency on heavy metals and antibiotics in solution, has larger particle size ratio, and has magnetism which enables the nano-grade zero-valent iron to be separated and recovered from aqueous solution more easily under the action of external magnetism, so that the nano-grade zero-valent iron can be separated from the solution easily. In addition, the invention adopts the biochar material as the supporting material of the nanoscale zero-valent iron, overcomes the defects of unstable and easy aggregation of the nanoscale zero-valent iron, and ensures that the composite material can effectively disperse the zero-valent iron and reduce the aggregation of the zero-valent iron, thereby improving the reactivity of the zero-valent iron.

The invention further aims to provide the zero-valent iron-loaded biochar composite material and application of the preparation method in removing heavy metals and/or organic pollutants.

As a preferred embodiment of the use according to the invention, the organic contaminants include tetracycline and oxytetracycline. Preferably, the heavy metal is cupric ion and the organic contaminant is tetracycline and oxytetracycline.

The invention has the following beneficial effects:

1. the invention takes agricultural wastes as biomass raw materials, and prepares the zero-valent iron-loaded biochar composite material prepared by taking waste soil as an iron source at high temperature by fully mixing the agricultural wastes with the iron-rich solid waste soil, and the material has high removal efficiency on heavy metals and antibiotic solutions.

2. The material prepared by the invention has magnetism, and can separate iron-loaded biochar from water by externally adding a magnet after treating heavy metal and antibiotic solution, thereby realizing solid-liquid separation.

3. The zero-valent iron loaded biochar composite material can be obtained at a lower temperature of 500-900 ℃, and can effectively reduce energy consumption. Meanwhile, the obtained material does not need post-treatment processes such as washing, drying, removing an activator and the like, namely has excellent performance, and effectively saves cost.

4. The composite material has higher stability, zero-valent iron still stably exists in the material after one-time treatment, and no other ions are released in the treatment process, so that secondary pollution is avoided.

5. The invention fully utilizes the agricultural solid waste and the iron-rich solid waste, so that the waste can be recycled, the copper-containing and the sewage containing antibiotics can be synchronously and efficiently removed, the raw material sources are wide, the price is low, and the wastewater treatment cost can be reduced.

Drawings

FIG. 1 is an X-ray diffraction pattern of the composite material of examples 1-2 of the present invention;

FIG. 2 is a scanning electron microscope image of the composite material of example 1-2 of the present invention; wherein (a) is example 1 and (b) is example 2;

FIG. 3 is a transmission electron microscope image of the composite material of example 1-2 of the present invention; wherein (a) is example 1 and (b) is example 2;

FIG. 4 shows a composite material, an iron-based material (Fe ₂ O ₃ ) And a Biochar (BC) removal kinetics profile for heavy metals and antibiotic solutions; wherein (a) is copper ion (Cu) ²⁺ ) (b) tetracycline, (c) oxytetracycline;

FIG. 5 shows a composite material, an iron-based material (Fe ₂ O ₃ ) And the removal rate of Biochar (BC) from the complex solution of heavy metals and antibiotics; wherein (a) is the addition of different amounts of copper ions to the tetracycline solution, (b) is the addition of different amounts of copper ions to the oxytetracycline solution, (c) is the addition of different amounts of tetracycline to the copper ion solution, and (d) is the addition of different amounts of oxytetracycline to the copper ion solution;

FIG. 6 is an X-ray diffraction chart of the composite material of examples 1-2 of the present invention after copper ions are treated; wherein (a) is example 1 and (b) is example 2;

FIG. 7 is an X-ray diffraction pattern of the composite material of examples 1-2 of the present invention after treatment of the four rings; wherein (a) is example 1 and (b) is example 2;

FIG. 8 is an X-ray diffraction pattern of the composite material of examples 1-2 of the present invention after oxytetracycline has been treated; wherein (a) is example 1 and (b) is example 2;

FIG. 9 shows a composite material, an iron-based material (Fe ₂ O ₃ ) And Biochar (BC) to Cu respectively ²⁺ Concentration of zinc release measured in the kinetics of removal experiments for tetracycline and oxytetracycline; wherein (a) is copper ion, (b) is tetracycline, and (c) is oxytetracycline;

FIG. 10 shows a composite material, an iron-based material (Fe ₂ O ₃ ) And Biochar (BC) to Cu respectively ²⁺ Manganese release concentrations measured in the kinetics of tetracycline and oxytetracycline removal experiments; wherein (a) is copper ion, (b) is tetracycline, and (c) is oxytetracycline.

Detailed Description

For a better description of the objects, technical solutions and advantages of the present invention, the present invention will be further described with reference to the following specific examples. It will be appreciated by persons skilled in the art that the specific embodiments described herein are for purposes of illustration only and are not intended to be limiting.

The test methods used in the examples are conventional methods unless otherwise specified; the materials, reagents and the like used, unless otherwise specified, are all commercially available. The waste soil iron precursor used in the following examples and comparative examples contains 40% -50% of Fe element, 4% -5% of S element, 0.3% -0.5% of Zn element, 0.05% -0.1% of Mn element, and pH value of 2-3.

Example 1

The preparation method of the zero-valent iron-loaded biochar composite material comprises the following steps:

(1) Crushing, grinding and drying a biomass raw material durian shell, sieving with a 100-mesh sieve to obtain a powdery biomass raw material, naturally air-drying waste soil of an iron precursor, grinding with a 20-mesh sieve to remove impurities, grinding with a mortar, and sieving with the 100-mesh sieve to obtain the iron precursor;

(2) Respectively adding water into the sieved biomass raw material and the iron precursor, stirring for 20 hours, and drying;

(3) Mixing the dried biomass raw material and an iron precursor according to a mass ratio of 1:1.6, fully mixing, placing in a ceramic boat, placing in a tube furnace, introducing nitrogen as a protective gas, heating the tube furnace to 750 ℃ under the condition of a heating rate of 10 ℃/min, maintaining the heating time for 1h, and grinding into powder after natural cooling, so that powder particles can pass through a 100-mesh sieve to obtain the zero-valent iron-loaded biochar composite material prepared by using waste soil as an iron source. Is marked as Fe ⁰ @BC-A。

Example 2

(3) Mixing the dried biomass raw material and an iron precursor according to a mass ratio of 1:2, fully mixing, placing in a ceramic boat, placing in a tube furnace, introducing nitrogen as a protective gas, heating the tube furnace to 750 ℃ under the condition of a heating rate of 10 ℃/min, maintaining the heating time for 1h, and grinding into powder after naturally cooling, so that powder particles can pass through a 100-mesh sieve to obtain the zero-valent iron-loaded biochar composite material prepared by using waste soil as an iron source. Is marked as Fe ⁰ @BC-B。

Comparative example 1

An iron-based material was prepared in the same manner as in example 1 except that the biomass raw material was not added and the remaining was the same as in example 1, and the main component of the iron-based material was Fe ₂ O ₃ 。

Comparative example 2

A biochar material was prepared by the same method as in example 1 except that no iron precursor was added, and the remainder was the same as in example 1, and the prepared biochar material was designated BC.

Characterization of materials

Testing the materials of examples 1 and 2, fig. 1 is an X-ray diffraction pattern of the composite materials of examples 1-2 of the present invention, and it can be seen from fig. 1 that the materials of examples 1 and 2 exhibit characteristic peaks of zero-valent iron at 2θ= 44.67 °, 65.02 ° and 82.33 °, characteristic peaks of hexagonal pyrite (FeS) at 2θ= 43.15 °, and SiO at 2θ= 26.61 ° ₂ The characteristic peaks of the two materials are mainly composed of zero-valent iron and SiO ₂ And a ferro-sulphur compound.

FIG. 2 is a scanning electron microscope image of the composite material of example 1-2 of the present invention, wherein (a) is example 1 and (b) is example 2; as can be seen from fig. 2, a plurality of zero-valent iron particles are distributed on the surfaces of the two materials, are embedded on the surfaces of the materials and uniformly dispersed, can well improve the adsorption effect of the biochar, and in addition, the surfaces of the materials also have sulfur element distribution.

FIG. 3 is a transmission electron microscope image of the composite material of example 1-2 of the present invention, wherein (a) is example 1 and (b) is example 2; in fig. 3, the gray part is charcoal, the black larger spherical particles are zero-valent iron, and fig. 3 shows that the zero-valent iron is uniformly distributed on the surface of the charcoal material.

The composite materials of examples 1-2 were subjected to BET specific surface area and pore size distribution tests, and the test results are shown in Table 1.

TABLE 1 BET specific surface area and pore size distribution of the composites of examples 1-2

Samples	Specific surface area (m) ² /g)	Total pore volume (cm) ³ /g)	Mesoporous volume (cm) ³ /g)	Micropore volume (cm) ³ /g)	Average pore diameter (nm)
						Fe ⁰ @BC-A	125	0.176	0.138	0.0110	5.65
Fe ⁰ @BC-B	92.3	0.151	0.115	0.00766	6.57

As can be seen from Table 1, the pore structure of the materials of examples 1-2 of the present invention is mainly a mesoporous structure, and the mesoporous volume accounts for 78.4% and 76.2% of the total pore volume, respectively.

Elemental composition analysis was performed on the zero-valent iron-supported biochar composite materials of examples 1-2, and the results are shown in table 2.

TABLE 2 elemental composition of the composites of examples 1-2

Sample	Fe ⁰ @BC-A	Fe ⁰ @BC-B
			C(％)	10.7±0.27	9.11±0.04
H(％)	0.460±0.05	0.320±0.01
			N(％)	0.213±0.02	0.23±0.04
S(％)	4.27±0.06	3.95±0.01
			O(％)	28.3±2.57	22.2±2.20
Fe(％)	56.1±2.76	64.2±2.12
			C/H	1.94±0.140	2.37±0.0939
C/N	56.3±4.33	46.2±8.45
			O/C	2.00±0.156	1.83±0.190
(O+N)/C	1.08±0.0828	0.986±0.0995

As can be seen from Table 2, the main element in the composite material of the present invention is iron, fe ⁰ @BC-A and Fe ⁰ Iron content in BC-B is 56.1% and 64.2%, and Fe is mixed and cracked with biomass due to the large amount of Fe in waste soil ⁰ @BC-A and Fe ⁰ The @ BC-B is rich in Fe.

Effect example 1

Heavy metal copper ion removal test: 10mg of the material to be measured was added to 10mL of copper sulfate (CuSO) having a concentration of 0.8mmol/L ₄ ) Vibrating for 10min, 20min, 30min, 60min, 120min, 240min, 360min respectively in the solutionAfter min, 480min and 720min, cu in the reacted solution was measured ²⁺ Is a concentration of (3).

As shown in FIG. 4 (a), the solutions of the composite materials and biochar materials of examples 1 and 2 after treatment reached equilibrium at about 10min, at which time the materials were balanced against Cu ²⁺ The removal efficiency of (2) reaches 100%. And Fe-based material Fe ₂ O ₃ The treated solution reaches equilibrium within about 120min, and the material is balanced to Cu ²⁺ The removal efficiency of (2) was only 57.5%.

Tetracycline removal test: 10mg of the test material was added to 10mL of tetracycline (C) at a concentration of 0.8mmol/L ₂₂ H ₂₄ N ₂ O ₈ ) And respectively vibrating for 10min, 20min, 30min, 60min, 120min, 240min, 360min, 480min and 720min in the solution, and then measuring the concentration of the tetracycline in the solution after the reaction.

As shown in FIG. 4 (b), the removal rate of the composite materials of examples 1 and 2 was fast, the removal efficiency of the composite material in the first 30 minutes was up to 98% or more, the removal of the composite material was slow, the composite material was equilibrated in about 480 minutes, and the removal efficiency of the composite material in the equilibration was up to 99.8%. The biochar material BC can rapidly remove the tetracycline in the first 30min, and is slower, the removal efficiency of the tetracycline reaches the highest at 120min, and the removal efficiency is 22.2%. Iron-based material Fe ₂ O ₃ Adsorption of the tetracycline is increased with time, the removal rate is slow, and the removal efficiency is highest at 720min, but only 22.7%.

Oxytetracycline removal test: 10mg of the test material was added to 10mL of tetracycline (C) at a concentration of 0.8mmol/L ₂₂ H ₂₄ N ₂ O ₉ ) And respectively vibrating for 10min, 20min, 30min, 60min, 120min, 240min, 360min, 480min and 720min in the solution, and then measuring the concentration of terramycin in the solution after the reaction.

As shown in FIG. 4 (c), the composite materials of examples 1 and 2 were fast in the removal rate of oxytetracycline up to 98% or more in the first 30min, then were slowly removed, and were equilibrated at about 240min, and the removal efficiency of oxytetracycline from the materials at equilibration was 99.3%. The biochar material BC basically does not adsorb terramycin, and the iron base materialFe material ₂ O ₃ The removal rate of the terramycin is slow, and the removal efficiency of the terramycin reaches the highest at 720min and is only 9.2%.

The result of FIG. 4 shows that the zero-valent iron loaded biochar composite material of the invention can reduce Cu by adsorption ²⁺ Removal is performed while tetracycline and oxytetracycline may be removed by adsorption degradation. Zero valent iron loaded biochar composite of examples 1 and 2 versus Cu ²⁺ The removal effect of the tetracycline and the oxytetracycline is good, the speed is high, the equilibrium can be reached quickly, and Cu is removed in the first 30min ²⁺ The removal efficiency of the tetracycline and the oxytetracycline can reach more than 98 percent.

Effect example 2

And (3) composite pollution removal test: adding equal volumes of deionized water and copper sulfate solutions with equal volume concentrations of 0.10mM, 0.16mM and 0.20mM respectively to the tetracycline solution with the concentration of 0.16 mM; adding an equal volume of deionized water to an oxytetracycline solution having a concentration of 0.16mM and copper sulfate solutions having an equal volume concentration of 0.10mM, 0.16mM and 0.20mM, respectively; adding equal volumes of deionized water and tetracycline solutions with equal volume concentrations of 0.10mM, 0.16mM and 0.20mM respectively to a copper sulfate solution with a concentration of 0.16 mM; to a copper sulfate solution having a concentration of 0.16mM, an equal volume of deionized water and an equal volume of terramycin solution having a concentration of 0.10mM, 0.16mM and 0.20mM, respectively, were added.

Weighing 10mg of material to be measured, adding into 10mL of the prepared solution, placing into a vibrator, vibrating at 180r/min for 12h, taking out, and measuring Cu in the reacted solution ²⁺ Concentration of tetracycline, oxytetracycline.

The results are shown in FIG. 5, where FIG. 5 (a) shows the removal rate of tetracycline with Cu for various amounts of copper ions added to the tetracycline solution ²⁺ The removal efficiency of the zero-valent iron loaded biochar composite material on the tetracycline is not affected by the increase of the addition concentration, and can reach more than 98%.

FIG. 5 (b) shows the removal rate of oxytetracycline with varying amounts of copper ions added to oxytetracycline solution, with Cu ²⁺ The removal efficiency of the zero-valent iron loaded biochar composite material on terramycin is almost unchanged due to the increase of the addition concentrationCan reach more than 98 percent.

FIG. 5 (c) shows the removal rate of copper ions by adding different amounts of tetracycline to the copper ion solution, with the increase of the added concentration of tetracycline, the zero-valent iron loaded biochar composite Fe ⁰ @BC-A and Fe ⁰ Cu of @ BC-B pair ²⁺ The removal efficiency of (c) is not changed much and is almost completely removed.

FIG. 5 (d) shows the removal rate of copper ions by adding different amounts of oxytetracycline to copper ion solutions, with the addition concentration of oxytetracycline increasing, the zero-valent iron loading biochar composite Fe ⁰ @BC-A and Fe ⁰ Cu of @ BC-B pair ²⁺ Still having a removal efficiency of nearly a hundred percent.

FIG. 5 shows Cu removal by the zero valent iron loaded biochar composite of examples 1 and 2 of this invention ²⁺ Or tetracycline or terramycin is hardly affected by another pollutant, and copper ions and antibiotics in the solution can be removed simultaneously and efficiently. While the biochar material is used for removing Cu ²⁺ And the tetracycline compound solution can be inhibited by another pollutant, and the tetracycline acts on Fe-based material ₂ O ₃ Cu removal ²⁺ Plays a role in inhibiting. And Cu is ²⁺ The presence of (3) can promote Fe of the iron-based material ₂ O ₃ Removal of tetracyclines and Cu ² ⁺ The tetracycline in the complex solution, however, had a maximum removal efficiency of only 57.8%.

And the biological carbon material BC is used for treating Cu ²⁺ And the terramycin composite solution, the terramycin is removed and subjected to high-concentration Cu ²⁺ Is effective in promoting Cu removal ²⁺ Can be inhibited by terramycin. Iron-based material Fe ₂ O ₃ Treatment of Cu ²⁺ And removing oxytetracycline or Cu when the oxytetracycline is compounded with the aqueous solution ²⁺ Can be promoted by another pollutant, but the efficiency of synchronously removing copper ions and terramycin is still low, and the Fe-based material Fe ₂ O ₃ Neither biochar material BC is effective in the simultaneous removal of copper ions nor antibiotics.

The results of fig. 5 show that in the removal of mixed contaminants, contaminants can interact with each other, thereby affecting removal efficiency. Zero-valent iron-supported biochar complex of examples 1 and 2The composite material has very good removal effect on the composite solution of heavy metal and antibiotics, and can almost completely remove Cu in the solution of heavy metal and antibiotics composite pollution ²⁺ Tetracycline and oxytetracycline.

Effect example 3

Stability test: the zero-valent iron-loaded biochar composite material obtained by carrying out the removal experiment on copper ions, tetracycline and oxytetracycline in effect example 1 is separated from the solution by adding a magnet, and the separated zero-valent iron-loaded biochar composite material is analyzed by adopting X-ray diffraction, and the results are shown in figures 6-8.

Fig. 6 (a) is an XRD pattern after treatment of copper ions for the composite of example 1, fig. 6 (b) is an XRD pattern after treatment of copper ions for the composite of example 2, fig. 7 (a) is an XRD pattern after treatment of tetracycline for the composite of example 1, fig. 7 (b) is an XRD pattern after treatment of tetracycline for the composite of example 2, fig. 8 (a) is an XRD pattern after treatment of oxytetracycline for the composite of example 1, and fig. 8 (b) is an XRD pattern after treatment of oxytetracycline for the composite of example 2. As can be seen from FIGS. 6 to 8, the zero-valent iron-loaded biochar composite materials of examples 1 and 2 of the present invention are relatively stable, and after the first removal kinetics test, fe in the composite materials ⁰ And still exist stably.

Effect example 4

The waste soil contains zinc and manganese impurities, and the zero-valent iron loaded biochar composite material and the iron-based material Fe are measured ₂ O ₃ And biochar to Cu respectively ²⁺ And testing the concentration of released zinc and the concentration of released manganese in the kinetic removal experiments of tetracycline and oxytetracycline, and detecting whether secondary pollution is caused.

FIG. 9 shows a composite material, an iron-based material (Fe ₂ O ₃ ) And Biochar (BC) to Cu respectively ²⁺ Concentration of zinc release measured in the kinetics of removal experiments for tetracycline and oxytetracycline; wherein (a) represents copper ions, (b) represents tetracycline, and (c) represents oxytetracycline.

The results in fig. 9 show that the iron-based material releases zinc from the material into solution during the treatment of copper ions, and does not release during the treatment of antibiotics. Biological materialCarbon material and zero-valent iron loaded biochar material in Cu treatment ²⁺ Neither tetracycline nor oxytetracycline released zinc into solution, which was relatively stable.

FIG. 10 shows a composite material, an iron-based material (Fe ₂ O ₃ ) And Biochar (BC) to Cu respectively ²⁺ Manganese release concentrations measured in the kinetics of tetracycline and oxytetracycline removal experiments; wherein (a) represents copper ions, (b) represents tetracycline, and (c) represents oxytetracycline.

The results in FIG. 10 show that the iron-based material Fe ₂ O ₃ During the treatment of heavy metals and antibiotics, manganese in the material is released into the solution to pollute the environment. The biochar material and the zero-valent iron loaded biochar material do not release manganese into the solution when Cu (II), tetracycline and oxytetracycline are treated, so that the biochar material and the zero-valent iron loaded biochar material are relatively stable.

As can be seen from fig. 9 to 10, the zero-valent iron-loaded biochar composite materials in the embodiment 1 and the embodiment 2 of the invention do not release zinc and manganese in the process of treating pollutants, are relatively stable, and do not cause secondary pollution.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted equally without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. The application of the zero-valent iron-loaded biochar composite material in synchronously removing copper and tetracycline or terramycin is characterized in that the preparation method of the zero-valent iron-loaded biochar composite material comprises the following steps: mixing a biomass raw material and an iron precursor, calcining in an inert atmosphere, cooling and grinding to obtain the biomass; the iron precursor is waste soil, wherein the waste soil contains 40% -50% of Fe element, 4% -5% of S element, 0.3% -0.5% of Zn element and 0.05% -0.1% of Mn element; the biomass raw material is at least one of straw, durian shell, miscanthus and rice husk; the temperature of the calcination is 750 ℃; the mass ratio of the biomass raw material to the iron precursor is 1: (1-3).

2. The use according to claim 1, characterized in that the biomass feedstock and the iron precursor are separately ground, sieved, stirred in a solvent and dried before the mixing.

3. Use according to claim 2, wherein the stirring is for a period of 12-24 hours.

4. The use according to claim 1, wherein the pH of the waste soil is 2-3.